Reactor construction

Abstract

The invention relates to a reactor construction (1) comprising an upper compartment (2) located above a discharge tank compartment (3), said upper compartment (2) comprising: a molten salt reactor (MSR) (4) comprising a reactor vessel (5) containing a molten fuel salt (6); a molten salt discharge system connected to the reactor vessel (5); the discharge tank compartment (3) comprises: one or more discharge tanks (10) in communication with a molten salt discharge system; a buffer water tank (15) comprising an inner wall (16) and an outer wall (17) and buffer water (21) located in a gap between the inner wall (16) and the outer wall (17) of the buffer water tank (15), the buffer water tank (15) surrounding the one or more discharge tanks (10), in which a first conduit structure (22) defines a circuit for at least a portion of the buffer water (21) and comprises a heat exchanger (23) in thermal contact with the water storage tank (30), the water storage tank (30) is located at the horizontal height above the buffer water tank (15), and the stored water is in thermal contact with the environment; and / or the second conduit structure (24) defines a circuit for at least a portion of the buffer water (21) and comprises a heat exchanger (25) in thermal contact with the environment, said heat exchanger (25) being located at a level above the buffer water tank (15); and / or a seawater heat exchanger (26) in thermal contact with the buffer water (21) and seawater, said seawater heat exchanger (26) being located below the seawater level outside the outer wall (17) of the buffer water tank (15).

Description

TECHNICAL FIELD

[0001] The present invention relates to a reactor configuration for a small modular reactor (SMR), for example a molten salt reactor (MSR), wherein the reactor configuration comprises a cooling system for decay heat from nuclear fission reactions. The reactor configuration comprises a water tank for transferring heat to achieve a fully passive decay heat removal system. Furthermore, the present invention also relates to a method for heat transfer from a molten salt. BACKGROUND

[0002] Molten salt reactors (MSR) are based on critical concentrations of fissile material dissolved in a molten salt. The molten salt containing the fissile material is often referred to as fuel salt or molten fuel salt. In the 1950s and 60s, the Oak Ridge National Laboratory (ORNL) initially researched MSRs, but they have not yet been successfully commercialized. MSRs have many advantages over other reactor types, including those currently in commercial use. MSRs are able to breed fissile U-233 from thorium, resulting in a much lower level of transuranic waste than in uranium / plutonium fuel reactors; are able to operate at high temperatures; are able to avoid the accumulation of volatile radioactive fission products in solid fuel rods; and are able to burn a much larger amount of fissile material than in conventional reactors. Other particularly attractive properties of MSRs are operation at ambient or low pressure and retention of fission products as strongly bonded salts, which are often fluoride or chloride salts.

[0003] Much of the attention for safety systems for nuclear reactors has been focused on removing heat generated by decay of fission products, especially in the event of a failure of the cooling pumps that are normal to nuclear power plants (sometimes referred to as a loss of coolant accident (LOCA)). These accidents can be caused by loss of off-site power (LOOP) or other causes. Conventional light water reactors (LWRs) are of the second generation type, with a few of the third generation type. Reactors of the second and third generation type use active cooling systems for cooling using heat exchangers for removal of residual heat. Advanced designs (third and third+) rely at least to a certain grace period on passive safety systems to allow the active system time to start up and run to remove the large amount of decay heat for most existing nuclear power plants.

[0004] Molten salt reactors (MSRs) are categorized with other advanced small modular reactors (SMRs) such as high temperature gas cooled reactors (HTGRs) as fourth generation designs. These reactor types are expected to rely on passive and inherent safety features for an indeterminate period of time. Reactor vessel auxiliary cooling systems (RVACS) and direct reactor auxiliary cooling systems (DRACS) are examples of this relatively new class of safety systems. RVACS and DRACS are particularly well suited as cooling systems for SMRs, while for traditional nuclear reactors the attractiveness of these systems is less due to the potentially one order of magnitude larger heat removal requirements.

[0005] ORNL-314 "Quarterly Progress Report on Molten Salt Reactor Program" dated December 15, 1960 discloses heat removal associated with the operation of the original Molten Salt Reactor Experiment (MSRE). The document discloses that heat was removed from the molten fuel salt after it had been discharged into several discharge tanks. Forty submerged jacketed coolers were used with boiling water as the coolant in order to make the heat removal as uniform as possible throughout the discharge tanks. The reason for choosing water cooling over gas, molten salt or NaK was its simplicity and relative immunity to utility failures. However, there is a certain risk associated with directly submerging the jacketed tubes containing water into the molten fuel salt in case of a rupture of the jacket material, typically a metal alloy, which would be accompanied by a contact of the molten fuel salt with the water, resulting in a sudden burst of high temperature steam.

[0006] KR20090021722 discloses a cooling system for removing decay heat from a high temperature gas cooled reactor (HTGR). The system is intended to minimize parasitic heat losses during normal operation. Decay heat from the reactor core is transferred to a piping system for water, at which water pipes are air cooled. The water piping is in thermal contact with a water reservoir via a water bath heat exchanger, and water is actively pumped through the water piping. A passive air cooling system serves as the primary cooling system, and only the air cooling means is used during normal operation, while the water cooled part of the system is used in case of an accident. Although a large passive cooling capacity can be obtained in case of an accident in a nuclear reactor, especially a high temperature gas reactor, the system also relies on active cooling to minimize parasitic heat losses during normal operation.

[0007] US2019035510 discloses a reactor vessel auxiliary cooling system (RVACS) for removing decay heat from MSR and spent molten fuel salt. The cooling system comprises a duct structure defining a sealed closed loop through which a cooling gas or fluid is circulated by natural convection. In some embodiments, the cooling system is always running so that the cooling system continuously extracts heat from the nuclear reactor core. The heat is further transferred directly to the environment, e.g. the external environment, via heat transfer (e.g. through a large roof structure above the reactor building as a medium).

[0008] KR20220106618 discloses a reactor cooling system for a nuclear reactor installed on a marine vessel. A water reservoir is in fluid communication with a reactor vessel cabin. The water reservoir can be periodically filled with seawater and provides a reservoir for cooling the reactor. The system is described as a passive cooling system for a floating nuclear power plant utilizing seawater, with the advantage of improving the safety of the floating nuclear power plant by eliminating uncertainties due to equipment failure of a pump, since a pump is not needed. The nuclear reactor is continuously cooled during operation. SUMMARY

[0009] It is an object of the present invention to provide a cooling system for a MSR which implements a fully passive method of transferring decay heat from the molten fuel salt of a MSR.

[0010] It is a further object of the present invention to provide a cooling system for a MSR to be located on a marine structure with limited space.

[0011] According to an aspect of the present invention, there is provided a reactor configuration comprising an upper cabin located above an exhaust tank cabin,

[0012] The upper cabin comprises:

[0013] a molten salt reactor (MSR) comprising a reactor vessel containing a molten fuel salt;

[0014] a molten salt exhaust system connected to the reactor vessel;

[0015] The exhaust tank cabin comprises:

[0016] one or more exhaust tanks in communication with the molten salt exhaust system;

[0017] a buffer water tank comprising an inner wall and an outer wall and a buffer water located in a gap between the inner wall and the outer wall of the buffer water tank, the buffer water tank surrounding the one or more exhaust tanks,

[0018] wherein,

[0019] The first piping structure defines a circuit for buffering at least a portion of the water and comprises a heat exchanger in thermal contact with a water reservoir, said water reservoir being located at a level above the buffer water tank, said water reservoir being in thermal contact with the environment,

[0020] and / or

[0021] The second piping structure defines a circuit for buffering at least a portion of the water and comprises a heat exchanger in thermal contact with the environment, said heat exchanger being located at a level above the buffer water tank,

[0022] and / or

[0023] a seawater heat exchanger in thermal contact with the buffer water and the seawater, said seawater heat exchanger being located below the seawater level outside the outer wall of the buffer water tank.

[0024] According to another aspect of the application, there is provided a reactor configuration, said reactor configuration comprising an upper compartment located above an exhaust tank compartment,

[0025] said upper compartment comprising:

[0026] a molten salt reactor (MSR) comprising a reactor vessel containing a molten fuel salt;

[0027] a molten salt exhaust system connected to the reactor vessel;

[0028] said exhaust tank compartment comprising:

[0029] one or more exhaust tanks in communication with the molten salt exhaust system;

[0030] a pipe system comprising an inner pipe and an outer pipe, wherein the inner pipe and the outer pipe are joined together, wherein the buffer water is located within a tube within the joined inner pipe and outer pipe of the pipe system, said pipe system surrounding said one or more exhaust tanks,

[0031] wherein,

[0032] The first piping structure defines a circuit for buffering at least a portion of the water and comprises a heat exchanger in thermal contact with a water reservoir, said water reservoir being located at a level above the pipe system, said water reservoir being in thermal contact with the environment,

[0033] and / or

[0034] The second piping structure defines a circuit for buffering at least a portion of the water and comprises a heat exchanger in thermal contact with the environment, said heat exchanger being located at a level above the pipe system,

[0035] and / or

[0036] a seawater heat exchanger in thermal contact with the buffer water and the seawater, the seawater heat exchanger being located below the seawater level outside the outer wall of the pipe system.

[0037] According to another aspect of the application, there is provided a method of heat transfer from a molten salt, the method comprising the steps of:

[0038] - providing molten fuel salt in one or more drain tanks for molten fuel salt;

[0039] - surrounding the one or more drain tanks for molten fuel salt with a buffer water tank, the buffer water tank comprising buffer water in a gap between an inner wall and an outer wall of the buffer water tank, the molten fuel salt being in thermal transfer with the inner wall by at least one of thermal radiation, thermal conduction or thermal convection to heat the buffer water to steam;

[0040] - providing a first pipe structure, the first pipe system comprising:

[0041] at least one riser pipe above at least a portion of the buffer water, the riser pipe collecting steam and directing the steam to a heat exchanger in stored water in a stored water tank above the buffer water tank to condense the steam to water;

[0042] at least one downcomer pipe to direct water from the heat exchanger in stored water in the stored water tank to the buffer water tank;

[0043] and / or

[0044] - providing a second pipe structure, the second pipe structure comprising:

[0045] at least one riser pipe above at least a portion of the buffer water, the riser pipe collecting steam and directing the steam to a gas heat exchanger in thermal contact with an environment comprising a gas, the gas heat exchanger being located above the buffer water tank to condense the steam to water;

[0046] at least one downcomer pipe to direct water from the gas heat exchanger to the buffer water tank,

[0047] and / or

[0048] - providing a seawater heat exchanger in thermal contact with the buffer water, the seawater heat exchanger being located below the seawater level outside the outer wall of the buffer water tank, wherein the buffer water is circulated through the seawater heat exchanger.

[0049] Detailed description

[0050] The reactor configuration comprises an upper compartment above the drain tank compartment,

[0051] the upper compartment comprises:

[0052] - a molten salt reactor (MSR) comprising a reactor vessel with a molten fuel salt;

[0053] - a molten fuel salt drain system connected to the reactor vessel;

[0054] The drain tank compartment comprises:

[0055] - one or more drain tanks in communication with the molten fuel salt drain system;

[0056] - a buffer water tank comprising an inner wall and an outer wall and buffer water in a gap between the inner wall and the outer wall of the buffer water tank, the buffer water tank surrounding the one or more drain tanks,

[0057] wherein,

[0058] The first piping structure defines a circuit for at least a portion of the buffer water and comprises a heat exchanger in thermal contact with a water storage tank at a level above the buffer water tank;

[0059] and / or

[0060] The second piping structure defines a circuit for at least a portion of the buffer water and comprises a heat exchanger in thermal contact with the environment, the heat exchanger being at a level above the buffer water tank.

