Molten salt reactor and isotope production system and method based on molten salt reactor

Abstract

The invention discloses a molten salt reactor and an isotope production system and method.The molten salt reactor comprises a reactor core, an active area of the reactor core comprises a plurality of lattice cells, the lattice cells are provided with channels for molten salt to flow, part of the channels are communicated with one another to form a first molten salt flowing pipeline, and the other part of the channels are communicated with a second molten salt flowing pipeline; the rest channels are communicated with each other to form a second molten salt flowing pipeline, and the first molten salt flowing pipeline and the second molten salt flowing pipeline are independent from each other. According to the isotope production system composed of the molten salt reactor, a first molten salt flowing loop and a second molten salt flowing loop which are independent can be formed and are respectively used for power generation heat supply and isotope production of the liquid fuel molten salt reactor.

Description

Technical Field

[0001] The present invention specifically relates to a molten salt reactor and an isotope production system and method based on the molten salt reactor. Background Art

[0002] As an important platform for isotope production, nuclear reactors have the core advantage of providing high-flux neutron fields (>10 14 n / cm²·s), low cost, and scalable production capacity. Liquid-fueled molten salt reactors can be refueled and reprocessed online, making them more flexible when used for isotope production. Liquid-fueled molten salt reactor isotope production mainly uses fission or transmutation methods. The fission method of isotope production refers to extracting target isotopes by separating fission products from reactor operation. For example, it can be extracted from the exhaust gas of liquid-fueled molten salt reactors. 99 Mo. Transmutation method refers to adding precursor nuclei to the fuel to obtain the target isotope through multiple neutron absorption in a nuclear reactor. For example, it can be added to the fuel of a liquid fuel molten salt reactor. 242 Pu and other pioneer nuclear production 252 Cf. Alternatively, isotope production can be performed in liquid-fuel molten salt reactors using target irradiation, a method commonly used in light-water / heavy-water moderated water-cooled reactors. However, this method cannot be combined with the online charging and post-processing features of liquid-fuel molten salt reactors. Furthermore, solid-state target irradiation presents challenges such as difficulty removing heat and the need for frequent replacement, which can lead to reactor downtime.

[0003] The fission method in liquid-fuel molten salt reactors (MLSRs) fully utilizes the technical features of online reprocessing to obtain a variety of target isotopes from fission products. However, this method places high demands on the separation capability and throughput of online reprocessing. The fission yields of some target isotopes are very small, and their concentrations in the molten salt or tail gas are low. Some target isotopes have short half-lives, and their concentrations decrease rapidly after leaving the reactor.

[0004] Transmutation generally requires the addition of precursor nuclei, or target elements, to the primary loop of a liquid-fuel molten salt reactor. The addition of these nuclei alters the physicochemical properties of the fuel salt, impacting the economics, stability, and safety of reactor operation. Excessive concentrations of these nuclei can result in a positive temperature reactivity coefficient, failing to meet the reactor's design requirements for negative temperature feedback.

[0005] The primary purpose of liquid-fueled molten salt reactors (LFRs) is to generate nuclear power and provide high-temperature process heat. Given the technical characteristics of LFRs, such as online fueling and post-processing, combining power and heat generation with isotope production can further improve neutron utilization and maximize economic benefits. Considering the current status of isotope production in LFRs, there is still a lack of an isotope production method that can achieve efficient isotope production without compromising reactor operational safety. Summary of the Invention

[0006] In order to solve the problem that the existing isotope production technology based on molten salt reactors cannot achieve efficient, continuous and safe isotope production while taking into account the power generation and heat supply of liquid fuel molten salt reactors, the present invention proposes a molten salt reactor and an isotope production system and method based on the molten salt reactor. By setting up independent first and second circulation loops for liquid fuel molten salt reactor power generation and heat supply and isotope production respectively, the present invention can achieve at least one of the following effects: (1) increased isotope production, (2) avoidance of contamination of the fuel in the first circulation loop, (3) reduced isotope separation operation volume and separation difficulty, (4) can be used to produce a variety of different types of isotopes, and (5) high operational safety.

[0007] The present invention adopts the following solutions to solve the above technical problems:

[0008] The present invention provides a molten salt reactor, which includes a core, wherein the active area of ​​the core includes a plurality of gate elements, and the gate elements are provided with channels for molten salt flow. Some of the channels are interconnected to form a first molten salt flow pipeline, and the remaining channels are interconnected to form a second molten salt flow pipeline. The first molten salt flow pipeline and the second molten salt flow pipeline are independent of each other.

