CN216596965U

CN216596965U - Fuel assembly and fused salt fast reactor body for isotope production

Info

Publication number: CN216596965U
Application number: CN202122331410.2U
Authority: CN
Inventors: 刘小林; 徐洪杰; 邹杨; 周波; 严睿; 赵恒�
Original assignee: Shanghai Institute of Applied Physics of CAS
Current assignee: Shanghai Institute of Applied Physics of CAS
Priority date: 2021-09-18
Filing date: 2021-09-18
Publication date: 2022-05-24
Anticipated expiration: 2031-09-18

Abstract

The utility model provides a fuel assembly and a molten salt fast reactor body for isotope production. This fuel assembly includes that the fuel holds the pipe, and the fuel holds the pipe and includes subassembly fuel area and fuel gas chamber from bottom to top, and its upper portion is equipped with first support grid and first top fixing device from bottom to top in proper order, and the upper portion of supporting the grid is equipped with first pressure release exhaust hole. This molten salt fast reactor body, including a plurality of fuel assembly, reflection stratum, irradiation cabin, molten salt cooling pond, gaseous collection room, molten salt heat exchanger and heap container, fuel assembly soaks and locates in the molten salt cooling pond, and the reflection stratum is covered to the reflection stratum, and during the reflection stratum was located to the irradiation cabin, gaseous collection room cover was located the fuel assembly top, and the periphery department in molten salt cooling pond is located to the molten salt heat exchanger, and the reflection stratum is outside to the heap container. The utility model is convenient for the production and extraction of various isotopes, and has good advantages in economy and safety.

Description

Fuel assembly and fused salt fast reactor body for isotope production

Technical Field

The utility model relates to a fuel assembly and a molten salt fast reactor body for isotope production.

Background

Nuclear medicine is the main subject of radioisotope application, e.g. the most commonly used radionuclides for nuclear medicine diagnosis^99mTc, by its parent nuclide⁹⁹Mo decays; radionuclides for radiation therapy¹³¹I, and the like. The main way to produce such medical radionuclides is to build dedicated medical isotope production stacks. At present, most reactors producing such isotopes are Water-cooled reactors, such as High Flux Isotope Reactors (HFIR) of Oak Ridge National Laboratory (ORNL), Open Pool Light-Water reactors (OPAL) of australia, Chinese Advanced Research Reactor (CARR) and chinese sun Research Reactor (CMRR). The reactor for producing the isotope has high reactor building cost, fuel element preparation and target piece preparation cost, the extraction of the isotope relates to the processes of cutting, dissolving, chemical treatment and the like of the target piece, the post-treatment process is complex, the comprehensive cost is further increased, and simultaneously, a large amount of solid and liquid radioactive wastes are generated. To achieve in the United states⁹⁹Localization rate of MoFirstly, the method is carried out by using a uniform aqueous solution pile⁹⁹Production of Mo as UO₂(NO₃)₂Solution or UO₂SO₄The solution is used as nuclear fuel. A Medical Isotope Production Reactor (MIPR) such as that proposed by Babcock and Wilcox (BW) is a Reactor used in the UO industry₂(NO₃)₂Is a water solution pile of fuel, but water molecules in the water solution pile are easily irradiated by neutrons to generate a large amount of H₂And O₂The accumulation of a gas mixture of these two gases can, on the one hand, affect the stable operation of the reactor and, on the other hand, can also present a potential explosion risk. Part of the target pieces adopt high-concentration uranium and do not meet the requirement of nuclear diffusion prevention of civil nuclear technology application.

The existing solution type reactor has a few radioactive entity containing barriers, and the potential leakage risk of fission products is high. Economic cost and nuclear safety issues are therefore key factors that limit such solution-type isotope production stacks. However, the existing liquid molten salt reactor generally uses a graphite channel type component, fuel salt circulates in the graphite channel, and an isotope on-line extraction process is difficult.

