MOX powder tank and shielding container cooling structure

Abstract

The utility model discloses an MOX powder charging bucket and shielding container cooling structure which comprises a charging bucket bottom center pipe and a shielding container ventilation pipe. The material tank bottom center pipe is arranged in an inner cavity of a material tank shell, the bottom of the material tank bottom center pipe is open and connected with the bottom face of the material tank shell in a sealed mode, and the top of the material tank bottom center pipe is closed. The shielding container ventilation pipe is connected into a shielding container and is formed on a shielding container bottom plate; the charging bucket shell and the shielding container form a positioning structure which is matched with each other, and the charging bucket shell is placed in the shielding container through the positioning structure; and the shielding container ventilation pipe is arranged in the central pipe at the bottom of the charging bucket in a penetrating manner. The MOX powder tank and shielding container cooling structure solves the problems of effective cooling and geometric safety of MOX powder in the MOX powder tank.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of radioactive material container cooling structure, especially relates to a MOX powder tank and shielding container cooling structure. BACKGROUND

[0002] The spent fuel unloaded after reactor irradiation contains more than 200 kinds of nuclides, and uranium, plutonium and fission products account for about 95%, 1% and 4% respectively. Through reprocessing, 96% of useful nuclear materials are separated and recovered, and long-lived minor actinide elements such as fissile products, neptunium, americium and curium are solidified and disposed in deep geological layers or separated and transmuted. Not only can it greatly reduce the volume of high-level waste, reduce the long-term potential hazards and toxicity of spent fuel, but also can greatly improve the utilization rate of uranium resources.

[0003] The conventional nuclear fuel uses low-enriched U-235 with enrichment less than 4.95%, which is a naturally occurring fissile nuclide that can undergo fission reaction under the action of thermal neutrons to release a large amount of energy. The atomic nucleus of U-235 is stable, and the decay type is alpha decay, with very weak penetration ability, so it is usually not necessary to specially consider its external exposure problem but to avoid internal exposure. From the perspective of radioactivity and radiation protection, it can be generally considered as a basically stable nuclide. Therefore, the powder process of U-235 fuel manufacturing is a continuous process in a conventional negative pressure plant, and the powder material is sequentially passed through each production equipment by pipeline, without the need to set up a retention area and use a special storage and transportation container for frequent batch transfer of materials. However, the raw materials need to be transported from the upstream plant to the element manufacturing plant using a special transportation container, which can be referred to in GB / T 42343-2023 Uranium Hexafluoride Transport Container.

[0004] The uranium-plutonium mixed-oxide (MOX) powder is a main end product of the reprocessing process, mainly composed of the fissile nuclide Pu-239 and the transmutation nuclide U-238 (the mass content of Pu is not more than 12.5%), and is a key intermediate material for the production of new fuel returned to the reactor for reuse to realize the closed cycle of nuclear fuel and ensure the sustainable development of nuclear energy. The U-238 decays extremely slowly and has little radioactivity, and can be considered as a stable nuclide, which is converted into Pu-239 after absorbing one fast neutron and undergoing two beta decays. The Pu-239 has different neutron physical properties from uranium, is an artificial radioactive nuclide, has extremely low nuclear stability, is a highly fissile isotope, has a much larger neutron absorption cross section and fission cross section than U-235, can spontaneously decay to emit multi-energy state alpha particles and certain beta particles, and can easily capture neutrons to produce more neutrons and release a large amount of energy, so the critical mass of Pu-239 is very low and has high toxicity and strong radioactivity. This causes the MOX powder to have typical characteristics of radioactive material release, ionizing radiation, criticality and decay heat in a macroscopic manner, and needs to meet the requirements of avoiding leakage, radiation shielding, preventing criticality, continuous cooling and remote control in operation.

