Modular molten salt nuclear reactor

Abstract

The present invention relates to a nuclear reactor loop capable of containing molten salt containing nuclear fuel in channels arranged substantially vertically and providing up and down flow paths. The loop can be used to build a modular reactor from removable individual molten salt nuclear loops, a portion of which ("channels") have been placed in a critical configuration in which the channels contain non-critical amounts of nuclear material, but together produce a critical region of a reactor core. The present invention further relates to a method of operating a modular nuclear reactor loop and nuclear reactor.

Description

Technical Field

[0001] This invention relates to a modular nuclear reactor loop, specifically a modular molten salt nuclear reactor loop. The invention also relates to a modular nuclear reactor, specifically a modular molten salt nuclear reactor comprised of a nuclear reactor loop. The invention further relates to a method for operating a modular nuclear reactor loop. The invention further relates to a method for operating a modular nuclear reactor, and to a method for testing / qualifying a nuclear reactor. The invention also relates to a method for exchanging a portion of a nuclear reactor loop. Background Technology

[0002] Despite the shortcomings of early nuclear power plants, nuclear energy remains necessary as the world's energy demands continue to increase. A new generation (Generation 4 and Generation 5) of nuclear power plants is under development, specifically designed to supply large quantities of safe and clean energy while taking a prudent approach to the proliferation of nuclear materials and the generation of nuclear waste.

[0003] One generation of these nuclear power plants is the so-called molten salt reactor.

[0004] A molten salt reactor (MSR) is a type of nuclear reactor in which the primary coolant, or even the fuel itself, is a mixture of molten salt. Many designs have been proposed for this type of reactor, and several prototypes have been built. Early concepts and many current concepts rely on nuclear fuel dissolved in a fluoride molten salt. The fluid reaches criticality by flowing into a core where a moderator, such as graphite, may be present. Many known concepts rely on flowing the fuel through channels in a graphite matrix, where the molten salt provides low-pressure, high-temperature cooling. Some newly developed concepts have ruled out the use of moderators to create fast neutron spectrum system characteristics, instead employing specific moderators to locally generate specialized neutron spectra for specific purposes (e.g., burning long-lived actinides in nuclear waste streams).

[0005] Despite the successful design, construction, and operation of molten salt reactors in the past, the knowledge and experience required to redevelop this type of reactor remain limited. The key advantages of molten salt reactor systems in terms of safety, waste stream minimization, and resource efficiency maximization have been detailed in numerous examples, and increasingly so in the last 5 to 10 years. Undoubtedly, the enormous potential of molten salt reactor systems, particularly those fueled by thorium, to provide secure energy for millennia can be considered, with minimal radioactive waste burden. However, while the U.S. efforts in molten salt reactors during the 1950s and 60s successfully demonstrated the proof of principle, technical and economic feasibility, along with the long time to market, are major obstacles to timely implementation and thus investment.

[0006] Molten salt reactors typically provide optimized neutron economy by: frequently removing molten salt from neutron-absorbing fission and activation products, thereby minimizing neutron loss; providing an opportunity to shut down the nuclear fuel cycle, where the fuel used for fission is produced from excess neutrons generated from the fission reaction; and being able to convert neutrons such as... 232 Th or 238 Convertible elements such as U are transformed into, for example, 233 U and 239 Pu and other fissile elements.

[0007] Especially with a closed thorium fuel cycle, the prospect of shutting down the nuclear fuel cycle and creating extremely high resource utilization efficiency makes molten salt reactors a very promising reliable future energy source, given their extremely high level of (passive) safety and minimal long-life waste generation.

[0008] When considering the fuel and coolant in an MSR system, such technology presents a key and major complexity: all physics and engineering disciplines converge in a primary system, significantly influencing each other. In molten salt primary system components, chemistry, neutron physics, materials science, thermal hydraulics, thermodynamics, and other fields all come together. Therefore, establishing a molten salt reactor requires a multidisciplinary approach, employing multidisciplinary analysis and design, as well as multidisciplinary experimental verification.

[0009] Developing and validating multidisciplinary design tools, specifications, and licensing frameworks for molten salt deployments requires significant effort. Given the complexity of multidisciplinary approaches, even simple in-pile experiments or small-scale demonstrations struggle to adequately predict and justify safety without a sufficient and validated foundation of multidisciplinary knowledge and experience. Summary of the Invention

[0010] This invention details a method for minimizing the time-to-market for MSR-based power plants by proposing an efficient nuclear qualification approach that encompasses the full range of multidisciplinary complexities, and an MSR power plant design principle that fully leverages the nuclear qualification strategy. This will largely eliminate complex intermediate steps that are both expensive and time-consuming. The combination of this efficient nuclear qualification approach and a design closely matched to qualification could enable molten salt-based nuclear power plants to be commercially operational within 15 years, significantly shorter than the currently considered more realistic 20 to 30 years. This estimate assumes the feasibility of MSR technology, which can be assumed to be proven by the successful operation in the United States during the 1950s and 1960s.

[0011] Molten salt nuclear reactors have been previously described, for example, in US2015 / 0243376, US2017 / 0117065, WO 2017 / 098228, GB2508537, and WO 2017 / 070791.

[0012] In molten salt reactors, the coolant-fuel composition can be tuned and therefore adjusted during operation. This is not the case for the structural materials and components in the primary systems of known MSRs. The interaction between the coolant fuel and the components and materials of the primary system, as well as the intense radiation fields to which these materials and components will be exposed, are major challenges. Testing of materials capable of withstanding these harsh conditions, typically anticipated for the 40-60 year lifespan of a nuclear power plant, is necessary or essential. Many early MSR concept designs either neglect this aspect or include some form of radiation shielding buffer or sacrificial material layer to protect primary materials from radiation-induced degradation and chemical-salt interactions.

[0013] US2 999 057 describes one of these MSR designs. In US 2 999 057, a loop-based design is used for a complete nuclear reactor, in which several separate liquid streams are fed into and removed from the reactor core, circulated, and fed back into the core or moderator. The design causes the moderator to contain multiple channels in which liquid streams are fed to the bottom of the moderator and exit as a single stream at the top. The overall construction is a completely fixed design.

[0014] US2009 / 0279658 also discloses a molten salt reactor in a two-fluid reactor design. In this design, the molten salt reactor is essentially a vessel filled with molten salt, through which individual tubes exist in a fixed configuration and through which molten salt fuel is pumped. The size of the tubes and the fissile contents make each tube subcritical, and criticality is only reached when the tubes are close to each other. The design is a fixed design, consisting of a large vessel / containment, in which the tubes using molten salt circulation are located in a fixed configuration when there is no possibility of removing and replacing the core assemblies. The vessel has a single molten salt inlet and outlet.

[0015] US 3403076 describes a stationary molten salt breeder reactor in which a graphite fuel cell unit with a vertically positioned passageway is provided, through which molten salt fuel can be pumped and enclosed in a molten salt regeneration zone as a heat exchanger. This system has a single large reactor pressure vessel and feeds the graphite fuel cell unit with molten salt through a single inlet and outlet.

[0016] GB 2073938 shows a single reactor vessel and containment structure filled with molten salt, with pipes containing molten salt fuel passing through the reactor vessel and containment structure. The containment structure is a single containment structure containing molten salt and having a single inlet and outlet.

[0017] All these configurations share the common feature that the overall build is fixed. The tubular or fuel cell unit that delivers molten salt fuel is placed in a critical configuration and within an enclosed large reactor vessel / containment with a single molten salt inlet and outlet, thereby allowing the primary or regenerable molten salt to circulate centrally within the reactor vessel volume or the tubular or fuel cell unit.

[0018] Typically, reactor concepts conceived using liquid fuel coolants in existing technologies employ and teach relatively large and indivisible volumes of molten salt to fill the system core and support piping systems and equipment. This presents numerous challenges to the feasibility of these types of systems. Large containment containers are required to maintain the nuclear material containment. These large containers are complex to manufacture and operate, expensive, not easily replaceable, and not easily discardable after use. The "defense in depth" concept is a cornerstone of nuclear safety thinking and emphasizes the use of multiple barriers to prevent the release of contained nuclear source terms. A container containing all the fuel maximizes the source terms within a containment and forms a single first line of defense against release. After use, the large container becomes contaminated and may have been neutron-activated, which in itself is a major waste problem. The problem is exacerbated if the container and the components connected to it are still filled with highly reactive and toxic fuel coolant waste. Handling, storing, and disposing of this volume is challenging due to its size and potential radioactive exposure hazards. The large container forming the containment structure complicates core assembly replacement because it needs to be openable and accessible, and allows for the import and export of components. Core assemblies and materials in fuel-cooled systems typically suffer severe radiation damage under extreme temperature and chemical (corrosive) conditions. Since materials capable of withstanding the harsh conditions in the critical region of fuel-cooled systems for extended durations have not yet been found or developed, convenient replacement of core materials and assemblies would significantly accelerate the implementation of these systems.