SUMMERY OF THE UTILITY MODEL

The utility model aims to overcome the defect that the prior molten salt reactor generally uses a graphite channel type assembly, fuel salt circularly flows in the graphite channel and an isotope on-line extraction process is difficult, and provides a fuel assembly and a molten salt fast reactor body for isotope production, which are convenient for production and extraction of various isotopes, maximize neutron economy and byproduct economy and simultaneously give consideration to high-efficiency power generation. Therefore, the design has good advantages in economy and safety.

The utility model solves the technical problems through the following technical scheme:

the fuel assembly of the present invention comprises a fuel containing tube for filling with fuel salt;

the fuel containing pipe comprises an assembly fuel area 12 and a fuel gas chamber 13 from bottom to top;

the upper part of the fuel containing pipe is sequentially provided with a first supporting grid 15 and a first top fixing device 17 from bottom to top; and a first pressure relief vent hole 16 is formed in the upper part of the first support grid. Wherein, the length of the fuel containing pipe can be 51-520cm, and the radius can be 1-5 cm. Preferably, the height of the fuel area of the assembly can be 50-500cm, and the height of the fuel gas chamber can be 1-20 cm.

Wherein the outer wall of the fuel containing tube is an alloy cladding 14; the thickness of the alloy clad may be 0.01-0.5 cm. In general, those skilled in the art will appreciate that the cladding material may be a TZM alloy and the alloy density may be 10.22g/cm³。

Wherein the fuel salt can be conventional fuel salt in the field, and is generally NaCl molten salt as carrier salt, UCl₃As fuel, dissolved in NaCl; NaCl UCl₃May be 55:45, and the density is generally 1.2-3.6g/cm³，²³⁵The U enrichment may be 0-19.75%,³⁷the Cl enrichment may be 90% to 99%. In general terms, the amount of the surfactant is,⁹⁹Mo、¹³¹I、⁸⁹Sr、¹³¹Te、⁸⁹the isotopes such as Kr can pass through the fuel assembly directly²³⁵U fission production, wherein fuel assemblies are loaded and unloaded without stopping the reactor, and the fuel assemblies can be directly taken out for separation, purification and extraction of isotopes after reaching an isotope extraction period; the fuel salt is loaded in the fuel assembly area without pump actuation. The sodium chloride molten salt is used as carrier salt, and the heavy metal solubility of the chloride molten salt is high, the neutron scattering cross section is small, so that the loading capacity of the fission nuclide in the fuel salt and the fast neutron flux of the reactor core of the fast reactor body can be improved, and the sodium chloride molten salt is suitable for being used as fast reactor fuel. The liquid molten salt can form local natural convection under the condition of thermophoretic force, and is beneficial to eliminating local hot spots, so that the thermal safety characteristic of the fuel assembly is greatly improved. Fuel salt process²³⁵U fission reaction production⁹⁹Mo、¹³¹I、⁸⁹Sr and other fissile isotopes.

Wherein the cross-sectional dimension of the first support grid is not limited, but may be generally smaller in radius than the fuel containing tube radius; preferably, the first support grid may have a radius of 0.5-4.5 cm.

As known to those skilled in the art, a reactor fuel cell is a representative basic unit in a reactor grid. The cross section of the reactor fuel grid element is a regular hexagon, and the radius of the reactor fuel grid element can be 2-6 cm.

Wherein the cross-sectional dimensions of the first top fixture are known to the person skilled in the art to be generally larger than the dimensions of the first support grid, typically the radius may be of the same size as the cross-sectional radius of the reactor fuel cell, e.g. may be 2-10 cm. The first support grid may have a height of 4-20 cm.

Wherein the reactor fuel cells may generally be wholly immersed in the molten salt cooling pool by a mechanical support structure. The skilled person knows that the molten salt cooling bath is a molten salt cooling zone formed directly by a cooling salt within the area surrounded by the reflective layer, as is conventional in the art.