[0005] Through the above discussion and analysis, it is shown that the process environment of the MOX powder is much more severe than that of the low-enriched uranium, and therefore the MOX powder is processed in a glove box with high sealing and a negative pressure barrier, which involves the problems of remote operation, intermediate storage and transfer of the MOX powder. At present, there is a lack of mature and reliable MOX powder storage and transportation equipment in China that can well meet the above operation requirements, and this unfavorable situation is more prominent under the strong situation of the active and orderly promotion of the reprocessing plant project and the supporting MOX fuel manufacturing facilities in China. In order to solve the problems that the existing radioactive material storage and transportation containers cannot meet the operation requirements of the MOX powder and the MOX powder needs to be transferred, cooled and weighed on the continuous conveying equipment during the process of receiving, mixing, ball milling, homogenization, pellet pressing and material recycling, a MOX powder tank and shielding container system of a hundred kilograms is designed, and the cooling structure is an indispensable core functional part and is an important component for ensuring the function implementation and operation safety. SUMMARY

[0006] In view of the deficiencies in the prior art, the MOX powder tank and shielding container cooling structure is provided, which solves the problems of effective cooling of the MOX powder in the MOX powder tank and geometric safety.

[0007] In order to achieve the above object, the utility model provides a MOX powder tank and shielding container cooling structure, including a tank bottom center tube and a shielding container ventilation pipe, the tank bottom center tube sets up in the inner chamber of a tank shell, the tank bottom center tube bottom opening and sealedly connected the bottom surface of the tank shell, the top of tank bottom center tube is closed, the shielding container ventilation pipe is connected in a shielding container and is formed in a shielding container bottom plate, the tank shell and the shielding container form the positioning structure of mutual cooperation, the tank shell is placed in the shielding container through the positioning structure, the shielding container ventilation pipe is worn in the tank bottom center tube.

[0008] As an implementation form, the tank bottom center tube is vertically arranged in the tank shell and connected to the center of the bottom surface of the tank shell.

[0009] As an implementation form, the top of the tank bottom center tube forms a convex conical top.

[0010] As an implementation form, the shielding container ventilation pipe is worn in the tank bottom center tube and extends to the top of the tank bottom center tube.

[0011] As an implementation form, the positioning structure forms a gap between the tank shell and the shielding container.

[0012] As an implementation form, the positioning structure includes a bottom flange, a center flange, a bottom flange installation groove and a plurality of center flange installation grooves, the bottom flange is connected to the outer edge of the bottom of the tank shell, the center flange is connected to the bottom opening of the tank bottom center tube, the bottom flange installation groove and the center flange installation groove are formed in the shielding container bottom plate, and the position of the bottom flange installation groove is matched with the bottom flange, and the position of the center flange installation groove is matched with the center flange, the bottom flange is placed in the bottom flange installation groove, and the center flange is placed in the center flange installation groove.

[0013] As an implementation form, the bottom flange is detachably connected with the tank shell, and the center flange is detachably connected with the tank bottom center tube.

[0014] As an implementation form, the material of the bottom flange and the center flange is ultra-high molecular boron-containing polyethylene.

[0015] As an implementation form, the bottom surface of the bottom flange is lower than the bottom surface of the center flange to form a height difference, and the flange height of the bottom flange and the center flange is greater than the depth of the bottom flange installation groove and the center flange installation groove respectively, so that the gap is formed between the bottom surface of the tank shell and the bottom plate of the shielding container.

[0016] As an implementation, three heat dissipation and weighing avoidance holes are further included; the heat dissipation and weighing avoidance holes are formed in the shielding container bottom plate; the heat dissipation and weighing avoidance holes are fan-shaped and evenly distributed around the shielding container ventilation pipe in the circumferential direction.

[0017] The above technical scheme is adopted, and the following beneficial effects are achieved.

