Small modular nuclear reactor power plant

Abstract

A small modular nuclear reactor power plant arranged in a configuration to minimize the spatial impact of installation is disclosed. Each individual module may be arranged in parallel to transfer vertical impact into horizontal impact. Additionally, components may be separated into different enclosures to distribute spatial impact on a horizontal plane. Additionally, the small modular nuclear power plant may include a reactor enclosure configured to enable reactor core replacement.

Description

PCT Specification Attorney Docket No. 27569.105078WO SMALL MODULAR NUCLEAR REACTOR POWER PLANTRELATED APPLICATION

[0001] The present application claims priority to U.S. Provisional Application No. 63 / 740,001, filed on December 30, 2024, and U.S. Provisional Application No. 63 / 764,429 filed on February 27, 2025, in which the entirety of both are incorporated by reference herein.TECHNICAL FIELD

[0002] The described examples relate generally to nuclear power plants and more particularly to small modular nuclear reactor power plants.BACKGROUND

[0003] Small Modular Reactors or “SMRs” provide an alternative to traditional nuclear reactor power plants. SMRs are a class of nuclear reactors where each component or subsystem (i.e., “module”) is manufactured in a factory and shipped to operational sites rather than being constructed and installed onsite. Thereafter, each module may be assembled and connected to collectively produce and harness power and / or heat. One of the many advantages SMRs have over traditional nuclear reactors is in their small size and flexibility. An SMR system may be desired where size constraints are at issue and a sizeable amount of power is not necessarily needed. Even still, an SMR power plant may take up considerable space when factoring in safety requirements, accessibility, and functionality constraints. As such, there is a need for SMR systems and power plant designs to minimize the spatial impact of installation.SUMMARY

[0004] In one example, a modular power plant system is disclosed. The modular power plant system includes a first section, and a second section associated with the first section. The second section includes a segmented compartment structure configured to house distinct functional components of the modular power plant system. The segmented compartment structure includes a plurality of functional compartments segmented from one another by one or more dividing walls. A first functional compartment of the plurality of functional compartments defines a reactor compartment configured to house a reactor system. A second functional compartment of thePCT Specification Attorney Docket No. 27569.105078WO plurality of functional compartments defines a heat removal compartment configured to house a heat removal system for operable coupling with the reactor system. The first section includes a plurality of removable lids collectively enclosing the segmented compartment structure and defining a thermal or radiation barrier. The first section further includes an energy conversion system operatively coupled with the heat removal system and configured to use an output thereof.

[0005] In another example, the second section is positioned elevationally below the first section. The second section is positioned below a ground surface.

[0006] In another example, the modular power plant system further includes the reactor system. The reactor system includes a reactor core operable to facilitate fission of a fissile material. The modular power plant system further includes a reactor vessel configured to contain the reactor core. The modular power plant system further includes a reactor enclosure configured to enclose the reactor vessel. The reactor enclosure is disposed within the first functional compartment. The reactor enclosure is configured to receive the reactor vessel by a removable lid about an upper portion of the reactor enclosure.

[0007] In another example, the modular power plant system further includes the heat removal system. The heat removal system includes at least one primary heat exchanger and at least one secondary heat exchanger. The at least one primary heat exchanger is positioned within a primary loop enclosure positioned at a first end of the second functional compartment. The at least one secondary heat exchanger is positioned outside the primary loop enclosure and positioned at a second end of the second functional compartment. The second end is positioned elevationally above the first end.

[0008] In another example, the second functional compartment is positioned elevationally above the first functional compartment. The heat removal system is operable to gravitationally drain into the reactor system.

[0009] In another example, a third functional compartment of the plurality of functional compartments defines a fuel storage compartment configured to house a fuel storage vessel operatively coupled to the reactor system. A fourth functional compartment of the plurality of functional compartments defines an off-gas compartment configured to house an off-gas system.PCT Specification Attorney Docket No. 27569.105078WO

[0010] In another example, the energy conversion system includes a steam generator operable to generate a steam output from a heat output from the heat removal system.

[0011] In another example, the one or more diving walls defines a thermal and / or radiation barrier as between adjacent functional compartments of the segmented compartment structure.

[0012] In yet another example, the modular power plant further includes a natural gas system operably coupled to the energy conversion system.

[0013] In one example, a nuclear power plant is disclosed. The nuclear power plant includes a reactor system including a reactor core and operable to generate a heat output derived from fission reactions. The reactor system is enclosed in a first functional compartment of a segmented compartment structure. The nuclear power plant further includes a heat removal system operable to transfer the heat output from the reactor system. The heat removal system is arranged in a second functional compartment of the segmented compartment structure adjacent to the first functional compartment. The nuclear power plant further includes an energy conversion system operatively coupled to the heat removal system and configured to receive the heat output. The energy conversion system associated with the segmented compartment structure collectively defining an integrated nuclear power plant unit.

[0014] In another example, the segmented compartment structure is configured to house functional components of a nuclear reactor and is positioned elevationally below and thermally and radioactively shielded from the energy conversion system.

[0015] In another example, the segmented compartment structure includes a plurality of dividing walls separating a plurality of functional compartments and defining thermal and / or radiation barriers therebetween.

[0016] In another example, the first subsurface functional compartment is separated from the second subsurface functional compartment by a first dividing wall of the plurality of dividing walls. The reactor system and the heat removal system are coupled with one another via at least one molten salt line penetrating the first dividing wall.

[0017] In another example, the nuclear power plant further includes a fuel storage system operable to store a molten fuel salt, the fuel storage system arranged in a third functional compartment of the segmented compartment structure.PCT Specification Attorney Docket No. 27569.105078WO

[0018] In another example, the third functional compartment is separated from the first functional compartment by a second dividing wall of the plurality of dividing walls. The fuel storage system and the reactor system are coupled with one another via at least one molten salt line penetrating the second dividing wall.

[0019] In another example, the nuclear power plant further includes an off-gas system operable to process an off-gas produced by the reactor system, the off-gas system arranged in a fourth functional compartment of the segmented compartment structure.

[0020] In another example, the fourth functional compartment is separated from the third subsurface functional compartment by a third dividing wall of the plurality of dividing walls. The off-gas system and the heat removal system are coupled with one another via at least one off-gas line penetrating the third dividing wall.

[0021] In yet another example, the energy conversion system is coupled to a power grid.

[0022] In one example, a method of operating a modular nuclear power plant is disclosed. The method includes generating heat through fission reactions by a reactor system. The reactor system is enclosed in a first functional compartment of a segmented compartment structure. The method further includes transferring the generated heat from the reactor system by a heat removal system. The heat removal system is enclosed in a second functional compartment of the segmented compartment structure. The method further includes receiving the generated heat from the heat removal system by an energy conversion system. The energy conversion system associated with the segmented compartment structure.

[0023] In yet another example, the method of operating a modular nuclear power plant further includes thermally and / or radioactively shielding the reactor system from the heat removal system by a dividing wall of the segmented compartment structure interposed between the first functional compartment and the second functional compartment.

[0024] In one example, a modular power plant is disclosed. The modular power plant includes a first section, and a second section associated with the first section. The second section includes a segmented compartment structure configured to house distinct functional components of the modular power plant system. The segmented compartment structure includes a plurality of functional compartments segmented from one another by one or more dividing wall. The one orPCT Specification Attorney Docket No. 27569.105078WO more diving walls defines a thermal and / or radiation barrier as between adjacent functional compartments of the segmented compartment structure. A first functional compartment of the plurality of functional compartments defines a reactor compartment configured to house a reactor system. A second functional compartment of the plurality of functional compartments defines a heat removal compartment configured to house a heat removal system for operable coupling with the reactor system. The surface section includes a plurality of removable lids collectively enclosing the segmented compartment structure and defining a thermal or radiation barrier. The first section further includes an energy conversion system operatively coupled with the heat removal system and configured to use an output thereof.

[0025] In another example, the second section is positioned elevationally below the first section.

[0026] In another example, the second section is positioned below a ground surface.

[0027] In another example, the modular power plant system further includes a reactor core of the reactor system enclosed in a reactor vessel disposed in the first functional compartment.

[0028] In another example, the reactor core includes a downcomer about an annulus of the reactor core configured to receive a flow of molten fuel salt and direct the flow of molten fuel salt through one or more apertures of the reactor core.

[0029] In another example, the reactor vessel is configured to receive the reactor core by a removable lid about an upper portion of the reactor vessel.

[0030] In another example, the modular power plant further includes the heat removal system and wherein the heat removal system includes at least one primary heat exchanger and at least one secondary heat exchanger.

[0031] In another example, the at least one primary heat exchanger is disposed within a primary loop enclosure positioned on a first end of the second functional compartment.

[0032] In another example, the at least one secondary heat exchanger is disposed outside of the primary loop enclosure and positioned on a second end of the second functional compartment.PCT Specification Attorney Docket No. 27569.105078WO

[0033] In another example, a third functional compartment of the plurality of functional compartments defines a fuel storage compartment configured to house a fuel storage vessel for operatively coupling to the reactor core.

[0034] In another example, a fourth functional compartment of the plurality of functional compartments defines an off-gas compartment configured to house an off-gas system.

[0035] In another example, the off-gas system includes a plurality of gas tanks operable to process an off-gas produced by the reactor system.

[0036] In another example, the energy conversion system includes a steam generator configured to receive heat from the heat removal system.

[0037] In another example, the primary heat exchanger is configured to transfer heat from a molten fuel salt to a primary coolant salt.

[0038] In another example, the primary loop enclosure defines a thermal and / or radiation barrier.

[0039] In another example, the secondary heat exchanger is configured to transfer heat from a primary coolant salt to a secondary coolant salt.

[0040] In another example, the modular power plant further includes a natural gas system.

[0041] In yet another example, the energy conversion system and the natural gas system are functionally coupled to a transfer switch operable to receive a collective electrical output from the natural gas system and the energy conversion system.

[0042] In one example, a nuclear power plant is disclosed. The nuclear power plant includes a reactor system housing a reactor core and operable to generate heat through fission reactions, the reactor system enclosed in a first functional compartment of a segmented compartment structure. The nuclear power plant further includes a heat removal system operable to transfer the heat from the reactor system, the heat removal system arranged in a second functional compartment of the segmented compartment structure adjacent to the first functional compartment. The nuclear power plant further includes an energy conversion system operatively coupled to the heat removal system and configured to receive the heat, the energy conversion system associated with the segmented compartment structure collectively defining an integrated nuclear power plant unit.PCT Specification Attorney Docket No. 27569.105078WO

[0043] In another example, the segmented compartment structure is configured to house functional components of a nuclear reactor and is positioned elevationally below and thermally and radioactively shielded from the energy conversion system.

[0044] In another example, the second functional compartment is separated from the fist functional compartment by a dividing wall defining a thermal and / or radiation barrier.

[0045] In another example, the reactor system and heat removal system are flui di cally coupled with one another.

[0046] In another example, the segmented compartment structure includes a plurality of dividing walls separating a plurality of functional compartments.

[0047] In another example, the reactor system and the heat removal system are coupled with one another via at least one molten salt line penetrating the dividing wall between the first and the second functional compartment.

[0048] In another example, the nuclear power plant further includes a fuel storage system operable to storage a molten fuel salt, the fuel storage system arranged in a third functional compartment of the segmented compartment structure.

[0049] In another example, the third functional compartment is separated from the first functional compartment by a dividing wall defining a thermal and / or radiation barrier.

[0050] In another example, the fuel storage system and the reactor system are fluidically coupled with one another.

[0051] In another example, the fuel storage system and the reactor system are coupled with one another via at least one molten salt line penetrating the dividing wall between the third and the first functional compartment.

[0052] In another example, the nuclear power plant further includes an off-gas system operable to process an off-gas produced by the reactor system, the off-gas system arranged in a fourth functional compartment of the segmented compartment structure.

[0053] In another example, the fourth functional compartment is separated from the third functional compartment by a dividing wall defining a thermal and / or radiation barrier.PCT Specification Attorney Docket No. 27569.105078WO

[0054] In another example, the off-gas system and the heat removal system are fluidically coupled with one another.

[0055] In another example, the off-gas system and the heat removal system are coupled with one another via at least one off-gas line penetrating the dividing wall between the fourth and third functional compartment.

[0056] In yet another example, the energy conversion system is coupled to a power grid.

[0057] In another example, the nuclear power plant further includes a natural gas system.

[0058] In yet another example, the natural gas system is coupled to the power grid.

[0059] In one example, a primary heat removal system is disclosed. The primary heat removal system includes a vessel defining an interior volume. The primary heat removal system further includes a first primary heat exchanger and a second primary heat exchanger each disposed with the interior volume. The primary heat removal system further includes a first pump coupled to the first primary heat exchanger and disposed within the interior volume. The primary heat removal system further includes a second pump coupled to the second primary heat exchanger and disposed within the interior volume. The vessel is configured to receive a first and a second elevated temperature molten fuel salt flow from a common nuclear reactor system, and independently remove heat therefrom.

[0060] In another example, the vessel defines a thermal and / or radiation barrier between the interior volume and an environment exterior to the vessel.

[0061] In another example, the thermal and / or radiation barrier is defined by one or more layers of the vessel operable to insulate the interior volume.

[0062] In another example, the first primary heat exchanger and second primary heat exchanger are operable to transfer heat from a molten fuel salt to a primary coolant salt.