The utility model also provides a molten salt fast reactor body for isotope production, which comprises a plurality of fuel assemblies 1, a reflecting layer 2, an irradiation cabin 3, a molten salt cooling pool 4, a gas collecting chamber 5, a molten salt heat exchanger 6 and a reactor container 19;

a plurality of fuel assemblies form a fuel assembly array and are immersed in the molten salt cooling pool; the reflecting layer covers the molten salt cooling pool; the irradiation cabins are arranged on the reflecting layer; the gas collecting chamber is covered on the top of the fuel assembly and is used for collecting gas generated in the fuel assembly through the pressure relief exhaust hole; the molten salt heat exchanger is arranged at the periphery of the molten salt cooling pool; the stack container is disposed outside the reflective layer.

The fast reactor body can have a diameter of 170-600cm and a height of 120-520 cm.

Wherein the fuel assembly array may be hexagonal in cross-section.

Wherein the fuel assembly array further comprises a plurality of control rod passages as is conventional in the art. The number of the fuel assemblies in the fuel assembly array is a plurality, and the number of the control rod channels can be 6.

Generally, the control rod channelThe tracks may have a radius of 2-6cm, a length of 60-530cm and a sidewall thickness of 0.01-0.5 cm. The control rod passage is provided with⁵⁹Co control rods which absorb neutrons to activate and produce radioisotope byproducts⁶⁰Co, thereby improving the overall economy of the reactor. In general, those skilled in the art will appreciate that the sidewall material may be a TZM alloy and that the alloy density may be 10.22g/cm³。

Generally, the control rod includes a double-layer alloy thimble 22 and an absorber 23 provided in a sandwich layer of the double-layer alloy thimble; a gap 24 can be arranged between the double-layer alloy sleeve and the absorber; those skilled in the art will appreciate that the inner pipe of the double layer alloy sleeve is typically an inert gas channel.

Wherein, the inert gas channel is used for conveying inert gas, and can be helium; the length of the alloy casing pipe can be 60-510cm, the inner diameter can be 0.4-1cm, the thickness can be 0.2-0.6cm, the outer diameter can be 2-3cm, and the thickness can be 0.1-0.5 cm. In general, those skilled in the art will appreciate that the alloy sleeve material is a TZM alloy, and the alloy density may be 10.22g/cm³。

Wherein the length of the absorber can be 60-510cm, the inner diameter can be 1-1.1cm, and the outer diameter can be 1.5-3 cm; the material of the absorbent body in general may be⁵⁹Co。

Wherein the gap 24 may have a thickness of 0.01-0.1 cm.

Wherein the thickness of the reflecting layer can be 0-200cm but is not 0. In general, those skilled in the art will appreciate that the reflective layer is a graphite material and may have a density of 1.5-2.5g/cm³The reactor core neutron leak-proof device can reduce neutron leakage, improve reactor core neutron economy of the fast reactor body, reduce fuel consumption and reduce irradiation of neutrons to the reactor vessel. The graphite material of the reflecting layer has strong moderation effect on neutrons, the thermal neutron flux of an irradiation area in the reflecting layer can be improved, and the high thermal neutron flux can be improved²³⁸Yield and specific activity of irradiated isotopes such as Pu.

Wherein the molten salt heat exchanger comprises a cooling salt channel, cooling salt flows in from an inlet 9 of the molten salt heat exchanger, and the cooling salt flows out from an outlet 10 of the molten salt heat exchanger to discharge heat of a reactor core of the fast reactor body.

Wherein, the position of the irradiation cabin is known by the technical personnel to be arranged in the reflecting layer according to the isotope type or the production, and the irradiation target piece can be arranged in the irradiation cabin to carry out the production of the irradiation isotope.

Wherein, the number of the irradiation cabins can be 1-10.

Wherein the irradiation target is similar to the fuel assembly in design and comprises an irradiation accommodating pipe used for filling irradiation nuclide molten salt, and is irradiated by high-flux thermal neutrons in an irradiation region for production²³⁸Industrial isotopes for aviation nuclear batteries such as Pu and other neutron-activated isotopes.