[0061] We find that such a reactor configuration has many advantages.

[0062] Most conventional cooling systems for nuclear reactors imply cooling of the reactor itself. For small modular reactors (SMR), such as molten salt reactors (MSR), the cooling system relies extensively on passive and inherently safe systems, such as direct cooling of the reactor in a DRACS system or direct cooling of the reactor vessel in a RVACS system. In such systems that are passively cooled (e.g. without the use of pumps), the cooling is continuous during reactor operation. Hence, in the above-mentioned systems there is a constant cooling of the reactor, resulting in parasitic heat losses, instead of using the heat generated by the reactor for e.g. steam generation.

[0063] The proposed reactor configuration does not cool the reactor or reactor compartment during normal operation and avoids parasitic heat losses, even when it is a passive cooling system. Rather, after the molten fuel salt has been drained into the drain tank (e.g. during an emergency event or during a planned maintenance operation), the decay heat is removed from the molten fuel salt.

[0064] The proposed reactor configuration is also directed at a specific accident event, the so-called "molten salt spill" scenario. In this case, a large amount of molten fuel salt cannot be contained by the reactor or the drain tank and can be caused accidentally during a planned maintenance operation or can be caused by extreme events such as a plane crash, a bomb impact or an exceptional hurricane. In this case, the majority of the spilled molten salt will eventually flow down in any configuration and rest on the floor or similar. In the proposed reactor configuration, the spilled molten fuel salt can be collected with a fuel salt trap installed at the lowest position of the drain tank compartment when a molten fuel salt leak occurs. This enables the cooling of the spilled molten fuel salt, as the cooling system is operated in the drain tank compartment as a lower part of the reactor configuration.

[0065] When cooling a reactor, especially when directly cooling the reactor core with a cooling medium such as air or water, the irradiation of the cooling medium is unavoidable, leading to procedures for handling large amounts of contaminated cooling medium. The proposed system reduces this drawback by simply not cooling the reactor, but cooling the molten fuel salt in the drain tank where no nuclear fission process takes place. However, the decay processes in the molten fuel salt will cause the surrounding environment to also be irradiated and activated, but the radiation level will decrease over time.

[0066] The provision of a buffer water around the drain tank provides an effective heat sink for the decay heat and works immediately as soon as the molten fuel salt starts to fill the drain tank during the draining of the molten fuel salt from the reactor. The heat accumulation in the buffer water is further processed with at least one additional heat removal system, so that the decay heat is transferred to a selected final heat sink or to two types of final heat sinks working in parallel. Both ways of transferring heat to the final heat sink are also passive heat transfer and thus have a strong safety performance. The selection of buffer water (water) as a cooling medium reduces the volume of the cooling system compared to the preferred air as a cooling medium.

[0067] Molten salt reactor (MSR) and molten salt

[0068] A molten salt reactor (MSR) is based on reaching a critical state with fissile material that is usually dissolved in a molten salt. When a MSR uses fissile material dissolved in a molten salt, this molten salt is called fuel salt (or molten fuel salt).

[0069] Nuclear fission produces high-energy neutrons, typically in the range of 100 keV to 2 MeV. The probability of a fission event occurring depends on the neutron energy. In so-called fast reactors, the unmoderated (fast) neutrons produced by fission events interact directly with other atomic nuclei. Thermal neutron fission reactors and ultrathermal neutron fission reactors rely on moderators to first reduce the energy of high-energy neutrons (100 keV to 2 MeV) to thermal neutrons, typically 0.025 eV, which is the kinetic energy at ambient temperature. These thermal neutrons have a higher probability of inducing fission events; U-235 is a prominent example of fissile material. In summary, nuclear fission reactors can therefore operate on two different principles: fast reactors and thermal / ultrathermal neutron reactors. In fast reactors, high-energy neutrons interact directly with fissile material to produce energy, fission products, and high-energy neutrons. In thermal neutron reactors and ultrathermal neutron reactors, high-energy neutrons produced by fission exchange energy with moderators such as graphite and eventually interact with fissile material to produce energy, fission products, and more high-energy neutrons.

[0070] When using molten fuel salt, the fissile material is dissolved in the molten salt, which includes a carrier salt, preferably a fluoride-based or chloride-based salt.

[0071] In one embodiment, the MSR comprises a molten salt as a molten fuel salt, which is circulated in channels or fissures within the graphite reactor core.

[0072] Another type of reactor, also known as an MSR, is one in which the fuel is solid and molten salt is used as a coolant salt to accommodate the temperature rise in the solid, which is spherical fuel (more commonly TRISO type fuel). US8442182 describes such a reactor in which molten salt is used as a coolant for spherical fuel immersed in a coolant.

[0073] Coolant salt is a salt that does not contain fissile substances.

[0074] In one embodiment, the MSR comprises a molten salt as a molten fuel salt that circulates inside and outside the reactor vessel, the vessel comprising spheres of solid moderator.

[0075] According to one aspect of the invention, a reactor structure is provided, the reactor structure including an upper compartment located above the discharge tank compartment.

[0076] The upper compartment includes:

[0077] - A molten salt reactor (MSR), wherein the molten salt reactor includes a reactor vessel containing molten fuel salt;

[0078] - A molten salt removal system connected to the reactor vessel;

[0079] The drain tank compartment comprises:

[0080] - one or more drain tanks in communication with the molten salt drain system;

[0081] - a buffer water tank implemented as a pipe system comprising an inner pipe and an outer pipe, wherein the inner pipe and the outer pipe are joined together, wherein the buffer water is located within the pipes of the joined together inner pipe and outer pipe of the pipe system, the buffer water tank surrounding the one or more drain tanks,

[0082] wherein,

[0083] the first pipe structure defines a circuit for at least a portion of the buffer water and comprises a heat exchanger in thermal contact with a water storage tank located at a level above the buffer water tank, the water storage being in thermal contact with the environment,

[0084] and / or

[0085] the second pipe structure defines a circuit for at least a portion of the buffer water and comprises a heat exchanger in thermal contact with the environment, the heat exchanger being located at a level above the buffer water tank,

[0086] and / or

[0087] a seawater heat exchanger in thermal contact with the buffer water and the seawater, the seawater heat exchanger being located below the seawater level outside the outer wall of the buffer water tank.

[0088] According to an aspect of the application, there is provided a reactor configuration comprising an upper compartment located above a drain tank compartment,

[0089] the upper compartment comprises:

[0090] - a molten salt reactor (MSR) comprising a reactor vessel containing a molten fuel salt;

[0091] - a molten salt drain system connected to the reactor vessel;

[0092] the drain tank compartment comprises:

[0093] - one or more drain tanks in communication with the molten salt drain system;

[0094] - a buffer water tank implemented as a pipe system comprising an inner pipe and an outer pipe, wherein the inner pipe and the outer pipe are joined together, wherein the buffer water is located within the pipes of the joined together inner pipe and outer pipe of the pipe system, the buffer water tank surrounding the one or more drain tanks, wherein the joined together inner pipe and outer pipe of the pipe system comprises a section in which the buffer water evaporates, a section in which the buffer water is adiabatic and a section in which the buffer water condenses,

[0095] wherein,

[0096] the first piping structure defines a circuit for buffering at least a portion of the water and comprises a heat exchanger in thermal contact with a water storage tank, said water storage tank being located at a level above the buffer water tank, said water storage being in thermal contact with the environment,

[0097] and / or

[0098] the second piping structure defines a circuit for buffering at least a portion of the water and comprises a heat exchanger in thermal contact with the environment, said heat exchanger being located at a level above the buffer water tank,

[0099] and / or

[0100] a seawater heat exchanger in thermal contact with the buffer water and the seawater, said seawater heat exchanger being located below the seawater level outside the outer wall of the buffer water tank.

[0101] According to an aspect of the application, there is provided a reactor configuration comprising an upper compartment located above an exhaust tank compartment,

[0102] the upper compartment comprises:

[0103] a molten salt reactor (MSR) comprising a reactor vessel containing a molten fuel salt;

[0104] a molten salt exhaust system connected to the reactor vessel;

[0105] the exhaust tank compartment comprises:

[0106] one or more exhaust tanks in communication with the molten salt exhaust system;

[0107] a buffer water tank implemented as a tube system comprising an inner tube and an outer tube, wherein the inner tube and the outer tube are joined together, wherein the buffer water is located within the tube within the joined inner tube and outer tube of the tube system, said buffer water tank surrounding said one or more exhaust tanks, wherein the joined inner tube and outer tube of the tube system comprises a section in which the buffer water evaporates, a section in which the buffer water is adiabatic and a section in which the buffer water condenses,

[0108] wherein,

[0109] a seawater heat exchanger in thermal contact with the buffer water and the seawater, said seawater heat exchanger being located below the seawater level outside the outer wall of the buffer water tank and within a rectangular or cylindrical recess, preferably within the sea valve box.

[0110] In one embodiment, the reactor configuration comprises an upper compartment located above an exhaust tank compartment,

[0111] the upper compartment comprises:

[0112] - a molten salt reactor (MSR) comprising a reactor vessel containing a molten fuel salt;

[0113] - a molten salt drain system connected to the reactor vessel;

[0114] The drain tank compartment comprises:

[0115] - one or more drain tanks in communication with the molten salt drain system;

[0116] - a buffer water tank comprising an inner wall and an outer wall and a buffer water located in a gap between the inner wall and the outer wall of the buffer water tank, the buffer water tank surrounding the one or more drain tanks,

[0117] wherein,

[0118] a first piping structure defining a circuit for at least a portion of the buffer water and comprising a heat exchanger in thermal contact with a water storage tank located at a level above the buffer water tank, the water storage being in thermal contact with the environment,

[0119] and / or

[0120] a second piping structure defining a circuit for at least a portion of the buffer water and comprising a heat exchanger in thermal contact with the environment, the heat exchanger being located at a level above the buffer water tank,

[0121] and / or

[0122] a seawater heat exchanger in thermal contact with the buffer water and with seawater, the seawater heat exchanger being located below the seawater level outside the outer wall of the buffer water tank.

[0123] In one embodiment, the reactor configuration comprises an upper compartment located above the drain tank compartment,

[0124] The upper compartment comprises:

[0125] - a molten salt reactor (MSR) comprising a reactor vessel containing a molten fuel salt;

[0126] - a molten salt drain system connected to the reactor vessel;

[0127] The drain tank compartment comprises:

[0128] - one or more drain tanks in communication with the molten salt drain system;

[0129] - a buffer water tank comprising an inner wall and an outer wall and a buffer water located in a gap between the inner wall and the outer wall of the buffer water tank, the buffer water tank surrounding the one or more drain tanks,

[0130] wherein,

[0131] the first piping structure defines a circuit for buffering at least a portion of the water, and comprises a heat exchanger in thermal contact with a water reservoir, said water reservoir being located at a level above the buffer water tank, said water reservoir being in thermal contact with the environment,

[0132] and / or

[0133] the second piping structure defines a circuit for buffering at least a portion of the water, and comprises a heat exchanger in thermal contact with the environment, said heat exchanger being located at a level above the buffer water tank,

[0134] and, optionally

[0135] a seawater heat exchanger in thermal contact with the buffer water and the seawater, said seawater heat exchanger being located below the seawater level outside the outer wall of the buffer water tank.