[0019] The inventors of this invention have now essentially discovered an improved design for a molten salt nuclear reactor loop. This improved design provides greater flexibility, for example, in that individual loops can be built and tested before being assembled into a complete nuclear reactor. The loop is configured such that it can be placed in and removed from the reactor or moderator without dismantling the entire reactor or without affecting (not dismantling, not removing) other loops in the reactor.

[0020] The inventors' fundamental choice was to distribute the molten fuel coolant into separate, individual, and independent modules placed in a configuration in which a stable nuclear fission reaction can be maintained in the core region composed of the modules' core components. Each module has independent functionality and its own pumps, heat exchangers, and processing units. Each module is a self-contained system with its own (dual) containment. The modules can only be connected via a secondary non-nuclear coolant system or other secondary systems. Therefore, the modules do not share molten salt or nuclear material; each module has its own separate amount of molten salt and nuclear material. Each module is itself an independent nuclear reactor, but criticality is only achieved when two or more modules are brought close together.

[0021] In this way, modules can be easily removed and placed close to each other. Each module or loop can be removed independently from the nuclear reactor. Figure 6 An example is given in Figure 7. The (exemplary: cylindrical) design of the modules allows them to be placed side by side, and removing a module from the array can be done, for example, by raising or lowering the corresponding module.

[0022] This invention generally relates to a nuclear reactor including a nuclear reactor loop, a nuclear reactor loop, and a method for operating the nuclear reactor and the nuclear reactor loop.

[0023] The nuclear reactor loop of this invention is not a conventional MSR reactor vessel filled with molten salt, but rather a configuration of pipes, pipe bundles, or channelized blocks / cylinders, in which the molten salt circulates in separate and independent loops. The individual nuclear reactor loops and the molten salt loops therein are not coupled to each other or connected to each other via molten salt loops in the regeneration zone.

[0024] Each nuclear reactor loop is independent of the others and can operate independently.

[0025] This differs from existing technologies where the molten salt loop is a system interconnected via a central primary molten salt circulation system or a regeneration zone molten salt circulation system. Existing molten salt configurations are typically indivisible. Therefore, the nuclear reactor concept of this invention is modular. Separately constructed, individualized nuclear reactor loops or modules, along with modular molten salt loops, are placed adjacent to each other but do not share tubing, molten salt, or fuel. Each module contains its own molten salt, fuel, and tubing. Each module is an independent compartment within the nuclear reactor.

[0026] For example, in Figure 6 US2999057 illustrates a configuration in which conduits converge to form a core and then disperse. However, the entire configuration remains fixed and cannot be removed from the reactor without complete dismantling.

[0027] The modular core method of the present invention has the following advantages:

[0028] - Each module maintains at least two containments (i.e., two lines of defense), and the integrity of the two containments can be continuously monitored by measuring the fission product content in the gas flowing between the first and second containments and the fission product content in the coolant outside the second containment.

[0029] Monitoring of the containment enables the use of disconnectable primary containment components. Typically, the integrity of the primary boundary is ensured by welding or brazing, turning the primary boundary into a single component, and maintaining the containment closure without a doubt. Monitoring the integrity of the containment allows for the disconnection of components.

[0030] - Each module contains a portion of the total fuel coolant volume, which reduces the source item for each containment.

[0031] Each module contains a subcritical amount of fuel coolant, which cannot introduce a critical state at the module level. The fission reaction can only begin and be maintained when the modules are placed in a specific configuration, with the fuel coolant from multiple modules combined.

[0032] - When a module fails, the fuel coolant in the module can be passively discharged from the critical core area, reducing or stopping the criticality of the entire core, while the remaining functions of the module are unaffected.

[0033] - Avoid large components, thereby reducing costs and facilitating handling, transportation (where container size is feasible), and replacement. For example, large components or entire modules can be extracted and replaced, thus providing not only the opportunity to extend system life through replacement but also the ability to introduce new modules with improved performance or alternative fuel coolants.

[0034] - Because the total fuel coolant inventory is subdivided into modules, fuel coolant waste volumes are processed at the module level, which are manageable volumes that can be transported and further processed at separate locations.

[0035] - Without requiring complex disassembly of the entire reactor, modules can be placed in and removed from the reactor. Module replacement can be achieved by raising or lowering modules from the array of modules constituting the reactor, and module replacement only requires disconnecting secondary connections (e.g., instrumentation, power, secondary heat exchangers, etc.).

[0036] From a neutron physics perspective, the modular core approach yields suboptimal core configurations because the configuration is determined by practical design considerations at the module level (e.g., replaceability and the introduction of containment for each module in the critical core region). Since nuclear safety is a prerequisite for the feasibility of fuel coolant systems, the inventors prioritized nuclear safety. Even though this approach limits the possibility of optimizing core configurations to maximize neutron economy, the use of fuel coolant provides benefits to compensate for the neutron economic shortcomings of the chosen modular approach. In particular, the use of fuel coolant offers the potential for higher neutron efficiency than solid-fuel reactors, especially where unwanted neutron-absorbing fission products can be effectively removed online from the fuel coolant. Because the fuel coolant system primarily functions as a low-pressure liquid and gas barrier, the low pressure allows the containment to remain relatively thin. This minimizes the negative impact of neutron absorption by the containment material in the reactor core region on core performance, while optimizing safety and relatively rapid development, licensing, approval, and implementation timelines.

[0037] The construction of the nuclear reactor loop of the present invention (as a single pipe, multiple pipes, pipe bundles, or a block / cylinder with channels) enables nuclear testing and loop system qualification in a suitable nuclear test reactor facility using a single loop system.

[0038] On one hand, the nuclear reactor loop of the present invention includes a loop capable of containing and / or circulating nuclear fuel. The loop includes channels arranged substantially vertically, optionally substantially straight. These channels provide vertical passages for liquids within the loop.

[0039] Individual molten salt nuclear loops or representative versions thereof can be placed in the radiation field of an existing reactor (e.g., a suitable materials test reactor), and thus can be used for the design, development, testing, and certification of materials and components for molten salt nuclear reactor loops.

[0040] Individual molten salt core loops can be used as components of molten salt nuclear reactors, which in turn are composed of multiple such individual loops.

[0041] On the other hand, the present invention relates to nuclear reactors incorporating one or more loops of the present invention. A nuclear reactor containing one loop can be used to verify and test the loop. Based on individual molten salt loops, multiple loops can be combined to form a nuclear reactor.

[0042] The nuclear reactor includes a core region and a shell region. The core region is surrounded by the shell region. Multiple nuclear reactor loops are provided in the nuclear reactor. Each nuclear reactor loop includes a loop containing one or more channels.

[0043] The loop is capable of containing a liquid containing convertible and / or fissile materials. One or more liquid tanks are arranged (selectively detachably) connected to the loop and are capable of containing liquid containing convertible and / or fissile materials. Channels of multiple loops are arranged in the core region. The arrangement of the channels in the core forms the critical region of the nuclear reactor, thereby sustaining the nuclear fission reaction.

[0044] Multiple individual loop channels can be placed in a critical configuration with inherent safety and efficiency to develop and operate a molten salt nuclear reactor. Each individual loop contains a subcritical amount of nuclear fuel. The channels in each individual loop configuration can each contain a subcritical amount of nuclear fuel.

[0045] Nuclear reactors built with separate loops allow for flexibility in the fuel cycle (the loop can contain different fuel / molten salt combinations, or the fuel / molten salt combinations can be changed), and the primary components of the loop, and therefore the primary components of the nuclear reactor, are replaceable. With loops and reactors having replaceable primary components, the reactor's lifespan can be extended and its lifespan can be reliably managed. Because system components can be replaced with new and improved components, the nuclear reactor loop and the reactor built from it can also be further optimized. The design of the loop allows for individual testing and certification of the loop's components. Because the configuration can be designed to deactivate the nuclear reactor when one or more molten salt loops deviate from the intended function of the design, the nuclear reactor loop (or circuit) and the design of the nuclear reactor built from these loops exhibit improved safety characteristics.