[0018] 1. The existence of the bottom center pipe of the material tank and its geometric structure form a flat annular cavity inside the material tank, which limits the mass distribution and bulk density of the MOX powder to avoid criticality and heat accumulation, and at the same time, the area of the whole material tank for heat dissipation and cooling is increased, and geometric safety of MOX powder operation is achieved. Through the cooperation of the bottom center pipe of the material tank and the shielding container ventilation pipe, when the lower end of the shielding container ventilation pipe is connected with the cold gas input device, the cooling gas can continuously pass through the shielding container ventilation pipe into the top of the bottom center pipe of the material tank, and under the deflection guiding action of the conical top of the bottom center pipe of the material tank, the cooling gas is circulated and discharged downward along the inner wall of the bottom center pipe of the material tank, so that the MOX powder in the material tank is continuously and forcibly cooled.

[0019] 2. The adoption of the positioning structure enables the material tank to be placed in the shielding container smoothly, stably and correctly.

[0020] 3. The material of the bottom flange and the center flange is ultra-high molecular boron-containing polyethylene, which mainly functions to create a buffer between the material tank and the shielding container to avoid hard contact and prevent impact, wear or extrusion deformation of the material tank, and form a gap between the bottom of the material tank and the bottom plate of the shielding container to facilitate heat dissipation and blowing and cooling of the circulating air discharged from the bottom center pipe of the material tank.

[0021] 4. The detachable structure of the bottom flange and the center flange enables the bottom flange and the center flange to be removed from the material tank and replaced regularly, which is convenient for maintenance and saves maintenance cost.

[0022] 5. The setting of the heat dissipation and weighing avoidance holes increases the heat dissipation and air cooling area of the bottom of the material tank, together with the gap between the bottom of the material tank and the bottom plate of the shielding container, effectively forms a circulating air cooling channel to achieve comprehensive and continuous cooling effect of the MOX powder in the material tank during transfer or storage. At the same time, the vertical support rods for avoiding the weighing system enable the three vertical support rods of the weighing system to pass through the corresponding three fan-shaped areas into the bottom center pipe of the material tank to complete the weighing of the material tank. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical scheme in the embodiments of the present application, the drawings needed to be used in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort on the premise of not paying creative effort.

[0024] Fig. 1 It is a whole section view of the MOX powder tank and shielding container cooling structure of the embodiment of the present application.

[0025] Fig. 2 It is a top structure schematic view of the MOX powder tank and shielding container cooling structure of the embodiment of the present application.

[0026] Fig. 3 It is a bottom structure schematic view of the MOX powder tank and shielding container cooling structure of the embodiment of the present application.

[0027] Fig. 4 It is an application state view of the MOX powder tank and shielding container cooling structure of the embodiment of the present application.

[0028] Explanation of the drawing reference numerals:

[0029] 1-tank shell;

[0030] 2-tank bottom center tube;

[0031] 3-bottom flange;

[0032] 4-center flange;

[0033] 5-custom rivet;

[0034] 6-shielding container shielding layer;

[0035] 7-shielding container interlayer outer wall;

[0036] 8-shielding container bottom plate;

[0037] 8'-bottom flange arrangement groove;

[0038] 8"-center flange arrangement groove;

[0039] 9-shielding container ventilation pipe;

[0040] 10-heat dissipation and weighing avoidance hole. DETAILED DESCRIPTION

[0041] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be clearly and completely described below, obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work belong to the protection scope of the present application.

[0042] In the description of the present application, it should be pointed out that the orientation or position relationship indicated by the terms "upper", "lower", "left", "right", "center", "vertical", "horizontal", "inner", "outer" and the like is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as limiting the devices or elements indicated or implied to have a specific orientation, structure and operation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" and the like are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0043] In the description of the present application, it should be pointed out that unless otherwise explicitly specified and limited, the terms "mounting", "setting", "connecting", "connecting" and the like should be broadly understood, for example, "connecting" can be fixed connection, or detachable connection, or integrally connected; can be mechanical connection, or electrical connection; can be direct connection, or indirect connection through intermediate medium, or communication between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0044] Embodiment 1