The irradiation containing pipe comprises an assembly irradiation area and an air chamber from bottom to top;

the outer wall of the irradiation containing pipe is an alloy cladding;

the upper part of the irradiation containing pipe is sequentially provided with a second support grid and a second top fixing device from bottom to top; and a second pressure relief vent hole is formed between the second support grid and the second top fixing device.

Wherein the thermal neutron flux in the irradiation target can be 1 x 10¹²n/cm²·s-1×10¹⁵n/cm²Of the order of s.

Wherein, the molten salt cooling pool generally takes chloride molten salt or fluoride molten salt as a coolant; can be chloride molten salt with density of 1.2-1.55g/cm³The high-temperature vapor pressure heat exchanger has low vapor pressure at high temperature, and can realize heat energy conversion and application with higher energy conversion efficiency. And the neutron scattering cross section of the chloride molten salt is small, the fast neutron flux of the reactor core of the fast reactor body can be improved, and the chloride molten salt is suitable for serving as a coolant of the fast reactor. The heat generated by the reactor core of the fast reactor body is transferred to the molten salt cooling pool through heat conduction, the coolant in the cooling pool does not need to be driven by a pump, and the heat is led out through the molten salt heat exchanger, so that the mechanical damage of pressure generated by the flow of molten salt to the fuel assembly in the molten salt cooling pool is reduced.

Wherein the gas collection chamber is further conventionally provided with a vent inlet 7 and a vent outlet 8, the fuel stackThe gas generated in the device enters the gas collecting chamber through the pressure relief vent hole; when in use, the gas can be carried to enter from the ventilating inlet and flow out from the ventilating outlet, the fission gas of the reactor core of the fast reactor body can be carried out, and simultaneously, the fission gas of the reactor core can be collected¹³¹Te、⁸⁹Gaseous isotopes of Kr and the like and some noble metal isotopes such as¹³¹Te, and then entering isotope separation and purification systems according to the conventional practice in the field; the gas collecting chamber is used for avoiding the damage of the fuel salt expansion or the generation of fission gas to the assembly caused by pressure¹³¹Te、⁸⁹And the gaseous isotopes such as Kr can be discharged to the gas collecting chamber through the pressure relief exhaust hole, so that the gaseous isotopes can be conveniently collected and extracted. Therefore, the pressure relief exhaust hole reduces the influence of harmful fission gas on the reactivity of the fuel assembly array, and improves the safety and stability of the operation of the reactor.

Wherein the thickness of the stack container may be 0.2-5 cm. In general, those skilled in the art will appreciate that the bulk material of the stack may be a TZM alloy and the alloy density may be 10.22g/cm³。

In general, those skilled in the art know that the fuel assembly array is in the high-flux fast neutron spectrum.

In general, the skilled person knows that the reflective layer is a region of the high-flux thermal neutron spectrum.

Compared with the traditional molten salt reactor, the reactor core external fuel loop without the fast reactor body is designed, so that fuel can be saved, critical safety problems caused by delayed neutron loss are not needed to be considered, and the reactivity is more controllable. And the fuel assembly is flexibly assembled and disassembled, so that the isotope can be conveniently extracted and processed in time.

The positive progress effects of the utility model are as follows:

1. the fuel assembly provided by the utility model is filled with the liquid molten salt with lower saturated vapor pressure, the working pressure is normal pressure, local natural convection can be formed inside the fuel assembly, so that the internal temperature is more uniform, local hot spots at the boundary of the cladding material can be eliminated, the cladding material and the pressure boundary alloy material do not need to be too thick, the safety is higher, the operating temperature of the molten salt can be 500-1000 ℃, and the thermoelectric conversion efficiency is higher;

fission gas neutron poisons generated in fuel assemblies, e.g.¹³⁵Xe can enter the fuel gas chamber through the first pressure relief vent hole and is discharged out of the pile; and the fuel gas chamber can collect gaseous isotope and separation and purification on line when not shutting down the heap, has effectively improved neutron economy, and does not have the problem that the iodine pit starts after shutting down the heap, and the mobility is higher.