[0046] Essentially, the reactor is based on multiple individual loops, which can be arranged in a circular configuration. A portion of each loop is located at a smaller radius (“channel” or “hot section”), creating a critical configuration (“critical region”) that sustains the nuclear reaction, while the remainder of the loop is located at a larger radius, largely outside the radiation field of the critical region, in a non-critical configuration. The loop channels or piping systems are in direct contact with molten salt. By providing a sufficient amount of fissile material in the critical configuration formed by the combined channels, and using moderator material in the case of aligned (extensional) thermal neutron spectrum reactors, the channels contain molten salt and form the critical region of the reactor. The channels are exposed to high radiation flux. The use of piping allows for replacement once material limits in terms of radiation exposure and / or molten salt exposure are reached, and replacement can be performed relatively easily. The channels can be a single pipe, a bundle of pipes, or a block with channels. Due to the high radiation flux exposed to the reactor critical region, combined with contact with (corrosive) molten salt and fissile products, the channels degrade relatively quickly. The channels are also relatively small components that can be replaced, thus increasing reactor lifetime. Even if a single pipeline system and channel replacement requires significant remote processing development, it is considered more feasible than trying to find and identify materials that can withstand MSR conditions for up to a decade.

[0047] Alternative locations, such as Figure 6 As illustrated in Figure 7, the loops can be arranged vertically, with the channels located in the upper half of the loop and the other components at the bottom. By placing the vertically arranged loops together, the channels are close to each other, allowing neutron exchange between modules and establishing a critical core configuration in which nuclear fission reactions can be sustained. Removing a loop or deactivating a loop by venting molten salt from the channels into a container in the lower half will destroy the reactor's criticality.

[0048] A nuclear reactor comprises multiple separate and individual nuclear reactor loops or modules, each module containing, as a primary system, a noncritical amount of molten salt liquid and convertible or fissile material as nuclear fuel.

[0049] Each module is connected to the reactor's secondary system.

[0050] Each module is placed in a reactor within a configuration of the other modules.

[0051] Each module is placed within the neutron flux of one or more other modules.

[0052] When multiple modules are combined and placed within a configuration of one or more other modules and within a neutron flux, the multiple modules contain critical amounts of convertible and / or fissile materials.

[0053] This involves removing modules (components) from the secondary system while maintaining the configuration of other modules in the reactor; each module can be removed individually from the reactor system.

[0054] The primary system of the module includes pumps, primary heat exchangers, and primary treatment devices such as discharge tanks, either separately or integrated in the loop.

[0055] The secondary system includes a secondary control device that can exchange heat with the primary heat exchanger of the module and a secondary non-nuclear heat exchanger.

[0056] In the implementation, the module may have a vertically elongated polygonal or cylindrical shape. In the implementation, the primary system is a vertically arranged (closed) loop within the module. In the implementation, the module containing the molten salt loop is primarily placed in the upper half of the vertically elongated polygonal or cylindrical shape, and another element, such as a pump, a primary heat exchanger, and a primary treatment device such as a discharge tank, is placed in the lower half. When the modules are placed in a configuration that places the molten salt loop of one module within the neutron flux of other modules, achieves a critical configuration for sustaining nuclear reactions and generating energy.

[0057] In another aspect, the present invention relates to a method for operating a nuclear reactor loop, the method being implemented by arranging a channel of the nuclear reactor loop, or a representative version of the nuclear reactor loop, near the core of another nuclear reactor, such that the channel of the loop is exposed to the neutron flux of the other nuclear reactor. This simulates loop operation in a nuclear reactor consisting of numerous reactor loops, with the aim of testing, characterizing, and evaluating loop materials, loop fluids, and loop assemblies in a representative test environment that includes the multidisciplinary complexity of MSR.

[0058] In another aspect, the present invention relates to a method of operating a nuclear reactor, the method comprising the steps of providing a nuclear reactor comprising the nuclear reactor loop of the present invention and, possibly, a (neutron) moderator. The method further comprises: providing multiple nuclear fuels containing convertible and / or fissile materials; and providing multiple nuclear fuels to the multiple loops. The nuclear fuel and moderator material and / or the configuration of the channels in part or all of the channels create a critical region in which nuclear fission reactions can be sustained. The method of the present invention enables the loop of the present invention to be used in a nuclear reactor for various purposes, some of which are to generate energy, to serve as a breeder facility by converting convertible elements into fissile elements using neutron / neutron absorption, thereby producing nuclear fuel, and / or to produce isotopes and materials and combinations thereof for other applications. The modular construction of a nuclear reactor having the nuclear loop of the present invention enables the operation of the nuclear reactor to simultaneously or subsequently meet various needs without making significant changes to the reactor configuration, but rather by changing individual loops and / or changing the liquids contained in the loops and / or changing the moderator materials. Attached Figure Description

[0059] Figure 1 A schematic representation of a top view of a nuclear reactor is shown, in which passages are placed within the reactor core.

[0060] Figure 1A A schematic representation of a top view of four separate loops (separated by schematic dashed lines) with channels located at points represented in a pie chart. When the channel (4) is placed in the reactor, the channel (4) is the part of the nuclear reactor loop closest to the other independent nuclear reactor loops that together form the nuclear reactor core through their individual (subcritical) neutron contributions via a combined critical equilibrium that produces neutrons.

[0061] Figure 2 A schematic representation of a nuclear reactor loop is shown.

[0062] Figures 3A-3C A schematic representation (side view) of a nuclear reactor loop is shown, in which the channel is positioned at a distance from the return line and in a substantially vertical position. The channel contains a bidirectional flow established by one or more U-bends, tube-in-tube configurations, or block configurations with channels.

[0063] Figure 4 The diagram shows a schematic representation of the components of a nuclear reactor loop and the inlet and outlet flows.

[0064] Figure 5 A schematic representation of a side view of a nuclear reactor loop is shown.

[0065] Figure 6The diagram shows a schematic representation of a nuclear reactor loop in a cylindrical configuration, with a side view (left) and a top view (right). In the upper section, the channel is situated in a circular arrangement with vertical upper and lower channels. Pumps, heat exchangers, expansion tanks, fission product extraction devices, storage units, and instrumentation are located in the lower section below the channels, outside the neutron flux field. The top view shows a preferred arrangement of the upper and lower channels.

[0066] Figure 7A The illustration shows a configuration in which nuclear reactor loops (here, seven loops arranged in a circular configuration) are placed separately. When the individual loops are placed close to each other, the channels of each individual loop are also placed close to each other, and criticality can be achieved by selecting appropriate amounts and concentrations of fuel in the channels. The loops can be removed from the configuration.

[0067] Figure 7B The placement of loops in a square array reactor is shown.

[0068] Figure 7C An embodiment is shown in which multiple alternative loops are placed around the circular core region of a reactor. These alternative loops may facilitate fission reactions in the core region or have another function, such as generating fuel by multiplication or neutron activation using neutrons emanating radially from the core region. In cases where neutrons are primarily absorbed and not generated by the circumferential loops, these neutrons form what is known as the reactor shell (or regeneration zone) region. Detailed Implementation

[0069] On one hand, the present invention relates to a nuclear reactor loop, the nuclear reactor loop comprising:

[0070] A loop (3), wherein the loop (3) is capable of containing a liquid containing convertible and / or fissile materials as nuclear fuel, and, if necessary, the loop (3) is capable of circulating the convertible and / or fissile materials.

[0071] The loop (3) therein contains a channel (4) that is preferably substantially straight, the channel (4) being part of the loop and arranged in a substantially vertical manner, wherein the channel (4) provides vertical passage (4a, 4b) for liquid in the loop.

[0072] The nuclear reactor loop according to the invention may include a loop (3) containing channels (4) and connectable to a liquid tank (5). The loop may include a feed line (6), channels (4), an outlet line (7), and a return line (8). In the loop, the feed line, channels, outlet line, and return line are connected and arranged to form a loop capable of containing liquid. The liquid may contain convertible and / or fissile materials. A liquid tank is connected to the loop and arranged to contain liquid. The channels of each loop may be placed independently in a substantially vertical arrangement.