[0063] In another example, the primary heat removal system further includes a first molten fuel salt line fluidically coupling the common nuclear reactor system to the first primary heat exchanger.PCT Specification Attorney Docket No. 27569.105078WO

[0064] In another example, the primary heat removal system further includes a second molten fuel salt line fluidically coupling the common nuclear reactor system to the second primary heat exchanger.

[0065] In another example, the common nuclear reactor system is enclosed in a first functional compartment of a segmented compartment structure and the vessel is enclosed in a second functional compartment of the segmented compartment structure.

[0066] In another example, the first functional compartment is separated from the second functional compartment by a dividing wall of the segmented compartment structure and defining a thermal and / or radiation barrier therebetween.

[0067] In another example, the primary heat removal system further includes a first secondary heat exchanger and a second secondary heat exchanger.

[0068] In another example, the first secondary heat exchanger and the second secondary heat exchanger are disposed within the first functional compartment and exterior to the vessel.

[0069] In another example, the first secondary heat exchanger is fluidically coupled to the first primary heat exchanger and operable to transfer heat from a primary coolant salt to a secondary coolant salt.

[0070] In another example, the second secondary heat exchanger is fluidically coupled to the second primary heat exchanger and operable to transfer heat from a primary coolant salt to a secondary coolant salt.

[0071] In another example, the first secondary heat exchanger and the second secondary heat exchanger are fluidically coupled to a common energy conversion system.

[0072] In another example, the common energy conversion system is positioned substantially elevationally above the first functional compartment.

[0073] In another example, the vessel is operable to be selectively isolated from the common nuclear reactor system and removed from the first functional compartment.

[0074] In another example, the primary heat removal system further includes a first reactor access vessel fluidically coupled the first primary heat exchanger and a second reactor access vessel fluidically coupled to the second primary heat exchanger.PCT Specification Attorney Docket No. 27569.105078WO

[0075] In yet another example, the first reactor access vessel and the second reactor access vessel are disposed within the interior volume.

[0076] In one example, a multi-reactor system including the modular power plant system of the present disclosure and a second section is disclosed. The second section includes a second segmented compartment structure configured to house distinct functional components of a second modular power plant system. The second modular power plant system includes a reactor system and a heat removal system operably coupled to the reactor system. The reactor system of the second modular power plant system is operably coupled to the energy conversion system of the modular power plant system of the present disclosure.

[0077] In yet another example, the second section is positioned adjacent to the section of the modular power plant system of the present disclosure.

[0078] In one example, A multi-reactor system including a plurality of modular power plant systems is disclosed.

[0079] In yet another example, each of the plurality of modular power plant systems includes a reactor section comprising a distinct segmented compartment structure operably coupled to a common energy section including a common energy conversion system.

[0080] In one example, a method of operating a modular nuclear power plant is disclosed. The method includes generating heat through fission reactions by a reactor system, the reactor system enclosed in a first functional compartment of a segmented compartment structure. The method further includes transferring the generated heat from the reactor system by a heat removal system, the heat removal system enclosed in a second functional compartment of the segmented compartment structure. The method further includes receiving the generated heat from the heat removal system by an energy conversion system, the energy conversion system arranged substantially elevationally above the segmented compartment structure.

[0081] In another example, the method further includes thermally and / or radioactively shielding the reactor system from the heat removal system by a dividing wall of the segmented compartment structure interposed between the first functional compartment and the second functional compartment.PCT Specification Attorney Docket No. 27569.105078WO

[0082] In another example, the method further includes storing a molten fuel salt in a fuel storage system fluidically coupled to the reactor system, the fuel storage system in a third functional compartment of the segmented compartment structure.

[0083] In another example, the method further includes thermally and / or radioactively shielding the fuel storage system from the reactor system by a dividing wall of the segmented compartment structure interposed between the first functional compartment and the third functional compartment.

[0084] In another example, the method further includes treating an off-gas by an off-gas system fluidically coupled to the heat removal system, the off-gas system in a fourth functional compartment of the segmented compartment structure.

[0085] In another example, the method further includes thermally and / or radioactively shielding the fuel storage system from the off-gas system by a dividing wall of the segmented compartment structure interposed between the third functional compartment and the fourth functional compartment.

[0086] In another example, the transferring step further includes receiving a first flow of heated molten fuel salt from the reactor system by a first primary heat exchanger. The transferring step further includes receiving a second flow of heated molten fuel salt from the reactor system by a second primary heat exchanger. The transferring step further includes transferring heat from the first flow of heated molten salt to a first flow of primary coolant salt by the first primary heat exchanger. The transferring step further includes transferring heat from the second flow of heated molten salt to a second flow of primary coolant salt by the second primary heat exchanger.

[0087] In another example, the transferring of the heat from the heat removal system further includes receiving the first flow of primary coolant salt from the first primary heat exchanger by a first secondary heat exchanger. The transferring further including receiving the second flow of primary coolant salt from the second primary heat exchanger by a second secondary heat exchanger. The transferring further including transferring heat from the first flow of primary coolant salt to a first flow of secondary coolant salt by the first secondary heat exchanger. The transferring further including transferring heat from the second flow of primary coolant salt to a second flow of secondary coolant salt by the second secondary heat exchanger.PCT Specification Attorney Docket No. 27569.105078WO

[0088] In yet another example, the transferring further includes receiving the first flow of secondary coolant salt and the second flow of secondary coolant salt by a common steam generator of the energy conversion system.

[0089] In one example, a method of maintaining a modular nuclear power plant is disclosed. The method includes operating the modular nuclear power plant. Salt-bearing components of the modular nuclear power plant are enclosed in a plurality of functional compartments of a segmented compartment structure. An energy conversion system of the modular nuclear power plant is exterior to and elevationally offset from the segmented compartment structure. The method further includes removing a reactor core of the modular nuclear power plant from a first functional compartment of the segmented compartment structure. The method further includes inputting a second reactor core of the modular nuclear power plant into the first functional compartment of the segmented compartment structure. The method further includes continuing to operate the modular nuclear power plant.

[0090] In another example, the method further includes, prior to removing the reactor core, activating a third reactor core positioned in a second functional compartment.

[0091] In another example, the method further includes removing a heat removal system of the modular nuclear power plant from a second functional compartment of the segmented compartment structure. The method further includes returning the heat removal system of the modular nuclear power plant to the second functional compartment following a maintenance of the heat removal system. The method further includes continuing to operate the modular nuclear power plant.

[0092] In one example, a modular power plant system is disclosed. The modular power plant system includes a first section, and a second section associated with the first section. The second section includes a segmented compartment structure configured to house distinct functional components of the modular power plant system. The segmented compartment structure includes a plurality of functional compartments segmented from one another by one or more dividing walls. The distinct functional components of the modular power plant system include a common reactor system and a heat removal system each enclosed in one or more functional compartments of the plurality of functional compartments. The first section includes a common energy conversion system operatively coupled with the heat removal system and configured to use an output thereof.PCT Specification Attorney Docket No. 27569.105078WO The heat removal system includes a first circulation path transferring thermal energy from the common reactor system and to the common energy conversion system and a second circulation path additionally transferring thermal energy from the common reactor system and to the common energy conversion system. The first circulation path is a parallel fluid circuit to, and distinct from, the second circulation path.

[0093] In another example, the heat removal system further includes a primary loop enclosure defining an interior volume, the primary loop enclosure disposed in a first functional compartment of the plurality of functional compartments.

[0094] In another example, the first circulation path includes a first primary heat exchanger and a first secondary heat exchanger, and the second circulation path includes a second primary heat exchanger and a second secondary heat exchanger.

[0095] In another example, the first primary heat exchanger and the second primary heat exchanger are disposed within the interior volume of the primary loop enclosure.

[0096] In another example, the first secondary heat exchanger and the second secondary heat exchanger are disposed exterior to the interior volume and in the first functional compartment.

[0097] In another example, the first primary heat exchanger and second primary heat exchanger are operable to transfer the thermal energy from a molten fuel salt to a primary coolant salt.

[0098] In another example, the first secondary heat exchanger and second secondary heat exchanger are operable to transfer the thermal energy from a primary coolant salt to a secondary coolant salt.

[0099] In another example, wherein the one or more dividing walls is at least interposed between the reactor system and the heat removal system defining a thermal barrier therebetween.

[0100] In another example, the segmented compartment structure includes a plurality of removable covers enclosing the plurality of functional compartments.

[0101] In another example, the heat removal system further includes at least one penetrating salt line, penetrating at least one of the plurality of removable covers, coupling the heat removal system to the energy conversion system.PCT Specification Attorney Docket No. 27569.105078WO

[0102] In another example, the first circulation path comprises at least one salt pump and wherein the second circulation path comprises at least one pump.

[0103] In another example, the second section is positioned elevationally below the first section.

[0104] In yet another example, the second section is positioned below a ground surface.BRIEF DESCRIPTION OF THE DRAWINGS

[0105] FIG. 1 illustrates an example molten salt reactor system.

[0106] FIG. 2A illustrates an example arrangement of a small modular nuclear reactor power plant.

[0107] FIG. 2B illustrates another example arrangement of a small modular nuclear reactor power plant.

[0108] FIG. 2C illustrates another example arrangement of a small modular nuclear reactor power plant.

[0109] FIG. 2D illustrates yet another example arrangement of a small modular nuclear reactor power plant.

[0110] FIG. 3 illustrates an example small modular nuclear reactor power plant.[OHl] FIG. 4 illustrates a removable trench cover of an example small modular nuclear reactor power plant.

[0112] FIG. 5 illustrates an exploded view of an example small modular nuclear power plant.

[0113] FIG. 6 illustrates a side view of the example small modular nuclear power plant of FIG.5.

[0114] FIG. 7 illustrates another side view of the example small modular nuclear power plant of FIG. 5.

[0115] FIG. 8 illustrates an example multi-reactor system.

[0116] FIG. 9 illustrates another example multi-reactor system.

[0117] FIG. 10 illustrates a transparent view of an example primary loop enclosure.PCT Specification Attorney Docket No. 27569.105078WO

[0118] FIG. 11 illustrates an isometric view of an example reactor enclosure.

[0119] FIG. 12 illustrates a semi-transparent view of the reactor enclosure of FIG. 11.

[0120] FIG. 13 illustrates an exploded view of the reactor enclosure of FIG. 11.

[0121] FIG. 14 illustrates a cross-section view of an example reactor vessel.

[0122] FIG. 15 illustrates a heat balance diagram of an example small modular nuclear power plant.

[0123] FIG. 16 illustrates a flow diagram of an example method for operating a modular nuclear power plant.

[0124] FIG. 17 illustrates a flow diagram of an example method for maintaining a modular nuclear power plant.

[0125] FIG. 18 illustrates a flow diagram of another example method for maintaining a modular nuclear power plant.

[0126] FIG. 19 illustrates an example modular power plant.

[0127] The use of cross-hatching or shading in the accompanying figures is generally provided to clarify the boundaries between adjacent elements and also to facilitate legibility of the figures. Accordingly, neither the presence nor the absence of cross-hatching or shading conveys or indicates any preference or requirement for particular materials, material properties, element proportions, element dimensions, commonalities of similarly illustrated elements, or any other characteristic, attribute, or property for any element illustrated in the accompanying figures.

[0128] Additionally, it should be understood that the proportions and dimensions ( either relative or absolute) of the various features and elements (and collections and groupings thereof) and the boundaries, separations, and positional relationships presented therebetween, are provided in the accompanying figures merely to facilitate an understanding of the various embodiments described herein and, accordingly, may not necessarily be presented or illustrated to scale, and are not intended to indicate any preference or requirement for an illustrated embodiment to the exclusion of embodiments described with reference thereto.DETAILED DESCRIPTIONPCT Specification Attorney Docket No. 27569.105078WO

[0129] The description that follows includes example systems, methods, and designs that embody various elements of the present disclosure. However, it should be understood that the described disclosure may be practiced in a variety of forms in addition to those described herein.

[0130] The follow disclosure relates generally to a small modular reactor nuclear power plant (sometimes abbreviated to “SMR power plant”). The particular small modular reactor may be substantially any small modular reactor configured to produce power and / or heat. For example, the SMR may be a molten salt reactor (MSR) configured to produce power and / or heat via fission reactions of fissile material (e.g., uranium) dissolved in a molten salt, collectively a “molten fuel salt” (e.g., LiF-BeF2-UF4). In this regard, the small modular reactor may include a variety of functional components or modules, which may be manufactured in a factory setting then subsequently shipped to an operational site. Each module may be arranged in a particular configuration during installation.

[0131] As used herein, the term “Small Modular Reactor” or SMR refers to a class of advanced nuclear reactors defined by their ability to be built in a factory, shipped to an operational site for installation, and then used to power or heat a variety of operations. Example SMRs include but are not limited to Pressurized Water Reactors (PWRs), Molten Salt Reactors (MSRs), liquid metal cooled reactors, gas-cooled reactors, and other generation IV reactors.

[0132] As used herein, the term “nuclear power plant” and more particularly “SMR power plant” refers to the collection of components or modules operable to produce power and / or heat for a variety of applications. Such SMR power plants may be arranged in a variety of configurations based on the need, with certain arrangements necessitating alternative system designs.