[0136] In one embodiment, the reactor configuration comprises an upper compartment located above the drain tank compartment,

[0137] said upper compartment comprising:

[0138] a molten salt reactor (MSR) comprising a reactor vessel containing a molten fuel salt;

[0139] a molten salt drain system connected to the reactor vessel;

[0140] said drain tank compartment comprising:

[0141] one or more drain tanks in communication with the molten salt drain system;

[0142] a buffer water tank comprising an inner wall and an outer wall and a buffer water located in a gap between the inner wall and the outer wall of the buffer water tank, said buffer water tank surrounding said one or more drain tanks, and

[0143] the first piping structure defines a circuit for buffering at least a portion of the water, and comprises a heat exchanger in thermal contact with a water reservoir, said water reservoir being located at a level above the buffer water tank, said water reservoir being in thermal contact with the environment; and, optionally, the second piping structure defines a circuit for buffering at least a portion of the water, and comprises a heat exchanger in thermal contact with the environment, said heat exchanger being located at a level above the buffer water tank; and, optionally, a seawater heat exchanger in thermal contact with the buffer water and the seawater, said seawater heat exchanger being located below the seawater level outside the outer wall of the buffer water tank.

[0144] Separating the upper plenum including the MSR from the drain tank plenum located below the upper plenum enables cooling of the molten salt (e.g. molten fuel salt) to take place when the reactor is not in operation and thus avoids parasitic heat loss during normal operation.

[0145] The reactor vessel has an inner surface made of a liner material. The reactor vessel can be made of any material, e.g. a metal, a metal alloy, a ceramic material or a combination thereof, and in the present context the material is referred to as reactor vessel material. The inner surface can be a surface of the reactor vessel material, such that the liner material is the reactor vessel material, or, the reactor vessel material can be coated with a further material, thereby providing the liner material. For example, the reactor vessel material can be a metal alloy, e.g. a nickel-based alloy, a nickel-based superalloy or a hastelloy, or nickel. In the present context, a nickel-based alloy is an alloy having at least 50% w / w of nickel.

[0146] The molten salt drain system comprises a piping system connected to the reactor vessel and one or more opening devices, e.g. valves or salt plugs, to enable molten salt to flow when the opening devices are open, thereby draining the molten salt from the reactor vessel to one or more drain tanks. In one embodiment, the one or more drain tanks is one or more molten fuel salt drain tanks. In one embodiment, the molten salt drain system is a molten fuel salt drain system connected to the reactor vessel and one or more molten fuel salt drain tanks.

[0147] The piping and the valves can be made of the same material as the reactor vessel, e.g. made of a metal alloy, e.g. a nickel-based alloy. The molten fuel salt drain system comprises piping connected to the reactor vessel in the upper plenum, which piping extends to the area of the drain tank plenum where the piping is connected to the one or more drain tanks.

[0148] The opening devices, such as one or more valves, can be placed on the piping in the vicinity of the reactor vessel in the upper plenum, or in the vicinity of the one or more drain tanks.

[0149] In one embodiment, the buffer water tank holds buffer water in a tank that partially surrounds the one or more drain tanks, e.g. along 95% of the contour of all of the one or more drain tanks, e.g. along 80% of the contour of all of the one or more drain tanks. In one embodiment, the buffer water tank completely surrounds the one or more drain tanks.

[0150] In one embodiment, the buffer water tank has a substantially cylindrical inner wall and outer wall in concentric relationship, or a substantially rectangular inner wall and outer wall in concentric relationship. In one embodiment, the minimum distance between the inner wall and the outer wall of the buffer water tank can be less than 3 meters, e.g. less than 2 meters, e.g. less than 1 meter.

[0151] The first piping structure is intended to transport the steam produced by the buffer water in the buffer water tank to the heat exchanger inside the storage water tank and to transport the condensed water from the heat exchanger inside the storage water tank back to the buffer water tank. This circuit of evaporated water and condensed water provides a mechanism for taking heat away from the molten salt that heats the buffer water in the discharge tank. In one embodiment, the first piping structure defines a sealed circuit comprising the heat exchanger. The heat exchanger is present in the storage water tank to assist the cooling process and is preferably partially or totally submerged in the storage water.

[0152] In one embodiment, the storage water tank is an open water tank.

[0153] In one embodiment, the storage water tank is a closed water tank.

[0154] The second piping structure is also intended to transport the heat and steam produced by the buffer water in the buffer water tank away and to send the condensed water back to the buffer water tank. In one embodiment, the second piping structure defines a sealed circuit. The heat exchanger in thermal contact with the second piping structure exchanges heat to an environment such as the external environment and thus to the air. The exchange can also be of a gas (e.g. air) in a closed volume, wherein the heated gas in the closed volume transfers heat to the external environment in thermal contact with the closed volume. This thermal contact can be, for example, between the enclosure of the closed volume and the external environment.

[0155] The use of seawater as the final heat sink provides a diversified choice for the final heat sink of the reactor configuration deployed at sea or on a barge or another marine structure. The seawater heat exchanger is connected to a marine piping system comprising a pipe in contact with the buffer water in the buffer water tank, so that the buffer water can be circulated from the buffer water tank to the seawater heat exchanger in the sea. In one embodiment, the marine piping system comprises a pipe passing through the outer wall of the buffer water tank, the pipe being connected to the seawater heat exchanger.

[0156] In one embodiment, the seawater heat exchanger is provided with an anti-fouling system.

[0157] In one embodiment, the first piping structure comprises:

[0158] - at least one riser pipe, the first end of which is an inlet for at least a portion of the buffer water, the second end of which is in contact with an inlet for the heat exchanger in the storage water tank; and

[0159] - at least one downcomer pipe, the first end of which is in contact with an outlet of the heat exchanger in the storage water tank, the second end of which is an outlet for at least a portion of the buffer water.

[0160] The riser or the downcomer of the first piping system can have any cross-sectional shape, such as circular, elliptical or rectangular, and can be made of an alloy, such as stainless steel. The minimum cross-sectional dimension is the diameter in the case of a circular cross-section, and the minor axis in the case of an elliptical cross-section.

[0161] In an embodiment, two sets of risers and downcomers are provided, preferably the two sets are opposite each other along the profile surrounding the one or more discharge tanks.

[0162] In an embodiment, the first end of the riser and / or the second end of the downcomer is located above the buffer water surface water level.

[0163] The riser will collect or capture buffer water vapor evaporating from the buffer tank through the first end of the riser, and the buffer water vapor will rise upwards and forwards through the riser by means of natural convection. The buffer water vapor can partially condense on the inner walls of the riser, and in general some of the buffer water in the riser can be in liquid state, some can be in gaseous state, thus buffer water vapor. Likewise, some of the buffer water in the downcomer can be in liquid state, some can be in gaseous state, thus buffer water vapor.

[0164] In an embodiment, the minimum cross-section of the first end of the riser is larger than the minimum cross-section of the second end of the downcomer.

[0165] In an embodiment, the minimum cross-section of the first end of the riser is larger than the minimum cross-section of the second end of the downcomer, and the minimum cross-section of the first end of the riser is in the interval of 1 cm to 20 cm, such as in the interval of 1.5 cm to 10 cm, and the minimum cross-section of the second end of the downcomer is in the interval of 0.5 cm to 15 cm, such as in the interval of 1 cm to 8 cm.

[0166] In an embodiment, the buffer water in the buffer tank comprises a natural convection enhancer comprising a tank wall located in a gap between the inner wall and the outer wall, the tank wall dividing the buffer tank into an inner tank region and an outer tank region, the tank wall extending above the buffer water level into a dry wall section, the dry wall section contacting the outer wall at a wall contact location, wherein

[0167] - the dry wall section and / or the inner wall comprises perforations to allow air to circulate between the inner tank region and the outer tank region;

[0168] - the first end of the riser is allocated above the wall contact location, while the second end of the downcomer is allocated below the wall contact location.

[0169] In an embodiment, the end of the downcomer allocated below the wall contact location will have a nozzle capable of condensing any vapor in a gas volume above the buffer water surface.

[0170] The natural convection enhancer can be a wall structure placed in the buffer water, preferably said wall structure concentrically surrounds the inner wall of the buffer tank. The wall structure is preferably made of an alloy, such as stainless steel. The dry wall section is preferably integrated with the wall structure and can also be made of an alloy, such as stainless steel.

[0171] In one embodiment, the tank wall is a substantially vertical structure below the buffer water level and continuing above the water into a dry wall section, which is a plate structure at an angle to the substantially vertical structure, preferably said angle is between 30 to 120 degrees, such as between 60 to 100 degrees.

[0172] The outer tank area has a gas volume above the buffer water level, which is defined by the surface of the dry wall section, the surface of the outer wall and the buffer water surface. The perforations in the dry wall section allow circulation of gas (e.g. steam and air) and prevent any build-up of pressure on either side of the dry wall separating the inner tank area and the outer tank area. This prevents situations where pressure builds up in the outer tank area, which can thereby hinder the free flow of water down through the downcomer into the outer tank area.

[0173] In one embodiment, there are no perforations in the tank wall or dry wall section between the inner tank area and the outer tank area. Advantageously, a certain high pressure can be maintained to help the circulation of steam and condensed water.

[0174] In one embodiment, a sea water heat exchanger is provided, which has an inlet for buffer water, which inlet passes through a perforation in the tank wall, and which sea water heat exchanger has an outlet for buffer water into the buffer tank, wherein the outlet is positioned lower than the inlet.

[0175] The inlet through the perforation in the tank wall has the effect that only the buffer water in the inner tank area initiates circulation through the sea water heat exchanger. The buffer water in the inner tank area closer to the discharge tank has a higher temperature and is advantageously cooled in the sea water heat exchanger before it enters the outer tank area of the buffer tank through the outlet.

[0176] In one embodiment, the inner wall of the buffer tank is connected to the inner floor such that the inner wall and the inner floor have a bowl shape.

[0177] The bowl completely surrounds said one or more discharge tanks and the buffer water completely surrounds the bowl. The bowl can have a substantial rotational symmetry around an axis extending from the upper cabin to the discharge tank cabin, such as a substantially circular bowl shape around the discharge tank cabin with a circular perimeter. The bowl can also be an open box shape, wherein the open box shape surrounds the discharge tank cabin and has a rectangular perimeter.

[0178] The buffer water is located outside the inner wall and inside the outer wall, thus between the inner wall and the outer wall. The buffer water is located between the inner floor and the tank floor of the buffer water tank.

[0179] In the event of a severe accident, commonly referred to as a fuel salt spill accident, the bowl acts as a "fuel salt catcher". The accident can be due to a minor or extensive rupture of the vessel, tank or pipe containing the fuel salt. The inner floor acts as a heat barrier to protect the containment integrity while facilitating a heat transfer path to the buffer water in the buffer water tank. Preferably, the inner floor is constructed to have a thickness greater than the thickness of the inner wall, for example, the thickness is 3 times the thickness of the inner wall, for example, the thickness is 2 times the thickness of the inner wall. This means that the "fuel salt catcher" has two main safety functions, namely, both to protect the containment integrity in the event of a severe accident and to ensure the ability to remove decay heat in the event of a severe accident. In one embodiment, the inner floor is a multi-layered structure, for example, a double-layered structure, wherein the layer facing the drain tank has a greater thickness than the inner wall, for example, 2 times the thickness, or 1.5 times the thickness.

[0180] In one embodiment, the inner wall of the buffer water tank is a double-walled structure, wherein the double-walled structure is closed and contains a gas between the two walls of the double-walled structure, or the double-walled structure is open and the air between the two walls is in communication with the surrounding air.