2. The molten salt fast reactor body provided by the utility model has higher design power, higher neutron utilization rate, higher isotope production capacity and potential thermoelectric conversion efficiency, and the cobalt control rods in the fuel assembly array are used as a reactivity control system and can absorb neutron activation to generate isotopes⁶⁰Co, the outer reflecting layer of the reactor is provided with an irradiation cabin, and the leakage neutrons are effectively utilized for production²³⁸Pu can maximize the neutron economy and simultaneously maximize the in-pile isotope byproducts, and has good comprehensive economic advantages. Meanwhile, the heat capacity of the coolant is large after the shutdown of the accident, natural circulation can be formed to realize waste heat derivation, and the safety is high.

Certain components in the reactor body can be replaced without stopping the reactor, and fission products dissolved in the molten salt can be treated¹³¹I、⁸⁹Sr、⁹⁹The isotopes such as Mo and the like are subjected to chemical separation and purification extraction, and complex process flows such as target cutting, dissolution and the like are not needed.

3. Compared with the traditional loop type molten salt reactor, the utility model greatly saves nuclear fuel in the loop and is more economic; the fuel radioactive entity barrier is arranged in a layer, so that the safety is higher; the problem of loss of a precursor nucleus of delayed neutrons does not exist, the multiplication period is longer, and the reactivity is more controllable; the system has no thermal safety problems such as decay heat inflow loop and the like, thereby having higher economical efficiency and safety characteristics.

Drawings

FIG. 1 is a longitudinal cross-sectional view of a molten salt fast reactor body according to an embodiment of the utility model.

FIG. 2 is a schematic longitudinal cross-sectional view of a fuel assembly according to an embodiment of the present invention.

FIG. 3 is a schematic core cross-section of a molten salt fast reactor body according to an embodiment of the utility model.

FIG. 4 is a schematic cross-sectional view of a fuel cell in accordance with an embodiment of the present invention.

FIG. 5 is a cross-sectional schematic view of a control rod according to one embodiment of the present invention.

FIG. 6 is a schematic view of the position of an irradiation capsule according to an embodiment of the present invention.

The reference numerals in the drawings denote: 1. an array of fuel assemblies; 2. a reflective layer; 3. an irradiation chamber; 4. a molten salt cooling pool; 5. a gas collection chamber; 6. a molten salt heat exchanger; 7. a vent inlet; 8. a vent outlet; 9. an inlet of a molten salt heat exchanger; 10. an outlet of the molten salt heat exchanger; 11. a mechanical support structure; 12. a component fuel zone; 13. a fuel gas chamber; 14. alloy cladding; 15. a first support grid; 16. a first pressure relief vent; 17. a first top fixture; 18. fuel assembly (cross-section); 19. a stack container; 20. a control rod passage; 21. a helium gas passage; 22. a double-layer alloy sleeve; 23. an absorbent body; 24. a gap.

Detailed Description

The present invention will be more clearly and completely described in the following description of preferred embodiments, taken in conjunction with the accompanying drawings. The present invention will be described in further detail, and the exemplary embodiments and descriptions thereof are only for explaining the present invention and are not to be construed as limiting the present invention.