[0133] One of the many advantages SMRs have over conventional nuclear power plants is in their small size, modularity, and adaptability to different use cases. For example, SMRs may be employed where size constraints are at issue (e.g., a small or awkwardly shaped operational site, geological obstacles, hydrological obstacles, etc.), where the operational site needs a varying amount of power, among other reasons. Despite SMRs small and flexible size, further lessening of installation size impact may be achieved through the particular arrangement of modules of the SMR power plant. In some cases, such a configuration may necessitate SMR design adaptations.PCT Specification Attorney Docket No. 27569.105078WO For example, a particular module may need to be separated into two components to transfer vertical size to horizontal size or vice versa.

[0134] While a variety of arrangements are contemplated herein, the present disclosure relates to an SMR power plant arrangement that minimizes the spatial impact of installation while providing functionality and modularity to accommodate additional reactors and interchangeability of said reactors. In this regard, the SMR power plant may include a subsurface section, and a surface section positioned vertically offset from the subsurface section. The subsurface section may include a segmented compartment structure including a plurality of distinct subsurface functional compartments, each configured to house distinct functional components of the SMR power plant. Certain components may be positioned on the surface section and certain components may be positioned in the subsurface section. For example, an energy conversion system may be positioned on the surface section while the salt-bearing components (e.g., those containing molten salt, or making contact with molten salt) of the SMR power plant may be positioned in the subsurface section.

[0135] The SMR power plant of the present disclosure may be a multi-reactor system that includes more than one SMR or SMR components. For example, the multi-reactor system may include a single, common energy conversion system but multiple heat generating reactor systems. As another example, the multi-reactor system may include a single, common surface section with multiple subsurface sections connected thereto. As yet another example, the multi-reactor system may include multiple surface sections or energy conversion systems and multiple subsurface sections or heat generating reactor systems all coupled to a common energy grid connection. Advantageously and as discussed in greater detail with reference to FIGS. 8 and 9, the SMR power plant of the present disclosure enables installation of one or more independent SMRs onto the same established power plant in a variety of configurations.

[0136] The SMR power plant of the present disclosure may facilitate ease of replacement of functional components. For example, the SMR power plant may include a reactor enclosure configured to enable replacement of a reactor core disposed therein following its lifecycle. As another example, the SMR power plant may include two reactor enclosures (each including a reactor vessel and core), with the second reactor enclosure being activated to continue heat production while the first is being replaced. As another example, the SMR power plant may includePCT Specification Attorney Docket No. 27569.105078WO a heat remove system disposed within a distinct vessel, which may be fluidly isolated from the remainder of the SMR power plant functional components and removed from the power plant, for example for maintenance purposes. Advantageously, the SMR power plant of the present disclosure may enjoy a longer operational life by enabling replacement of certain components following installation.

[0137] The SMR nuclear power plant may generally include a reactor system, a heat removal system, and an energy conversion system among other components and systems, each of which comprising a variety of modular components. Some of the foregoing modules and systems may be above ground (i.e., disposed on a surface section) or below ground (i.e., disposed in a subsurface section). The reactor system may generally include a reactor core operable to facilitate fission reaction to generate heat. The heat removal system may generally include one or more heat exchangers and pumps operable to circulate a heat transferring medium (e.g., molten salt) and transfer the generate heat to one or more coolant mediums (e.g., a primary coolant salt and a secondary coolant salt). The energy conversion system may generally include a steam generator and / or a turbine operable to convert the generated heat into electrical power. In one example, the energy conversion system includes a supercritical carbon dioxide power cycle instead of or in addition to the steam generator to convert the generated heat into electrical power. While the SMR nuclear power plant may employ a variety of different SMR designs, in one example, an MSR is employed.

[0138] For instance, and with reference to FIG. 1, an example molten salt reactor system 100 to which the SMR power plant may employ is shown schematically. As will be discussed in greater detail herein, the SMR power plant may employ one or more SMR systems 100, with each functional component disposed in one or more subsurface functional compartments of a segmented compartment structure.

[0139] In one example, the SMR system 100 is an MSR system that utilizes fuel salt with enriched uranium (e.g., high-assay low-enriched uranium) dissolved therein to create thermal power via nuclear fission reactions. For example, the molten salt (e.g., FLiBe) may have enriched uranium (e.g., in the form of UF4) dissolved and mixed therein, collectively forming a molten fuel salt. In one example, the composition of the molten fuel salt is LiF-BeF2-UF4, though other compositions of fuel salts may be utilized as fuel salts within the reactor system 100. The fuel saltPCT Specification Attorney Docket No. 27569.105078WO within the system 100 is heated to high temperatures (about 600-700 °C) and melts as the system 100 is heated. The SMR system 100 may include a reactor vessel 102 where the nuclear reactions occur within the molten fuel salt, a fuel salt pump 104 that pumps the molten fuel salt to a primary heat exchanger 106, such that the molten fuel salt re-enters the reactor vessel 102 after flowing through the heat exchanger, and piping in between each component. The piping between each component facilitates circulations of the molten salt and may be collectively referred to as the molten salt loop. The SMR system 100 may also include additional components, such as, but not limited to, drain tank 108 and reactor access vessel 110. The drain tank 108 may be configured to store the fuel salt once the fuel salt is in the reactor system 100 but in a subcritical state, and also acts as storage for the fuel salt if power is lost in the system 100. The reactor access vessel 110 may be configured to allow for introduction of small pellets of uranium fluoride (UF4) to the system 100 as necessary to bring the reactor to a critical state and compensate for depletion of fissile material.

[0140] Certain functional components of SMR system 100 may be housed in enclosures. For example, the SMR system 100 may include a reactor enclosure 122 and a primary loop enclosure 124. The reactor enclosure 122 and the primary loop enclosure 124 may generally include one or more distinct layers, for example a thermal insulation layer and an outer radiation shielding layer. In one example, the reactor enclosure 122 and / or the primary loop enclosure 124 includes a thermal insulation layer defining a thermal region therein operable to maintain a high temperature necessary to maintain a molten phase of the fuel salt (i.e., 500 - 700 °C). In this regard, the reactor enclosure 122 may enclose a reactor system including certain salt-bearing components operable to cause fission reaction and disposed within the thermal region. For example, the reactor enclosure 122 may encloses the reactor vessel 102 and the drain tank 108. As another example, the primary loop enclosure 124 may enclose the reactor access vessel 110, the reactor pump 104, and the primary heat exchanger 106. The insulating layer effectively functioning as an oven by insulating the heat produced via fission reactions (or by external heaters) within the reactor vessel 102 to maintain an operational temperature of the SMR system 100. Each enclosure may include heaters positioned within the enclosure to increase the temperature of an interior volume therein. Reactor enclosure 122 may be distinct from and separated from the primary loop enclosure 124, but fluidically coupled via molten salt piping connections.PCT Specification Attorney Docket No. 27569.105078WO

[0141] The SMR system 100 may further include a fuel storage enclosure 140 generally operable to store the molten fuel salt prior to entering the reactor vessel 102. The fuel storage enclosure 104 may be operable to maintain a proper chemistry for the reactor vessel 102, such that fission reactions and heat generation may be facilitated. In one example, the fuel storage enclosure 140 is distinct from and separated from the reactor enclosure 122 and the primary loop enclosure 124, but fluidically coupled via molten salt piping connections.

[0142] The SMR system 100 may further include an off-gas system 130 operable to process off-gas produced by the MSR system 100. As a consequence of nuclear fission and general operation, the SMR system 100 may produces a wide variety of potentially radioactive gasses or “off-gas” which needs to be proceed. Additionally, the SMR system 100 may employ certain gasses for operation, for example to alter a pressure within the reactor vessel 102 and the drain tank 108 thereby controlling molten salt flow. These gasses may also be categorized as off-gas and may need to be processed. The off-gas may include gaseous fission products (e.g., radioactive iodine, krypton, xenon, tritium, fluoride-gasses, etc.). The off-gas system 130 may include a number of interrelated systems operable to handle and / or process large quantities of off-gas ranging from non-radioactive, potentially radioactive, and always radioactive. For example, the off-gas system may include one or more charcoal beds generally operable to filter and / or trap off-gas to allow radioactive gasses (e.g., krypton and xenon) to decay prior to discharge. Additionally, the off-gas system 130 may include one or more isotope catchers comprising metal-organic frameworks operable to capture fission product gasses, such as hydrogen fluoride, tritium gas, and tritium fluoride, that may be corrosive to charcoal beds.

[0143] SMR system 100 may further include a secondary heat exchanger 112 fluidically coupled to primary heat exchanger 106. While the primary heat exchanger 106 may be operable to transfer the generated heat from a molten fuel salt to a primary coolant salt, secondary heat exchanger 112 may be operable to transfer the generated heat from the primary coolant salt (e.g., a FLiBe salt) to a secondary coolant salt (e.g., another FLiBe salt, a nitrate salt, simple solar salt, etc.). As will be understood by those skilled in the art, the molten fuel salt includes radioactive material, which must be contained, for example, by primary loop enclosure 124, but the primary coolant salt and secondary coolant salt may not be substantially radioactive, thus not requiring anPCT Specification Attorney Docket No. 27569.105078WO enclosure of its own. Primary heat exchanger 106 and secondary heat exchanger 112 may be fluidically connected via molten salt lines penetrating the primary loop enclosure 124.

[0144] Secondary heat exchanger 112 may be fluidically coupled to an energy conversion system 114, generally operable to take the generated heat (i.e., that transferred to the secondary coolant salt by the secondary heat exchanger 112) and convert it into electrical power or utilize a heat output for certain industrial applications requiring a process heat. For example, energy conversion system 114 may include one or more steam generators, turbines, and cooling towers to facilitate conversion of heat energy into electrical power. In one example, the energy conversion system 114 includes a super critical carbon dioxide (sCCh) energy conversion system. In this example, the sCCh energy conversion system may include gas turbine operable to utilizing a super critical CO2 as a coolant medium. In this regard, the SCO2 energy conversion system may employ a gas turbine using a super critical carbon dioxide to generate power.

[0145] In addition to the aforementioned systems and components, SMR system 100 may include and / or employ other systems and components not specifically illustrated in FIG. 1. For example, the SMR system 100 may include additional pumps, valves, compressors, and the like to facilitate the general functions depicted in relation to FIG. 1. Such additional components may be positioned along the molten salt loop and operable to cause the flow of molten fuel salt or other coolants from one functional component to another. In this regard, as discussed in greater detail with reference to FIG. 15, SMR system 100 may include a pump between primary heat exchanger 106 and secondary heat exchanger 112, between secondary heat exchanger 112 and energy conversion system 114, and / or other locations along the molten salt loop. As another example, SMR system 100 may include an inert gas system, and an equalization system.

[0146] The inert gas system may be operable to provide inert gas (e.g., nitrogen) to a head space of the drain tank 108, among other functions. The inert gas system may further relieve inert gas from the headspace of the drain tank as needed. The inert gas system is therefore operable to maintain pressurized inert gas in the headspace of the drain tank 108 that is sufficient to substantially prevent the flow of molten fuel salt into the drain tank during normal operations. In one example, the inert gas system is operable to maintain a pressure below atmospheric pressure within the headspace. For example, with the headspace of the drain tank 108 pressurized by the inert gas system, molten fuel salt may generally circulate between the reactor vessel 102 and thePCT Specification Attorney Docket No. 27569.105078WO primary heat exchanger 106 without substantially draining into the drain tank 108. In some cases, the inert gas system may be configured to supply inert gas to the headspace of various other components of the molten salt reactor system 100, such as to the headspace of the reactor access vessel 110, to the seal of reactor pump 104, among other components. Upon the occurrence of a shutdown event, the inert gas system may cease providing inert gas to the head space of the drain tank 108, and other components to which the system supplies inert gas. Consequently, this causes the pressure of the headspace of the drain tank 108 to decrease, which causes the fuel salt to gravitational drain to the drain tank 108, which may be disposed at a lowermost section of the MSR system 100. Advantageously, in the event of a loss of power, emergency situation, or other failure event, the inert gas system may allow the fuel salt to drain into the drain tank 108 rather than circulating to the reactor vessel 102, passively, thereby potentially avoiding pressure build up during such loss of power or other failure event.

[0147] The SMR system 100 may further include an equalization system to work in conjunction with the inert gas system. The equalization system is operable to equalize the pressure between the headspace of the drain tank 108 and the reactor vessel 102 upon the occurrence of a shutdown event. In this regard, the equalization system may be operable to fluidically couple (via opening one or more valves) the head space of the drain tank 108 and the reactor vessel 102 to reduce or eliminate the pressure differential, thereby allowing the fuel salt to readily flow into the drain tank upon the shutdown event as described with reference to the inert gas system 112.

[0148] As will be discussed in greater detail herein, the functional components of MSR system 100 and energy conversion system 114 may be disposed in a first section or “nuclear section” and a second section or “energy section,” respectively. The first section (containing the functional components of the MSR system 100) may include a segmented compartment structure including a plurality of segmented compartments to house each functional component of the MSR system 100. In one example, the segmented compartment structure is positioned below-grade or below the ground, (i.e., in a ditch, pit, channel, or other below ground structure) and may be referred to as a “subsurface section.” However, the segmented compartment structure may be positioned above ground where geological or hydrological barriers make below ground installation impractical. Advantageously, by including salt-bearing components in a subsurface section, for example in a trench, ditch, pit, channel, or other below the ground structure, the radiation and thermal energyPCT Specification Attorney Docket No. 27569.105078WO produced by operation may be appropriately contained. In one example, the subsurface section is enclosed by one or more removable lids or covers configured to provide a thermal and / or radiation barrier. Additionally, such a subsurface section may minimize the spatial impact of installation by providing a surface (i.e., above the subsurface section) for other components. Lastly, and as will be discussed in greater detail with reference to FIGS. 2A-2C, the subsurface section may include a configurable segmented compartment structure including a plurality of subsurface functional compartments, each of which configured to house a functional component of an SMR system. The segmented compartment structure may be configured into a variety of geometric configurations based on the spatial constraints involved with installation.