[0181] Providing a double-walled structure to the inner wall of the buffer tank enables an additional containment barrier to be provided in the event of a rupture of the inner wall, which would otherwise allow water to enter the drain tank compartment, which can damage the drain tank containing the molten fuel salt. When the double-walled structure is closed and contains a gas between the two walls, a gas leak detection system can be used to measure the pressure between the two walls to alert any sudden pressure changes indicative of a rupture of the wall. The double-walled structure can also provide some thermal stress relief, for example, when in contact with the molten salt during a fuel salt spill accident.

[0182] In one embodiment, the molten salt drain system is a molten fuel salt drain system and comprises a salt piping system comprising at least one salt plug.

[0183] The salt plug can be a freeze valve ("freeze plug") which is a plug of salt in the salt piping system which is cooled and thus remains solid during cooling. When cooling is stopped, the salt melts due to the high temperature of the molten fuel salt in contact with the plug in the salt piping system. The salt piping system is part of the drain system, so when the salt plug has melted, the molten fuel salt is drained.

[0184] A unique safety feature of this design is that actuation is fully passive in case of loss of power (no operator action or power supply required). In this event, active cooling of the freeze valve is lost and the freeze plug will melt, allowing passive salt discharge. The salt piping system is connected to other piping, for example piping for a carrier gas. Depending on the operational mode (for example, discharge mode or normal power generation mode), parts of the piping system and the salt piping system can contain molten fuel salt or a gas such as a carrier gas.

[0185] For other types of events (no loss of power), active cooling has to be shut down in a more conventional way by the reactor protection system and using safety class instrumentation and signals. In any case, actuation and the system can be run fully passively if desired.

[0186] In one embodiment, the reactor configuration further comprises a gas supply system, the gas supply system comprising:

[0187] - a carrier gas reservoir;

[0188] - a carrier gas piping comprising at least one valve, the carrier gas piping being connected from the carrier gas reservoir to the one or more discharge tanks.

[0189] In one embodiment, the gas supply system further comprises a waste gas system, the waste gas system comprising:

[0190] - a waste gas reservoir;

[0191] - a carrier gas piping comprising at least one valve, the carrier gas piping being connected to the chemical control system and to the reactor vessel.

[0192] In most cases, during normal operation of the reactor in which heat is generated by the nuclear fission process, the gas supply system supplies gas to the reactor.

[0193] The supplied gas can continuously carry gaseous fission products from the reactor to the waste gas system as a carrier gas, in order to further process the gaseous fission products. The supplied gas can also, alone or in addition, supply gaseous reactants (for example, H2) to the molten fuel salt, to adjust, for example, the redox potential of the molten fuel salt. The purpose of this is to reduce the corrosiveness of the molten fuel salt. During the above-mentioned normal operation, the valves are in the open state.

[0194] If, for example, during a maintenance operation, the molten fuel salt has been discharged and it is desired to load the molten fuel salt back into the reactor, the gas supply system can be used to press the molten fuel salt from the one or more discharge tanks via the piping system into the reactor.

[0195] This provides a procedure for refueling operations with molten fuel salt without the need to use molten fuel salt pumps for transporting the molten fuel salt, but rather utilizing the existing gas supply system.

[0196] In one embodiment, the molten fuel salt has a composition selected from the group consisting of compositions comprising:

[0197] sodium fluoride + potassium fluoride + uranium fluoride;

[0198] lithium fluoride + thorium fluoride + plutonium fluoride;

[0199] lithium fluoride + thorium fluoride + uranium fluoride;

[0200] lithium fluoride + beryllium fluoride + uranium fluoride;

[0201] lithium fluoride + beryllium fluoride + uranium fluoride + thorium fluoride;

[0202] lithium fluoride + beryllium fluoride + uranium fluoride + thorium fluoride + zirconium fluoride;

[0203] sodium fluoride + rubidium fluoride + uranium fluoride;

[0204] sodium fluoride + beryllium fluoride + uranium fluoride + thorium fluoride + zirconium fluoride;

[0205] potassium chloride + plutonium chloride + uranium chloride;

[0206] sodium chloride + plutonium chloride;

[0207] sodium chloride + plutonium chloride + uranium chloride.

[0208] When using molten fuel salt, the fissile material is dissolved in a molten salt comprising a carrier salt, preferably a fluoride-based or chloride-based salt. Fluoride salts include F-19, which is the only natural isotope of fluorine and has a low probability of neutron capture. Fluoride salts are therefore particularly suitable for thermal MSR, which are very demanding in terms of neutron economy. The fissile material can be a fluoride salt or a chloride salt comprising a fissile isotope (e.g. U-235, U-233 or Pu-239).

[0209] In one embodiment, the molten fuel salt is a fluoride fuel salt or a chloride fuel salt based on one or more fluoride compounds or chloride compounds, which form the fuel salt composition, respectively.

[0210] The fuel salt comprising U-235 can have different enrichment levels, e.g. SEU (<2% U-235), LEU (typically 3-5% U-235), HALEU (5-20% U-235), or even natural uranium grade.

[0211] In one embodiment, the MSR further comprises a moderator based on a material selected from the group of graphite material, beryllium compound containing material, molten salt of metal hydroxide, wherein, when the moderator is a molten salt of metal hydroxide, the reactor configuration further comprises a molten salt of metal hydroxide drain system comprising a molten salt of metal hydroxide drain tank.

[0212] In one embodiment, the MSR comprises a molten salt of metal hydroxide or metal deuterated hydroxide.

[0213] In one embodiment, a molten salt reactor (MSR) comprising a reactor vessel contains a molten fuel salt and a moderator, the moderator being a molten salt of metal hydroxide or metal deuterated hydroxide. Such a reactor is known from EP3639279B1, wherein the molten fuel salt is present in an inner pipe in the reactor vessel, while the molten salt of metal hydroxide or metal deuterated hydroxide is in the reactor vessel surrounding the inner pipe.

[0214] When using a molten moderator salt (e.g. a molten salt of metal hydroxide or metal deuterated hydroxide), the upper compartment further comprises a molten moderator salt drain system connected to the reactor vessel and one or more molten moderator salt drain tanks.

[0215] Other moderators that can be used are water, heavy water (D2O), beryllium compounds or hydrides (e.g. zirconium hydride).

[0216] In one embodiment, the reactor configuration comprises a compartment divider comprising:

[0217] a grid structure forming a substantially horizontal surface separation between the upper compartment and the drain tank compartment, the grid structure comprising a metal grid and a thermal insulation layer and one or more funnels penetrating the grid structure, each funnel comprising a plug made of a sacrificial material.

[0218] The upper compartment comprising the reactor and the drain tank compartment comprising the drain tank for the molten salt can generally be located within the same spatial volume in the reactor configuration. The upper compartment and the drain tank compartment can be separated by a physical barrier. The advantage of such a compartment divider is that a relatively lower temperature is maintained in the upper compartment, in which the reactor instrumentation needs to be protected from the high temperature from the drain tank compartment, in which the drain tank can be preheated at a constant high temperature. The reason for preheating the drain tank is that a fast drain of the molten salt in case of an emergency event can cause thermal shock to the drain tank material, facing the risk of rupture and salt spillage in case the temperature in the drain tank is not high enough. Furthermore, the compartment divider should preferably provide a walkable surface in the upper compartment for MTSI (maintenance, testing, monitoring and inspection).

[0219] However, salt spills in the upper compartments, such as those associated with reactor piping, must be mitigated by allowing spilled salt to reach the fuel salt trap installed at the lowest point of the discharge tank compartment. The compartment partition addresses this issue by incorporating a grating structure that includes a funnel. If the compartment partition is to provide a walkable surface, the metal grating provides load-bearing characteristics.

[0220] In one embodiment, solid metal sheets are applied to the grid structure to enhance the structural strength of the compartment partition, the solid metal sheets, the insulation layer, and the metal grid forming a sandwich structure.

[0221] In one embodiment, the plug includes a disc-shaped component, preferably having one or more isolation discs below the disc-shaped component, the one or more isolation discs facing the discharge tank compartment.

[0222] The disc-shaped component is made of a sacrificial material, in the sense that the material is heated and melted and decomposed, for example, at a temperature below the normal operating temperature of molten salt.

[0223] The disc-shaped component can be made of a low-melting-point metal alloy or a polymer, such as a carbon-containing or fluoropolymer. The polymer can be made of polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), or ethylene tetrafluoroethylene (EFTE).

[0224] Insulating discs may include insulating materials selected from a list of glass wool, aerogel, and polymer foam.

[0225] The insulation layer may include insulating materials selected from the list of glass wool, rock wool, ceramic wool, aerogel, and silicate composites.

[0226] In one embodiment, the number of funnels penetrating the grid structure is per 5m 2 The surface area of ​​the grid structure should be at least one funnel-shaped, for example, per 5m². 2 The surface area of ​​the grid structure is divided into two funnels, each 5m² 2 The grid structure has three funnels on its surface. Setting several funnels in a compartment partition is a lower vertical configuration for molten salt discharge compared to one or more large funnels used for collecting and draining molten salt. This is because if only a small number of funnels are used to cover most of the compartment partition's surface area, the funnel angle required for the molten salt to flow freely at a sufficient velocity would necessitate a more robust construction.

[0227] In one embodiment, the reactor structure is located on an ocean structure, preferably on a barge.

[0228] The marine structure may be a barge that includes a power generation structure, which comprises one or more MSRs and a steam turbine capable of generating electricity.

[0229] According to an aspect of the application, there is provided a reactor configuration comprising an upper compartment above a drain tank compartment, the upper compartment comprising:

[0230] - a molten salt reactor (MSR) comprising a reactor vessel containing a molten fuel salt;

[0231] - a molten salt drain system connected to the reactor vessel;

[0232] the drain tank compartment comprising:

[0233] - one or more drain tanks in communication with the molten salt drain system;

[0234] - a pipe system comprising an inner pipe and an outer pipe, wherein the inner pipe and the outer pipe are joined together, wherein buffer water is located within a tube within the joined inner pipe and outer pipe of the pipe system, the pipe system surrounding the one or more drain tanks,

[0235] wherein,

[0236] a first pipe arrangement defining a circuit for at least a portion of the buffer water and comprising a heat exchanger in thermal contact with a water storage tank at a level above the pipe system, the water storage being in thermal contact with the environment,

[0237] and / or

[0238] a second pipe arrangement defining a circuit for at least a portion of the buffer water and comprising a heat exchanger in thermal contact with the environment, the heat exchanger being at a level above the pipe system,

[0239] and / or

[0240] a seawater heat exchanger in thermal contact with the buffer water and seawater, the seawater heat exchanger being below a seawater level outside an outer wall of the pipe system.

[0241] According to an aspect of the application, there is provided a reactor configuration comprising an upper compartment above a drain tank compartment, the upper compartment comprising:

[0242] - a molten salt reactor (MSR) comprising a reactor vessel containing a molten fuel salt;

[0243] - a molten salt drain system connected to the reactor vessel;

[0244] the drain tank compartment comprising:

[0245] - one or more drain tanks in communication with the molten salt drain system;

[0246] - a pipe system comprising an inner pipe and an outer pipe, wherein the inner pipe and the outer pipe are joined together, wherein the buffer water is located in a pipe within the joined inner pipe and outer pipe of the pipe system, the pipe system surrounding the one or more drain tanks, wherein the joined inner pipe and outer pipe of the pipe system comprise a section in which the buffer water evaporates, a section in which the buffer water is adiabatic and a section in which the buffer water condenses,

[0247] wherein,

[0248] the first pipe structure defining a circuit for at least a portion of the buffer water and comprising a heat exchanger in thermal contact with a water storage tank, said water storage tank being located at a level above the pipe system, said water storage being in thermal contact with the environment,

[0249] and / or

[0250] the second pipe structure defining a circuit for at least a portion of the buffer water and comprising a heat exchanger in thermal contact with the environment, said heat exchanger being located at a level above the pipe system,

[0251] and / or

[0252] a seawater heat exchanger in thermal contact with the buffer water and the seawater, said seawater heat exchanger being located below the seawater level outside the outer wall of the pipe system.