[0009] In the present invention, the shape of the gate element can be conventional in the art, such as a quadrangular prism or a hexagonal prism.

[0010] In the present invention, the moderator in the gate cell is preferably selected from one or more of graphite, zirconium hydride and beryllium, more preferably graphite.

[0011] In the present invention, the channel is preferably arranged at the center of the gate cell.

[0012] In the present invention, the plurality of gate elements are preferably arranged in a hexagonal or quadrilateral shape. Using a quadrilateral or hexagonal arrangement can achieve a better neutron moderation effect, flatten the neutron flux, reduce coolant flow resistance, and improve cooling efficiency.

[0013] In the present invention, the shape of the channel is preferably circular or slit-shaped.

[0014] In the present invention, in the gate cell, the volume of the channel is preferably 10-15% of the volume of the gate cell.

[0015] In the present invention, preferably, the channels in the first molten salt flow line are spaced apart from the channels in the second molten salt flow line. This preferred solution allows more channels in the second molten salt flow line to be distributed around the channels in the first molten salt flow line, making full use of the high neutron flux in the second molten salt flow line.

[0016] In the present invention, the channel in the first molten salt flow conduit is preferably arranged in the central area of ​​the active region. The central area of ​​the active region has the highest neutron flux, and this arrangement can further increase the isotope yield.

[0017] In the present invention, preferably, the number of channels in the first molten salt flow conduit is less than the number of channels in the second molten salt flow conduit. The number of channels in the first molten salt flow conduit is related to the type of isotopes produced and the neutron flux energy spectrum, and can be 1 to 10, for example 7.

[0018] In the present invention, the first molten salt flow pipeline preferably includes two main pipes and several branch pipes. Each of the channels in the first molten salt flow pipeline is provided with a branch pipe, and both ends of all the branch pipes are connected in parallel or in series to the two main pipes. More preferably, both ends of all the branch pipes are connected in series to the two main pipes. This is more conducive to increasing the in-pile flow time and achieving a higher neutron flux, thereby improving isotope production capacity.

[0019] The outer diameter of the branch pipe preferably matches the inner diameter of the channel in which the branch pipe is provided.

[0020] The branch pipe is generally made of silicon carbide, which is resistant to molten salt corrosion and has a small neutron absorption cross section.

[0021] Preferably, a graphite reflective layer is provided on the inner wall of the branch tube at the portion of the active zone to increase the thermal neutron flux.

[0022] The inner diameter of the channel formed by the graphite reflective layer is preferably equal to the diameter of the channel in the second molten salt flow pipeline.

[0023] In the present invention, the molten salt reactor may further include a shell, the core is arranged in the shell, an upper chamber is arranged between the core and the top of the shell, a lower chamber is arranged between the core and the bottom of the shell, and the second molten salt flow pipeline is connected to the upper chamber and the lower chamber; an outlet is provided at the upper part of the shell, the outlet is connected to the upper chamber, and an inlet is provided at the lower part of the shell, the inlet is connected to the lower chamber.

[0024] The present invention also provides an isotope production system based on a molten salt reactor, which includes the aforementioned molten salt reactor, a first molten salt flow loop and a second molten salt flow loop;

[0025] The first molten salt flow loop includes the first molten salt flow pipeline and a first external pipeline connecting the first and second ends of the first molten salt flow pipeline; the second molten salt flow loop includes the second molten salt flow pipeline and a second external pipeline connecting the first and second ends of the second molten salt flow pipeline.

[0026] In the present invention, the first external pipeline is preferably provided with one or more of a first processing device, a first sampling and monitoring device, a first heat exchanger, a first circulation pump and a first feeding device. The first processing device is used to separate the isotopes in the molten salt on the first molten salt flow loop, the first sampling and monitoring device is used to monitor the composition of the molten salt on the first molten salt flow loop, the first heat exchanger is used to remove the heat of the molten salt in the first molten salt flow loop, and the first feeding device is used to add molten salt to adjust the molar composition of the flowing molten salt pile in the loop.

