The method of packaging of spent nuclear fuel

 

(57) Abstract:

The invention can be used for packaging of spent nuclear fuel (SNF) during transportation and/or long-term storage. The method includes loading the SNF with the spacer elements in the container from corrosion-resistant metal, heating the container, fill the spent molten metal holding solidification of the melt and seal the container. Fill the spent fuel is carried out by melting of fusible metal or alloy directly into a container and dip the SNF in the melt. The sealing of the container is performed using the cap. The technical result of the invention is to reduce the likelihood of leaks in the fuel cladding and the reduction of the release of radioactive substances from the spent fuel during packaging and storage. 3 C.p. f-crystals, 4 Il.

The invention relates to nuclear technology, and can be used for packaging of spent nuclear fuel (SNF) during transportation and/or long-term storage.

There is a method of storing cassettes containing spent fuel in cooling pools under a layer of water [1]. The disadvantage of this method should recognize the high probability of release of radionuclides sleet such spent fuel storage limited.

The closest analogue is possible to recognize packing SNF (cassettes or bundles of fuel rods), characterized by the placement of spent fuel using the spacer elements in the thin-walled container made of corrosion-resistant metal, welding to the container top cover with holes for pouring molten metal and ventilation, heat the container with spent fuel, fill the container through the holes of the molten low-melting metal or alloy based on it, solidification of the melt in the container, welding holes in the top cover and the operations of the current and final control of tightness of the container of spent nuclear fuel [2]. The disadvantage of this method should recognize the high probability of leaks in the fuel cladding during heating in the process of pouring the melt or in preparation for filling and release significant amounts of radioactive gases into the gas purification system or in the environment, as well as the multistage and the complexity of the process of filling containers.

The technical result is obtained as a result of implementation of the invention is to reduce the likelihood of leaks in the fuel cladding and the reduction of the release of radioactive substances from spent fuel for packaging of metal or alloy, spend the melting of fusible metal or alloy, using the spacer elements are immersed preheated SNF in the melt, utverjdayut melt sealing of the container is carried out by welding the top cover. Preferably the melt fusible metal or alloy and heating the spent fuel is carried out in a single sealed volume, bounded from below by the container top is connected with the container boot vacuum chamber to accommodate the spent fuel. Usually as a fusible metal or alloy used lead or alloy based on it, and choose the volume of the melt is equal to or greater volume of gas cavities in the container in the area of the spent fuel.

In Fig. 1 to 4 show various stages in the process.

In a container, comprising (Fig. 1) of the cylindrical shell 1 and welded to the bottom part 2, download the fusible metal 3 (Fig. 2). The container is placed in a heating furnace 4. The upper end of the shell 1 is sealed (with sealing 11) connect with boot vacuum chamber 5 (Fig. 3) in which with the use of fastening elements 6 SNF 7. The camera 5 is connected to the gas purification system 8. Spend the melt fusible metal or splat using fastening elements in the molten metal 3 (Fig. 3). Spend pouring molten gas cavities and gaps, cooled and crystallized melt to obtain monolith 10. Then disconnect from the container chamber 5 and seal the container by welding thereto of a cover 9 (Fig. 4).

The use of the proposed method will improve the reliability of long-term storage of SNF through the creation of additional high-performance corrosion-resistant barrier between the SNF and the environment, to ensure the retention of radioactive products inside the container, loosen the radiation from the spent fuel, to increase the efficiency of cooling of spent fuel, as well as to expand the scope of application of the method not only for storage but also for transportation.

1. The method of packaging of spent nuclear fuel (SNF), including its load by using the spacer elements in the container from corrosion-resistant metal, welded to the container top cover, heating the container, fill SNF molten low-melting metal or alloy, conducting solidification of the melt and seal the container, characterized in that the pouring of the spent fuel is carried out by melting of fusible metal or alloy directly in a container and dip the SNF in the melt, and gerlene fusible metal or alloy in the container and additional heating is carried out in a single sealed volume, bounded from below by the container, and the top is connected with the container boot vacuum chamber to accommodate the spent fuel.

3. The method according to p. 1, characterized in that as a fusible metal or alloy used lead or alloy based on it.

4. The method according to p. 1, characterized in that the amount of melt is chosen equal to or greater than the amount of gas cavities in the container in the area of the spent fuel.

 

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