[0253] According to an aspect of the application, there is provided a reactor configuration comprising an upper compartment located above a drain tank compartment, said upper compartment comprising:

[0254] - a molten salt reactor (MSR) comprising a reactor vessel containing a molten fuel salt;

[0255] - a molten salt drain system connected to the reactor vessel;

[0256] said drain tank compartment comprising:

[0257] - one or more drain tanks in communication with the molten salt drain system;

[0258] - a pipe system comprising an inner pipe and an outer pipe, wherein the inner pipe and the outer pipe are joined together, wherein the buffer water is located in a pipe within the joined inner pipe and outer pipe of the pipe system, the pipe system surrounding the one or more drain tanks, wherein the joined inner pipe and outer pipe of the pipe system comprise a section in which the buffer water evaporates, a section in which the buffer water is adiabatic and a section in which the buffer water condenses,

[0259] wherein,

[0260] - a seawater heat exchanger in thermal contact with the buffer water and the seawater, the seawater heat exchanger being located below the seawater level outside the outer wall of the pipe system and inside a rectangular or cylindrical recess, preferably inside a sea chest.

[0261] According to an aspect of the present application, there is provided a method of heat transfer from a molten salt, the method comprising the steps of:

[0262] - providing molten fuel salt in one or more drain tanks for molten fuel salt;

[0263] - surrounding the one or more drain tanks for molten fuel salt with a buffer water tank, the buffer water tank comprising buffer water in a gap between an inner wall and an outer wall of the buffer water tank, the molten fuel salt transferring heat by at least one of thermal radiation, thermal conduction or thermal convection to the inner wall to heat the buffer water to steam;

[0264] - providing a first pipe structure, the first pipe structure comprising:

[0265] at least one riser pipe above at least a portion of the buffer water, the riser pipe collecting steam and directing the steam to a heat exchanger in water storage in a water storage tank above the buffer water tank to condense the steam to water;

[0266] at least one downcomer pipe to direct water from the heat exchanger in water storage in the water storage tank to the buffer water tank,

[0267] and / or

[0268] - providing a second pipe structure, the second pipe structure comprising:

[0269] at least one riser pipe above at least a portion of the buffer water, the riser pipe collecting steam and directing the steam to a gas heat exchanger in thermal contact with an environment comprising a gas, the gas heat exchanger being located above the buffer water tank to condense the steam to water;

[0270] at least one downcomer pipe to direct water from the gas heat exchanger to the buffer water tank,

[0271] and / or

[0272] - providing a seawater heat exchanger in thermal contact with the buffer water, the seawater heat exchanger being located below the seawater level outside the outer wall of the buffer water tank, wherein the buffer water is circulated through the seawater heat exchanger.

[0273] In one embodiment, a method of heat transfer from a molten salt, the method comprising the steps of:

[0274] - providing molten fuel salt in one or more drain tanks for molten fuel salt;

[0275] - surrounding the one or more drain tanks for molten fuel salt with a buffer water tank, the buffer water tank comprising buffer water in a gap between an inner wall and an outer wall of the buffer water tank, the molten fuel salt transferring heat to the inner wall by at least one of thermal radiation, thermal conduction or thermal convection to heat the buffer water to steam;

[0276] - providing a first piping structure, the first piping structure comprising:

[0277] at least one upcomer above at least a portion of the buffer water, the upcomer collecting steam and directing the steam to a heat exchanger in stored water in a stored water tank above the buffer water tank to condense the steam to water;

[0278] at least one downcomer to direct water from the heat exchanger in stored water in the stored water tank to the buffer water tank;

[0279] and / or

[0280] - providing a second piping structure, the second piping structure comprising:

[0281] at least one upcomer above at least a portion of the buffer water, the upcomer collecting steam and directing the steam to a gas heat exchanger in thermal contact with an environment comprising a gas, the gas heat exchanger being located above the buffer water tank to condense the steam to water;

[0282] at least one downcomer to direct water from the gas heat exchanger to the buffer water tank;

[0283] and / or

[0284] - providing a seawater heat exchanger in thermal contact with the buffer water, the seawater heat exchanger being located below a seawater level outside the outer wall of the buffer water tank, wherein the buffer water is circulated through the seawater heat exchanger.

[0285] In one embodiment, a method of heat transfer from a molten salt, comprising the steps of:

[0286] - providing molten fuel salt in one or more drain tanks for molten fuel salt;

[0287] - surrounding the one or more drain tanks for molten fuel salt with a buffer water tank, the buffer water tank comprising buffer water in a gap between an inner wall and an outer wall of the buffer water tank, the molten fuel salt transferring heat to the inner wall by at least one of thermal radiation, thermal conduction or thermal convection to heat the buffer water to steam;

[0288] - providing a first piping structure, the first piping structure comprising:

[0289] At least one riser pipe located above at least a portion of the buffer water, the riser pipe collecting steam and directing the steam to a heat exchanger in a water storage tank located above the buffer water tank, to condense the steam into water;

[0290] At least one downcomer is used to guide water from the heat exchanger in the storage tank to the buffer tank.

[0291] and / or

[0292] - Provide a second piping structure, the second piping structure comprising:

[0293] At least one riser pipe located above at least a portion of the buffer water, the riser pipe collecting steam and directing the steam to a gas heat exchanger that comes into thermal contact with the environment, which includes gases, located above the buffer water tank to condense the steam into water;

[0294] At least one downcomer is provided for guiding water from the gas heat exchanger to a buffer tank, and optionally...

[0295] - Provide a seawater heat exchanger that comes into thermal contact with the buffer water, the seawater heat exchanger being located below the seawater level on the outer side of the outer wall of the buffer water tank, wherein the buffer water circulates through the seawater heat exchanger.

[0296] The method of heat transfer from molten salt is applicable to molten salt, regardless of the type of container in which the molten salt is contained.

[0297] In one embodiment, the molten salt is a molten fuel salt.

[0298] This method can transfer the heat generated by the decay of fission products in molten fuel salt. The heat can be transferred from the discharge tank for molten fuel salt to the inner wall via at least one of thermal radiation, thermal conduction, or thermal convection to heat the buffer water into buffer steam.

[0299] The riser collects or traps buffer water vapor evaporating from the buffer tank at its first end, and the buffer water vapor rises upward and forward through the riser by natural circulation. The buffer water vapor may partially condense on the inside of the riser, and generally, some of the buffer water in the riser may be in a liquid state, while some may be in a gaseous state, thus forming buffer water vapor. In one embodiment, the riser is at least partially insulated, for example, by pipe segment insulation. This mitigates any problems caused by condensation in the riser. Eventually, the water condensed on the inside of the riser will re-evaporate, and the resulting buffer water vapor will rise upward. Similarly, some of the buffer water in the downcomer may be in a liquid state, while some may be in a gaseous state, thus forming buffer water vapor. Eventually, the buffer water vapor in the downcomer will condense and be drawn downward within the downcomer.

[0300] The method is well suited for transferring heat from the molten fuel salt contained in one or more drain tanks as described above.

[0301] In one embodiment, a method of heat transfer from a molten salt, comprising the steps of:

[0302] - providing a molten fuel salt in a reactor vessel;

[0303] - surrounding the reactor vessel with a buffer water tank, the buffer water tank comprising a buffer water in a gap between an inner wall and an outer wall of the buffer water tank, the molten fuel salt transferring heat by at least one of thermal radiation, thermal conduction or thermal convection to the inner wall to heat the buffer water to steam;

[0304] - providing a first piping structure, the first piping structure comprising:

[0305] at least one riser pipe above at least a portion of the buffer water, the riser pipe collecting steam and guiding the steam to a heat exchanger in stored water in a stored water tank above the buffer water tank to condense the steam to water;

[0306] at least one downcomer pipe to guide the water from the heat exchanger in the stored water in the stored water tank to the buffer water tank,

[0307] and / or

[0308] - providing a second piping structure, the second piping structure comprising:

[0309] at least one riser pipe above at least a portion of the buffer water, the riser pipe collecting steam and guiding the steam to a gas heat exchanger in thermal contact with an environment comprising a gas, the gas heat exchanger being located above the buffer water tank to condense the steam to water;

[0310] at least one downcomer pipe to guide the water from the gas heat exchanger to the buffer water tank, and, optionally

[0311] - providing a seawater heat exchanger in thermal contact with the buffer water, the seawater heat exchanger being located below a seawater level outside the outer wall of the buffer water tank, wherein the buffer water is circulated through the seawater heat exchanger.

[0312] Alternatively, the method of heat transfer from a molten fuel salt can be used in an MSR in an operational state generating heat by a fission process or in an operational state for an anticipated operational event, the MSR comprising a reactor vessel containing a molten fuel salt. The method of heat transfer from a molten fuel salt can also be used in an MSR that is temporarily or permanently shut down. The method of heat transfer from a molten fuel salt can also be used in an accident state.

[0313] When the MSR is operating, a trade-off is required, i.e. to allow for a certain parasitic heat loss in exchange for a passive heat removal system that achieves improved safety performance compared to an active heat removal system.

[0314] In one embodiment, the method of transferring heat from the molten salt further comprises the step of transferring heat from the molten salt of the metal hydroxide or metal deuterated hydroxide used as a moderator, wherein the reactor cavity further comprises a molten moderator salt drain system connected to the reactor vessel and one or more molten moderator salt drain tanks.

[0315] Advantageously, when the one or more drain tanks for molten fuel salt are located near the ocean, a seawater heat exchanger can be used to transfer heat to the seawater, the ultimate heat sink. This is particularly advantageous when the one or more drain tanks for molten fuel salt are located below sea level. Other water-based ultimate heat sinks can be lakes, fjords, rivers or ponds, and a heat exchanger submerged in water can serve the same purpose as a seawater heat exchanger. Such a heat exchanger located below the water level outside the outer wall of the buffer tank will transfer heat from the buffer water.

[0316] In one embodiment, there is heat transfer from the water storage tank to the environment, e.g. the external environment in thermal contact with the water storage tank.

[0317] In one embodiment, the heat transfer from the water storage tank is at least partly through evaporation of the stored water to the external environment.

[0318] The heat exchanger in the water storage tank transfers heat from the buffer water to the stored water in the water storage tank. The heat is further transferred to the environment, e.g. the external environment, and thus to the air. The water storage tank can be an enclosed volume, wherein the heated stored water in the enclosed volume transfers heat to the external environment in thermal contact with the enclosed volume. This thermal contact can be, for example, thermal contact between the outer shell of the enclosed volume and the external environment.

[0319] The water storage tank can also be an at least partly open tank, wherein the heated stored water transfers heat to the external environment through evaporation of the stored water. Evaporation of the stored water provides a very efficient way of heat transfer. The stored water is in thermal contact with the buffer water in the heat exchanger but not in direct contact, although the buffer water can be activated by radiation from the molten salt in the drain tank, the stored water is not activated and can thus evaporate to the external environment without being a safety concern.

[0320] In one embodiment, the heat transfer is a passive heat transfer method.

[0321] The method of heat transfer from the molten salt can be done without a pump or other active mechanism that can also require manual intervention to activate. The heat transfer with steam from the heated buffer water relies on the heat carrying vapor of evaporation naturally passing upwards through a permanently installed riser pipe to a heat exchanger in thermal contact with the cooler stored water where the vapor will condense. The condensed water then naturally passes downwards through a permanently installed downcomer pipe to the buffer water tank under the force of gravity. Water molecules will obtain a higher velocity at a given temperature than surrounding air molecules (N2 and O2) and preferentially flow upwards in the riser pipe faster than air molecules.