Examples

The present embodiment describes a fuel assembly and a molten salt fast reactor body with reference to fig. 1 to 5. As shown in figure 2, the fuel assembly comprises a fuel containing pipe for filling fuel salt, and comprises an assembly fuel area 12 and a fuel air chamber 13 from bottom to top, the outer wall of the fuel containing pipe is an alloy cladding 14, the upper part of the fuel containing pipe is sequentially provided with a first supporting grid 15 and a first top fixing device 17 from bottom to top, and the upper part of the first supporting grid is provided with a pressure relief vent hole 16. The radius of the fuel assembly is 3.5cm and can also be 1-5cm, the fuel area 12 of the assembly is loaded with fuel salt, the height is 268cm and can also be 50-500cm, the height of a fuel gas chamber is 6cm and can also be 1-20cm, and the existence of the gas chamber avoids the volume of molten saltThe pressure created by the expanding and fissile gases can damage the fuel assembly structure. Using sodium chloride molten salt as carrier salt, UCl₃As fuel, dissolved in NaCl, UCl₃Has a molar ratio of 55:45 and a density of 3.56g/cm³And may be 1.2 to 3.6g/cm³In fuel molten salt²³⁵The U enrichment degree is 0-19.75%,³⁷the enrichment degree of Cl is 90-99%.⁹⁹Mo、¹³¹I、⁸⁹Sr、¹³¹Te、⁸⁹Molten fuel salt capable of being directly passed through fuel assembly by fission isotope such as Kr²³⁵And U fission production, loading and unloading the fuel assembly without stopping the reactor, and directly taking out the fuel assembly to separate, purify and extract the isotope after reaching the isotope extraction period. The outer wall of the fuel containing tube is an alloy cladding 14 made of TZM alloy and having a density of 10.22g/cm³The cladding thickness is 0.1cm, and may be 0.01-0.5cm, and can gather fission products in the fuel assembly to serve as a first nuclear fuel entity barrier to prevent fission product diffusion. The radius of the cross section of the first support grid is smaller than the radius of the fuel containing pipe and is 0.5-4.5 cm. As shown in fig. 4, the reactor fuel cells are representative basic units in the reactor grid, and the cross section of each basic unit is a regular hexagon, the radius of each basic unit is 5cm, the radius of each basic unit can also be 2-6cm, and the whole basic unit is immersed in the molten salt cooling pool through a mechanical support structure. A first pressure relief vent 16 is located above the plenum and is fission gas venting means for automatically venting fission gas from the fuel assembly when it has accumulated to a certain level and into the gas collection chamber 5,¹³¹Te、⁸⁹gaseous isotopes such as Kr can be collected there. The first top fuel assembly fixing device 17 is located above the first support grid 15, the radius of the first top fuel assembly fixing device is 5cm, the radius of the first top fuel assembly fixing device can be 2-10cm, the height of the first support grid can be 4-20cm, the fuel assemblies can be fixed, the distance of the fuel grid cells can be determined, the influence of harmful fission gas on the reactivity of the fuel assembly array is reduced, and the safety and the stability of the operation of a reactor are improved.