[0045] Please refer to Figs. 1-4 The utility model discloses a MOX powder tank and shielding container cooling structure, including a tank bottom center tube 2 and a shielding container ventilation pipe 9, the tank bottom center tube 2 sets up in the inner chamber of a tank shell 1, the tank bottom center tube 2 bottom opening and sealing connection the bottom surface of tank shell 1, the top of tank bottom center tube 2 is closed, the shielding container ventilation pipe 9 is connected in a shielding container and is formed in a shielding container bottom plate 8, the tank shell 1 with shielding container forms the positioning structure of mutual cooperation, the tank shell 1 is placed in shielding container through positioning structure, the shielding container ventilation pipe 9 is worn in tank bottom center tube 2.

[0046] The tank bottom center tube 2 is vertically arranged in the tank shell 1 and connected to the center of the bottom surface of the tank shell 1.

[0047] The top of the tank bottom center tube 2 forms a convex conical top.

[0048] The shielding container ventilation pipe 9 is arranged in the tank bottom center pipe 2 and extends to the top of the tank bottom center pipe 2.

[0049] The positioning structure forms a gap between the tank shell 1 and the shielding container.

[0050] In this embodiment, the positioning structure includes a bottom flange 3, a center flange 4, a bottom flange installation groove 8', and a center flange installation groove 8''. The bottom flange 3 is connected to the outer edge of the bottom of the tank shell 1. The center flange 4 is connected to the bottom opening of the tank bottom center pipe 2. The bottom flange installation groove 8' and the center flange installation groove 8'' are formed in the shielding container bottom plate 8, and the position of the bottom flange installation groove 8' matches the bottom flange 3, and the position of the center flange installation groove 8'' matches the center flange 4. The bottom flange 3 is placed in the bottom flange installation groove 8', and the center flange 4 is placed in the center flange installation groove 8''.

[0051] In this embodiment, the bottom surface of the bottom flange 3 is lower than the bottom surface of the center flange 4 to form a height difference. The flange heights of the bottom flange 3 and the center flange 4 are greater than the depths of the bottom flange installation groove 8' and the center flange installation groove 8'', respectively, to form the gap between the bottom surface of the tank shell 1 and the shielding container bottom plate 8.

[0052] The MOX powder tank and shielding container system is applied as a whole in a glove box for remote operation, intermediate buffering, and transfer of MOX powder in a MOX fuel manufacturing batch process. Scientific and reasonable measures are taken to address the typical characteristics and risks of MOX powder, such as inherent release of radioactive substances, ionizing radiation, criticality, and decay heat, to meet the operation requirements and effectively ensure the safety of process operation and nuclear safety.

[0053] The shielding container is installed on a flow transfer station of a continuous transfer device or a storage station of a buffer glove box through the shielding container bottom plate 8. The MOX powder is sealed and contained in the tank and placed in the shielding container together with the tank, and then continuously transferred or buffered and stored. The shielding container cladding outer wall 7 of the shielding container is internally provided with a shielding container shielding layer 6 made of ultra-high molecular boron-containing polyethylene material, which has strong thermal neutron absorption capacity and covers the entire height of the tank, and can fully shield the neutrons and γ radiation released by the MOX powder.

[0054] In the embodiment, the lower edge of the tank shell 1 and the bottom edge of the tank bottom center tube 2 are connected to the bottom flange 3 and the center flange 4 respectively by custom rivets 5 to form an integral whole, and the bottom flange 3 and the center flange 4 are positioned and connected to the bottom flange installation groove 8' and the center flange installation groove 8" of the shielding container bottom plate 8, so that the tank can be placed in the shielding container smoothly, stably and correctly.

[0055] The presence of the tank bottom center tube 2 and its geometric structure make the tank form a flat annular cavity, which well increases the overall heat dissipation and cooling area of the tank while limiting the mass distribution and bulk density of the MOX powder to avoid criticality and heat accumulation.