[0322] In an embodiment, a natural convection enhancer is provided, the natural convection enhancer comprising a tank wall in a gap between an inner wall and an outer wall, the tank wall dividing a buffer water tank into an inner tank region and an outer tank region,

[0323] - boiling evaporation of the buffer water in the inner tank region, and

[0324] - providing a path for the vapor to flow upwards.

[0325] The tank wall of the natural convection enhancer separates the water close to the heated inner wall from the rest of the buffer water tank, resulting in the water close to the inner wall to be heated to locally boil. The natural convection enhancer also acts as a thermal barrier for the water close to the outer wall. The difference in temperature and density promotes the flow driven by buoyancy. Furthermore, the natural convection enhancer provides a path for the vapor to flow upwards.

[0326] In an embodiment, the tank wall extends above the buffer water level into a dry wall section, the dry wall section being in contact with the outer wall at a wall contact location, wherein the dry wall section and / or the inner wall comprises perforations to allow air circulation between the inner tank region and the outer tank region, and wherein a first end of the riser pipe is allocated above the wall contact location and a second end of the downcomer pipe is allocated below the wall contact location.

[0327] The outer tank region has a gas volume above the buffer water surface, the gas volume being defined by the surface of the dry wall section, the surface of the outer wall and the buffer water surface. The perforations in the dry wall section allow circulation of gases such as steam and air and prevent any pressure build-up on either side of the dry wall separating the inner tank region and the outer tank region. This prevents the situation where pressure builds up in the outer tank region, which can thereby hinder the free flow of water down through the downcomer pipe into the outer tank region.

[0328] In an embodiment, the buffer water in the inner tank region has a higher temperature than the buffer water in the outer tank region and enters through an inlet to a seawater heat exchanger through the perforations of the tank wall, after which the buffer water is cooled in the seawater heat exchanger and enters the buffer water tank through an outlet for the buffer water, wherein the outlet is positioned lower than the inlet.

[0329] In one embodiment, there are no perforations in the dry wall section and the tank wall. In this embodiment, the internal gas space pressure will rise due to steam generation and can enhance the steam and condensate circulation. BRIEF DESCRIPTION OF DRAWINGS

[0330] The application will be explained in more detail below by means of examples and with reference to the schematic drawings, in which:

[0331] Figure 1 An embodiment of the reactor configuration is shown when the MSR is in operational state.

[0332] Figure 2 An embodiment of the reactor configuration is shown when the MSR is in accident state.

[0333] Figure 3 A reactor configuration is shown mounted on a barge.

[0334] Figure 4 A reactor configuration is shown, wherein the buffer water tank is embodied as a tube system.

[0335] Figure 5 A reactor configuration is shown, wherein the buffer water tank is embodied as a tube system, wherein the tube system comprises a section, in which the buffer water evaporates, a section, in which the buffer water is thermally insulated, and a section, in which the buffer water condenses.

[0336] Figure 6 A reactor configuration is shown, wherein the buffer water tank is embodied as a tube system, wherein the tube system comprises a section, in which the buffer water evaporates, a section, in which the buffer water is thermally insulated, and a section, in which the buffer water condenses, wherein the buffer water and the seawater are in thermal contact below the seawater level.

[0337] LIST OF REFERENCE NUMBERS

[0338] 1 reactor configuration

[0339] 2 upper cabin

[0340] 3 drain tank cabin

[0341] 4 molten salt reactor (MSR)

[0342] 5 reactor vessel

[0343] 6 molten fuel salt

[0344] 7 fuel salt pump

[0345] 8 main heat exchanger

[0346] 9 drain system

[0347] 10 drain tank

[0348] 11, 110, 111, 112 valve

[0349] 12 carrier gas line

[0350] 13 salt plug

[0351] 14 salt cooling pump

[0352] 15 buffer water tank

[0353] 16 inner wall

[0354] 17 outer wall

[0355] 18 inner bottom plate

[0356] 19 tank bottom plate

[0357] 20 fuel salt trap

[0358] 21 buffer water

[0359] 22 first piping arrangement

[0360] 23 heat exchanger in thermal contact with storage water

[0361] 24 second piping arrangement

[0362] 25 gas heat exchanger in thermal contact with the environment

[0363] 26 seawater heat exchanger

[0364] 27 riser pipe

[0365] 28 first end of riser pipe

[0366] 29 second end of riser pipe

[0367] 30 storage water tank

[0368] 31 downcomer pipe

[0369] 32 first end of downcomer pipe

[0370] 33 second end of downcomer pipe

[0371] 34 tank wall

[0372] 35 inner tank region

[0373] 36 outer tank region

[0374] 37 dry wall section

[0375] 38 wall contact location

[0376] 39 dry wall section perforation

[0377] 40 barge

[0378] 41 double-walled outer shell

[0379] 42 upper deck

[0380] 43 outlet for water vapor

[0381] 44 heat exchanger structure

[0382] 45 opening for hot air

[0383] 46 first wall

[0384] 47 second wall

[0385] 48 opening for hot sea water

[0386] 49 water storage tank

[0387] 50 condenser

[0388] 51 cold outer tube

[0389] 52 hot inner tube

[0390] 53 reserve tank

[0391] 54 sea water level

[0392] 55 condensing section of the pipe system

[0393] 56 adiabatic section of the pipe system

[0394] 57 evaporating section of the pipe system

[0395] 58 sea water discharge valve box

[0396] The invention is not limited to the embodiment / embodiments shown in the drawings. Thus, it is to be understood that where the description in the accompanying claims is followed by references to the drawings, such references are included merely for the purpose of enhancing the intelligibility of the claims and in no way limit the scope of the claims.

[0397] The term "comprising", used in the description and in the claims, means "consisting at least in part of". When interpreting each statement in this document in accordance with the term "comprising", features other than those expressly identified by each statement can also be present. Related terms such as "comprise" and "comprised" are to be interpreted in the same manner. DETAILED DESCRIPTION

[0398] The invention will now be explained with reference to the drawings and the following non-limiting examples.

[0399] Figure 1 A reactor configuration 1 of the invention is shown, having an upper compartment 2 above a discharge tank compartment 3.Figure 1 An embodiment of the reactor configuration 1 is shown in which the MSR 4 is in operation.

[0400] The entire reactor configuration 1, including the upper plenum 2 and the drain tank plenum 3, is surrounded by a wall configuration. The molten salt reactor (MSR) 4 is located in the upper plenum 2 and is shown with a reactor vessel 5 supported by a reactor floor (not shown). The fission process occurring in the molten fuel salt 6 in the reactor core generates heat in the core, and the heated fuel salt produced thereby is circulated from the core out by a fuel salt pump 7 to a primary heat exchanger 8. The primary heat exchanger 8 can be connected to a steam generator (not shown) to generate electricity, either directly or via other (not shown) heat exchangers. Gaseous fission products are collected and processed by a gas removal system to separate and store the gaseous fission products. The gas supply system is capable of supplying a carrier gas (e.g., helium) to the gas removal system to carry the gaseous fission products away from the reactor core. The gas supply system is also capable of supplying gas to a chemical control unit in which reactants are supplied to the molten salt 6 to maintain a target chemical composition of the molten salt. The gas supply system includes gas piping 12 to bring the carrier gas to the various facilities described above, but also has a piping system to the drain tank in the drain tank plenum. The piping system to the drain tank can be opened or closed by valves 11, 110 on the carrier gas piping system.

[0401] The reactor 4 is shown in operational mode, wherein the reactor vessel 5 contains the molten fuel salt 6 and the drain tank 10 is empty. The salt piping system is shown with a salt plug 13, which is actively cooled by the salt cooling system 14. The part of the salt piping system below the salt plug 13 towards the drain tank 10 located below the upper compartment 2 is free of fuel salt 6, which is shown in the figure without molten salt 6, but with helium gas. The drain tank compartment 3 shows that the drain tank 10 is completely surrounded by the rectangular buffer water tank 15, which is shown in cross section. The buffer water tank 15 contains the buffer water 21 between the inner wall 16 and the outer wall 17, which are shown in cross section in the figure. The buffer water tank 15 also surrounds the drain tank 10 from below with the buffer water 21, where the inner floor 18 faces the drain tank 10 on one side and the buffer water 21 on the other side of the inner floor 18. The inner floor 18 is shown as a two-layered plate with a shallow bowl shape, where the plate of the two-layered plate facing the drain tank 10 can act as a fuel salt catcher. The tank floor 19 is shown at the lowest position of the buffer water tank 15. The natural convection enhancer is shown in cross section in the figure, comprising the tank wall 34. The tank wall 34 is supported at its lower part by tank wall supports (not shown in the figure), allowing circulation and convection of the buffer water 21 below the lowest edge of the tank wall 34. The tank wall 34 divides the buffer water tank 15 into an inner tank area 35 facing the drain tank 10 and an outer tank area 36. The dry wall section 37 connects the tank wall 34 and the outer wall 17, where the dry wall section 37 is a rectangular annular plate with a ring width that corresponds approximately to the width of the outer tank area 36. The outer wall 17 is assembled with the rectangular annular plate connected to it, forming a closed barrier between the inner tank area 35 and the outer tank area 36, but with the exception of the above-mentioned gap below the lowest edge of the tank wall 34 and the dry wall section 37 of the natural convection enhancer and / or the perforations 39 in the tank wall 34. The perforations 39 are shown in the tank wall 34 above the water level of the buffer water 21 in the buffer water tank 15.

[0402] A first pipe arrangement 22 is shown and described below. The riser pipe 27 is shown with its first end 28 inside the inner tank region 35 and above the annular drywall section 37. The first end 28 of the riser pipe is above the water level of the buffer water 21 and any steam (not shown) in the inner tank region 35 can enter the first end 28 of the riser pipe, thus the first end is an inlet for buffer water steam. During normal operation, the evaporation of the buffer water 21 will be very limited. The riser pipe 27 extends upwardly from its first end 28 and the riser pipe 27 is shown entering the water storage tank 30 near the level of the MSR 4 above the discharge tank chamber 3. The second end 29 of the riser pipe is connected to the heat exchanger 23 which is surrounded by and in thermal contact with the stored water in the water storage tank 30. Any buffer water steam is at least partially condensed in the heat exchanger 23 and the buffer water 21 exits the heat exchanger 23 at the outlet end of the heat exchanger 23 into the first end 32 of the downcomer pipe. As mentioned above, during normal operation, the amount of evaporation and condensation of the buffer water 21 will be very limited. The downcomer pipe 31 extends downwardly from its first end 32 and into the outer tank region 36 of the buffer water tank 15 where the buffer water 21 can be introduced into the buffer water 21 in the outer tank region 36 through the second end 33 of the downcomer pipe. The second end 33 of the downcomer pipe is below the annular drywall section 37 and above the water level of the buffer water.

[0403] A second pipe arrangement 24 is shown and described below.