[0073] An advantageous feature of the invention is that, when the channels are arranged in a substantially vertical configuration, separate loops for upward, reverse, and downward flow can be accommodated within the channels. This configuration allows the channels to be enclosed within a containment vessel, which is closed at one end (preferably the top) and connected to the loops at locations where the channels also connect. This enables convenient vertical disconnection, removal, and replacement of the containment vessel and channels via the upper reflector and / or radiation shield of the reactor containment vessel. For MSR systems, convenient and periodic replacement of core materials and components is an important aspect of reactor life and economics, given the combination of core assembly exposure to high temperatures, high radiation flux, and potentially harmful chemical interactions with molten salt and its components.

[0074] The channel can be detachably connected (i.e., connected in such a way that the channel can be detached, optionally, along with the containment (29)). By providing the channel as an upper and lower passage, the inlet and outlet are positioned on the same side (top or bottom) of the loop. This allows the loop (and / or the channel) to be removed from its surrounding environment (near the reactor core where the loop is positioned to receive radiation from or interact with radiation from the nuclear reactor) or from the moderator (in the case where the channel of the loop is placed in the reactor's moderator). Removal can then be achieved by raising or lowering the (detached) channel and / or the entire loop from the reactor without having to dismantle the reactor. This removal offers significant advantages over conventional (molten salt) reactors because it allows for the replacement, repair, or otherwise manipulation of reactor components without having to dismantle (most) the reactor.

[0075] The passageway can be surrounded or enclosed within a removable and / or replaceable containment. An inert gas may be present between the containment and the passageway to provide thermal insulation. This inert gas can be monitored (online) to detect molten salt leaks and can be used to (pre)heat primary components.

[0076] The remainder of the loop is also protected by appropriate layers of defense to prevent breaches of the defense-in-depth design and to prevent the release of radioactive materials from the containment or seal. Similar to channels, containment functions and gas gaps may include loop system heating and / or leak monitoring / detection capabilities.

[0077] Between separate (inclusive) channels, moderator materials can be placed or avoided to adjust and optimize the neutron spectrum specifically designed for the system's envisioned fuel cycle (e.g., a simple uranium combustion cycle, or a thorium-uranium or uranium-plutonium breeder cycle). For thermal reactor designs, using a separate reactor loop allows the moderator to be decoupled from the molten salt. Unlike other known or known-under-development thermal MSR system designs, the moderator function and the molten salt containment or molten salt flow guidance function are separate.

[0078] Therefore, in another aspect of the invention, a method is provided in which components of a reactor loop are removed by disconnecting the channel, channel containment, and / or liquid tank from the loop and removing the channel, channel containment, and / or liquid tank from the loop, or by removing the entire loop from the reactor. In the case of a loop placed in a reactor configuration, replaceable connecting channels, channel containment, and liquid tanks can be removed and / or replaced from the reactor shell region or core region. In some embodiments, removing the channel, channel containment, and / or liquid tank from the loop includes removing the entire nuclear reactor loop from the reactor before removing the channel, channel containment, and / or liquid tank from the loop. In other embodiments, the channels, channel containment, and / or liquid tanks of the loop can be removed from the nuclear reactor, while the remainder of the nuclear reactor loop remains within the nuclear reactor.

[0079] The inlet line for the channel is located at one end of the channel. The outlet line is located at the other end of the channel. The channel has a supply end (inlet line) and a discharge end (outlet line), both of which are part of and / or connected to a loop, such that liquid is supplied to and discharged from the channel from the same side of the channel.

[0080] The loop may contain liquid and circulate the liquid. The loop includes a loop containing a channel (4).

[0081] The channel (sometimes considered a hot section) used herein is a portion of the loop most exposed to neutron radiation from nuclear fission reactions inside and / or outside the channel (when the loop is exposed to external neutron radiation), and wherein the channel and the fluid within the channel are heated by nuclear fission reactions and / or nuclear heating (energy deposited in the channel material and fluid through radiation absorption). The loop fluid flows through the channel in a bidirectional manner (up and down or down and up). The channel can be selected from a single pipe, a bundle of pipes, a tube-in-tube, or a block / cylinder with a channel that allows up and down flow. The channel can enable unidirectional or bidirectional molten salt flow. The channel can be connected to a feed line (6) and a return line (8) to supply liquid to and retrieve liquid from the channel. Preferably, a channel that allows bidirectional flow, such as a bundle of pipes, a tube-in-tube, or a block / cylinder with a channel, is preferred.

[0082] The substantially straight position of the channel is preferably suitable for the external placement of the channel in the loop. In an alternative embodiment, the channel may have a spiral upward (or downward) and a spiral downward (or upward) loop on the outer periphery of the channel to complete the upper and lower passages of the passage.

[0083] The channel can be connected to the feed line at one end. The channel is connected to the outlet line (7) at the other end. The outlet line is connected to one end of the channel. The outlet line is connected to the other end of the return line. The return line is connected to one end of the outlet line. The return line is connected to the feed line at the other end. This configuration of the feed line, channel, outlet line, and return line provides a closed loop or circuit as used in this invention.

[0084] Typically, channels are connected at both ends (inlet and outlet) of the channel, making the channel part of a closed loop capable of containing and circulating liquid. At one of these ends, a feed line can be located upstream of the channel, and an outlet line can be located downstream of the channel. A return line can be located downstream of the outlet line and upstream of the feed line, thus providing a loop containing the channel.

[0085] One or more liquid tanks (5) can be connected to the loop. The loop is capable of containing liquid. The liquid may contain convertible and / or fissile materials. In such a way that the channel can be placed within the flux of an existing nuclear reactor (i.e., a suitable materials test reactor) during operation, the nuclear loop of the present invention forms a loop, wherein the channel can be placed at a distance from and spaced apart from the rest of the loop. The channel itself and its contents may be exposed to radiation from the existing (test) nuclear reactor. Furthermore, other elements of the nuclear reactor loop can be placed outside the flux of the existing reactor.

[0086] This provides a construct that allows for testing and qualification of the materials and configuration of the nuclear reactor loop itself. Therefore, the nuclear reactor loop can be used for general testing, model verification, and qualification of new reactor concepts by placing the nuclear reactor loop within the flux of a test nuclear reactor. One or more liquid tanks connected to the loop can be used to fill the nuclear reactor loop and can be used to store liquid contents.

[0087] In one implementation, preferably, the channel does not contain a critical amount of nuclear material, i.e., the channel is subcritical.

[0088] In some embodiments, the circuit may contain a liquid. The liquid may contain a convertible element and / or a fissile element. The liquid may be a molten salt. The liquid may be circulated through the circuit, for example, by convection and / or by a pump integrated into the circuit.

[0089] Molten salt typically has a high coefficient of thermal expansion. Therefore, natural circulation can occur within the loop when molten salt is used. The salt in the channel, heated by the fission reaction, rises to the top of the channel or is further propelled, where heat can be extracted from the molten salt, for example, through an optional heat exchanger. The molten salt, with its high coefficient of thermal expansion, becomes denser and tends to move back through the loop's outlet and return lines, where it is replaced by molten salt that has been heated in the active zone. As the cooled molten salt moves through the loop, it passes through a "critical zone" in the channel, where it may be exposed to external radiation. Passing through the critical zone generates heat in the molten salt, causing it to become less dense and circulate back to the top of the container channel to repeat the process. Thus, natural flow circulates hot molten salt through the loop and optional heat exchangers, where heat can be extracted, and allows cooler molten salt to return through the critical zone where it is heated. This natural circulation can form the primary driving force for flow within the loop.

[0090] The natural circulation effect in the loop can reduce the need for pumps in the loop or circuit to circulate material through the reactor core. Pumps can be provided to supplement this natural circulation effect and / or may be required as the primary force for circulation. For example, when a large amount of energy is generated in the loop, pumps are preferred to actively move heat from the channels to the loop section where heat is removed.

[0091] In some embodiments, the channels are arranged in a substantially vertical configuration. In this context, substantially vertical means that liquid in the channels can move through the channels by convection and / or gravity. The channels may be at an angle of up to about 45 degrees to the vertical direction, preferably not exceeding about 20 degrees, 15 degrees, or 10 degrees. More preferably, the angle is less than about 5 degrees. Preferably, the elements of the loops and circuits are arranged and positioned in such a manner that the loops allow or facilitate the passive discharge of fluid into the liquid tank by gravity.

[0092] In an implementation of a nuclear reactor loop that is a molten salt reactor that may contain convertible and / or fissile materials, a liquid tank can be connected to the loop via an active or passive start valve or through-hole.