As shown in figure 1, the molten salt fast reactor body for isotope production comprises a plurality of fuel assemblies 1, a molten salt cooling pool 4, a molten salt heat exchanger 6, a reflecting layer 2, an irradiation cabin 3, a gas collecting chamber 5 and a reactor container19. The diameter of the fast reactor body is 356cm, and can also be 170-600cm, and the height can be 295cm, and can also be 120-520 cm. The array of the fuel assemblies 1 is a high-flux fast neutron spectrum area, is provided with a plurality of fuel assemblies and is also provided with 6 control rod channels which are regularly arranged to form a shape with a hexagonal cross section; wherein the control rod channel has a radius of 3.33cm, a length of 267cm, a sidewall thickness of 0.17cm, and a thickness of 10.22g/cm³A TZM alloy material; (the size of the control rod channel can also be 2-6cm in radius, 60-530cm in length and 0.01-0.5cm in side wall thickness); the control rod passage is provided with a control rod⁵⁹And Co is immersed in the molten salt cooling pool, and heat generated by the fuel molten salt is transferred into the molten salt cooling pool through heat conduction. In the control rod⁵⁹Co absorbs neutron and activates to generate radioactive isotope by-product⁶⁰Co, thereby improving the overall economy of the reactor. As shown in FIG. 5, the control rods comprise a TZM alloy having a density of 10.22g/cm³And a double-layer alloy sleeve 22 provided in the interlayer of the double-layer alloy sleeve⁵⁹ A Co absorber 23; a gap 24 of 0.01-0.1cm is arranged between the double-layer alloy sleeve and the absorber, and an inner-layer pipeline of the double-layer alloy sleeve is a helium channel; the length of the alloy sleeve is 258cm, the inner diameter is 0.6cm, the thickness is 0.4cm, the outer diameter is 1.9cm, and the thickness is 0.45 cm; (the size of the alloy sleeve pipe is that the length can also be 60-510cm, the inner diameter can also be 0.4-1cm, the thickness can also be 0.2-0.6cm, the outer diameter can also be 1.5-3cm, and the thickness can also be 0.1-0.5 cm); the length of the absorber is 258cm, the inner diameter is 1.05cm, and the outer diameter is 1.85 cm; (the size of the absorber: length can also be 60-510cm, inner diameter can also be 1-1.1cm, outer diameter can also be 1.5-3 cm). The reflecting layer covers the molten salt cooling pool, and the thickness of the reflecting layer can be 100cm or 0-200cm but not 0 and is 1.86g/cm³And may be 1.5 to 2.5g/cm³The graphite material of density can reduce neutron leakage, improve the reactor core neutron economy of fast reactor body, reduce fuel consumption, reduced the irradiation of neutron to the reactor container simultaneously, and the graphite material of reflector layer has very strong slowing down effect to the neutron, can improve the thermal neutron flux of irradiation zone in the reflector layer, and high thermal neutron flux can improve the output and the specific activity of irradiation isotope. Irradiation cabins are arranged in the reflecting layer 2, the number of the irradiation cabins is 6, and can also be 1-10The specific location is determined by geometric optimization of the core of the fast reactor body, with the criteria being to minimize the impact on the reactivity of the fuel assemblies while maximizing isotope production, for example,²³⁸the irradiation chamber for Pu is shown in (1, 5) of FIG. 6 and its symmetrical position. An irradiation target is arranged in the irradiation cabin and comprises an irradiation accommodating pipe, and nuclides in the irradiation target are irradiated by high-flux thermal neutrons to produce²³⁸Industrial isotope or other neutron activated isotope for aviation nuclear batteries such as Pu, the irradiation accommodating tube comprises an assembly irradiation area and an air chamber from bottom to top, the outer wall of the irradiation accommodating tube is an alloy cladding, the upper part of the irradiation accommodating tube is sequentially provided with a second support grid and a second top fixing device from bottom to top, a second pressure relief exhaust hole is arranged between the second support grid and the second top fixing device, and the thermal neutron flux in the irradiation target piece can be 1 x 10¹²n/cm²·s-1×10¹⁵n/cm²Of the order of s. The molten salt heat exchanger comprises a cooling salt channel, sodium chloride molten salt is used as a coolant, and the density is 3.6g/cm³And may be 1.2 to 1.55g/cm³And the coolant transfers the heat of the primary loop to the two-loop molten salt heat exchanger 6 in a natural circulation mode. The two-loop molten salt heat exchanger 6 is composed of independent coolant channels, coolant flows in from an inlet 9 of the molten salt heat exchanger, and flows out from an outlet 10 of the molten salt heat exchanger, and heat in the molten salt cooling pool 4 is brought out and transferred to a next-stage heat energy utilization system. The gas collecting chamber is covered on the top of the fuel assembly and is used for collecting gas generated in the fuel assembly through the pressure relief exhaust hole, the gas collecting chamber is provided with a ventilation inlet 7 and a ventilation outlet 8, the gas collecting chamber can carry gas to enter from the ventilation inlet and flow out from the ventilation outlet, the fission gas carried out of the fuel assembly is carried, and meanwhile, the fission gas is collected¹³¹Te、⁸⁹Gas isotopes of Kr and the like and some noble metal isotopes such as¹³¹Te enters systems for isotope separation, purification and the like; the gas collection chamber is to avoid damage to the assembly from pressure generated by fuel salt expansion or fission gas generation. The outside of the reflecting layer is provided with a stacking container 19 which is made of TZM alloy with the density of 10.22g/cm³The thickness is 2cm, and can also be 0.2-5 cm.