[0056] The shielding container ventilation pipe 9 is located on the shielding container bottom plate 8 and at the center of the shielding container, and can be centered and sleeved in the tank bottom center tube 2 when the tank is placed in the shielding container. The lower end of the shielding container ventilation pipe 9 is connected to the corresponding cold gas pipe port in the glove box, and the upper end is close to the conical top of the tank bottom center tube 2. Cooling gas continuously enters the top of the tank bottom center tube 2 through the shielding container ventilation pipe 9, and is guided by the baffle of the conical top of the tank bottom center tube 2 to circulate downward along the inner wall of the tank bottom center tube 2, so as to continuously and forcibly cool the MOX powder in the tank.

[0057] Embodiment 2

[0058] The MOX powder tank and shielding container cooling structure of the second embodiment of the utility model is basically same in structure with the first embodiment, and the difference lies in that the bottom flange 3 is detachably connected with the tank shell 1, and the center flange 4 is detachably connected with the tank bottom center tube 2.

[0059] The detachable structure of the bottom flange 3 and the center flange 4 can realize the removal of the bottom flange 3 and the center flange 4 from the tank and the periodic replacement, so that the maintenance is facilitated and the maintenance cost is saved. The removed bottom flange 3 and center flange 4 are disposed by cementing after the incineration volume reduction of the medium-level radioactive waste.

[0060] Embodiment 3

[0061] The MOX powder tank and shielding container cooling structure of the third embodiment of the utility model is basically same in structure with the second embodiment, and the difference lies in that the material of the bottom flange 3 and the center flange 4 is ultra-high molecular boron-containing polyethylene.

[0062] The material of the bottom flange 3 and the center flange 4 is selected as ultra-high molecular boron-containing polyethylene, which mainly functions to make a buffer between the tank and the shielding container to avoid hard contact, prevent impact, wear or extrusion deformation of the tank, and form a certain gap between the bottom of the tank shell 1 and the shielding container bottom plate 8 to facilitate heat dissipation and blowing and cooling of the circulating air discharged from the tank bottom center tube 2.

[0063] Embodiment 4

[0064] The MOX powder tank and shielding container cooling structure of the embodiment four is basically same as that of the embodiment three, and the difference is that it further comprises three heat dissipation and weighing avoidance holes 10; the heat dissipation and weighing avoidance holes 10 are formed in the shielding container bottom plate 8; the heat dissipation and weighing avoidance holes are fan-shaped and are uniformly distributed around the shielding container ventilation pipe 9.

[0065] The MOX powder tank and shielding container cooling structure of the embodiment mainly aims at the decay heat characteristics and corresponding risks of the MOX powder, and it mainly comprises a tank bottom center pipe 2, a shielding container ventilation pipe 9 and three heat dissipation and weighing avoidance holes 10.

[0066] The heat dissipation and weighing avoidance holes 10 increase the heat dissipation and air cooling area of the tank bottom, and together with the gap between the tank bottom and the shielding container bottom plate 8, effectively form a circulating air cooling channel to achieve the comprehensive and continuous cooling effect of the MOX powder in the tank during the transfer or storage process, and also act on the weighing of the tank.

[0067] The quality of the powder material needs to be strictly controlled in each process and process link of the MOX fuel manufacturing powder process to ensure the process safety, nuclear safety and the operation safety of the subsequent MOX fuel in the reactor. The MOX powder weighing is carried out by the online tank weighing at the weighing station before and after each process link. The MOX powder tank and shielding container are horizontally transferred to the station by the continuous conveying equipment, and the weighing system with three vertical supporting rods is arranged below the vertical conveying mechanism and directly opposite the bottom center of the MOX powder tank and shielding container. When weighing, the vertical conveying mechanism with the MOX powder tank and shielding container is lowered together, so that the three vertical supporting rods of the weighing system pass through the three fan-shaped area vertex positions corresponding to the heat dissipation and weighing avoidance holes 10 of the shielding container bottom plate 8 to contact the conical top of the tank bottom center pipe 2 and apply a supporting force, and the vertical conveying mechanism with the shielding container continues to descend to make the tank completely separate from the three vertical supporting rods of the weighing system, so that the weighing can be carried out without interference. After the weighing is completed, the vertical conveying mechanism with the shielding container is raised to collect the tank until it returns to the default state.