[0027] The first charging device is conventional in the art and typically consists of a molten salt storage tank, a heater, a gas storage tank, and a control system. The molten salt storage tank is connected to the pipeline of the first molten salt flow loop via a check valve. The first charging device typically uses pneumatic pressure to fill the first molten salt flow loop with molten salt before reactor startup. After startup, molten salt is added to the first molten salt flow loop based on sampling and monitoring results and the isotope production plan.

[0028] In some preferred embodiments of the present invention, the first feeding device, the first heat exchanger, the first sampling and monitoring device, the first processing device and the first circulation pump are preferably arranged in sequence on the first external pipeline along the flow direction of the molten salt.

[0029] In the present invention, the second external pipeline is preferably provided with one or more of a second processing device, a second sampling and monitoring device, a second heat exchanger, a second circulation pump and a second feeding device. The second processing device is used to separate the fission products in the fuel salt on the second molten salt flow loop. The second sampling and monitoring device is used to monitor the composition of the fuel salt on the second molten salt flow loop. The second heat exchanger is used to transfer the heat generated by the core to the secondary cooling loop or the power conversion system. The second feeding device is used to add fuel salt to adjust the molar composition of the flowing molten salt pile in the loop.

[0030] Wherein, the second feeding device is the same as the first feeding device.

[0031] In some preferred embodiments of the present invention, the second feeding device, the second heat exchanger, the second sampling and monitoring device, the second processing device and the second circulation pump are preferably sequentially arranged on the second external pipeline along the flow direction of the fuel salt.

[0032] In the present invention, the molten salt reactor may further include an outer shell, the core is arranged in the shell, an upper chamber is arranged between the core and the top of the shell, a lower chamber is arranged between the core and the bottom of the shell, and the second molten salt flow pipeline is connected to the upper chamber and the lower chamber; an outlet is provided at the upper part of the shell, the outlet is connected to the upper chamber, an inlet is provided at the lower part of the shell, the inlet is connected to the lower chamber, one end of the second external pipeline is connected to the inlet, and the other end of the second external pipeline is connected to the outlet.

[0033] The present invention also provides an isotope production method, which uses the aforementioned isotope production system based on a molten salt reactor for production, and specifically comprises the following steps:

[0034] Molten salt is loaded into the first molten salt flow loop and the second molten salt flow loop respectively, the molten salt reactor is started up to the design power and maintained in stable operation, and isotopes are produced through the first molten salt flow loop.

[0035] In the present invention, preferably, energy production is performed through the second molten salt flow loop, and the energy production is conventional in the art, generally including power generation and heat supply.

[0036] In the present invention, the stable operation means that the power change rate of the molten salt reactor is within 2%.

[0037] Among them, the power change rate is kept within 2% by adjusting the control rod position.

[0038] In the present invention, the core neutron spectrum of the molten salt reactor is a thermal neutron spectrum.

[0039] In the present invention, the molten salt in the first molten salt flow loop can be conventional in the art, for example, a mixture of a carrier salt and a target element salt, wherein the carrier salt can be selected from one or more of LiF, LiF-BeF2, NaF-BeF2 and LiF-BeF2-ZrF4. The target element salt is determined according to the desired isotope, for example, a fluoride salt of a high-mass actinide nuclide in depleted uranium, and a high-mass actinide nuclide can be selected from 242 Pu, 241 Am, 243 Am, 244 Cm, 245 Cm, 246 Cm and 248 One or more of Cm.

[0040] In some specific embodiments, the molten salt in the first molten salt flow loop is LiF-BeF2-ZrF4-CmF3, with a molar ratio of 77.24%:20.92%:0.84%:1%; Cm is 244 Cm,245 Cm composition, the molar ratio is 88.9%:11.1%.

[0041] In the present invention, the molten salt in the second molten salt flow loop may be conventional in the art, for example, a mixture including a carrier salt and a fuel salt, wherein the carrier salt may be selected from one or more of LiF, NaF-BeF2, LiF-BeF2, LiF-BeF2-ZrF4 and LiF-BeF2-ZrF4-ThF4; the fuel salt may be UF4 or PuF3.

[0042] In some specific embodiments, the molten salt in the second molten salt flow loop is LiF-BeF2-ZrF4-ThF4-UF4, with a molar ratio of 67.38%:16%:4.32%:10.25%:2.05%. 235 The enrichment of U is 19.75%, 7 The abundance of Li is 99.995%.