[0093] An example of passively initiated penetration is a molten salt plug (or cryo-plug) (11) in the connection between the loop and the liquid tank, typically achieved by active cooling of a portion of the connection to solidify the molten salt. This portion of the connection is usually positioned between the loop and the tank. Once cooling is deactivated or removed, or the temperature rises, the molten salt plug melts, and the contents of the loop are discharged into the tank. Molten salt plugs are often useful in the event of overheating of the reactor loop and effectively reduce or stop nuclear fission reactions by passively discharging fissile material from the core via the molten salt plug. The liquid tank is preferably located near the lowest point of the reactor loop. The combination of at least the substantially vertical arrangement of the channels and the placement of the molten salt plug and the liquid tank near the lowest point of the loop enables the emptying of the loop contents from the tank in an emergency (i.e., runaway or overheating) situation, thus removing fissile material from the loop and from the critical core region of the reactor, thereby stopping or reducing nuclear fission reactions in the loop and decriticalizing the reactor system. Preferably, the tank is located outside the reactor flux, or at least at a location where the reactor flux cannot sustain the nuclear reaction in the loop. The liquid tank can be used to discharge liquid from the loop (shutdown) and / or to fill the loop with liquid (startup). The liquid tank can be suitable for liquid storage and has temperature control capabilities for molten salt conditioning purposes. The liquid tank can be removed and replaced. Having a removable and replaceable liquid tank allows for the introduction of new molten salt compositions into the loop, or the management of molten salt purification or alteration at other locations. Alternatively, individual tanks can be discharged into removable and replaceable transport tanks or containers.

[0094] In some embodiments, the loop may further include other components such as an expansion vessel to handle pressure changes and molten salt volume changes, for example, due to thermal expansion. The loop may further include a pump for conveying liquid in the loop, a heat exchanger for heating the fluid in the loop, or removing heat from the fluid in the loop to a second medium for transferring heat to an energy generation unit. The loop may further contain or be connected to means for chemical treatment, such as for removing impurities, unwanted byproducts, neutron-activated or fissile products, or elements generated in the molten salt that would enhance system degradation through corrosion or deposition. Potential non-diffusion issues with material extraction should and can be managed by design. The loop may further contain or be connected to means for adding and / or removing one or more of the following: convertible materials, fissile materials, fissile products, source materials and neutron-activated materials for neutron activation, and liquids (e.g., molten salt).

[0095] In one embodiment, there are multiple liquid tanks. The amount of nuclear material in the loop and / or channel may be less than the critical amount (i.e., the channel of the loop contains a subcritical amount of nuclear material). In this embodiment, preferably, the channel does not contain a critical amount of nuclear material, i.e., the channel is subcritical. Therefore, in some embodiments, multiple liquid tanks may be provided such that one liquid tank may contain a portion of the liquid contained in the loop, and thus contain only a subcritical amount of nuclear fuel.

[0096] The liquid tank can be removed from the structure and placed in a transport container to move the liquid to a location for molten salt cleaning, molten salt composition optimization, or other molten salt treatment purposes, including adjustments for waste storage and disposal.

[0097] The liquid in the nuclear reactor loop (and therefore in the reactor) according to the invention may contain preferably selected from... 232 Th、 238 Pu、 238 U、 240 Pu、 242 Convertible materials of one or more isotopes of Pu and other actinide elements.

[0098] The liquid in the nuclear reactor loop (and therefore in the reactor) according to the invention may contain preferably selected from... 233 U、 235 U、 239 Pu、 241 fissile materials of one or more isotopes of Pu and other actinide elements.

[0099] In this respect, the term convertible material refers to a material that can be converted into fissile material through neutron transmutation and subsequent nuclear decay. In this respect, the term fissile material refers to a material that can undergo nuclear fission through neutron irradiation (i.e., the material is fissile) and also produces neutrons from such fission that can sustain nuclear reactions under the correct conditions. The process of converting convertible material into fissile material by absorbing neutrons is called fuel breeding.

[0100] The liquid in the nuclear reactor loop (and therefore in the reactor) according to the invention may contain preferably selected from... 233 U、 235 U、 239 Pu、 241 fissile materials of one or more isotopes of Pu and other actinide elements.

[0101] The liquid in the nuclear reactor loop (and therefore in the reactor) according to the invention may contain long-lived isotopes extracted from nuclear waste, such as isotopes from neptunium, plutonium, americium, curium and other actinide elements, for example for the purpose of reducing the lifetime of nuclear waste.

[0102] The liquid in the nuclear reactor loop (and therefore in the reactor) according to the invention may contain isotopes specifically designed for generating activating or fission products with medical or industrial uses, from sources such as... 176 Yb (used for generation) 177 Lu), 160 Gd (used to generate) 161 Tb and other enriched stable isotopes to, for example 235 U / 233 U / 239 Pu (generated through fission) 99 Mo、 90 Sr and 131 I) 237 Np (used for generation) 238 Pu) and 226 Ra (used to generate) 227 Ac、 228 Th、 229 Th、 225 Selected semi-stable or unstable isotopes such as Ac, etc.

[0103] The liquid in the nuclear reactor loop according to the present invention can be a molten salt. In a preferred embodiment, the molten salt is selected from fluorides and / or chlorides, preferably one or more of LiF, NaF, KF, RbF, BeF2, ZrF4, LiCl, NaCl, KCl, RbCl, BeCl2, ZrCl4, and mixtures thereof.

[0104] The channel of the present invention is made of a material that can sufficiently withstand corrosion caused by molten salt in the circuit and minimize degradation due to neutron flux and radiation, while minimizing neutron absorption to optimize neutron economy. A material with high resistance to molten salt corrosion can withstand radiation damage relatively well and has low neutron absorption. Suitable materials include molybdenum alloys, graphite, silicon, and other carbides.

[0105] The channel of the present invention is, in its simplest form, a single pipe (pipe) or channel. In one embodiment, the channel (4) comprises an upper pipe (4a) and a lower pipe (4b) connected to each other at the top or bottom. It can also be conceived as a U-shaped pipe (single pipe) that bends at the top or bottom (preferably at the top).

[0106] Therefore, preferably, the channel is a U-shaped tube, wherein the inlet line and the outlet line are respectively placed independently at or near the lower end (in the lower half) of the channel. Figure 3A ).

[0107] In one implementation, the channel is a tube-in-tube ( Figure 3B The tube-in-tube (casing, bidirectional) comprises an inner tube (14) located inside an outer tube (15), wherein the outer diameter of the inner tube is smaller than the inner diameter of the outer tube, wherein one end (preferably the bottom end) of the inner tube is connected to a feed line, and one end (preferably the bottom end) of the outer tube is connected to an outlet line, wherein the outer tube has a closed end (preferably at the top) away from the end connected to the outlet line.

[0108] or

[0109] One end of the inner tube is connected to the outlet line, and one end of the outer tube is connected to the inlet line. The outer tube has a closed end away from the end connected to the inlet line, and the other end of the inner tube has an opening located near the closed top of the outer tube. The length of the inner tube within the outer tube is shorter than the length of the outer tube. This creates a section where the liquid flows in opposite directions.

[0110] In another embodiment of the channel, the inner or riser tube is placed coaxially with respect to the return or outer tube, or vice versa.

[0111] In another embodiment, the channel may include a single tube for upward (or downward) liquid flow and multiple tubes for downward (or upward) liquid flow. The tubes may have different diameters to accommodate this configuration. See also [link to relevant documentation]. Figure 3C .

[0112] In another embodiment, the channel can be configured as a solid block or cylinder, wherein the channel is configured to pass through the block or cylinder to accommodate integrated upward flow, reverse flow, and downward flow. Figure 3C The block design can be optimized for optimal fuel distribution and may also contain deceleration elements, and / or the block design itself may be made of deceleration material.

[0113] Preferably, the channel is adapted for both upward and downward flow, and this flow reversal portion is important because it allows the connection of the entire channel to be broken at an end position (preferably at the lower end), where the channel is connected to the rest of the loop. This also applies to the containment vessel surrounding the channel, which can also be connected at the same end (preferably the lower end) to form an outer shell that can be replaced by vertically removing the containment vessel from the reactor via the upper neutron reflector and / or radiation shield of the reactor containment vessel after disconnecting from it.

[0114] Essentially as explained elsewhere in this document, a nuclear reactor loop, including loops containing channels, may contain and / or connect to other components and / or functional elements, such as heat exchangers, pumps, chemical processing units, etc., to form a separate, independent loop.

