The canister for storage of spent nuclear fuel

 

(57) Abstract:

The invention relates to the field of nuclear energy. The invention consists in that in a case for storage of spent nuclear fuel, comprising a housing with a bottom, the proposed building run of concentrically spaced insulating and bearing shells, and the insulating shell proposed to run from shock-resistant ceramic material or glass fibre fabric with epoxy resin. The technical result of the present invention is that this solution will prevent the depressurization as a result of corrosion processes of structural materials of the case during the period of storage of spent fuel in the pool and, consequently, to improve the environmental safety of nuclear power plants. 3 C.p. f-s, 5 Il.

The invention relates to the field of nuclear energy and can be used in spent nuclear fuel storage facility (ISF) for storage of spent nuclear fuel (SNF) and for radiation technologies.

Transportation and storage of spent fuel produced in the canisters. The need to use canisters dictated by the conditions of protection of the fuel assemblies from mechanical is looking for a pool if possible drop of the fuel Assembly. Currently there are no tools to create the entire infrastructure for long-term storage of spent fuel in containers. The cost of containers for transportation and storage, equipment for cutting fuel assemblies (FA) with SNF is very high, the transportation to the place of processing or storage is also expensive. The design of containers for transportation and storage of SNF are still under development, and ISF are available at the stations. Thus, increasing the capacity of the existing water ISF when NPP is a national problem. However, the implementation of inventions is constrained by the maximum allowable loads on the joists and the bottom of the pool ISF and the requirement to maintain the water-chemical regime. Therefore, reducing the weight of the canisters, increase their reliability and environmental safety will allow for the next 15 - 20 years to solve the problem of spent fuel storage near the nuclear power plant at a minimum cost without cutting, transportation, manufacturing containers, using proven technologies, designs ISF and canisters. Known canisters for spent nuclear fuel storage [1]. The pencil case is a case with waterproof walls and bottom. In a canister placed SNF.

The closest analogies case bottom. The spent fuel is loaded into a water-filled enclosure of the box, close the lid. Then pencil case set in a water-filled pool store, where fix it either suspended or mounted on the bottom of the pool.

The disadvantage is the closest analogue is the high intensity case, the possibility of release of radionuclides from the canister into the pool when corrosion damage of structural metal pencil case. For SNF storage, surrounded by a zirconium cladding, steel pencil case filled with water, zirconium sheath and steel pencil case form a galvanic couple, which is one of the main causes of electrochemical corrosion, which is enhanced in conditions of water radiolysis case, the irradiated from the SNF. Over time, there has been increasing electrochemical corrosion due to accumulation of the products formed in the process of electrochemical corrosion, which leads in some cases to the destruction of zirconium shell and more intense penetration of the radioactive products in the pencil case. And tightness of a canister of radioactive products fall into the water, polluting it. For pool water treatment is necessary to spend large sums of money. When this wall is HERMETIQUE spent fuel assemblies (SFA) during storage of fuel assemblies in canisters pool is not always possible.

Tasks to be solved by the invention: reducing the likelihood of release of radionuclides from the fuel Assembly in the box, next to the pool and consequently solves the problem of improving the reliability of the canister during operation and environmental safety in the storage of spent nuclear fuel canisters. Another problem solved by the invention is the reduction of the metal case.

The invention consists in that in a case for storage of spent nuclear fuel, comprising a housing with a bottom, the proposed building run of concentrically spaced insulating and bearing shells, and the insulating shell proposed to run from shock-resistant ceramic material or glass fibre fabric with epoxy resin. As a clarifying and developing signs offered an insulating body installed inside the carrier, an insulating shell to seal with the inner wall of the bearing shell. In one embodiment of the insulating shell proposed to be installed outside of the bearing shell. Alternatively the carrier shell invited to perform in the form of frame construction.