[0043] In the present invention, the molten salts in the first molten salt flow circuit and the second molten salt flow circuit may be the same or different.

[0044] In the present invention, the designed thermal power refers to the power corresponding to the usable thermal energy output by the reactor that is preset.

[0045] The positive progress effect of the present invention is:

[0046] (1) The present invention provides a first molten salt flow circuit and a second molten salt flow circuit that are independent of each other in a molten salt reactor. On the one hand, the two circuits are used for power generation and heat supply of the liquid fuel molten salt reactor and isotope production, respectively, thereby improving the flexibility of operation. On the other hand, by isolating the first molten salt flow circuit and the second molten salt flow circuit in the core area, the neutron flux distribution characteristics of the core are fully utilized, thereby improving the isotope production capacity.

[0047] Specifically, compared with the prior art that directly utilizes the main circulation loop of the liquid fuel molten salt reactor for isotope production, the system of the present invention uses two loops for liquid fuel molten salt reactor power generation and heat supply and isotope production, respectively, and has the following advantages:

[0048] The isotope yield is increased; it will not affect the molten salt composition in the main circulation loop of the liquid fuel molten salt reactor (i.e., the second molten salt flow loop), thus avoiding contamination of the fuel in the second molten salt flow loop and improving the economic efficiency of the main circulation loop operation; it reduces the amount of isotope separation operations and the difficulty of separation; it can be used to produce a variety of different types of isotopes; the first molten salt flow loop uses liquid molten salt for circulation, and there is no problem of difficulty in removing heat generated by irradiation of solid targets and no shutdown problem caused by target unloading; it has high operational safety.

[0049] (2) The online isotope separation operation volume of the isotope production system of the present invention can reach 1 / 200 to 1 / 10 of the existing production method (i.e., isotope production using the main circulation loop of the liquid molten salt reactor). The target isotope concentration obtained with the same irradiation time can reach 10 to 200 times that of the existing production method, and the production efficiency can reach 50 to 150 times that of the existing production method. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Schematic diagram of the flow channel layout of the independent loop for isotope production in Example 1.

[0051] Figure 2 Schematic diagram of the main loop of the liquid fuel molten salt reactor and the independent loop for isotope production in Example 1.

[0052] Figure 3 Schematic diagram of the first molten salt flow pipeline and the second molten salt flow pipeline in the calculation model of Example 3 Figure 1 .

[0053] Figure 4 Schematic diagram of the first molten salt flow pipeline and the second molten salt flow pipeline in the calculation model of Example 3 Figure 2 .

[0054] Figure 5 Schematic diagram of the molten salt flow pipeline in the calculation model of comparative example 1 Figure 1 .

[0055] Figure 6 Schematic diagram of the molten salt flow pipeline in the calculation model of comparative example 1 Figure 2 .

[0056] Description of the reference numerals in the accompanying drawings:

[0057] 1-core, 2-shell, 3-gate element, 4-first molten salt flow pipeline, 5-second molten salt flow pipeline, 6-control rod, 7-first external pipeline, 8-second external pipeline, 9-first charging device, 10-first heat exchanger, 11-first sampling and monitoring device, 12-first processing device, 13-first circulation pump, 14-second charging device, 15-second heat exchanger, 16-second sampling and monitoring device, 17-second processing device, 18-second circulation pump, 19-hot chamber;

[0058] 201-graphite reflective layer, 202-shell;

[0059] 301-channel;

[0060] 401-main pipe, 402-three branch pipes. DETAILED DESCRIPTION

[0061] The present invention is further illustrated by way of examples below, but the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions, or selected according to the product specifications.

[0062] Example 1

[0063] This embodiment discloses a molten salt reactor, such as Figure 1 As shown, it includes a core 1 and a shell 2 arranged in sequence from the inside to the outside. The shell 2 includes a graphite reflective layer 201 and an outer shell 202. The graphite reflective layer 201 is coated on the core 1, and the outer shell 202 is coated on the graphite reflective layer 201. An upper chamber is provided between the top of the core 1 and the graphite reflective layer 201 at the top of the shell 2. A lower chamber is provided between the bottom of the core 1 and the graphite reflective layer 201 at the bottom of the shell 2. An outlet is provided at the upper part of the shell 2, and the outlet is connected to the upper chamber. An inlet is provided at the lower part of the shell 2, and the inlet is connected to the lower chamber. The active area of ​​the core 1 includes a plurality of gate elements 3. The shape of the gate element 3 is a quadrangular prism or a hexagonal prism. When the shape of the gate element 3 is a quadrangular prism, the plurality of gate elements 3 are arranged in a quadrilateral array. When the shape of the gate element 3 is a hexagonal prism, the plurality of gate elements 3 are arranged in a hexagonal array. As shown Figure 1 The diagram shows a structure in which the gate cells 3 are arranged in a quadrilateral array.