[0068] The above embodiments of the utility model are described in detail in combination with the drawings, and those skilled in the art can make various change examples of the utility model according to the above description. Thus, some details in the embodiments should not constitute a limitation on the utility model, and the protection scope of the utility model will be defined by the appended claims.

Claims

1. A MOX powder can and shielding container cooling structure, characterized by, The application relates to a shielding container ventilation pipe and a tank bottom center pipe, wherein the tank bottom center pipe is arranged in the inner cavity of a tank shell, the bottom of the tank bottom center pipe is open and is sealingly connected to the bottom surface of the tank shell, and the top of the tank bottom center pipe is closed; the shielding container ventilation pipe is connected to a shielding container and is formed in a shielding container bottom plate; the tank shell and the shielding container form a positioning structure matched with each other, and the tank shell is placed in the shielding container through the positioning structure; the shielding container ventilation pipe is arranged in the tank bottom center pipe and extends to the vicinity of the top of the tank bottom center pipe.

2. The MOX powder can and shielding container cooling structure according to claim 1, characterized by, The tank bottom center pipe is vertically arranged in the tank shell and is connected to the center part of the bottom surface of the tank shell.

3. The MOX powder can and shielding container cooling structure according to claim 2, characterized by, The top of the tank bottom center pipe is formed in a convex conical shape.

4. The MOX powder can and shielding container cooling structure according to claim 3, characterized by, The shielding container ventilation pipe is arranged in the tank bottom center pipe and extends to the vicinity of the top of the tank bottom center pipe.

5. The MOX powder can and shielding container cooling structure according to any one of claims 1 to 4, characterized by, The positioning structure forms a gap between the tank shell and the shielding container.

6. The MOX powder can and shielding container cooling structure according to claim 5, characterized by The positioning structure comprises a bottom flange, a center flange, a bottom flange accommodation groove and a center flange accommodation groove; the bottom flange is connected to the outer edge of the bottom of the tank shell; the center flange is connected to the bottom opening of the tank bottom center pipe; the bottom flange accommodation groove and the center flange accommodation groove are formed in the shielding container bottom plate, and the position of the bottom flange accommodation groove is matched with the bottom flange, and the position of the center flange accommodation groove is matched with the center flange; the bottom flange is arranged in the bottom flange accommodation groove; and the center flange is arranged in the center flange accommodation groove.

7. The MOX powder can and shielding container cooling structure according to claim 6, characterized by The bottom flange is detachably connected to the tank shell; and the center flange is detachably connected to the tank bottom center pipe.

8. The MOX powder can and shielding container cooling structure according to claim 6, characterized by, The material of the bottom flange and the center flange is ultra-high molecular boron-containing polyethylene.

9. The MOX powder can and shielding container cooling structure according to claim 6, characterized by, The bottom surface of the bottom flange is lower than the bottom surface of the center flange to form a height difference; the flange height of the bottom flange and the center flange is respectively greater than the depth of the bottom flange accommodation groove and the center flange accommodation groove, so that the gap is formed between the bottom surface of the tank shell and the bottom plate of the shielding container.

10. The MOX powder can and shield container cooling structure according to claim 6, characterized by, Three heat dissipation and weighing avoiding holes are further arranged; the heat dissipation and weighing avoiding holes are formed in the shielding container bottom plate; the heat dissipation and weighing avoiding holes are fan-shaped and are uniformly distributed around the shielding container ventilation pipe.

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