[0149] Turning now to FIG. 2A, which illustrates an example arrangement of a small modular nuclear reactor power plant 200a. The SMR power plant 200a may generally include functional components of an SMR, such as those described in reference to FIG. 1. For example, SMR power plant 200a may include a reactor system 202a, a heat removal system 204a, a fuel salt enclosure system 206a, an off-gas system 208a, and off-gas exhaust 236a, and an energy conversion system 234a. The aforementioned components may be substantially similar to those described in reference to FIG. 1, redundant explanation of which is excluded for clarity.

[0150] The SMR power plant 200a may further include a segmented compartment structure 220a including a plurality of subsurface functional compartments, each configured to house distinct functional compartments of the SMR power plant 200a, such as the aforementioned functional compartments. The segmented compartment structure 220a may be disposed substantially below a ground surface (i.e., at least substantially underground) in a trench, ditch, pit, channel, or the like. Segmented compartment structure 220a may include a subsurface reactor compartment 222a configured to house the reactor system 202a, a subsurface heat removal compartment 224a configured to house the heat removal system 204a, a subsurface fuel storage compartment 226a configured to house a fuel salt enclosure system 206a, and a subsurface off-gas compartment 228a configured to house an off-gas system 208a. As will be understood by those skilled in the art, while the segmented compartment structures described herein may be described as being included in a subsurface section, they may be disposed above grade or above a ground surface. In this regard, the segmented compartment structure 220a (and those described withPCT Specification Attorney Docket No. 27569.105078WO reference to FIGS. 2B-2D) may be positioned at least partially above ground, substantially above ground, or completely above ground.

[0151] Each subsurface functional compartment (i.e., compartments 222a, 224a, 226a, and 228a) may be separated by one or more dividing walls 230a disposed within the segmented compartment structure 220a. In one example, the one or more dividing walls 230a defines a thermal and / or radiation barrier between each subsurface functional compartment. In one example, the one or more dividing walls 230a are composed of concrete. In one example, the one or more dividing walls 230a at least substantially fill the space of the segmented compartment structure 220a, not occupied by a subsurface functional compartment.

[0152] The subsurface functional compartments may be fluidically coupled to one another by one or more molten salt lines 232a, 232b, 232c, 232d penetrating the one or more dividing walls 230a operable to transfer a molten salt from one functional compartment to another consequently transferring a molten salt from one or more functional system disposed therein. For example, and as depicted in FIG. 2A, molten salt line 232a may fluidically couple subsurface off-gas compartment 228a to subsurface fuel storage compartment 226a thereby fluidically coupling offgas system 208a to fuel storage system 206a; molten salt line 232b may fluidically couple subsurface fuel storage compartment 226a to subsurface reactor compartment 222a thereby fluidically coupling fuel storage system 206a to reactor system 202a; molten salt line 232c may fluidically couple subsurface reactor storage compartment 222a to subsurface heat removal compartment 224a thereby fluidically coupling reactor system 202a to heat removal system 204a; and molten salt line 232d may fluidically couple subsurface heat removal compartment 224a to subsurface off-gas compartment 228a thereby fluidically coupling heat removal system 204a to off-gas system 208a. However, as will be understood by those skilled in the art, other molten salt line connections not explicitly illustrated herein may be employed to connect functional components of the SMR system as needed.

[0153] SMR power plant 200a may further include an energy conversion system 234a and / or an off-gas exhaust 236a. In one example, the energy conversion system 234a and off-gas exhaust 236a are disposed outside of the segmented compartment structure 220a and may be disposed above ground or on a surface section. The energy conversion system 234a may be fluidically coupled to heat removal system 204a via coolant line 232e and generally operable to receive thePCT Specification Attorney Docket No. 27569.105078WO generated heat and transform it into an electrical output. Coolant line 232e may be operable to transfer a coolant medium from the heat removal system 204a to the energy conversion system 234a. In this regard, coolant line 232e may be a gas line operable to transport a steam or may be a molten salt line operable to transport a molten salt. The off-gas exhaust 236a may be fluidically coupled to off-gas system 208a via gas line 232f and generally operable to discharge gas following off-gas processing therein or transfer said gas for further processing based on the need.

[0154] As will be discussed in greater detail with reference to FIGS. 5 and 10, the heat removal system 204a may include a primary loop enclosure 238a coupled to a first secondary heat exchanger 240a and a second secondary heat exchanger 240b. In one example, primary loop enclosure 238a and the first and second secondary heat exchangers 240a, 240b are disposed within the same subsurface functional compartment 224a. In another example, the primary loop enclosure 238a is separated from the first and second secondary heat exchangers 240a, 240b by a partition 242a. The primary heat removal system 204a may include additional components not explicitly illustrated in FIG. 2A, such as pumps and additional molten salt lines.

[0155] FIG. 2A illustrates just one example SMR power plant 200a configuration. In this regard, FIG. 2A illustrates a configuration with the segmented compartment structure 220a in a generally rectangular geometric configuration composed of two parallel lines of functional components. Such a rectangular geometric configuration may be desired where the installation land includes no material obstacles and the SMR power plant 200a may be installed with functional components grouped in the same common area. However, and as illustrated in FIGS. 2B and 2C, the SMR power plant may include a segmented compartment structure and associated surface components in a variety of geometric configurations.

[0156] Turning now to FIG. 2B, which illustrates another example arrangement of a small modular nuclear reactor power plant 200b. In many respects, the SMR power plant 200b of FIG.2B is substantially similar to that of FIG. 2A, and includes a segmented compartment structure 220b, a subsurface reactor compartment 222b enclosing a reactor system 202b, a subsurface heat removal compartment 224b enclosing a heat removal system 204b, a subsurface fuel storage compartment 226b enclosing a fuel storage system 206b, a subsurface off-gas compartment 228b enclosing an off-gas system 208b, one or more dividing walls 230b therebetween, an off-gas exhaust 236b, a partition 242b, an energy conversion system 234b, and various salt lines 233a,PCT Specification Attorney Docket No. 27569.105078WO 233b, 233c, 233d, 233e, 233f positioned between functional components redundant explanation of which is excluded for clarity. However, SMR power plant 200b includes segmented compartment structure 220b having a substantially U-shaped geometric configuration. The U-shaped geometric configuration may be advantageous where a central obstacle (e.g., subsurface boulder, power lines, water lines, gas lines, etc.) is within the installment location. Advantageously, the SMR power plant of the present disclosure may include a segmented compartment structure with a particular configuration to accommodate, for example, said central obstacle by providing segmented compartment structure 200b while maintaining functionality.

[0157] Turning now to FIG. 2C, which illustrates yet another example arrangement of a small modular nuclear reactor power plant 200c. In many respects, the SMR power plant 200c of FIG.2C is substantially similar to that of FIGS. 2A and 2B, and includes a segmented compartment structure 220c, a subsurface reactor compartment 222c enclosing a reactor system 202c, a subsurface heat removal compartment 224c enclosing a heat removal system 204c, a subsurface fuel storage compartment 226c enclosing a fuel storage system 206c, a subsurface off-gas compartment 228c enclosing an off-gas system 208c, one or more dividing walls 230c therebetween, an off-gas exhaust 236c, a partition 242c, an energy conversion system 234c, and various salt lines 235a, 235b, 235c, 235d 235e, 235f positioned between functional components redundant explanation of which is excluded for clarity. However, SMR power plant 200c includes segmented compartment structure 220c having a substantially L-shaped geometric configuration. The L-shaped geometric configuration may be advantageous to avoid certain obstacles present in the installation site.

[0158] The SMR power plant configurations illustrated in FIGS. 2A-2C serve as mere example configurations and one skilled in the art will appreciate this exemplary purpose and understand the wide variety of geometric configurations disclosed herein. For example, the segmented compartment structure 220a, 220b, 220c may be in a circular geometric configuration, arched geometric configuration, square geometric configuration, and others based on the need. Such a configuration is exemplary of the various geometric configurations to which the segmented compartment structure may employ. Ultimately, the configurable segmented compartment structure of the SMR power plant disclosed herein may reduce the spatial impact of installation by adapting to the landscape of the installation location.PCT Specification Attorney Docket No. 27569.105078WO

[0159] The SMR power plant of the present disclosure may be configured to enable maintenance of different functional components. For example, certain functional components of the SMR power plant (e.g., reactor systems 202a, 202b, 202c) may be removed from the segmented compartment structure for refurbishment or replacement (e.g., following the lifecycle of the reactor system). In this regard, the SMR power plant may be configured to accommodate such maintenance while continuing operation of the SMR power plant. To facilitate the foregoing, the SMR power plant may include a second reactor system (or a “backup” reactor system) fluidically coupled to the SMR power plant and operable to continue power production while the first reactor system is being maintained or removed.

[0160] Turning now to FIG. 2D, which illustrates yet another example arrangement of a small modular nuclear reactor power plant 200d. In many respects, SMR power plant 200d is substantially similar to that of FIGS. 2A-2C and includes a segmented compartment structure 220d, a subsurface reactor compartment 222d enclosing a reactor system 202d, a subsurface heat removal compartment 224d enclosing a heat removal system 204d, a subsurface fuel storage compartment 226d enclosing a fuel storage system 206d, a subsurface off-gas compartment 228d enclosing an off-gas system 208d, one or more dividing walls 230d therebetween, an off-gas exhaust 236d, a partition 242d, an energy conversion system 234d, and various salt lines 237a, 237b, 237c, 237d, 237e, 237f positioned between functional components redundant explanation of which is excluded for clarity. However, SMR power plant 200d includes a second reactor system 250d enclosed within a subsurface reactor compartment 252d of segmented compartment structure 220d fluidically coupled to fuel storage system 206d by salt line 237g and heat removal system 204d by salt line 237h. In this regard, the second reactor system 250d may be activated once replacement procedures for reactor system 202d being, thereby maintaining continued operation of the SMR power plant. For example, once it is time to replace reactor system 202d (e.g., upon completion of the lifecycle of any component therein or desired maintenance for the same), the fuel salt may be transferred to the second reactor system 252d (e.g., via molten salt lines 237g, 237h) where it will undergo fission reactions and generate heat. Advantageously, in this example, the components of reactor system 202d may be allowed to cool and then be subsequently removed (and optionally replaced with a new or refurbished reactor system) all while the SMR power plant 200a maintains operation through use of the second reactor system 250d. Additionally, such section reactor system and subsurface reactor compartment 252d may included in the variousPCT Specification Attorney Docket No. 27569.105078WO configurations described with reference to FIGS. 2A-2C in order to accommodate any installation obstacles or as designed for the particular arrangement.

[0161] As discussed, the SMR power plant may generally include an above ground portion or “surface section” and a below ground portion or “subsurface section.” Generally, the energy conversion system is disposed on the surface section while the salt-bearing components are disposed in the subsurface section. The subsurface section may be enclosed by a plurality of removable covers or lids in line with a surface of the installation site. However, in one example, the SMR power plant includes an energy section and a nuclear section, with the nuclear section including the segmented compartment structure (e.g., segmented compartment structure 200a, 200b, 200c, 200d) positioned above grade (e g., where below grade installment is impractical) with the segmented compartment structure and dividing walls providing thermal and / or radiation shielding. In this regard, the SMR power plant may generally include an energy section and a nuclear section, which may be substantially analogous to the surface section and subsurface section, respectively save for their positioning relative to a ground surface. One having ordinary skill in the art will appreciate that even where the segmented compartment structure is described as being installed below a ground surface, it may be installed above a ground surface or even elevationally above the ground surface based on the need. In this regard, while it may be advantageous to install the segmented compartment structure below grade (e.g., to provide additional thermal and radiation protection), the segmented compartment structure is not limited to below ground installation.

[0162] Turning now to FIG. 3, which illustrates an example small modular nuclear reactor power plant 300. The SMR power plant 300 may include a subsurface section 302 and a surface section 304 with the subsurface section 302 positioned elevationally below the surface section 304. The subsurface section 302 may be separated from an environment of the SMR power plant 300 by a plurality of removable covers or lids 306 (e.g., concrete slabs), collectively and individually defining a radioactive and / or thermal barrier therebetween. Advantageously, by including a plurality of removable covers 306 enclosing salt-bearing components of the SMR power plant 300, the environment of the SMR power plant 300 may be shielded from the thermal and radioactive energy produced by operation while enabling operators to access particular compartments as desired, for example for maintenance purposes.PCT Specification Attorney Docket No. 27569.105078WO

[0163] The SMR power plant 300 of FIG. 3 may be installed into a building structure, that is, such that the subsurface section 302 and / or the surface section 304 are enclosed within a conventional building, warehouse, or other enclosed structure. In this regard, while not explicitly depicted in FIG. 3 one skilled in the art will appreciate that FIG. 3 illustrates how the SMR power plant 300 may be installed inside a structure, which is excluded here for clarity. For example, the SMR power plant 300 may be enclosed within structure having a square footage of about 57,600. In another example, the SMR power plant 300 may be enclosed within a structure having a square footage between about 57,600 square feet and about 115,200 square feet. The structure may be one story or have multiple stories. In one example, at top surface of the subsurface section 302 (i.e., in line with the removable covers of lids 306) is in line with the ground floor of the structure while the surface section 304 is in line with a second floor of the structure.