[0115] On the other hand, the present invention relates to a nuclear reactor, the nuclear reactor comprising a core region and a shell region, wherein the reactor is composed of multiple separate and individual nuclear reactor loops or modules, each loop comprising...

[0116] Loop (3), wherein the loop (3) is capable of containing a liquid containing convertible and / or fissile materials as nuclear fuel and optionally circulating the convertible and / or fissile materials.

[0117] The loop contains preferably substantially straight channels (4), which are part of the loop and arranged in a substantially vertical arrangement, wherein the channels provide vertical passages (4a, 4b) for the liquid in the loop, wherein each of the channels of the plurality of loops is arranged in the core region, and wherein each loop is independently removable from the nuclear reactor.

[0118] Therefore, the nuclear reactor includes a core region (1) and a shell region (2). The core region is surrounded by the shell region. The shell region may function as a neutron reflector, a radiation shield, or a neutron absorption and regeneration zone to generate materials and isotopes through neutron activation, or a combination of these functions. The regeneration zone function of the shell can be achieved by a loop that supplies fluid to the shell containing target materials for neutron activation and recovers fluid from the shell. In the nuclear reactor, multiple nuclear reactor loops are provided.

[0119] The channel is part of a loop located in the reactor critical region (i.e., subjected to neutron flux).

[0120] A nuclear reactor is constructed from a set (or more) of separate nuclear reactor loops.

[0121] The loop is an independent loop or module and is removable from the reactor without interfering with other modules. The channels of the loop are arranged adjacent to each other. Multiple loops can be placed in a configuration that forms the reactor (e.g., a circular configuration, a rectangular configuration, or other configurations). A circular configuration is preferred. The channels of the loop can be located at a smaller distance from each other (i.e., closer to each other) compared to other elements constituting the loop. An effective visualization is that, in the case of a reactor with a pie-shaped configuration in a top view, multiple individual loops form multiple pie sections, each pie having a channel of the loop facing the center of the pie. This effectively places other elements of the loop outside or further away from the critical region of the reactor. The loop can contain multiple channels. In a circular configuration, the radius of the channel from the reactor center will be smaller than the radius of other elements from the reactor center. The channels together form the critical region, which is the reactor core. In some embodiments, the channels can be placed in multiple circles to form the critical region. Another circle of the channel (9) can surround the critical region. The critical region is surrounded by a shell region that can provide the functions of a neutron reflector, neutron moderator, radiation shield, or regeneration zone. The regeneration zone function can be implemented by an additional loop that supplies the target material to the channel (9) in the shell region surrounding the critical zone. The regeneration zone can be used to generate fissile material from convertible material (breeding) or to produce isotopes for various applications. The regeneration zone function can be provided by a channel with the same or different geometry (cross-section) as the channel (4) used in the core. Both the channel (4) in the core loop within the shell and the channel (9) in the external core loop within the shell can have a circular geometry (cross-section) (e.g., Figure 1(As shown), but the channels can also be independently oval and / or elliptical. Channels in the shell region can be designed for absorbing neutrons from the reactor's critical region, and depending on their intended use, they can have dedicated configurations optimized for their function, very different from those in the core loop. Each channel can independently comprise a liquid containing convertible and / or fissile materials or another target material activated by the neutron flux in the shell region.

[0122] To ensure the reactor core reaches full criticality, selected loops or all loops can individually supply subcritical amounts of nuclear fuel to the reactor's critical region. The combined channels within the core (along with optional moderator materials in and / or between channels) then provide sufficient critical mass and moderator to achieve criticality in the reactor core. Criticality is strongly temperature-dependent; increased temperatures lead to a decrease in the density of fissile material in the channels, and vice versa, thus passively increasing the safety control over the fission reaction. To further control or stop the fission reaction, control rods can introduce neutron-absorbing material (if present between channels) or remove neutron-absorbing material from the core region by moving it between or near the channels in the moderator material or in the shell region.

[0123] In some embodiments, the reactor core contains two or more channels, four or more channels, six or more channels, ten or more channels, or twenty-five or more channels, preferably six to twenty channels. In some embodiments, the reactor contains two or more loops, four or more loops, six or more loops, eight or more loops, or ten or more loops.

[0124] In a typical implementation, the reactor is based on multiple separate loops containing loops that can be arranged in a circular configuration, with a portion of each loop located at a small radius (“channel” or “hot section”) to create a critical configuration (“critical region”) that sustains the nuclear reaction, while the remainder of the loop (other elements, functional components) is located at a larger distance or radius outside the radiation field of the critical region, forming a noncritical configuration.

[0125] The channel is a separate and separable component that can be disconnected, removed, and replaced. The channel containment (29) is a separate component that can be disconnected, removed, and replaced. The channel containment may include multiple enclosing containments. An inert gas that provides insulation may be present between the channel containment and the channel, and the inert gas can be monitored for cracking products or other molten salt (volatile) components to detect leaks, and the channel can be (pre)heated by purging the space between the channel containment and the channel with hot gas. The channel and / or containment are separate components that can be disconnected, removed, and replaced individually. The channel may be (partially) enclosed by one or more separate containments. Alternatively, the entire loop may be removed from the core area for replacement.

[0126] Each of the multiple loop channels (preferably with a containment structure) is arranged in the core region. In some embodiments, the core region may contain a moderator (10). The moderator (10) may be located between or around the channels. In this way, the channels (and the moderator) together form the critical region of the reactor core. A suitable moderator may be any low atomic weight solid material containing a carbon-based material and having low neutron absorption.

[0127] In some implementations, a moderator-free nuclear reactor, a so-called fast reactor, can be provided, thus offering a fast neutron spectrum. While these types of reactors present certain technical challenges, such as rapid material degradation, the concept of the loop of this invention will allow for relatively rapid and easy replacement of primary materials forming the loop, such as the loop channels and channel containment, or the entire loop.

[0128] In many applications that require more epitaxial thermal spectrum (hotter than fast neutrons, such as thorium cycle) or thermal spectrum, it is preferable to include a moderator in the reactor.

[0129] Deceleration can be further increased by selecting materials for the channels and channel containment and by adding decelerating materials between the loop channels, or deceleration can be minimized by using non-decelerating materials in the loop and filling the space between the loop channels with non-decelerating media or materials.

[0130] In this respect, criticality refers to the normal operating state of a nuclear reactor, in which nuclear fuel sustains fission reactions. A reactor reaches criticality (and is called critical) when each fission event releases a sufficient number of neutrons to sustain a series of ongoing nuclear fission reactions.

[0131] The reactor channels can be arranged such that each channel (and the liquid within it) experiences a similar neutron flux and neutron energy spectrum. Alternatively, the critical region can be arranged such that each channel within the critical region experiences a different flux and / or a different neutron energy spectrum. Such an arrangement would be useful where a specific neutron flux is required for a particular critical region (e.g., a region where the channel is located, which is part of a circuit dedicated to generating a specific isotope by neutron activation or by using neutron / neutron absorption to convert convertible elements into fissile elements).

[0132] Unlike conventional nuclear reactors, by disrupting one or more loops, rather than requiring disruption of all loops in the reactor, it is possible to sufficiently halt or decriticalize the reactor and thus trigger a fission chain reaction to bring the entire core into a noncritical state. In this way, not all loops need to be "offline" or decriticalized. This is extremely convenient in terms of maintenance and safety. For example, consider a reactor with 10 loops, each contributing 10% of the critical amount of nuclear material to the core, bringing it to criticality. In an emergency, simply taking one loop offline (draining its contents into a liquid tank) renders the entire reactor noncritical, while the other nine loops remain unaffected.

[0133] In another aspect, the present invention provides a method for operating a nuclear reactor comprising a plurality of separate nuclear reactor loops according to the present invention. The method utilizes the flexibility offered by a nuclear reactor comprising multiple nuclear reactor loops.

[0134] The method further includes: providing multiple nuclear fuels or target materials containing convertible and / or fissile materials and / or other materials to be activated by neutron flux; and providing the multiple nuclear fuels and / or target materials to multiple loops. The method further includes: providing multiple nuclear fuels containing convertible and / or fissile materials to the loops, preferably each loop in the loops, to bring the nuclear fuels in the channels of the loops into a critical configuration.

[0135] A critical reactor core can be formed by channels in a loop, thereby introducing fissile material in sufficient quantity and in appropriate configuration into the reactor core region.

[0136] The reactor energy spectrum can be slowed down by using dedicated moderators between or around molten salt, channel materials, containment materials, and / or loop channels.