[0404] The riser pipe 27 is shown with its first end 28 inside the inner tank region 35 and above the rectangular annular drywall section 37. The first end 28 of the riser pipe is above the water level of the buffer water 21 and any steam (not shown) in the inner tank region 35 enters the first end 27 of the riser pipe, thus the first end is an inlet for buffer water steam. As mentioned above for the first pipe: during normal operation, the evaporation of the buffer water 21 will be very limited. The riser pipe 27 extends upwardly from its first end 28 and the riser pipe 27 is shown connected to the gas heat exchanger 25 near the level of the MSR 4 above the discharge tank chamber 3. The second end 29 of the riser pipe is connected to the gas heat exchanger 25 which is surrounded by and in thermal contact with the outside environment. Any buffer water steam will be at least partially condensed in the heat exchanger 25 and the buffer water 21 exits the gas heat exchanger 25 at the outlet end of the gas heat exchanger 25 into the first end 32 of the downcomer pipe. The downcomer pipe 31 extends downwardly from its first end 32 and into the outer tank region 36 of the buffer water tank 15 where the buffer water 21 is introduced into the buffer water 21 in the outer tank region 36 through the second end 33 of the downcomer pipe. The second end 33 of the downcomer pipe is below the annular drywall section 37 and above the water level of the buffer water.

[0405] The seawater heat exchanger 26 is shown as being located outside the buffer tank 15 and submerged in seawater below sea level. The seawater heat exchanger 26 has an inlet and an outlet for the buffer water 21, where the inlet is positioned higher than the outlet. The inlet to the seawater heat exchanger 26 for the buffer water 21 ends with its open end in the inner tank area 35, where the buffer water 21 has a higher temperature than in the outer tank area 36. During normal operation, the temperature difference between the buffer water 21 in the inner tank area 35 and in the outer tank area 36 will be very limited. The buffer water 21 enters the inlet and is cooled by seawater having a lower temperature than the buffer water 21 in the inner tank area 35, whereafter the buffer water 21 is circulated back into the lower part of the buffer tank 15. This circulation of the buffer water 21 through the seawater heat exchanger 26 is performed as a natural circulation from a hot area to a cold area and is a passive circulation, without the need for active pumping of water through the seawater heat exchanger 26.

[0406] Figure 2 An embodiment of the reactor configuration 1 is shown, where the MSR 4 is in an accident situation.

[0407] The entire reactor configuration 1 is shown in Figure 1 The reactor configuration 1 comprises an upper compartment 2 and a drain tank compartment 3. The molten fuel salt 6 has been drained from the reactor core and no fission process is taking place in the molten fuel salt 6 in the reactor core. The draining is caused by an external power outage. This results in the cooling system 14 shutting down the active cooling of the salt plug 13, which in turn results in the salt plug 13 melting and thereby enabling the molten fuel salt 6 to flow freely from the MSR 4 to the drain tank 10 through the piping system. The drain tank 10, which is positioned lower than the upper compartment 2, is shown containing the fuel salt 6, which releases heat due to decay of fission products. As Figure 1 The drain tank compartment 3 is shown with the drain tank 10 completely surrounded by the rectangular buffer tank 15. The tank wall 34 divides the buffer tank 15 into an outer tank area 36 and an inner tank area 35 facing the drain tank 10, and the buffer water 21 in the inner tank area 35 gets heat due to its contact with the inner wall 16 facing the drain tank 10. As Figure 1 The dry wall section 37 connects the tank wall 34 and the outer wall 17 is shown.

[0408] The first piping structure 22 is shown in Figure 1As shown. The first end 28 of the riser is located above the water level of the buffer water 21. Steam (not shown) in the inner tank area 35 enters the first end 28 of the riser, thus serving as the inlet for buffer water vapor. Immediately after the molten fuel salt 6 is discharged, the buffer water 21, particularly the buffer water 21 in the inner tank area 35, may immediately evaporate extensively. The steam pressure can be controlled below a certain value by allowing the steam to escape through perforations 39 in the tank wall 34. The riser 27 extends upward from its first end 28 and is shown as including evaporated steam, which enters the water storage tank 30 above the discharge tank compartment 3 at approximately the level of MSR 4. The second end 29 of the riser connects to a heat exchanger 23, which is surrounded by and in thermal contact with the water storage in the water storage tank 30. The buffer water vapor condenses at least partially in the heat exchanger 23, and the buffer water 21 exits the heat exchanger 23 at its outlet end and enters the first end 32 of the downcomer. A downcomer 31 extends downward from its first end 32 and enters the outer tank region 36 of the buffer water tank 15, where buffer water 21 is drawn into the buffer water 21 in the outer tank region 36 through the second end 33 of the downcomer. The second end 33 of the downcomer is located below the annular dry wall section 37 and above the water level of the buffer water. The aforementioned circulation of buffer steam and buffer water 21 in the first piping structure 22 is supplemented by natural convection circulation of the buffer water 21 from the outer tank region 36 to the inner tank region 35 below the tank wall 34.

[0409] Second pipeline structure 24 Figure 1 As shown. The first end 28 of the riser pipe is located above the water level of the buffer water 21, and steam (not shown) in the inner tank area 35 enters the first end 28 of the riser pipe, thus this first end is the inlet for buffer water steam. The riser pipe 27 extends upward from its first end 28, and is shown connected to the gas heat exchanger 25 near the horizontal height of MSR 4 above the discharge tank compartment 3. The second end 29 of the riser pipe is connected to the gas heat exchanger 25, which is surrounded by and in thermal contact with the external environment. The buffer water steam is at least partially condensed in the heat exchanger 25, and the buffer water 21 exits the gas heat exchanger 25 at the outlet end of the gas heat exchanger 25 and enters the first end 32 of the downcomer. The downcomer 31 extends downward from its first end 32 and enters the outer tank area 36 of the buffer water tank 15, where the buffer water 21 is led into the buffer water 21 in the outer tank area 36 through the second end 33 of the downcomer. The second end 33 of the downcomer is located below the annular dry wall section 37 and above the water level of the buffer water.

[0410] The seawater heat exchanger 26 is shown as being located outside the buffer tank 15 and submerged in seawater below the sea level. The seawater heat exchanger 26 has an inlet and an outlet for the buffer water, wherein the inlet is positioned higher than the outlet. The inlet to the seawater heat exchanger 26 for the buffer water 21 ends with its open end in the inner tank region 35, where the buffer water 21 has a higher temperature due to the decay heat on the other side of the inner tank wall 16 as described above. The temperature difference between the buffer water 21 in the inner tank region 35 and the buffer water 21 in the outer tank region 36 will cause a natural circulation of the buffer water 21. The buffer water 21 enters the inlet to the seawater heat exchanger 26 for the buffer water 21 and is cooled by seawater having a lower temperature than the buffer water 21 in the inner tank region 35, whereupon the buffer water 21 circulates back into the lower part of the buffer tank 15. This circulation of the buffer water 21 through the seawater heat exchanger 26 is performed as a natural circulation from a hot region to a cold region and is a passive circulation, without the need for an active pumping of water through the seawater heat exchanger 26.

[0411] In Figure 3 , the reactor configuration 1 is shown as being mounted on a barge 40. The reactor configuration 1 is shown with the MSR 4 in an operational state and the molten fuel salt 6 located in the reactor core, and reference is made to the description of the above Figure 1 The upper compartment 2 and the drain tank compartment 3 are surrounded by a double-walled enclosure 41, which can constitute the structure required for the hull integrity, or alternatively constitute a biological shield for the reactor configuration.

[0412] The first pipe structure 22 and the second pipe structure 24 are shown. The first pipe structure 22 is shown as an outlet for the water vapor storage passing through the upper deck 42 of the barge 40. The second pipe structure 24 is shown as the end of the riser 27 and the beginning of the downcomer 31 being located outside the upper deck 42 of the barge 40. The gas heat exchanger 25 is located outside the upper deck 42 of the barge 40 and is surrounded by a heat exchanger 44 structure, which has openings 45 for the hot air produced from the heat exchanger 44. The hot air is led out to the atmosphere through these openings 45.

[0413] The seawater heat exchanger 26 is located in seawater outside a first wall 46 of the hull structure. A second wall 47 of the hull structure is shown with openings 48 for the produced hot seawater in heat exchange with the buffer water 21.

[0414] Figure 4 A reactor configuration is shown, wherein the buffer tank is implemented as a pipe system. This reactor configuration is similar to the one described above Figure 1The same applies to the reactor configuration shown. However, the buffer tank 15 is implemented as a tube system comprising an inner tube with a hot wall 52 and an outer tube with a cold wall 51, wherein the inner tube and the outer tube are joined together, wherein the buffer water from the water reservoir 49 is located in the tube inside the joined together inner tube and outer tube in the tube system, which is also connected to the reserve tank 53. The water reservoir 49 houses a condenser 50, which helps to condense the evaporated cooling water. The water reservoir 49 is located above the sea water level 54.

[0415] Figure 5 The same applies to the reactor configuration shown. However, the buffer tank 15 is implemented as a tube system comprising an inner tube with a hot wall 52 and an outer tube with a cold wall 51, wherein the inner tube and the outer tube are joined together, wherein the buffer water from the water reservoir 49 is located in the tube inside the joined together inner tube and outer tube in the tube system, which is also connected to the reserve tank 53. The water reservoir 49 houses a condenser 50, which helps to condense the evaporated cooling water. The water reservoir 49 is located above the sea water level 54. Figure 4 The same applies to the reactor configuration shown. However, the tube system comprises an inner tube with a hot wall 52 and an outer tube with a cold wall 51, each comprising a lower evaporation section 57, a middle adiabatic section 56 and an upper condensation section 55. In the evaporation section 57, the buffer water evaporates. In the adiabatic section 56, there is no heat exchange between the buffer water and the environment. In the condensation section 55, the buffer water condenses.

[0416] Figure 6 The same applies to the reactor configuration shown. However, the buffer tank 15 is implemented as a tube system comprising an inner tube with a hot wall 52 and an outer tube with a cold wall 51, wherein the inner tube and the outer tube are joined together, wherein the buffer water from the water reservoir 49 is located in the tube inside the joined together inner tube and outer tube in the tube system, which is also connected to the reserve tank 53. The water reservoir 49 houses a condenser 50, which helps to condense the evaporated cooling water. The water reservoir 49 is located above the sea water level 54. Figure 4 The same applies to the reactor configuration shown. However, instead of the tube system being in contact with the water reservoir 49 comprising a condenser 50, the tube system is in contact with the sea water below the sea water level via a sea valve box 58.

Claims

1. A reactor structure (1) including an upper compartment (2) located above a discharge tank compartment (3). The upper compartment (2) includes: - Molten salt reactor (MSR) (4), the molten salt reactor including reactor vessel (5), the reactor vessel containing molten fuel salt (6). - A molten salt discharge system connected to the reactor vessel (5); The discharge tank compartment (3) includes: - One or more discharge tanks (10), the discharge tanks being connected to the molten salt discharge system; - Buffer tank (15), the buffer tank including an inner wall (16) and an outer wall (17) and buffer water (21) in the gap between the inner wall (16) and the outer wall (17) of the buffer tank (15), the buffer tank (15) surrounding the one or more discharge tanks (10). in, The first piping structure (22) defines a loop for at least a portion of the buffer water (21) and includes a heat exchanger (23) in thermal contact with a water storage tank (30) located at a horizontal height above the buffer water tank (15), the water being in thermal contact with the environment. and / or The second piping structure (24) defines a loop for at least a portion of the buffer water (21) and includes a heat exchanger (25) in contact with ambient heat, the heat exchanger (25) being located at a horizontal height above the buffer water tank (15). and / or A seawater heat exchanger (26) that is in thermal contact with the buffer water (21) and seawater is located below the seawater level outside the outer wall (17) of the buffer water tank (15).