[0164] The subsurface section 302 is associated with and fluidically coupled to the surface section 304. For example, the subsurface section 302 may include a plurality of salt lines 308 coupled to a steam generator 310 of the surface section 304, operable to transfer the heat carrying medium (e.g., a secondary coolant salt) thereto. The plurality of salt lines 308 may penetrate a cover 306 of the plurality of covers 306.

[0165] The surface section 304 may include an energy conversion system 312 operable to convert a heat output from the SMR system into an electrical power and / or a process heat for direct heat application. In this regard, the energy conversion system 312 may include a steam generator 314, a turbine generator 316, a cooling tower 318, and / or a transformer 320. In one example, the energy conversion system 312 is coupled to a power grid 322. Such components may be operable to collectively transfer the heat output of the SMR into an electrical output. For example, the turbine generator 316 may be generally operable to generate electrical power ultimately derived from heat produced by an SMR system indirectly connected thereto. For example, the turbine generator 316 may be a system operable to convert mechanical energy from a rotating turbine into electrical power. In this regard, the turbine generator 316 may be connected to a power grid 322 and may transfer the generated power to remote location through the power grid. However, as will be understood by those skilled in the art, the turbine generator 322 may be connected to and configured to provide power to a variety of systems, for example to power an oil and gas well, a water desalination system, a chemical plant, or other system requiring power. Such mechanicalPCT Specification Attorney Docket No. 27569.105078WO energy may be derived from steam received from the steam generator 314. The steam generator 314 may be operable to facilitate heating of water to its boiling point, thereby converting it to steam. Said heat may be ultimately derived from the SMR system and received via plurality of salt lines 308. For example, the steam generator 314 may include a heat exchanger operable to transfer a thermal energy from a secondary salt to a water coolant. The cooling tower 318 may be generally operable to expel excess heat to the atmosphere. However, the energy conversion system 312 may include other components not explicitly illustrated herein but understood by those skilled in the art to be typically utilized when converting heat energy into electrical power.

[0166] Advantageously, by including certain components in the subsurface section 302 the spatial impact of installation is minimized or at least reduced and the area above the subsurface section 302 may be used for other facility components.

[0167] As discussed, the subsurface section may be enclosed by a plurality of removable covers (e.g., covers 306). Such removable covers may be, in one example, removable by a ceiling crane positioned above the subsurface section and optionally included in the SMR power plant. For example, and with reference to FIG. 4 an SMR power plant 400 is shown including a ceiling crane 430. Ceiling crane 430 may be attached to a ceiling of a building structure of the SMR power plant 400 or may include its own support structure. The ceiling crane 430 may be generally operable to raise the plurality of covers 406 uncovering the subsurface components disposed within subsurface section 402. In all other respects, SMR power plant 400 may be substantially similar to that of SMR power plant 300 of FIG. 3 and include the subsurface section 402, the plurality of removable covers 406, a surface section 404, a plurality of salt lines 408, an energy conversion system 412 including a steam generator 414, a turbine generator 416, a cooling tower 418, a transformer 420 redundant explanation of which is excluded for clarity.

[0168] The SMR nuclear power plant may be arranged to minimize the spatial impact of installation. In one example, the arrangement includes positioning a collection of modules below ground and a collection of modules above ground. As another example, the arrangement includes positioning the below-ground modules in parallel to distribute the spatial impact of installation horizontally rather than vertically, thereby enabling installation in a shallow or substantially shallow trench. Advantageously, this arrangement allows for a shallow trench to house the belowground components. In one example, each below-ground module is positioned on substantially thePCT Specification Attorney Docket No. 27569.105078WO same horizontal plant. In another example, the subsurface functional components include varying depths configured to house their assigned functional component. The below-ground modules may be arranged in two parallel lines extending from one end of the trench to another. In one example, a first parallel line includes the reactor enclosure, the primary loop enclosure, and the secondary heat exchanger section. Here, the second parallel line may include the fuel storage enclosure and the off-gas system. Each module may include piping connection therebetween to facilitate flow of salt and / or coolant between each module. In this regard, the SMR nuclear power plant may include the arrangement of modules illustrated in FIG. 2.

[0169] Turning now to FIG. 5, which illustrates an exploded view of an SMR power plant 500. Particularly, FIG. 5 highlights the subsurface distinct functional components of the SMR system, enclosed within a segmented compartment structure (e.g., that of FIGS. 2A-2C) of the subsurface section. As previously discussed, the SMR power plant may be arranged in a particular configuration to minimize the spatial impact of installation, that is, so the SMR power plant takes up less space. Furthermore, such an arrangement may include combining an above-ground portion or surface section with the below-ground portion or subsurface section. In this regard, SMR power plant 500 may include a subsurface section 502 and a surface section 504. The surface section 504 may include an energy conversion system 512 substantially similar to that of FIGS. 3 and 4 including a plurality of salt lines 508, a steam generator 514, a turbine generator 516, a cooling tower 518, and a transformer 520 redundant explanation of which is excluded for clarity.

[0170] SMR power plant 500 further includes a segmented compartment structure 530 within the subsurface section 502, that is positioned below ground. The segmented compartment structure 530 may include a plurality of subsurface functional compartments each configured to house a distinct functional component or “module” of the SMR and configurable in a variety of geometric configurations, for example as illustrated in FIGS. 2A-2C. In this regard, segmented compartment structure 530 includes a subsurface reactor compartment 532 configured to house a reactor system 542, a subsurface heat removal compartment 534 configured to house a heat removal system 544, a subsurface fuel storage compartment 536 configured to house a fuel salt enclosure system 546, and a subsurface off-gas compartment 538 configured to house an off-gas system 548. Each of the aforementioned compartments may be separated by one or more dividing walls positioned within the segmented compartment structure 530, such as those illustrated in FIGS. 2A-2C.PCT Specification Attorney Docket No. 27569.105078WO

[0171] The reactor system 542 may include a reactor core configured to facilitate fission reactions therein, thereby producing thermal energy. In one example, the reactor system 542 includes a reactor enclosure, a reactor vessel, and a drain tank, such as reactor enclosure 122, reactor vessel 122, and drain tank 108 of FIG. 1. As will be discussed in greater detail with reference to FIGS. 11-14, reactor system 542 may include a reactor enclosure housing a removable reactor vessel containing a reactor core both with fuel salt inlets and outlets collectively operable to introduce a preheated molten fuel salt into the reactor core and output a heated molten fuel salt following fission reactions. The reactor system 542 may be fluidically coupled to the heat removal system 544.

[0172] In one example, the reactor system 542 is fluidically coupled to the heat removal system 544 via a first circulation path 552 and a second circulation path 554. As will be discussed in greater detail with reference to FIG. 15, the first and second circulation paths 552, 554 may be operable to transfer a thermal energy produced by the reactor system 542 to the energy conversion system 512 via distinct parallel fluid circuits. In this regard, the heat removal system 544 may include a primary loop enclosure 556, a first primary coolant salt pump 558a, a second primary coolant salt pump 558b, a first secondary heat exchanger 560a, a second secondary heat exchanger 560b, a first secondary coolant salt pump 562a, and a second secondary coolant salt pump 562b all disposed within the subsurface heat removal compartment 534. Collectively, the aforementioned components of the heat removal system 544 may be operable to transfer a thermal energy produced by the reactor system 542 from a molten fuel salt to a primary coolant salt (e.g., via components within the primary loop enclosure), then from the primary coolant salt to a secondary coolant salt (e.g., via the first and second primary coolant salt pumps 558a, 558b and the first and second secondary heat exchangers 560a, 560b), and then from the secondary coolant salt to another coolant medium within the steam generator 514 (e.g., water) (e.g., via the first secondary coolant salt pump 562a and the second secondary coolant salt pump 562b). As will be discussed with reference to FIG. 10, certain components of the SMR system may be included in the primary loop enclosure 556, as opposed to being included in the reactor enclosure of the reactor system 542, to minimize the vertical impact of the SMR system. Advantageously, by separating components into two sections or modules, the spatial impact of installation may be minimized by allowing for a shallower trench. In this regard, the primary loop enclosure 556 may include one or more primary heat exchangers and one or more pumps.PCT Specification Attorney Docket No. 27569.105078WO

[0173] In one example, the primary loop enclosure 556 may be removed from the SMR power plant 500, as an example for maintenance purposes, and returned to the SMR power plant 500. In this example, the SMR power plant 500 may initially cease operation momentarily and the primary loop enclosure 556 fluidically isolated from the reactor system 542. Then, the primary loop enclosure 556 may be moved to some off-site location or other maintenance area where maintenance (such as replacement of primary heat exchangers) may be conducted. Following maintenance, the primary loop enclosure 556 may be returned to the subsurface heat removal compartment 534, fluidically recoupled to the reactor system 543, and operation of the SMR power plant may continue.

[0174] As illustrated in FIG. 5, the first and second secondary heat exchangers 560a, 560b (and salt pumps 558a, 558b, 562a, 562b) are disposed within the subsurface heat removal compartment 534, but outside of the primary loop enclosure 556. The primary loop enclosure 556 may include primary heat exchangers configured to circulate a molten fuel salt containing nuclear fuel that is anticipated to emit radiation. In this regard, the primary loop enclosure 556 may include one or more layers defining a radiation and / or thermal barrier in order to shield an environment exterior to the primary loop enclosure from the thermal and radiation anticipated to be given off by the nuclear fuel circulated therein. Advantageously, the secondary heat exchangers 560a, 560b, are not anticipated to house a nuclear fuel, giving off little to no radiation, thus not requiring an enclosure defining a radiation and / or thermal barrier.

[0175] In one example, the reactor system 542 is fluidically coupled to the fuel storage system 546. The fuel storage system 546 may be generally operable to store a molten fuel salt prior to circulation throughout the reactor system 542 and heat removal system 556 and maintain an operational chemistry of the molten fuel salt (i.e., purify and clean the molten fuel salt). For example, the fuel storage system 546 may be operable to maintain an operational ratio of transuranic elements (e.g., a proper uranium(III) to uranium(IV) ratio). As another example, the fuel storage system 546 may be operable to receive a nuclear fuel or molten fuel salt from outside the SMR power plant 500. In yet another example, the fuel storage system 546 may be operable to house and store a solid or frozen fuel salt and heat said frozen fuel salt to its melting point (e.g., via heaters coupled to the fuel storage system 546) thereby producing a molten fuel salt fit for use. Additionally or alternatively, the fuel storage system 546 may be operable to store the molten fuelPCT Specification Attorney Docket No. 27569.105078WO salt during reactor replacement or maintenance and / or during primary loop enclosure replacement or maintenance.

[0176] In one example, the off-gas system 548 is fluidically coupled to the fuel storage system 546 and / or the heat removal system 544 and may be generally operable to process an off-gas produced by the SMR power plant 500. In this regard, the off-gas system 548 may include one or more gas tanks 564 each housing purification systems collectively operable to process the off-gas. For example, the gas purification systems may include charcoal beds, decay beds, after filters, and the like. In one example, the one or more gas tanks 564 includes a metal-organic framework filter operable to capture certain corrosive fission products, such as tritium fluoride and hydrogen fluoride. The off-gas system 548 may further include an exhaust 566 configured to emit the offgas from the off-gas system 548 following processing. In one example, the exhaust 566 is disposed within the subsurface section 502 (e.g., within subsurface off-gas compartment 538) while in other examples, the exhaust 566 is disposed within the surface section 504.

[0177] Turning now to FIG. 6, which illustrates a side view of the example small modular nuclear power plant of FIG. 5. Particularly, FIG. 6 illustrates the segmented compartment structure 530 viewed from a side, such that the subsurface reactor compartment 532 enclosing the reactor system 542 and the subsurface heat removal compartment 534 enclosing the heat removal system 544 are in view. As illustrated in FIG. 6 the subsurface functional compartments (e.g., subsurface reactor compartment 532 and subsurface heat removal compartment 534) include a depth to enable the respective functional component to be fully disposed therein, enabling the segmented compartment structure 530 to be below a surface level. In one example, the depth of each subsurface compartment is varied to enable or otherwise encourage passive draining of coolant or molten salt to a drain tank of the reactor system. In another example, the depth of each subsurface compartment is equal such that the functional components are at the same elevation.

[0178] Additionally, the segmented compartment structure 530 may include one or more dividing walls separating each functional compartment. For example, segmented compartment structure 530 include dividing wall 564 separating subsurface reactor compartment 532 and subsurface heat removal compartment 534. Dividing wall 564 may be composed of a thermally insulative material and / or a radioactive shielding material, such as concrete. Additionally or alternatively, each dividing wall may include one or more penetrations configured to enable fluidPCT Specification Attorney Docket No. 27569.105078WO lines to pass through the dividing walls and fluidically couple the distinct functional modules to one another. For example, dividing wall 564 including penetration 566 configured to allow the first circulation path 552 to pass therethrough. As will be understood by those skilled in the art, dividing walls may include more than one penetration to allow a plurality of salt lines or pipes to extend therethrough, such as second circulation path 554. Additionally or alternatively, segmented compartment structure 530 may include dividing wall 565 separating heat removal system 544 from a surface section. Dividing wall 565 may include penetrator 567 to fluidically couple the second secondary heat exchanger 560b to an energy conversion system disposed on a surface section.