[0064] The moderator in the gate cell 3 is graphite. A circular channel 301 for molten salt flow is provided at the center of the gate cell 3. Part of the channels 301 located in the center of the active zone are interconnected to form a first molten salt flow pipeline 4. In this embodiment, the first molten salt flow pipeline 4 includes two main pipes 401 and three branch pipes 402. The three branch pipes 402 are respectively provided in the three channels 301, and the two ends of the three branch pipes 402 are respectively connected in parallel to the two main pipes 401. The inner diameter of the branch pipe 402 is equal to the diameter of the channel 301 in the second molten salt flow pipeline. The material of the branch pipe 402 is silicon carbide, which is resistant to molten salt corrosion and has a low neutron absorption cross-section. A graphite reflective layer is provided on the inner wall of the branch pipe 402 located in the active zone.

[0065] The remaining channels 301 are connected in parallel to form a second molten salt flow line 5, which is in communication with the upper chamber and the lower chamber. The first molten salt flow line 4 and the second molten salt flow line 5 are independent of each other.

[0066] In this embodiment, the molten salt reactor is further provided with a control rod 6 for controlling reactivity. The control rod sleeve and cladding are made of GH3535 alloy, and the absorber is boron carbide.

[0067] Example 2

[0068] This embodiment discloses an isotope production system based on a molten salt reactor, such as Figure 2 As shown, it includes the molten salt reactor described in Example 1, a first molten salt flow loop and a second molten salt flow loop, the first molten salt flow loop includes a first molten salt flow pipeline 4 and a first external pipeline 7 connecting the head and tail ends of the first molten salt flow pipeline 4; the second molten salt flow loop includes a second molten salt flow pipeline 5 and a second external pipeline 8 connecting the head and tail ends of the second molten salt flow pipeline 5.

[0069] In this embodiment, one end of the first external pipeline 7 is connected to one of the main pipes 401, and the other end of the first external pipeline 7 is connected to the other main pipe 401. A first feeding device 9, a first heat exchanger 10, a first sampling and monitoring device 11, a first processing device 12, and a first circulation pump 13 are sequentially arranged on the first external pipeline 7 along the flow direction of the molten salt. The first feeding device 9 is used to add molten salt to adjust the molar composition of the flowing molten salt pile in the loop. The first feeding device 9 consists of a molten salt storage tank, a heater, a gas storage tank, and a control system. The molten salt storage tank is connected to the pipeline in the first molten salt flow loop via a check valve. The first feeding device 9 uses gas pressure injection to fill the first molten salt flow loop with molten salt before reactor startup. After startup, molten salt is added to the first molten salt flow loop based on sampling and monitoring results and the isotope production plan.

[0070] The first heat exchanger 10 is used to remove heat from the molten salt in the first molten salt flow loop, the first sampling and monitoring device 11 is used to monitor the composition of the molten salt on the first molten salt flow loop, and the first processing device 12 is used to separate the isotopes in the molten salt on the first molten salt flow loop. The first processing device 12 is an online processing device that uses an electrochemical dry method for processing.

[0071] In this embodiment, one end of the second external pipeline 8 is connected to the inlet of the shell 2, and the other end of the first external pipeline 7 is connected to the outlet of the shell 2. A second feeding device 14, a second heat exchanger 15, a second sampling and monitoring device 16, a second processing device 17, and a second circulation pump 18 are sequentially arranged on the second external pipeline 8 along the flow direction of the fuel salt. The second feeding device 14 is identical to the first feeding device 9. The second heat exchanger 15 is used to transfer heat generated by the core to the secondary cooling circuit or the power conversion system. The second sampling and monitoring device 16 is used to monitor the composition of the fuel salt in the second molten salt flow circuit. The second processing device 17 is used to separate fission products in the fuel salt in the second molten salt flow circuit. The second processing device 17 is an online processing device. The first processing device 12 and the second processing device 17 share a hot chamber 19.