The embodiment of the casing of the pencil case of concentrically spaced insulating and bearing shells nade is ICEVI in the form of the frame structure, and an insulating shell of shock-resistant ceramic material or glass fibre with epoxy resin, a hardening in the process of radiation exposure will reduce the intensity of the pencil case. The use of these materials for the manufacture of insulating shell reduces corrosion damage of the bearing shells and, consequently, increases the level of security of spent fuel storage. Insulating shell, thus, prevents the formation of galvanic couples and thereby eliminates water pollution case with radionuclides and getting them into the pool. The insulating shell is a kind of barrier to prevent the intake of radionuclides in the pool, i.e., eliminates the main drawback of the nearest equivalent. The total weight of the case while also decreases, since reduced the total estimated wall thickness of the bearing shells (the amount of damage from corrosion). The magnitude of the tensile load on the bearing shell case due to the presence of the insulating shell, made for example of fiberglass with epoxy binder, slightly. The set of features claimed in the first claim, in addition, allows you to organize periodic monitoring of hermeticus two shells. The accumulation of water in this space will indicate the leakage zirconium shell and/or the bearing shell.

This technical solution is illustrated graphics. In Fig. 1 shows a canister of spent nuclear fuel consisting of concentrically arranged insulating and bearing shells; Fig. 2 - pencil case with a bearing shell made waterproof in the form of the frame structure of Fig. 3 - canister SNF with an insulating ring mounted inside the bearing shell; Fig. 4 - pencil case with insulating shell installed on the outside of the bearing shell; Fig. 5 - pencil case with insulating shell, bonded to the inner wall of the bearing shell.

The canister for storage of spent nuclear fuel (Fig. 1, 2, 3, 4, 5) consists of a housing 1 with a bottom 2 and a flange 3 at the top. Case 1 case consists of concentric spaced insulating 4 and carrier 5 shells. Within the entity claimed in the first claim, the possible options regarding the placement of insulation 4 and the bearing 5 shells:

- 4 insulating shell mounted within the bearing 5 of the shell (Fig. 1);

- 4 insulating shell mounted outside the bearing 5 of the shell (Fig. 2).

Carrier 5 shell signal is towline from shock-resistant ceramic material or glass fibre fabric with epoxy hardening in the process of radiation exposure, such as during storage. Possible that 4 insulating shell is bonded with the inner wall of the carrier 5 shells (Fig. 3).

The work of the canister for storage of spent nuclear fuel (for all variants of the canister illustrated in Fig. 1 - 5. Fuel Assembly 6 depending on the chosen method of storage is loaded into a water-filled or dry (not shown) isolating 4 sides, housed in a bearing 5 side of the housing 1. Then filled with water or dry case 1 case set in a water-filled pool 7 store, where fix pencil case in a suspended position on the flanges 3 or installed on the bottom of the pool 7.

The proposed solution will prevent the depressurization as a result of corrosion processes of structural materials of the case during the period of storage of spent fuel in the pool and, consequently, to improve the environmental safety of nuclear power plants. The canisters of the proposed design will not tighten requirements for water-chemical mode of storage of spent nuclear fuel canisters. The proposed solution can be used when designing new, so is ICICI.

Sources of information

1. Ostrainyn K. A. and others "Storage of spent fuel at nuclear power plants", proceedings of "Research in the field of reprocessing of irradiated fuel and the disposal of waste". Proceedings of the Symposium of the member countries of the CMEA. Czechoslovakia, Marianske Lazne, April 1981, S. 1 127.

2. RF patent N 2034346, CL G 21 F 9/36.

1. The canister for storage of spent nuclear fuel, comprising a housing with a bottom, wherein the body is made of concentrically arranged bearing and insulating shells, and an insulating shell made of shock-resistant ceramic material or glass fibre fabric with epoxy-bonded.

2. Pencil case under item 1, characterized in that the insulating shell is installed inside the bearing shell.

3. Pencil case under item 1, characterized in that the insulating shell is installed on the outside of the bearing shell.

4. Pencil case under item 1, characterized in that the bearing shell is made permeable in the form of the frame structure.

 

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FIELD: safety facilities for handling radioactive materials.

SUBSTANCE: proposed internal container designed for long-time storage and transport of high-radioactivity materials such as plutonium dioxide has container body closed with sealed cover and specified-volume charging box placed in this body and provided with its respective cover. Container body has cylindrical passage for charging box that mounts additional internal cover provided with gas filtering device and hermetically installed relative to its surface for axial displacement. External cover of container body is provided with shut-off valve accommodating gas filtering device installed therein between inner space of container and valve seat. Such mechanical design of container enables reducing irreparable loss of plutonium during its long-time storage and transport.

EFFECT: enhanced safety and reliability , enlarged functional capabilities of container.

7 cl, 2 dwg

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