[0179] As discussed, each subsurface functional compartment is configured to house distinct functional components or modulars of an SMR system. For example, subsurface heat removal compartment 534 includes a lower section 570 and an upper section 572 to accommodate the varying depths required to house the primary loop enclosure 556 and the second secondary heat exchanger 560b, respectively. Advantageously, by including a segmented compartment structure 530 that includes subsurface compartments with varying depths, the SMR system may be configured to gravitationally drain the coolant (e.g., molten salt) disposed therein. The varying depths allow each piping connection therebetween to be angled downwards, causing any coolant therein to flow downward (e.g., during a shutdown event) towards a drain tank. For example, upper section 572 is positioned elevationally above lower portion 570 and lower power 570 is positioned elevationally above subsurface reactor compartment 532. However, as will be understood by those skilled in the art, each functional compartment may be configured to have an equal depth, such that each functional component is at the same elevation.

[0180] Turning now to FIG. 7, which illustrates another side view of the example small modular nuclear power plant of FIG. 5. Particularly, FIG. 7 illustrates the segmented compartment structure 530 viewed from a side, such that the subsurface fuel storage compartment 536 enclosing the fuel storage system 546 and the subsurface off-gas compartment 538 enclosing the off-gas system 548 are in view. As illustrated in FIG. 7, the subsurface off-gas compartment 538 may include a depth shallower than that of the subsurface fuel storage compartment 536, such that their respective functional components (e.g., the off-gas system 548 and the fuel storage system 546) may be fully disposed therein.PCT Specification Attorney Docket No. 27569.105078WO

[0181] Additionally, the segmented compartment structure 530 may include one or more dividing walls separating each functional compartment. For example, segmented compartment structure 530 include dividing wall 574 separating subsurface fuel storage compartment 536 and subsurface off-gas compartment 538. Dividing wall 574 may be composed of a thermally insulative material and / or a radioactive shielding material, such as concrete. Additionally or alternatively, each dividing wall may include one or more penetrations configured to house fluid lines to fluidically couple the distinct functional modules to one another. For example, dividing wall 574 includes penetration 576 configured to allow a gas line 578 to pass therethrough, fluidically coupling fuel storage system 546 to off-gas system 548. Additionally or alternatively, segmented compartment structure 530 may include dividing wall 580 including penetrator 582 configured to enable gas line 578 to pass therethrough, fluidically coupling off-gas system 548 to off-gas exhaust 566. One skilled in the art will appreciate that while not explicitly illustrated herein the segmented compartment structure 530 may include additional dividing walls with additional penetrators to separate each subsurface functional compartment formed therein while enabling fluidic coupling between each functional component.

[0182] As previously mentioned, the segmented compartment structure 530 may be installed above ground and include a plurality of functional compartments (i.e., as opposed to “subsurface” functional compartments). In this regard, the segmented compartment structure 530 may be positioned on a ground surface or elevated above the ground surface by some other structure. In one example, each functional compartment may be positioned same surface-level elevation within the segmented compartment structure 530.

[0183] The SMR power plant of the present disclosure may be a multi-reactor system, that is, a power plant comprising more than one SMR. Advantageously, the SMR power plant of the present disclosure enables an operator to install additional reactors upon initial installation or at a later date, depending on the energy demands. In one example, the SMR power plant includes a single common energy conversion system or surface section, but multiple SMRs or subsurface sections. In another example, the SMR power plant includes multiple energy conversion systems or surface sections and multiple SMRs or subsurface sections, with each energy conversion system coupled to a common power grid.PCT Specification Attorney Docket No. 27569.105078WO

[0184] Turning now to FIG. 8, which illustrates an example multi-reactor system 800. The example multi-reactor system 800 includes three subsurface sections 802a, 802b, 802c and a common surface section 810. The subsurface sections 802a, 802b, 802c may be substantially similar to subsurface section 502 of FIG. 5, each including distinct functional components of an SMR disposed in distinct subsurface functional compartments of segmented compartment structures redundant explanation of which is excluded for clarity. As will be understood by those skilled in the art, FIG. 8 illustrates merely one example multi-reactor system and that multi-reactor systems including two, four, or more subsurface sections are contemplated by the present disclosure. Additionally, the surface section 810 may be substantially analogous to surface section 504 of FIG. 5, including an energy conversion system redundant explanation of which is excluded for clarity. Each subsurface section 802a, 802b, 802c may be operable to generate thermal energy through fission reaction and transport the generated thermal energy to an energy conversion system. In this regard, each subsurface section 802a, 802b, 802c may be fluidically coupled to a common fluid tank 820 via one or more salt lines 822a, 822b, 822c. Common fluid tank 820 may be configured to receive the collective thermal energy, via a secondary coolant salt, produced by each subsurface section 802a, 802b, 802c and distribute said thermal energy to the surface section 810. In turn, the surface section 810, including an energy conversion system (e.g., energy conversion system 512), may generate an electrical power proportional to the collective power output of three, in this example, SMRs.

[0185] Each subsurface section 802a, 802b, 802c may include a corresponding segmented compartment structure 804a, 804b, 804c each of which may include the same or a distinct geometric configuration (e.g., those illustrated in FIGS. 2A-2C). Advantageously, by including one or more configurable segmented compartment structure, the multi-reactor system 800 may minimize the spatial impact of installation by avoiding particular obstacles or accommodating preexisting fixtures.

[0186] The multi-reactor system of the present disclosure may include more than one surface section, such that each subsurface section includes a corresponding surface section. For example, and with reference to FIG. 9 another example multi-reactor system 900 is shown. Multi-reactor system 900 may include three subsurface sections 902a, 902b, 902c and three corresponding surface sections 920a, 920b, 920c, thereby enabling electricity production proportional to a powerPCT Specification Attorney Docket No. 27569.105078WO output of three SMR power plants. The subsurface sections 902a, 902b, 902c and the surface sections 920a, 920b, 920c may each be substantially analogous to subsurface section 502 and surface section 504 of FIG. 5, redundant explanation of which is excluded for clarity. Additionally and similar to multi-reactor system 800, each subsurface section 902a, 902b, 902c may include a configurable segmented compartment structure 904a, 904b, 904c able to be configured in a variety of geometric configurations, such as those illustrated in FIGS. 2A-2C. Unlike the multi-reactor system 800 of FIG. 8, multi-reactor system 900 of FIG. 9 includes three surface sections 920a, 920b, 920c. In this regard, each surface section 920a, 920b, 920c may include an energy conversion system each coupled to a power grid 926 via power lines 922a, 922b, 922c the multi-reactor system 900 to provide power to the grid or to some other system directly.

[0187] As discussed, the SMR power plant of the present disclosure is designed to minimize the spatial impact of installation. In this regard, particular salt bearing components of the SMR may be separated into distinct enclosures. Such a separation may provide further installation flexibility by positioning such enclosures in distinct subsurface functional compartments, as opposed to requiring them to be in a single enclosure and single distinct subsurface functional compartment. Such a separation may distribute the spatial impact of installation horizontally to minimize vertical impact of installation. This may require certain modules to be separated into more than one module. For example, certain components of the reactor enclosure that contribute to the vertical size of the SMR system may be included in a separate enclosure positioned parallel to the reactor enclosure. In this regard, the heat removal system of the SMR system may be disposed in a separate vessel distinct from but fluidically coupled to the reactor system.

[0188] Turning now to FIG. 10, which illustrates a transparent view of an example primary loop enclosure 1000. Primary loop enclosure 1000 may be included in any of the aforementioned SMR power plants, such as SMR power plants 200a, 200b, 200c, 500 or multi-reactor systems 800, 900. More particularly, Primary loop enclosure 1000 may be primary loop enclosure 124, 238a, 238b, 238c, 556.

[0189] Primary loop enclosure 1000 may enclose at least a portion of the heat removal system of the SMR power plant, that is the one or more primary heat exchangers operable to receive the heat generated by the reactor system. Primary loop enclosure 1000 may define an interior volume 1002 where certain functional components of the SMR power plant are positioned. For example,PCT Specification Attorney Docket No. 27569.105078WO primary loop enclosure 1000 may include a first salt pump 1004a coupled to a first primary heat exchanger 1006a, a second salt pump 1004b coupled to a second primary heat exchanger 1006b collectively operable to transfer a thermal energy (e.g., produced via reactor system 542) from a molten fuel salt to a primary coolant salt. Additionally, the first salt pump 1004a and first primary heat exchanger 1006a may define a first circulation path while second salt pump 1004b and second primary heat exchanger 1006b may define a second circulation path distinct from but parallel to the first circulation path. Primary loop enclosure 1000 may further include a first reactor access vessel 1008a and a second reactor access vessel 1008b, which may both be substantially analogous to reactor access vessel 110 of FIG. 1.

[0190] Primary loop enclosure 1000 may include at least one exterior layer 1010. Exterior layer 1010 may include one or more interior layers collectively defining a thermal and / or radioactive barrier. In one example, the exterior layer 1010 may be composed of stainless steel, lead, concrete, borated polyethylene, boron carbine, and / or other materials known in the art. Advantageously, the primary loop enclosure 1000 may protect an environment exterior to enclosure 1000 from the thermal energy and radiation anticipated to be given off by the molten fuel salt.

[0191] Turning now to FIG. 11, which illustrates an isometric view of an example reactor enclosure 1100. The reactor enclosure 1100 may include a reactor system (e.g., a reactor core and drain tank) operable to facilitate fission reactions and generate a thermal energy. Reactor enclosure 1100 may be substantially analogous to reactor enclosure 112, reactor system 202a, 202b, 202c, and / or reactor system 542 and arranged in distinct subsurface functional compartment of a segmented compartment structure as described herein. For example, reactor enclosure 1100 may be disposed and enclosed in subsurface reactor compartment 532 of segmented compartment structure 530.

[0192] The reactor enclosure 1100 may generally include a body 1102 and a lid 1104 with a flange 1106 interposed therebetween configured to facilitating removable connection of the lid 1104 to the body 1102 advantageously enabling access into an interior volume of the reactor enclosure 1100. The reactor enclosure 1100 may include one or more primary salt inlets and one or more primary salt outlets. For example, the reactor enclosure 1100 of FIG. 11 includes two molten salt inlets 1106a, 1106b for receiving pre-heated molten fuel salt (e.g., from fuel salt storagePCT Specification Attorney Docket No. 27569.105078WO system 546 and / or primary loop enclosure 556, 1000) and two molten salt outlets 1108a, 1008b for distributing heated molten fuel salt to the remainder of the system (e.g., primary loop enclosure).

[0193] Turning now to FIG. 12, which illustrates a semi-transparent view of the reactor enclosure 1100 of FIG. 11. As illustrated in FIG. 12, the reactor enclosure 1100 may include one or more layers (collectively defining a shielding system) operable to shield an environment of the reactor enclosure 1100 from the thermal energy and radiation anticipated to be emitted by the reactor system. For example, reactor enclosure 1100 includes thermal insulation layer 1111 and radiation shielding layer 1110. Thermal insulation layer 1111 may be operable to thermally insulate an interior volume 1112 defined therein and may be generally composed of an insulative material capable of withstanding a high radiation environment (e.g., kaowool material, a mineral wool material, or other similar material known in the art). Radiation shielding layer 1110 may be generally operable to provide radiation shielding to interior volume 1112 and may be generally composed of a radiation shielding material, gamma shielding material, and / or neutron shielding material (e.g., lead, concreate, borated polyethylene, boron carbide, and / or stainless steel.) Additionally, a gap 1114 may be disposed between radiation shielding layer 1110 and thermal insulation layer 1111. Gap 1114 may impart thermal insulating properties by including an inert gas (e g., nitrogen) under partial vacuum.

[0194] In at least one example, reactor enclosure 1100 utilizes a reactor thermal management system, such as those described in U.S. Nonprovisional application No. 18 / 450,884, which is hereby incorporated by reference in its entirety.

[0195] Reactor enclosure 1100 may be configured to house a reactor vessel 1120. Reactor vessel 1120 may be substantially similar to reactor vessel 102 and enclose a reactor core and a drain tank (e.g., drain tank 108) redundant explanation of which is excluded for clarity. In this regard, reactor vessel 1120 may include a main body 1122, a lid 1124 and a flange 1126 interposed therebetween. Flange 1126 may be operable to facilitate removable connection of lid 1124 to main body 1122, advantageously enabling selective access to the reactor core and other components (e.g., drain tank) enclosed therein.

[0196] Reactor vessel 1120 may be configured to receive a preheated molten fuel salt and generate a thermal energy therein through fission reactions and thereafter distribute the thermalPCT Specification Attorney Docket No. 27569.105078WO energy through the SMR system (e.g., to the primary loop enclosure 556). In this regard, reactor vessel 1120 may include a first fuel salt inlet 1130a, a second fuel salt inlet 1130b, a first fuel salt outlet 1132a, and a second fuel salt outlet 1132b. The fuel salt inlets 1130a, 1130b and outlets 1132a, 1132b are configured to fluidically couple to fuel salt inlets 1106a, 1106b, and fuel salt outlets 1106a, 1106b, respectively.

[0197] Reactor vessel 1120 may further include a plurality of control rod tubes 1136 operable to facilitate input of control rods into the core of the reactor vessel 1120. Control rod tubes 1136 may be generally disposed within a headspace 1138 of reactor enclosure 1100 and penetrate through radiation shielding layer 1110 and thermal insulation layer 1111. Advantageously, this configuration enables selective access to control rod tubes 1136 via removal of lid 1104.