[0072] Example 3

[0073] This embodiment uses the molten salt reactor-based isotope production system described in Example 2 to produce isotopes.

[0074] The calculation model of this embodiment is a liquid fuel molten salt reactor with a thermal power of 1000MWt. The gate cell 3 is hexagonal, the diameter of the channel 301 is 6.51cm, and the volume of the molten salt in the gate cell is 15% (that is, the volume of the channel accounts for the volume of the gate cell). The height of the upper and lower chambers of the reactor is 15cm, the thickness of the graphite reflector 201 on the side is 40cm, and the thickness of the graphite reflector 201 on the top and bottom is 50cm. The diameter of the active area of ​​the core 1 is 400cm, the height is 420cm, the thickness of the outer shell 202 is 5cm, and there are 517 gate cells in the core area. The average power density of the fuel salt is 91MW / m 3 The moderator material is graphite, and the outer shell 202 and control rod sleeve are GH3535 alloy.

[0075] In the central area of ​​the core active region, the channels 301 of 7 gate elements 3 are replaced with isotope production channels, such as Figure 3 and Figure 4 The figure shows the arrangement of the channels 301 in this calculation model. The seven channels 301 include the central channel and six channels adjacent to the central channel along the core radial direction, and these six channels are circumferentially distributed at the six corners of a regular hexagon, as shown in FIG. Figure 4 As shown in FIG. Each of the seven channels 301 is provided with a branch pipe 402 to achieve loop isolation. The branch pipe 402 is made of silicon carbide and has a thickness of 0.5 cm. The inner side of the branch pipe 402 is a 1 cm thick graphite reflective layer. The inner channel formed by the graphite reflective layer is the isotope production channel, which has a diameter of 6.51 cm. The outer side of the branch pipe 402 is a graphite grid element.

[0076] The fuel salt used in the second molten salt flow loop is LiF-BeF2-ZrF4-ThF4-UF4, with a molar ratio of 67.38%:16%:4.32%:10.25%:2.05%. 235 U enrichment is 19.75%, 7 The abundance of Li is 99.995%. The molten salt used in the first molten salt flow loop is LiF-BeF2-ZrF4-CmF3, with a molar ratio of 77.24%:20.92%:0.84%:1%. 244 Cm, 245 Cm composition, the molar ratio is 88.9%:11.1%, the first molten salt flow circuit 244 The loading capacity of Cm is 13.59kg, 245 The loading capacity of Cm is 1.70kg.

[0077] The specific method includes the following steps:

[0078] (1) Loading fuel salt: LiF-BeF2-ZrF4-CmF3 is loaded on the first molten salt flow loop, and LiF-BeF2-ZrF4-ThF4-UF4 is loaded on the second molten salt flow loop.

[0079] (2) Start the molten salt reactor to the design power of 1000MWt, and adjust the control rod position to keep the molten salt reactor in stable operation. Stable operation means that the power change rate of the molten salt reactor is within 2%. The first sampling monitoring device 11 is used to sample the molten salt in the first molten salt flow loop and detect the isotopes therein. 252 Cf content; the first processing device 12 is used to sample the first molten salt flow loop, and the isotopes in the molten salt are cooled. 252 Cf is separated by electrochemical method; after separation, the isotopes are packaged according to product specifications.

[0080] The heat generated by the core is transferred to the power conversion system through the second heat exchanger 15 for power generation or heat supply.

[0081] The burn-up period in the calculation is 2 years, with a burn-up point every 6 months. 18 months 252 Cf production was 0.58 g in 24 months 252 The Cf production was 1.24 g. After 24 months of operation, the isotope production circuit 252 The Cf concentration was 1.27e-05 g / mL and the production efficiency was 8.13e-05.

[0082] Comparative Example 1

[0083] The isotope production system of this comparative example differs from that of Example 2 in that the system of this comparative example does not have a first molten salt flow loop, and all channels in the molten salt reactor form a second molten salt flow loop. The rest is the same as that of Example 2.