[0137] Deceleration can be fine-tuned to the desired neutron spectrum of a fast neutron spectrum reactor core (to minimize deceleration) or (extended) to the desired neutron spectrum of a thermal neutron spectrum reactor core, or to different dedicated neutron spectra in separate portions of the core region, to optimize fission, breeding, or activation in different loops at different locations.

[0138] Modular core reactor systems can also progressively change individual loops from breeder functions to breeder-combustion functions and from combustion functions back to breeder functions. In most loops, for example through... 235 In cases where the fission ("burning") of U satisfies sufficient criticality to sustain nuclear fission reactions in the core region, one or more loops can utilize excess neutrons from the fission reaction in the core, for example, to convert... 232 Th transformation / transformation into fissionable 233 U (“breeding”), until a breeding-combustion equilibrium is established in the circuit, in which case, by 232 Th generated 233 U and the energy consumed in the fission reaction 233 The amount of U is the same. Sufficient optimization of the reactor and loop neutron economy is needed to avoid excessive neutron loss. A loop previously primarily used for combustion can be converted from a conventional combustion function to a breeder function by changing the molten salt or adding thorium to the molten salt. Over time, this loop will then change from a breeder loop to a breeder-combustion loop, eventually reaching breeder-combustion equilibrium. In this way, the reactor is gradually converted towards operating on a closed thorium cycle, where little or no fissile material needs to be added to the reactor loop to maintain the fission reaction. 232 Th transformed into 233 U-fuel.

[0139] This invention provides a method for a closed uranium-plutonium cycle, wherein fission reactions in the critical reactor region can ultimately be sustained by plutonium fission, and excess neutrons are used to convert convertible plutonium into plutonium. 238 U is converted into sufficient fissile material. 239 Pu.

[0140] This invention provides a method for reducing the lifetime of nuclear waste by burning long-lived isotopes recovered from it. In this case, the reactor is critical, but one or more loops in the critical zone / core region or shell region have specific molten salt compositions in which these long-lived isotopes extracted from nuclear waste can be transmuted and / or fissioned into short- to medium-lived isotopes and fission products.

[0141] This invention provides a method for producing specific isotopes through neutron activation of specific elements. In this case, the reactor is critical, but one or more loops in the critical region / core region or shell region have specific molten salt compositions containing the target material, and the desired activation product is extracted from the loop for a foreseeable application.

[0142] From the perspective of the (closed-loop) nuclear fuel cycle of this invention, whether in the loop or in the reactor, the advantages of this method are a combination of the following:

[0143] - The use of molten salt allows for online molten salt cleaning and conditioning, and optimizes neutron economy by minimizing neutron absorption losses through the removal of neutron-absorbing fission or activation products. Potential non-diffusion issues with material extraction should and can be managed by design.

[0144] - Separate channels are used to form the critical zone together, which in principle allows each loop to contain different molten salt mixtures and convertible-fissile material inclusions, which can be changed by adjusting or replacing the molten salt.

[0145] Because the activation and fission products of neutron absorption are contained within the fuel, they can only be removed through fine solid fuel reprocessing at separate locations. Furthermore, the activation and fission products lack the flexibility to easily (partially) alter, optimize, or fine-tune the core contents. Therefore, most conventional reactor systems operating on solid fuel cannot minimize the activation and fission products of neutron absorption by removing fission products. The loop and reactor of this invention are capable of removing fission products.

[0146] Conventional molten salt reactor systems mostly operate with a single molten salt volume, which complicates the gradual adjustment of the molten salt composition because such changes affect the entire molten salt volume, where the molten salt exhibits non-optimal and non-localized breeding and combustion capabilities. The reactor and loop of this invention allow operation with multiple molten salts and enable relatively easy and convenient gradual adjustment of the molten salt composition.

[0147] Compared to other molten salt reactor designs, the aforementioned benefits of modular core reactor systems, in addition to avoiding the disadvantages of handling large molten salt volumes such as large components (which are difficult to replace and rapidly degrade in a molten salt reactor environment), include limited knowledge of fuel location, problematic identification and permissive pathways where small-scale testing cannot be easily extrapolated to full-scale operation, and limited flexibility in optimizing reactor performance by replacing optimized components—all of which can be avoided by employing the modular core reactor system of this invention.

[0148] It is evident that, in the case of a nuclear reactor consisting of a separate nuclear reactor loop, the elements and embodiments of the nuclear reactor loop already described also constitute the elements and embodiments of the nuclear reactor, and the elements and embodiments of the nuclear reactor that are part of or associated with the nuclear reactor loop are also elements and embodiments of the nuclear reactor loop.

[0149] The present invention further relates to a method of operating a nuclear reactor loop as described elsewhere herein, the method being implemented by: providing a nuclear reactor loop; arranging a passage of the nuclear reactor loop near the core of another (test) nuclear reactor, such that the critical region of the loop passage is exposed to the radiation flux of the other reactor. The method further details providing a liquid to the loop, circulating the liquid through the loop, and subjecting the liquid to the flux of the test nuclear reactor in the passage. The method further includes monitoring the (elemental) properties of the loop and / or the liquid (which may be a molten salt and may contain fissile material and / or convertible material or other chemical elements). The method may further include providing nuclear fuel containing fissile material and / or convertible material. Nuclear fuel may be provided to the loop. The nuclear fuel may be circulated in the loop, and the nuclear fuel may preferably be subjected to the radiation flux of the other reactor in the critical region.

[0150] By placing a nuclear reactor loop (specifically, the loop's pathway) within the neutron flux of another nuclear reactor, the materials used to construct and form the loop, and / or the liquid (molten salt) and / or convertible and fissile materials in the nuclear fuel, can be tested and characterized, either in combination or separately. For example, in one embodiment, the method may include providing a loop as described elsewhere herein, providing a liquid (preferably molten salt), and exposing the loop and liquid to the flux of an existing nuclear reactor to monitor, test, and experiment with the performance of the loop materials, the liquid, and the overall performance of the loop. The data obtained can be used to improve the loop itself, the composition of the liquids used in the loop, and ultimately, to further design and optimize the nuclear reactor of the present invention.

[0151] Therefore, in some embodiments of the invention, parameters for the circuit (components) include the performance of materials exposed to degradation mechanisms under molten salt reactor conditions (e.g., contact with molten salt, high temperature and (neutron) radiation), typically in terms of corrosion resistance, strength, embrittlement, creep, fracture toughness, thermal expansion, thermal conductivity and other properties.

[0152] Therefore, in some embodiments of the present invention, parameters relating to liquid properties include chemical composition, dissolution or deposition of fission products, performance of activated products, degradation / decomposition under radiation, condensation of elements in molten salt, thermal and electrical conductivity, corrosivity, fluorine / chloride potential, and viscosity.

[0153] Therefore, in some embodiments of the present invention, parameters for nuclear fuel include dissolution in molten salt, deposition potential, and condensation with other elements in molten salt.

[0154] Therefore, in some embodiments of the present invention, parameters for loop performance include heat generation, operational safety, heat generation efficiency and heat transfer efficiency, and testing and qualification of loop components.

[0155] By operating the circuit in this manner, the circuit of the present invention can also be used in a wide range of applications that will be discussed elsewhere herein, such as generating specific isotopes through neutron activation, generating fissile materials from convertible materials, etc.

[0156] In certain embodiments, the method may further include steps of isotope generation, for example, for medical, diagnostic, or imaging applications. This embodiment would include steps of supplying a specific element to the loop, subjecting the element to a neutron flux from the reactor, transmutating the element into other elements, and separating the resulting element from the liquid. The separation can be performed online or offline (i.e., the liquid can be removed from the loop and the separation can be performed elsewhere). Similarly, fission products can be recovered from the loop where the fission reaction occurs, for example, for use in medical, diagnostic, or imaging applications.

[0157] The circuit of the present invention and the design of a nuclear reactor including the circuit of the present invention have certain advantages, not limited to the following:

[0158] - The loop of the present invention and the nuclear reactor including the loop of the present invention enable replacement strategies and reactor performance optimization by replacing the loop with an improved loop and loop channel design.

[0159] Multiple reactor loops together form the critical region of the reactor. Therefore, the critical mass within the critical region is divided into separate containment units. In the event of a loop being depleted, the critical mass within the critical region is effectively reduced, thereby decreasing or stopping the nuclear reaction.