[0198] The SMR nuclear power plant of the present disclosure enables replacement and interchangeability of reactor vessels via the lid and flange connection of the reactor enclosure. For example, an initially installed reactor vessel may be subsequently shut down and removed from the SMR nuclear power plant. Following shut-down, the reactor vessel may be replaced with a new reactor vessel to continue power production. To facilitate installation, the reactor enclosure may be configured to allow the reactor vessel to be lowered into the reactor enclosure and subsequently installed into the SMR nuclear power plant. In this regard and with reference to FIG.13, an exploded view of the reactor enclosure 1100 of FIG. 11 is shown. As illustrated in FIG. 13, lid 1104 may be removed (via flange 1106) such that reactor vessel 1120 may be lowered therein.

[0199] The SMR power plant of the present disclosure may include a reactor vessel housing a reactor core configured with a downcomer. The downcomer may be an annulus region of the reactor vessel surrounding the reactor core and may be configured to receive the pre-heated molten fuel salt and direct its flow to a lower section of the reactor core, such that the molten fuel salt may circulate up through apertures of the reactor core absorbing the generate thermal energy.

[0200] Turning now to FIG. 14, which illustrates a cross-section view of an example reactor vessel 1400. Reactor vessel 1400 may be the replaceable reactor vessel 1120 illustrated in FIGS.12 and 13 and included in the reactor systems of FIGS. 2A-2C and FIG. 5. In this regard, reactor vessel 1400 may be substantially analogous to reactor vessel 1120 and include a main body 1422, a lid 1424, a flange 1426, fuel salt inlets 1430a, 1430b, and a plurality of control rod tubes or thimbles 1436 redundant explanation of which is excluded for clarity. However, the cross-sectionalPCT Specification Attorney Docket No. 27569.105078WO view of reactor vessel 1400 highlights the reactor core 1402 and the drain tank 1440. The reactor core 1402 may be generally operable to receive the molten fuel salt, for example, from the fuel storage enclosure 546 or the primary loop enclosure 556, via the fuel salt inlets 1430a, 1430b. The reactor core 1402 may be a graphite core with a plurality of apertures 1442 or through portions for flow of the molten fuel salt, thereby enabling transfer of thermal energy to the molten fuel salt. The heated molten fuel salt may then proceed out of the reactor vessel (e.g., via fuel salt outlets 1132a, 1132b) to the heat removal system.

[0201] The reactor vessel may include a downcomer to direct the flow of molten fuel salt. For example, reactor vessel 1400 may include downcomer 1446 configured to direct the flow towards a lower portion 1444 of the reactor core 1402. Downcomer 1446 may be an annulus about the reactor vessel 1400 fluidically coupled to salt inlets 1430a, 1430b and terminating proximal to the lower portion 1444 such that molten fuel salt enters the plurality of apertures 1442. The reactor core may be operable to harness heat from fission reactions, such that the molten fuel salt is heated as it flows through the plurality of apertures 1442.

[0202] The reactor vessel 1400 may include one or more control rod thimbles 1436 disposed within the reactor core 1402, each configured to accommodate a control rod 1437 formed of a neutron absorbing material (e.g., hafnium, boron, etc.) enabling control of the fission reactions occurring within the reactor core 1402. In this regard, the plurality of control rod tubes or thimbles 1436 may be a sleeve or channel disposed into the graphite of reactor core 1402, such that the control rod 1437 may be dispersed and removed as desired. In one example, the control rod thimbles 1436 extend from outside the lid 1424 and into the reactor core 1402. In this regard, the reactor vessel 1400 may include penetrators 1435 disposed about the lid 1424 and configured to accommodate the thimble’s 1436 penetration into the reactor vessel 1400. Advantageously, by inclusion of control rod thimbles 1436, the safety of the system may be maintained. For example, the control rod thimbles 1436 may be formed of a structural material (e.g., stainless steel or other corrosion resistant material) so that in the event of a failure of the graphite of the reactor core 1402, the control rods 1437 may still be input to control fission reactions. In this regard, even if the graphite of the reactor core 1402 fails or otherwise crumbles, a pathway for control rods 1437 is maintained by the control rod thimbles 1436, allowing inclusion of control rods 1437 into the reactor core 1402 to slow fission reaction rate if needed.PCT Specification Attorney Docket No. 27569.105078WO

[0203] The reactor vessel 1440 may further include a drain tank 1440 operable to receive and store the molten fuel salt. The drain tank 1440 may be configured to receive the molten fuel salt in the event of the shutdown and store said salt for freezing.

[0204] Turning now to FIG. 15, which illustrates a heat balance diagram 1500 of an example nuclear power plant system. The heat balance diagram 1500 of FIG. 15 illustrates how heat may be transferred from one medium to another in the SMR nuclear power plant of the present disclosure. Such an SMR nuclear power plant may be that illustrated in FIG. 5. For example, about 853 MMBTU may be produced in the reactor system 1502 (e.g., reactor system 542) per hour and subsequently transferred to a first primary heat exchanger 1504a and second primary heat exchanger 1504b (e.g., first and second primary heat exchangers 1006a, 1006b) with each receiving about 426.52 MBTU per hour. The first and second primary heat exchangers 1504a, 1504b may be configured to transfer the thermal energy from a molten fuel salt to a primary coolant salt. Subsequently, the thermal energy may be transferred to a first secondary heat exchanger 1506a and second secondary heat exchanger 1506b (e.g., first and second secondary heat exchangers 560a, 560b) with each receiving about 426.50 MBTU per hour. The first and second secondary heat exchangers 1506a, 1506b may be configured to transfer the thermal energy from the primary coolant salt to a secondary coolant salt. Subsequently, the thermal energy may be transferred to a steam generator heat exchanger 1508. The steam generator heat exchanger 1508 may be disposed in steam generator 514 and may be configured to transfer the thermal energy from the secondary coolant salt to a water to produce steam.

[0205] The foregoing transfers may each be facilitated by the one or more pumps associated with each heat exchanger. For example, the first primary heat exchanger 1504a may be fluidically coupled to pump 1510a operable to circulate the molten fuel salt between the primary heat exchanger 1504a and the reactor system 1502. The second primary heat exchanger 1504b may be fluidically coupled to pump 1510b operable to circulate the molten fuel salt between the second primary heat exchanger 1504b and the reactor system 1502. The first secondary heat exchanger 1506a may be fluidically coupled to pump 1512a operable to circulate the primary coolant salt between the first secondary heat exchanger 1506a and the first primary heat exchanger 1504a. The second secondary heat exchanger 1506b may be fluidically coupled to pump 1512b operable to circulate the primary coolant salt between the second secondary heat exchanger 1506b and thePCT Specification Attorney Docket No. 27569.105078WO second primary heat exchanger 1504b. The steam generator heat exchanger 1508 may be fluidically coupled to pump 1514a operable to circulate a secondary coolant salt (e.g., a nitrate salt) between the first secondary heat exchanger 1506a and the steam generator heat exchanger 1508. The steam generator heat exchanger 1508 may be further coupled to pump 1514b operable to circulate a secondary coolant salt between the second secondary heat exchanger 1506b and the steam generator heat exchanger 1508.

[0206] The SMR power plant of the present disclosure may include two parallel but distinct fluid circulation paths. For example, a first circulation path 1520a is defined by the fluid connections of the reactor system 1502, the first primary heat exchanger 1504a, the first secondary heat exchanger 1506a and the steam generator heat exchanger 1508 while the second circulation path 1520b is defined by the fluid connections of the reactor system 1502, the second primary heat exchanger 1504b, the second secondary heat exchanger 1506b, and the steam generator heat exchanger 1508. The first and second circulation paths 1520a, 1502b may share a common reactor system 1502 and common energy conversion system (i.e., via the steam generator heat exchanger 1508) with each operable to transfer a thermal energy from the reactor system 1502 to the energy conversion system. However, the first and second circulation paths 1520a, 1502b are distinct and separate in their operation of transferring the thermal energy from molten fuel salt to primary coolant salt, and to secondary coolant salt, that is they utilize distinct and separate heat exchangers to facilitate said transfers.

[0207] In this regard, a molten fuel salt may flow from the reactor system 1502 to the steam generator heat exchanger 1508 (contained within, for example, steam generator 514) via circulation path 1520a and / or circulation path 1520b. Advantageously, by including an SMR power plant with separate circulation paths the thermal load on each component within the circulation path is lessened and the flexibility of installation is increased (i.e., by enabling separate placement of each component within the circulation path).

[0208] Turning now to FIG. 16, which illustrates a flow diagram of an example method 1600 for operating a modular nuclear power plant. At step 1602, a heat is generated through fission reactions by a reactor system enclosed in a first subsurface compartment of a segmented compartment structure. For example, and with reference to FIG. 1, the reactor system may include a reactor vessel 102 configured to facilitate fission reactions of fissile material dissolved in aPCT Specification Attorney Docket No. 27569.105078WO molten fuel salt. As another example, and with reference to FIG. 14, the reactor system may include a reactor vessel 1400 enclosing a reactor core 1402. Reactor vessel 1400 may receive a molten fuel salt via salt inlets 1430a, 1430b, for example from a heat removal system 544 and / or a fuel storage system 546. The reactor vessel 1400 may include a downcomer 1446 configured to facilitate flow of the molten fuel salt to a plurality of apertures 1442 of the reactor core 1402. The molten fuel salt may absorb thermal energy as it flows through the plurality of apertures 1442. The reactor system may be reactor system 542 of FIG. 5 and enclosed in subsurface reactor compartment 532 of segmented compartment structure 530.

[0209] At step 1604, the generated heat is transferred from the reactor system by a heat removal system. For example, and with reference to FIG. 5, heat removal system 544 may receive the generated heat by receiving the molten fuel salt via first circulation path 552 and / or second circulation path 554. The generated heat may then be transferred by a set of primary heat exchangers (e.g., first and second primary heat exchangers 1006a, 1006b, 1504a, 1504b) from the molten fuel salt to a primary coolant salt. Thereafter, the heat removal system 544 may transfer the generated heat from primary coolant salt to a secondary coolant salt by a set of secondary heat exchangers (e.g., first and second secondary heat exchangers 560a, 560b, 1506a, 1506b). Additionally, the heat removal system may be enclosed in a second subsurface functional compartment of the segmented compartment structure, such as subsurface heat removal compartment 534 of FIG. 5.

[0210] At step 1606, the generated heat is received by an energy conversion system that is arranged substantially elevationally above the segmented compartment structure. For example, and with reference to FIGS. 5 and 15, energy conversion system 512 may be disposed on a surface level 504 and include a steam generator 514. Steam generator 514 may include steam generator heat exchanger 1508 configured to transfer the generated heat from the secondary coolant salt to another coolant such as water. Thereafter, the steam generator 514 may convert the generated heat into an electrical power by boiling the water and turning a turbine (e.g., turbine generator 516).

[0211] Turning now to FIG. 17, which illustrates a flow diagram of an example method 1700 for maintaining a modular nuclear power plant. As used herein, “maintaining” may refer to various actioning done to ensure the continued operation of a modular nuclear power plant. For example, maintaining may include replacement of certain components following a predetermined amountPCT Specification Attorney Docket No. 27569.105078WO of time or their operational lifecycle. At step 1702, a modular nuclear power plant is operated. The modular nuclear power plant may be SMR power plant 500 of FIG. 5. The modular nuclear power plant may also be multi-reactor systems 800 and 900 of FIGS. 8 and 9, respectively. The modular nuclear power plant may include a variety of salt-bearing components and may be enclosed in a plurality of subsurface functional compartments of a segmented compartment structure, for example those illustrated in and described with reference to FIG. 5.

[0212] At step 1704, the reactor core of the modular nuclear power plant is removed from a first subsurface functional compartment of the segmented compartment structure. For example, and with reference to FIGS. 5 and 13, the reactor core may be included in reactor vessel 1120 further enclosed in reactor enclosure 1100 which may be disposed within subsurface reactor compartment 532 of segmented compartment structure 530. As illustrated in FIG. 13, the reactor vessel 1120 (containing, for example, reactor core 1402 of FIG. 14) includes a removable lid 1104, which upon removal, via flange 1106, allows an operator to raise reactor vessel 1120 out of reactor enclosure 1100 consequently removing it from the subsurface functional compartment. Advantageously, this configuration allows the SMR power plant to continue operation even after the lifecycle of the reactor core has been completed. Such reactor vessel replacement may also be accomplished by any one SMR system of the multi-reactor systems disclosed herein (e.g., multireactor system 800 and 900). In one example, at step 1704, the entire reactor vessel 1120 is removed from the first subsurface functional compartment. In another example, at step 1704, the entire reactor enclosure 1100 is removed from the first subsurface functional compartment. Advantageously, depending on the need, maintenance of the reactor core may involve replacement of just the reactor core, the reactor vessel and the reactor core, or the reactor enclosure containing the reactor vessel and reactor core.

[0213] At step 1706, a second reactor core of the modular nuclear power plant is input into the first subsurface functional compartment of the segmented compartment structure. For example and with continued reference to FIGS. 5 and 13, following removal of reactor vessel 1120 from reactor enclosure 1100, a new reactor vessel (e.g., one substantially similar to reactor vessel 1120) may be input and / or lowered into reactor enclosure 1100.