[0084] The calculation model of this comparative example is the same as that of Example 3. Figure 5 and Figure 6 The fuel salt in this comparative example is LiF-BeF2-ZrF4-ThF4-UF4-CmF3, with a molar ratio of 66.6%:16%:4.35%:10%:2.05%:1%, wherein 235 U enrichment is 19.75%, 7 The abundance of Li is 99.995%, and the Cm is 244 Cm, 245 Cm composition, the molar ratio is 88.9%:11.1%, the fuel 244 The loading capacity of Cm is 1088kg, 245 The loading capacity of Cm is 136kg.

[0085] The isotope production method of this comparative example comprises the following steps:

[0086] (1) Loading fuel salt: LiF-BeF2-ZrF4-ThF4-UF4-CmF3 is loaded on the second molten salt flow loop.

[0087] (2) Start the molten salt reactor to a designed thermal power of 1000 MWt, and maintain stable operation of the molten salt reactor by adjusting the position of the control rods. Stable operation means that the power change rate of the molten salt reactor is within 2%. The fuel salt in the second molten salt flow loop is sampled by the second sampling monitoring device 16 to detect the isotopes therein. 252 Cf content; using the second processing device 17 to sample from the second molten salt flow loop, and separating the fuel salt after cooling, the separation method is an electrochemical method; after separation, the isotopes are packaged in accordance with product specifications;

[0088] The heat generated by the core is transferred to the power conversion system through the second heat exchanger for power generation or heat supply.

[0089] The burn-up period in the calculation is 2 years, with a burn-up point every 6 months. 18 months 252 Cf production was 0.28 g in 24 months 252 The Cf production was 1.03 g. After 24 months of operation, the circuit 252 The Cf concentration was 9.35e-08 g / mL and the production efficiency was 8.40e-07.

[0090] Comparing the isotope production methods of Example 3 and Comparative Example 1, it can be found that after adopting the independent isotope production circuit (ie, Example 3), the loading amount of Cm is greatly reduced, and the production efficiency and 252 The Cf concentration is significantly improved. The production efficiency of Example 3 is 97 times that of Comparative Example 1. 252 The C concentration was 136 times higher than the original. Considering the recovery rate of 90%, 20 mg of 252 Cf, the volume of molten salt required for operation in Comparative Example 1 is 237.7 L, while that in Example 3 is only 1.7 L.

Claims

1. A molten salt reactor, characterized in that: It includes a core, the active area of ​​the core includes a plurality of gate elements, and the gate elements are provided with channels for molten salt flow. Some of the channels are interconnected to form a first molten salt flow pipeline, and the remaining channels are interconnected to form a second molten salt flow pipeline. The first molten salt flow pipeline and the second molten salt flow pipeline are independent of each other.

2. The molten salt reactor according to claim 1, wherein The channel in the first molten salt flow pipeline and the channel in the second molten salt flow pipeline are spaced apart; and / or, the channel in the first molten salt flow conduit is arranged in the central area of ​​the active zone; and / or, the number of the channels in the first molten salt flow pipeline is less than the number of the channels in the second molten salt flow pipeline; And / or, the number of the channels in the first molten salt flow pipeline is 1 to 10.

3. The molten salt reactor according to claim 1, wherein The first molten salt flow pipeline includes two main pipes and a plurality of branch pipes. Each of the channels of the first molten salt flow pipeline is provided with a branch pipe, and both ends of all the branch pipes are connected in parallel to the two main pipes. Preferably, a graphite reflective layer is provided on the inner wall of the branch pipe at the portion located in the active area.

4. The molten salt reactor according to claim 1, wherein The molten salt reactor also includes a shell, the core is arranged in the shell, an upper chamber is provided between the core and the top of the shell, a lower chamber is provided between the core and the bottom of the shell, and the second molten salt flow pipeline is connected to the upper chamber and the lower chamber; an outlet is provided at the upper part of the shell, the outlet is connected to the upper chamber, and an inlet is provided at the lower part of the shell, the inlet is connected to the lower chamber.

5. The molten salt reactor according to claim 1, wherein The shape of the gate element is a quadrangular prism or a hexagonal prism; And / or, the moderator in the gate cell is selected from one or more of graphite, zirconium hydride and beryllium; And / or, the channel is arranged at the center of the gate cell; and / or, the channel is circular or slit-shaped; And / or, in the gate cell, the volume of the channel is 10-15% of the volume of the gate cell; And / or, a plurality of the gate elements are arranged in a hexagonal or quadrilateral shape.