2. The reactor structure (1) according to claim 1, wherein, The reactor structure (1) includes an upper compartment (2) located above the discharge tank compartment (3). The upper compartment (2) includes: - Molten salt reactor (MSR) (4), the molten salt reactor including reactor vessel (5), the reactor vessel containing molten fuel salt (6). - A molten salt discharge system connected to the reactor vessel (5); The discharge tank compartment (3) includes: - One or more discharge tanks (10) connected to the molten salt discharge system; - Implemented as a buffer water tank (15) of a pipe system, the pipe system including an inner pipe (52) and an outer pipe (51), wherein the inner pipe and the outer pipe are connected together, wherein the buffer water is located in the pipe within the connected inner pipe and the outer pipe of the pipe system, the buffer water tank (15) surrounding the one or more discharge tanks (10). in, The first piping structure (22) defines a loop for at least a portion of the buffer water (21) and includes a heat exchanger (23) in thermal contact with a water storage tank (30) located at a horizontal height above the buffer water tank (15), the water being in thermal contact with the environment. and / or The second piping structure (24) defines a loop for at least a portion of the buffer water (21) and includes a heat exchanger (25) in contact with ambient heat, the heat exchanger (25) being located at a horizontal height above the buffer water tank (15). and / or A seawater heat exchanger (26) that is in thermal contact with the buffer water (21) and seawater is located below the seawater level outside the outer wall (17) of the buffer water tank (15).

3. The reactor structure (1) according to claim 1 or 2, wherein, The reactor structure (1) includes an upper compartment (2) located above the discharge tank compartment (3). The upper compartment (2) includes: - Molten salt reactor (MSR) (4), the molten salt reactor including reactor vessel (5), the reactor vessel containing molten fuel salt (6). - A molten salt discharge system connected to the reactor vessel (5); The discharge tank compartment (3) includes: - One or more discharge tanks (10) connected to the molten salt discharge system; - Implemented as a buffer water tank (15) of a pipe system, the pipe system including an inner pipe (52) and an outer pipe (51), wherein the inner pipe (52) and the outer pipe (51) are connected together, wherein the buffer water is located in the pipe within the connected inner and outer pipes of the pipe system, the buffer water tank (15) surrounding the one or more discharge tanks (10), wherein the connected inner and outer pipes of the pipe system include a section (57) in which the buffer water evaporates, a section (56) in which the buffer water is insulated, and a section (55) in which the buffer water condenses. in, The first piping structure (22) defines a loop for at least a portion of the buffer water (21) and includes a heat exchanger (23) in thermal contact with a water storage tank (30) located at a horizontal height above the buffer water tank (15), the water being in thermal contact with the environment. and / or The second piping structure (24) defines a loop for at least a portion of the buffer water (21) and includes a heat exchanger (25) in contact with ambient heat, the heat exchanger (25) being located at a horizontal height above the buffer water tank (15). and / or A seawater heat exchanger (26) that is in thermal contact with the buffer water (21) and seawater is located below the seawater level outside the outer wall (17) of the buffer water tank (15).

4. The reactor construction (1) according to any one of the preceding claims, wherein, The reactor structure (1) includes an upper compartment (2) located above the discharge tank compartment (3). The upper compartment (2) includes: - Molten salt reactor (MSR) (4), the molten salt reactor including reactor vessel (5), the reactor vessel containing molten fuel salt (6). - A molten salt discharge system connected to the reactor vessel (5); The discharge tank compartment (3) includes: - One or more discharge tanks (10) connected to the molten salt discharge system; - Implemented as a buffer water tank (15) of a pipe system, the pipe system including an inner pipe (52) and an outer pipe (51), wherein the inner pipe (52) and the outer pipe (51) are connected together, wherein the buffer water is located in the pipe within the connected inner and outer pipes of the pipe system, the buffer water tank (15) surrounding the one or more discharge tanks (10), wherein the connected inner and outer pipes of the pipe system include a section (57) in which the buffer water evaporates, a section (56) in which the buffer water is insulated, and a section (55) in which the buffer water condenses. in, The seawater heat exchanger (26) is in thermal contact with the buffer water (21) and the seawater. The seawater heat exchanger (26) is located below the seawater level outside the outer wall (17) of the buffer water tank (15) and is located in a rectangular or cylindrical recess, preferably in a sea valve box (58).

5. The reactor construction (1) according to any one of the preceding claims, wherein, The reactor structure (1) includes an upper compartment (2) located above the discharge tank compartment (3). The upper compartment (2) includes: - Molten salt reactor (MSR) (4), the molten salt reactor including reactor vessel (5), the reactor vessel containing molten fuel salt (6). - A molten salt discharge system connected to the reactor vessel (5); The discharge tank compartment (3) includes: - One or more discharge tanks (10) connected to the molten salt discharge system; - A buffer tank (15), the buffer tank comprising an inner wall (16) and an outer wall (17) and buffer water (21) in the gap between the inner wall (16) and the outer wall (17) of the buffer tank (15), the buffer tank (15) surrounding the one or more discharge tanks (10), and, The first piping structure (22) defines a loop for at least a portion of the buffer water (21) and includes a heat exchanger (23) in thermal contact with a water storage tank (30) located at a horizontal height above the buffer water tank (15), the water being in thermal contact with the environment; and optionally, The second piping structure (24) defines a loop for at least a portion of the buffer water (21) and includes a heat exchanger (25) in contact with ambient heat, the heat exchanger (25) being located at a horizontal height above the buffer water tank (15); and optionally A seawater heat exchanger (26) that is in thermal contact with the buffer water (21) and seawater is located below the seawater level outside the outer wall (17) of the buffer water tank (15).

6. The reactor construction (1) according to any one of the preceding claims, wherein, The first pipe structure (22) includes: - At least one riser pipe (27), the first end (28) of which is an inlet for at least a portion of the buffer water (21), and the second end (29) of which is in contact with the inlet for the heat exchanger (23) in the water storage tank (30); and - At least one downcomer (31) has a first end (32) in contact with the outlet of the heat exchanger (23) in the water tank (30) and a second end (33) as the outlet for at least a portion of the buffer water (21).

7. The reactor structure (1) according to claim 6, wherein, The minimum cross-section of the first end (28) of the riser is greater than the minimum cross-section of the second end (33) of the faller.

8. The reactor configuration (1) according to any one of the preceding claims, wherein, The buffer water (21) in the buffer tank (15) includes a natural convection enhancer, which includes a tank wall (34) located in the gap between the inner wall (16) and the outer wall (17), the tank wall dividing the buffer tank (15) into an inner tank region (35) and an outer tank region (36), the tank wall (34) extending above the buffer water level into a dry wall section (37) that contacts the outer wall (17) at a wall contact position (38), wherein, - The dry wall section (37) and / or the inner wall (16) include perforations (39) to allow air to circulate between the inner tank area (35) and the outer tank area (36); - The first end (28) of the riser is positioned above the wall contact position (38), and the second end (33) of the faller is positioned below the wall contact position (38).

9. The reactor configuration (1) according to any one of the preceding claims, wherein, The inner wall (16) of the buffer tank is connected to the inner bottom plate (18) such that the inner wall (16) and the inner bottom plate (18) have a bowl shape.

10. The reactor construction (1) according to any one of the preceding claims, wherein, The molten salt discharge system is a molten fuel salt discharge system and includes a salt pipeline system, which includes at least one salt plug (13).

11. The reactor configuration (1) according to any one of the preceding claims further includes a gas supply system, the gas supply system comprising: -Carrier gas reservoir; - Carrier gas pipeline (12), the carrier gas pipeline including at least one valve (11, 110, 111, 112), the carrier gas pipeline (12) is connected from the carrier gas reservoir to the one or more discharge tanks (10).

12. The reactor construction (1) according to any one of the preceding claims, wherein, The molten fuel salt (6) has components selected from the group consisting of the following components: Sodium fluoride + potassium fluoride + uranium fluoride; Lithium fluoride + thorium fluoride + plutonium fluoride; Lithium fluoride + thorium fluoride + uranium fluoride; Lithium fluoride + beryllium fluoride + uranium fluoride; Lithium fluoride + beryllium fluoride + uranium fluoride + thorium fluoride; Lithium fluoride + beryllium fluoride + uranium fluoride + thorium fluoride + zirconium fluoride; Sodium fluoride + rubidium fluoride + uranium fluoride; Sodium fluoride + beryllium fluoride + uranium fluoride + thorium fluoride + zirconium fluoride; Potassium chloride + plutonium chloride + uranium chloride; Sodium chloride + plutonium chloride; Sodium chloride + plutonium chloride + uranium chloride.

13. The reactor configuration according to any one of the preceding claims, wherein, The MSR also includes a moderator based on a material selected from the group consisting of graphite materials, beryllium-containing compound materials, and molten salts of metal hydroxides. When the moderator is a molten salt of metal hydroxides, the reactor structure also includes a molten salt discharge system for metal hydroxides, which includes a molten salt discharge tank for metal hydroxides.

14. The reactor configuration according to any one of the preceding claims, wherein, The reactor configuration includes compartmentalization components, which include: A grating structure forming a substantially horizontal surface separation between the upper compartment and the discharge tank compartment, the grating structure comprising a metal grating and an insulation layer; and One or more funnels penetrate the grid structure, each funnel comprising a plug made of sacrificial material.

15. The reactor configuration according to any one of the preceding claims, wherein, The MSR (4) is located on a marine structure, preferably on a barge (40).

16. A method for heat transfer from molten salt, comprising the following steps: - Molten fuel salt (6) is provided in one or more discharge tanks (10) for molten fuel salt (6); - A buffer tank (15) surrounds the one or more discharge tanks (10) for molten fuel salt (6), the buffer tank comprising buffer water (21) in a gap between an inner wall (16) and an outer wall (17) of the buffer tank (15), the molten fuel salt (6) being heated by heat transfer to the inner wall (16) through at least one of thermal radiation, thermal conduction or thermal convection to heat the buffer water (21) into steam; - Provide a first pipe structure (22), the first pipe structure comprising: At least one riser pipe (27) located above at least a portion of the buffer water (21) collects steam and directs the steam to a heat exchanger (23) in a water storage tank (30) located above the buffer water tank (15) to condense the steam into water. At least one downcomer (31) is used to guide water from the heat exchanger (23) in the water storage tank (30) to the buffer tank (15). and / or - Provide a second piping structure (24), the second piping structure comprising: At least one riser pipe (27) located above at least a portion of the buffer water (21), the riser pipe (27) collecting steam and directing the steam to a gas heat exchanger (25) in thermal contact with the environment including gases, the gas heat exchanger (25) being located above the buffer water tank (15) to condense the steam into water; At least one downcomer (31) is provided for guiding water from the gas heat exchanger (25) to the buffer tank (15). and / or - Provides a seawater heat exchanger (26) that is in thermal contact with the buffer water (21), the seawater heat exchanger (26) being located below the seawater level outside the outer wall (17) of the buffer water tank (15), wherein the buffer water (21) circulates through the seawater heat exchanger (26).

17. The method for heat transfer from molten salt according to claim 16, further comprising transferring heat from the water tank (30) to the environment, such as the external environment in thermal contact with the water tank (30).

18. The method for heat transfer from molten salt according to claim 17, wherein, Heat transfer from the water tank (30) is carried out at least in part by evaporating the stored water into the external environment.

19. The method for heat transfer from molten salt according to any one of claims 16 to 18, wherein, Heat transfer is a passive heat transfer method.

20. The method for heat transfer from molten salt according to any one of claims 16 to 19, wherein, The natural convection enhancer includes a tank wall (34) located in the gap between the inner wall (16) and the outer wall (17), which divides the buffer tank (15) into an inner tank region (35) and an outer tank region (36). - This causes the buffer water (21) in the inner tank area (35) to boil and evaporate, and - Provides a path for steam to flow upwards.

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