[0214] At step 1708, the modular nuclear power plant continues to operate. For example, and with reference to FIGS. 5, 8, and 9 the SMR power plant 500 and / or the multi-reactor systems 800,PCT Specification Attorney Docket No. 27569.105078WO 900 may continue to operate following reactor vessel replacement. For example, SMR power plant 500 and / or multi-reactor systems 800 may continue to generate heat through fission reactions and consequently produce electrical power as described herein. Advantageously, by replacing the reactor vessel (i.e., the reactor core), the SMR power plants and multi-reactor systems of the present disclosure may continue to operate even where the operational lifecycle of the reactor core has been spent.

[0215] In one example, and as illustrated in FIG. 2D, the SMR power plant includes a second reactor system to provide continued operation of the SMR power plant while the first reactor system is being maintained. Turning now to FIG. 18, which illustrates a flow diagram of an example method 1800 for maintaining a modular nuclear power plant utilizing a second reactor system.

[0216] At step 1802, a modular nuclear power plant is operated. The modular nuclear power plant may be SMR power plant 200d of FIG. 2D, SMR power plant 500 of FIG. 5, or the multireactor systems 800 and 900 of FIGS. 8 and 9, respectively. The modular nuclear power plant may include a variety of salt-bearing components and may be enclosed in a plurality of subsurface functional compartments of a segmented compartment structure, for example those illustrated in and described with reference to FIG. 2D.

[0217] At step 1804, a first reactor core of the modular nuclear power plant disposed within a first subsurface functional compartment of the segmented compartment structure may be disconnected from the remainder of the functional components of the power plant. For example, and with reference to FIG. 2D, a first reactor system 202d may be fluidically isolated from a fuel storage system 206d and heat removal system 204d. In this regard, each of the molten salt connections of the SMR power plant may include a valve system operable to divert the flow of molten salt from one reactor system to another.

[0218] At step 1806, a second reactor core of the segmented compartment structure of the modular nuclear power plant may be connected to the other functional components of the power plant. For example, and with reference to FIG. 2D, a second reactor system 250d of segmented compartment structure 220d may be fluidically coupled to fuel storage system 206d and heat removal system 204d. In this regard, the molten fuel salt of SMR power plant 200d may bePCT Specification Attorney Docket No. 27569.105078WO circulated through reactor system 250d to undergo fission reactions thereby producing heat and consequently power (i.e., via energy conversion system 234d).

[0219] At step 1808, the modular nuclear power plant continues to operate. For example, and with reference to FIG. 2D, the second reactor system 250d may serve as a “backup” reactor system to maintain continued operation of the power plant while the first reactor system 202d is being removed, maintained, repaired, etc. Advantageously, the SMR power plant of the present invention can continue power production despite including a reactor system requiring maintenance. Following the disconnection step at 1804, the first reactor core (e.g., of reactor system 202d) may be required to cool following removal from the segmented compartment structure. In this regard, the second reactor system (e.g., reactor system 250d) can maintain operation of the power plant while awaiting the first reactor core to get to an acceptable temperature to enable removal from the system and subsequent replacement, refurbishment, maintenance, etc.

[0220] In one example the small modular nuclear power plant of the present disclosure may include a natural gas system operable to produce an electrical output via combustion of natural gas. In this example, the power plant may include one or more natural gas systems and one or more small modular reactor systems and operable to harness the collective power produced. In one example, the natural gas system may be initially installed and operated to support power production prior to and / or during installation of the small modular reactor system. Thereafter, the natural gas system may be decommissioned with the small modular reactor system supporting power production during said decommission. Further both the small modular reactor system and the natural gas system may be functionally coupled to a transfer switch further coupled to a power grid. In this regard, the small modular nuclear power plant may be operable to produce an electrical output from operations of the natural gas system and the small modular reactor system. Advantageously, operations of the natural gas system may begin prior to and / or during installation and construction of the small modular reactor system, such that operations requiring a power output may be initially supported via operation of the natural gas system and then subsequently supported via operation of the small modular reactor system.

[0221] Turning now to FIG. 19, which illustrates an example modular power plant 1900. Modular power plant 1900 may generally include a small modular reactor system 1920a and a natural gas system 1920c each functionally coupled to an energy load transfer box or “transferPCT Specification Attorney Docket No. 27569.105078WO switch” 1990, which is further coupled to a power grid 1926. The natural gas system 1920c may be a simple cycle or combined cycle natural gas plant generally operable to produce a power output via combustion of natural gas. To facilitate the forgoing, the natural gas system 1920c may be installed in a first installation site 1902c on platform 1904c. Additionally, natural gas system 1920c may be functionally coupled to transfer switch 1990 via power lines 1922c. In this regard, natural gas system 1920c may be operable to produce a power output and provide electrical power to power grid 1926. In one example, power grid 1926 is operable to provide electrical power to industrial applications (e.g., oil and gas operations).

[0222] Small modular reactor system 1920a may be substantially analogous to the small modular reactor systems disclosed herein (e.g., SMR power plant 500) operable to produce an electrical output via heat production from fission reactions. In this regard, small modular reactor system 1920a may be installed in a second installation site 1902a via segmented compartment structure 1904a. In one example, installation site 1902a is proximal to installation site 1902c. Additionally, small modular reactor system 1920a may be functionally coupled to transfer switch 1990 via power lines 1922a. In this regard, small modular reactor system 1920a may be operable to produce a power output and provide electrical power to power grid 1926. In one example, power grid 1926 is operable to provide electrical power to industrial applications (e.g., oil and gas operations).

[0223] Transfer switch 1990 may be functionally coupled to natural gas system 1920c and small modular reactor system 1920a and receive an electrical output therefrom. Transfer switch 1990 may be operable to transfer electrical loads between the two power sources and facilitate this transfer without impacting downstream operations or introducing delay. For example, transfer switch 1990 may be operable to accommodate the collective power load from both natural gas system 1920c and small modular reactor system 1920a. In another example, transfer switch 1990 is operable to facilitate transfer of power production from the natural gas system 1920c to the small modular nuclear reactor system 1920a. In this regard, transfer switch 1990 may be operable to transfer the electrical load between the two power sources. In another example, transfer switch 1990 is operable to accommodate a gradual reduction in the power received from natural gas system 1920c while accommodating a gradual increase in the power received from small modular reactor system 1920a, such that no delay or reduction in power provide to power grid 1926 (andPCT Specification Attorney Docket No. 27569.105078WO consequently the powered operation) occurs. In another example, transfer switch 1990 is operable to accommodate a full power transfer between natural gas system 1920c and small modular reactor system 1920a (i.e., from natural gas system 1920c to small modular reactor system 1920a and vice versa).

[0224] Advantageously, by including two different electrical power producing systems (e.g., natural gas and nuclear fission), the example modular power plant 1900 may be configured to initially provide electrical power via operation of natural gas system 1920c and then subsequently provide electrical power via operation of small modular reactor system 1920a. For example, natural gas system 1920c may be initially installed into modular power plant 1900 and produce a power output as previously described. In this regard, natural gas system 1920c is operable to provide the electrical power needs while small modular reactor system 1920a is being installed, prepared for operation, undergoing maintenance, etc. In one example, following installation and operation of small modular reactor system 1920a, the natural gas system 1920c may be decommissioned or otherwise have its power output reduced, with transfer switch 1990 facilitating the changes in electrical load from natural gas system 1920c to small modular reactor system 1920a without interruption to the power operation of plant 1900.

[0225] Other examples and implementations are within the scope and spirit of the disclosure and appended claims. For example, features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations. The foregoing description, for purposes of explanation, uses specific nomenclature to provide a thorough understanding of the described examples. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the described examples. Thus, the foregoing descriptions of the specific examples described herein are presented for purposes of illustration and description. They are not targeted to be exhaustive or to limit the examples to the precise forms disclosed. It will be apparent to one of ordinary skill in the art that many modifications and variations are possible in view of the above teachings.

Claims

PCT Specification Attorney Docket No. 27569.105078WO CLAIMSWhat is claimed is:

1. A modular power plant system comprisinga first section, and a second section associated with the first section, wherein the second section comprisesa segmented compartment structure configured to house distinct functional components of the modular power plant system,wherein the segmented compartment structure comprises a plurality of functional compartments segmented from one another by one or more dividing walls, and wherein a first functional compartment of the plurality of functional compartments defines a reactor compartment configured to house a reactor system, and wherein a second functional compartment of the plurality of functional compartments defines a heat removal compartment configured to house a heat removal system for operable coupling with the reactor system;wherein the first section comprisesa plurality of removable lids collectively enclosing the segmented compartment structure and defining a thermal or radiation barrier; andan energy conversion system operatively coupled with the heat removal system and configured to use an output thereof.

2. The modular power plant system of claim 1, wherein the second section is positioned elevationally below the first section; and wherein the second section is positioned below a ground surface.

3. The modular power plant system of claim 1, further comprising the reactor system, the reactor system comprisinga reactor core operable to facilitate fission of a fissile material;a reactor vessel configured to contain the reactor core; anda reactor enclosure configured to enclose the reactor vessel; andPCT Specification Attorney Docket No. 27569.105078WO wherein the reactor enclosure is disposed within the first functional compartment; andwherein the reactor enclosure is configured to receive the reactor vessel by a removable lid about an upper portion of the reactor enclosure.

4. The modular power plant system of claim 3, further comprising the heat removal system, the heat removal system comprisingat least one primary heat exchanger and at least one secondary heat exchanger;wherein the at least one primary heat exchanger is positioned within a primary loop enclosure positioned at a first end of the second functional compartment;wherein the at least one secondary heat exchanger is positioned outside the primary loop enclosure and positioned at a second end of the second functional compartment; andwherein the second end is positioned elevationally above the first end.

5. The modular power plant system of claim 4, wherein the second functional compartment is positioned elevationally above the first functional compartment; and wherein the heat removal system is operable to gravitationally drain into the reactor system.

6. The modular power plant system of claim 1, whereina third functional compartment of the plurality of functional compartments defines a fuel storage compartment configured to house a fuel storage vessel operatively coupled to the reactor system; anda fourth functional compartment of the plurality of functional compartments defines an off-gas compartment configured to house an off-gas system.

7. The modular power plant system of claim 1, wherein the energy conversion system comprises a steam generator operable to generate a steam output from a heat output from the heat removal system.PCT Specification Attorney Docket No. 27569.105078WO 8. The modular power plant system of claim 1, wherein the one or more diving walls defines a thermal and / or radiation barrier as between adjacent functional compartments of the segmented compartment structure.

9. The modular power plant system of claim 1, further comprising a natural gas system operably coupled to the energy conversion system.

10. A nuclear power plant comprisinga reactor system comprising a reactor core and operable to generate a heat output derived from fission reactions, the reactor system enclosed in a first functional compartment of a segmented compartment structure;a heat removal system operable to transfer the heat output from the reactor system, the heat removal system arranged in a second functional compartment of the segmented compartment structure adjacent to the first functional compartment; andan energy conversion system operatively coupled to the heat removal system and configured to receive the heat output, the energy conversion system associated with the segmented compartment structure collectively defining an integrated nuclear power plant unit.

11. The nuclear power plant of claim 10, wherein the segmented compartment structure is configured to house functional components of a nuclear reactor and is positioned elevationally below and thermally and radioactively shielded from the energy conversion system.

12. The nuclear power plant of claim 10, wherein the segmented compartment structure comprises a plurality of dividing walls separating a plurality of functional compartments and defining thermal and / or radiation barriers therebetween.

13. The nuclear power plant of claim 12, wherein the first subsurface functional compartment is separated from the second subsurface functional compartment by a first dividing wall of the plurality of dividing walls; and wherein the reactor system and the heat removal system are coupled with one another via at least one molten salt line penetrating the first dividing wall.PCT Specification Attorney Docket No. 27569.105078WO14. The nuclear power plant of claim 12, further comprising a fuel storage system operable to store a molten fuel salt, the fuel storage system arranged in a third functional compartment of the segmented compartment structure.

15. The nuclear power plant of claim 14, wherein the third functional compartment is separated from the first functional compartment by a second dividing wall of the plurality of dividing walls; and wherein the fuel storage system and the reactor system are coupled with one another via at least one molten salt line penetrating the second dividing wall.

16. The nuclear power plant of claim 12, further comprising an off-gas system operable to process an off-gas produced by the reactor system, the off-gas system arranged in a fourth functional compartment of the segmented compartment structure.

17. The nuclear power plant of claim 16, wherein the fourth functional compartment is separated from the third subsurface functional compartment by a third dividing wall of the plurality of dividing walls; and wherein off-gas system and the heat removal system are coupled with one another via at least one off-gas line penetrating the third dividing wall.

18. The nuclear power plant of claim 10, wherein the energy conversion system is coupled to a power grid.

19. A method of operating a modular nuclear power plant comprisinggenerating heat through fission reactions by a reactor system, the reactor system enclosed in a first functional compartment of a segmented compartment structure;transferring the generated heat from the reactor system by a heat removal system, the heat removal system enclosed in a second functional compartment of the segmented compartment structure; andreceiving the generated heat from the heat removal system by an energy conversion system, the energy conversion system associated with the segmented compartment structure.PCT Specification Attorney Docket No. 27569.105078WO 20. The method of claim 19 further comprising thermally and / or radioactively shielding the reactor system from the heat removal system by a dividing wall of the segmented compartment structure interposed between the first functional compartment and the second functional compartment.

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