6. An isotope production system based on a molten salt reactor, characterized in that: It comprises a molten salt reactor according to any one of claims 1 to 5, a first molten salt flow loop and a second molten salt flow loop; The first molten salt flow loop includes the first molten salt flow pipeline and a first external pipeline connecting the first and second ends of the first molten salt flow pipeline; the second molten salt flow loop includes the second molten salt flow pipeline and a second external pipeline connecting the first and second ends of the second molten salt flow pipeline.

7. The isotope production system based on a molten salt reactor according to claim 6, characterized in that: The first external pipeline is provided with one or more of a first processing device, a first sampling and monitoring device, a first heat exchanger, a first circulation pump, and a first feeding device, wherein the first processing device is used to separate isotopes in the molten salt in the first molten salt flow loop, the first sampling and monitoring device is used to monitor the composition of the molten salt in the first molten salt flow loop, the first heat exchanger is used to remove heat from the molten salt in the first molten salt flow loop, and the first feeding device is used to add molten salt to adjust the molar composition of the flowing molten salt pile in the loop; Preferably, the first feeding device, the first heat exchanger, the first sampling and monitoring device, the first processing device and the first circulation pump are sequentially arranged on the first external pipeline along the flow direction of the molten salt; and / or, one or more of a second processing device, a second sampling and monitoring device, a second heat exchanger, a second circulation pump, and a second feeding device are provided on the second external pipeline, the second processing device is used to separate fission products in the fuel salt on the second molten salt flow loop, the second sampling and monitoring device is used to monitor the composition of the fuel salt on the second molten salt flow loop, the second heat exchanger is used to transfer heat generated by the core to the secondary cooling loop or the power conversion system, and the second feeding device is used to add fuel salt to adjust the molar composition of the flowing molten salt reactor in the loop; Preferably, the second feeding device, the second heat exchanger, the second sampling and monitoring device, the second processing device and the second circulation pump are sequentially arranged on the second external pipeline along the flow direction of the fuel salt.

8. The isotope production system based on a molten salt reactor according to claim 6, characterized in that: The molten salt reactor also includes a shell, the core is arranged in the shell, an upper chamber is provided between the core and the top of the shell, a lower chamber is provided between the core and the bottom of the shell, and the second molten salt flow pipeline is connected to the upper chamber and the lower chamber; an outlet is provided at the upper part of the shell, the outlet is connected to the upper chamber, an inlet is provided at the lower part of the shell, the inlet is connected to the lower chamber, one end of the second external pipeline is connected to the inlet, and the other end of the second external pipeline is connected to the outlet.

9. A method for producing isotopes, characterized in that: The isotope production system based on a molten salt reactor according to any one of claims 6 to 8 is used for production, and specifically comprises the following steps: Molten salt is loaded into the first molten salt flow loop and the second molten salt flow loop respectively, the molten salt reactor is operated to the design power, and isotopes are produced through the first molten salt flow loop.

10. The isotope production method according to claim 9, wherein: After the molten salt reactor is operated to a designed power, the control rod positions are adjusted to ensure stable operation of the molten salt reactor; preferably, the stable operation means that the power change rate of the molten salt reactor is within 2%; and / or, generating energy through the second molten salt flow circuit, wherein the energy generation is electricity and / or heat; And / or, the molten salt in the first molten salt flow loop is a mixture of a carrier salt and a target element salt, the carrier salt is selected from one or more of LiF, LiF-BeF2, NaF-BeF2 and LiF-BeF2-ZrF4, and the target element salt is a fluoride salt of a high-mass actinide nuclide in depleted uranium; preferably, the high-mass actinide nuclide is selected from 242 Pu, 241 Am, 243 Am, 244 Cm, 245 Cm, 246 Cm and 248 Cm one or more; more preferably, the molten salt in the first molten salt flow loop is LiF-BeF2-ZrF4-CmF3; And / or, the molten salt in the second molten salt flow loop includes a mixture of carrier salt and fuel salt, the carrier salt is selected from one or more of LiF, NaF-BeF2, LiF-BeF2, LiF-BeF2-ZrF4 and LiF-BeF2-ZrF4-ThF4, and the fuel salt is UF4 or PuF3; preferably, the molten salt in the second molten salt flow loop is LiF-BeF2-ZrF4-ThF4-UF4.

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