[0160] - Individual channels (or loops) may contain different molten salt compositions with different convertible materials, fissile materials, or other materials:

[0161] - The reactor core configuration can be selected such that individual loop channels are placed at different locations in the critical region for different purposes such as fission, breeding and neutron activation, in order to optimize performance.

[0162] - Core configurations can be selected such that individual loop channels are placed at different locations in the critical region to generate neutron flux, energy spectrum flux and distribution, thereby optimizing the performance of each channel at each location in the reactor.

[0163] - The molten salt in the channel can be replaced with another molten salt composition to change the channel's use in the reactor critical region or shell region.

[0164] Producing many relatively small components can be more cost-effective than producing a few very large components. Economics by quantity can outweigh economics by scale.

[0165] - The relatively small size of the components allows for convenient testing at a representative scale, which reduces the cost of component and reactor development and qualification and shortens the time required for component and reactor development and qualification.

[0166] Unlike other (hot) molten salt reactor designs, specific moderator materials such as graphite can be located outside and between channels, rather than in direct contact with the molten salt carrying the nuclear fuel. Therefore, the moderator function can be separated from the molten salt flow guiding function or containment function. This is particularly advantageous for graphite, which is a very suitable moderator but behaves very complexly in a nuclear reactor environment. As a measure to maintain and extend lifetime, the separated moderator around the channels can be subjected to temperature rises during or between operating cycles to anneal irradiation damage, thereby restoring the original material properties. This measure can be very effective for graphite, ensuring appropriate moderator performance through (repeated) annealing to the point where the moderator material no longer needs replacement during the reactor's lifetime.

[0167] The physical separation of the molten salt in the channel from the moderator between the channel and the channel also allows the moderator to be thermally optimized largely independently of the channel and molten salt temperatures. The moderator material can, for example, be at and maintained at temperatures other than the molten salt or channel temperatures to minimize the effects of radiation damage during operation, thereby maximizing lifetime. For example, graphite moderators can be maintained at temperatures lower than the typical molten salt temperature, thereby reducing the effects of radiation damage and maximizing lifetime.

[0168] Because modular core reactors are formed from separate, individual, and independent reactor loop components, the system and each individual loop consist of relatively small components operating at low pressure. Systems built from smaller components can, for example, disconnect channels from the loop and remove them from the loop into shielded containers for transport to locations for conditioning, disposal, or recovery (if applicable). New channels (or other elements) can then be introduced. This can be done vertically, for example, via a radiation shield on top of the reactor. The same method can be applied to other parts and components of the loop or the entire loop.

[0169] Figure label:

[0170] 1. Core area

[0171] 2. Shell area

[0172] 3. Ring Road

[0173] 4. Channel

[0174] 4a. Upper passage

[0175] 4b. Lower passage

[0176] 5. Liquid tank

[0177] 6. Feed pipeline

[0178] 7. Outlet pipeline

[0179] 8. Return line

[0180] 9. Shell Channel

[0181] 10. Moderators or non-decelerating media

[0182] 11. Active or passive valves (freezing plugs) for liquid tanks.

[0183] 12. Top tube

[0184] 13. Lowering the pipe

[0185] 14. Inner tube

[0186] 15. Outer pipe

[0187] 16. Expansion tank

[0188] 17. Heat exchanger

[0189] 18. Pump

[0190] 19. Processing

[0191] 20. Material Feeding

[0192] 21. Secondary heating system

[0193] 22. Fission and activation products

[0194] 23. Fission and activation products

[0195] 24. Convertible materials, fissile materials, and target materials

[0196] 25. Shielding cover

[0197] 26. Critical Region

[0198] 27. Single upper pipe

[0199] 28. Multiple downpipes

[0200] 29. Passage containment

[0201] 30. Containment Loop Connection

[0202] 31. Through the neutron reflector and / or radiation shield used for the channel and the channel containment structure to

[0203] The path can be removed / replaced.

[0204] 32. A passageway through the neutron reflector and / or radiation shield used for liquid tanks for removal / replacement.

Claims

1. A nuclear reactor comprising a core region and a containment region, and the reactor is constituted by a plurality of separate and individual nuclear reactor loops, each loop comprising: - a loop (3), wherein the loop (3) is capable of containing a liquid, the liquid containing a transmutable material and / or a fissile material as nuclear fuel, and the loop (3) is capable of circulating the transmutable material and / or fissile material, - the loop contains a straight channel (4) as part of the loop and arranged in a vertical arrangement, the channel providing an up and down passage (4a, 4b) for the liquid in the loop, each channel of the plurality of loops being arranged in the core region, - each separate and individual nuclear reactor loop is independently removable from the nuclear reactor.

2. The nuclear reactor according to claim 1, wherein the individual loops contain a subcritical amount of nuclear fuel in a critical region of the reactor.

3. The nuclear reactor according to claim 1, wherein the plurality of separate and individual nuclear reactor loops in the reactor provide a critical amount of fuel in a critical region, such that a nuclear reaction is capable of being sustained.

4. The nuclear reactor according to claim 1, wherein the channel in the loop is a single pipe, a bundle of pipes, a pipe-in-pipe or an integrated channelled block.

5. The nuclear reactor according to claim 1, wherein the channel is releasable.

6. The nuclear reactor according to claim 1, wherein the channel is provided with a releasable containment (29).

7. The nuclear reactor according to any of the preceding claims, wherein the channel has a supply end and a discharge end, both the supply end and the discharge end being part of and / or connected to the loop, such that the channel is supplied with liquid and liquid is discharged from the channel at the same side of the channel.

8. The nuclear reactor according to claim 2 or 3, wherein the arrangement of channels forms a critical region of the nuclear reactor.

9. The nuclear reactor according to claim 2 or 3, wherein each channel contains a subcritical amount of nuclear fuel in a critical region of the reactor.

10. The nuclear reactor according to claim 1, wherein the critical region of the reactor further comprises a moderator.

11. The nuclear reactor according to claim 1, wherein the channels are arranged in a core.

12. The nuclear reactor according to claim 10, wherein the channels are arranged in a moderator.

13. A method of operating a nuclear reactor, the method comprising the steps of: - providing a nuclear reactor comprising a plurality of loops as defined in any of claims 1 to 10; - providing a plurality of nuclear fuels containing transmutable material and / or fissile material; - providing the plurality of loops with the plurality of nuclear fuels; - bringing the nuclear fuel in the channels in the loops in a critical configuration.

14. The method according to claim 13, further comprising the step of: - operating the reactor in a critical configuration, wherein at least a portion of the loops provide fissile material to a critical region with or without a moderator to sustain a fission reaction. - running a part of the loop in breeder-burner mode in the critical zone, wherein surplus neutrons generated from fission reactions enable the generation of fissile material from the transmutable material and fission of at least a part of the generated fissile material; - establishing a balance between breeding and burning in one or more of the loops; - replacing the liquid in one or more other reactor loops, thereby changing the other loops from burn mode to breed mode; - allowing the loop to reach equilibrium, thereby providing a reactor system operating in a closed breed-burn nuclear fuel cycle.

15. A method of operating a nuclear reactor, comprising the steps of: - providing a nuclear reactor loop as defined in any one of claims 1 to 10; - providing nuclear fuel containing transmutable material and / or fissile material; - providing the nuclear fuel to the loop; - circulating the nuclear fuel in the loop; - subjecting the nuclear fuel in a critical zone of the loop to a neutron flux of another reactor and monitoring and / or modeling one or more of the following parameters: i. components of the loop; ii. liquid; iii. material sample performance; iv. nuclear fuel; and / or v. performance of the loop.

16. The method according to claim 15, wherein the nuclear reactor loop is placed in a nuclear reactor configuration comprising a plurality of nuclear reactor loops, wherein from one of the nuclear reactor loops, the replaceable connection channel, channel containment and liquid tank are removed and / or replaced from the containment area or the core area of the reactor.

17. The method according to claim 15 or 16, wherein the removal or replacement is performed by vertical translocation of the replaceable connection channel, channel containment and / or liquid tank.

18. A method of operating a nuclear reactor loop, the method being achieved by arranging a channel of a nuclear reactor loop as defined in any one of claims 1 to 5 in the vicinity of the core of another nuclear reactor, such that the channel of the loop is exposed to the neutron flux of the other reactor.

19. A method for removing and / or replacing a component of a nuclear reactor loop of a nuclear reactor according to claim 1, the method being achieved by disconnecting a channel, channel containment and / or liquid tank from the nuclear reactor loop; removing and / or replacing the channel, channel containment and / or liquid tank from the nuclear reactor loop.

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