The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only illustrative of the present invention and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, optimization improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A fuel assembly comprising a fuel containing tube for filling with fuel salt;

the fuel containing pipe comprises an assembly fuel area and a fuel gas chamber from bottom to top;

the upper part of the fuel containing pipe is sequentially provided with a first supporting grid and a first top fixing device from bottom to top; and a first pressure relief vent hole is formed in the upper part of the first support grid.

2. The fuel assembly of claim 1, wherein the fuel containment tube has a length of 51-520cm and a radius of 1-5 cm; the radius of the first supporting grid is 0.5-4.5 cm; the radius of the cross section of the first top fixing device is 2-10cm, and the height of the first supporting grid is 4-20 cm.

3. The fuel assembly of claim 2, wherein the assembly fuel zone has a height of 50-500 cm; the height of the fuel gas chamber is 1-20 cm.

4. The fuel assembly of claim 1, wherein the outer wall of the fuel containment tube is an alloy cladding; the thickness of the alloy cladding is 0.01-0.5 cm.

5. A molten salt fast reactor body for isotope production, characterized in that it comprises a number of fuel assemblies according to any one of claims 1-4, a reflective layer, an irradiation cabin, a molten salt cooling pool, a gas collection chamber, a molten salt heat exchanger and a reactor vessel;

a plurality of fuel assemblies form a fuel assembly array and are immersed in the molten salt cooling pool; the reflecting layer covers the molten salt cooling pool; the irradiation cabins are arranged in the reflecting layer; the gas collecting chamber is covered on the top of the fuel assembly and is used for collecting gas generated in the fuel assembly through the pressure relief exhaust hole; the molten salt heat exchanger is arranged at the periphery of the molten salt cooling pool; the stack container is disposed outside the reflective layer.

6. The molten salt fast reactor body as claimed in claim 5, wherein the molten salt fast reactor body has a diameter of 170-600cm and a height of 120-520 cm; the thickness of the stack container is 0.2-5 cm.

7. The molten salt fast reactor body of claim 5, characterized in that the cross section of the fuel assembly array is hexagonal; a plurality of control rod channels are arranged in the fuel assembly array; the number of the fuel assemblies in the fuel assembly array is a plurality, and the number of the control rod channels is 6.

8. The molten salt fast reactor body as claimed in claim 7, wherein the control rod channels have a radius of 2-6cm, a length of 60-530cm and a thickness of 0.01-0.5 cm; the control rod channel is provided with a control rod; the control rod comprises a double-layer alloy sleeve and an absorber arranged on an interlayer of the double-layer alloy sleeve, and a gap is formed between the double-layer alloy sleeve and the absorber.

9. The molten salt fast reactor body as claimed in claim 8, wherein the alloy sleeve has a length of 60-510cm, an inner diameter of 0.4-1cm, a thickness of 0.2-0.6cm, an outer diameter of 2-3cm, and a thickness of 0.1-0.5 cm; the length of the absorber is 60-510cm, the inner diameter is 1-1.1cm, and the outer diameter is 1.5-3 cm; the thickness of the gap is 0.01-0.1 cm.

10. The molten salt fast reactor body of claim 5,

the thickness of the reflecting layer is 0-200cm but not 0;

the molten salt heat exchanger comprises a cooling salt channel, cooling salt flows in from an inlet of the molten salt heat exchanger, and cooling salt flows out from an outlet of the molten salt heat exchanger; in the molten salt heat exchanger, the secondary circuit cooling salt flows in from the inlet of the molten salt heat exchanger and flows out from the outlet of the molten salt heat exchanger;

the gas collecting chamber is also provided with a ventilation inlet and a ventilation outlet;

an irradiation target is arranged in the irradiation cabin; the irradiation target comprises an irradiation containing pipe used for filling irradiation nuclide molten salt; the irradiation containing pipe comprises an assembly irradiation area and an irradiation air chamber from bottom to top; the outer wall of the irradiation containing pipe is an alloy cladding; the upper part of the irradiation containing pipe is sequentially provided with a second support grid and a second top fixing device from bottom to top; a second pressure relief vent is arranged between the second support grid and the second top fixing device;

the number of the irradiation cabins is 1-10.