RU123207U1 - CONTAINER FOR TRANSPORTATION AND LONG STORAGE OF WASTE HEATED FUEL ASSEMBLIES (SFA) NPP - Google Patents

Abstract

1. A container for transportation and long-term storage of spent fuel assemblies (SFA) of a nuclear power plant, containing an outer casing 1 with a lid 2, an inner casing 3 with a lid 4, a cover 5 located in the inner casing with slots 6 for spent fuel assemblies 8 and shock absorbers 9, characterized by that channels 10 are made in the outer casing along its longitudinal axis, which are filled with neutron-absorbing hydrogen-containing material. 2. The container according to claim 1, characterized in that a cavity 11 is made in the bottom of the outer casing, filled with a neutron-absorbing hydrogen-containing material. The container according to claim 1, characterized in that the lid 4 of the inner housing has a cavity 12 filled with a neutron-absorbing hydrogen-containing material. A container according to claims 1 to 3, characterized in that hydrogen-containing polymers are used as the neutron-absorbing hydrogen-containing material. The container according to claims 1 to 3, characterized in that a compound is used as a neutron-absorbing hydrogen-containing material, containing, wt%:

Description

The utility model relates to mobile protective containers and is intended for transportation and dry long-term storage of spent fuel assemblies (SFA) of nuclear power plants.

A known container for solid radioactive waste containing a multilayer body, one of the layers of which is made of SiC; the specified layer is made of silicon carbide containing free silicon in an amount of 3-30 wt.%, RU 2146402 C1; silicon carbide is reinforced with a carbon component and can be made of reactive silicon; optionally, gas phase silicon carbide can be deposited on the reaction sintered silicon carbide.

The container body, made of silicon carbide, does not have sufficient strength under shock loads, which is important in conditions of transportation.

A known container for transportation and long-term storage of SFA of nuclear power plants containing an outer casing with a cover, an inner casing with a cover, a cover with sockets for SFA and shock absorbers located in the inner casing, RU 2148864.

This technical solution was made as a prototype of this utility model.

This technical solution due to the presence of shock absorbers allows the container to be transported at emergency values, but its serious drawback is the lack of effective protection against neutron radiation of some SFAs with an increased level of such radiation. It should be noted that the current task of transporting and storing SFAs with a high degree of burnout and, accordingly, with a high level of neutron radiation. The prototype device provides protection against γ radiation, however, the metal walls of the container according to RU 2148864 are ineffective with respect to protection against neutron radiation.

The objective of this utility model is to provide effective protection against neutron radiation emanating from radioactive substances (SFA) in the container.

According to a utility model, in a container for transporting and long-term storage of spent fuel assemblies (SFA) of nuclear power plants containing an outer casing with a cover, an inner casing with a cover, a cover with sockets for SFA and shock absorbers placed in the inner casing, channels are made in the outer casing along its longitudinal axis which are filled with neutron-absorbing hydrogen-containing material; a cavity is filled in the bottom of the outer casing, filled with a neutron-absorbing hydrogen-containing material; a cavity is filled in the lid of the inner case, filled with a neutron-absorbing hydrogen-containing material; hydrogen-containing polymers were used as a neutron-absorbing hydrogen-containing material; as a neutron-absorbing hydrogen-containing material used compound containing wt.%:

dimethylsiloxane rubber - 98-99 ethyl silicate - 0.1-0.2 tin octoate - the rest.

The essence of the utility model is illustrated by drawings, which depict:

figure 1 is a longitudinal section of a container;

figure 2 is a section aa in figure 1;

figure 3 is a section bB in figure 1.

The container for transportation and storage of the SFA contains an outer casing 1, equipped with a sealed cover 2; the material of the outer casing 1 - low alloy steel 09G2SA-A or high-strength cast iron with spherical graphite; lid material 2 - low alloy steel 09G2SA-A or corrosion-resistant steel grade 12X18H1OT; the inner case 3 is equipped with a sealed cover 4 and is installed inside the outer case 1. The material of the inner case 3 and the cover 4 is low alloy steel or corrosion-resistant steel. Thus, the container has two independent leakage barriers. In the inner case 3 there is a cover 5 with sockets 6 for SFAs 8, the material of the cover 5 and sockets 6 is corrosion-resistant steel or aluminum alloy. At the ends of the outer casing shock absorbers 9 are installed to maintain the tightness of the container in emergency transportation conditions. In the outer casing 1, longitudinal channels 10 are made along its longitudinal axis, in a specific example, two rows of channels arranged in a “checkerboard pattern” that are filled with neutron-absorbing hydrogen-containing material.

To increase the level of safety in the conditions of transportation and storage of SFAs with a high degree of burnout, a cavity 11 is made in the bottom of the outer case 1, and a cavity 12 is made in the cover 4 of the inner case 3; cavities 11 and 12 are filled with neutron-absorbing hydrogen-containing material.

As a neutron-absorbing hydrogen-containing material used hydrogen-containing polymers; in particular, polyethylene, polypropylene, polystyrene, etc. It is possible to use other various hydrogen-containing substances: epoxy or organosilicon resins, rubbers, etc.

Hydrogen-containing materials are best for protection against neutron radiation. Hydrogen is a very good neutron moderator. The hydrogen nucleus - the proton has the same mass with a good degree of accuracy as the neutron, therefore, with each act of elastic scattering on the hydrogen nucleus, the neutron loses about half of the initial energy.

In a specific example, a compound containing, wt%: was used as a neutron-absorbing hydrogen-containing material

dimethylsiloxane rubber - 98-99 ethyl silicate - 0.1-0.2 tin octoate - the rest.

The use of this compound is preferable according to the conditions of the technology of filling cavities in the container elements.

Loading the container is as follows. The container is installed in a vertical position on the loading platform (not shown in the drawing). The cover 2 of the outer casing 1 and the cover 4 of the inner casing are docked. A cover 5 with SFA 8 is loaded into the inner casing 8. The inner casing 3 is hermetically closed by the lid 4, then the outer casing 1 is hermetically closed by the lid 2. The shock absorbers 9 are installed on the outer casing 1.

The container is prepared for transportation and storage of environmentally hazardous cargo - SFA.

In the interaction of neutrons with neutron-absorbing material occurs:

- elastic neutron scattering;

- inelastic neutron scattering;

- neutron absorption.

Elastic and inelastic neutron scattering are processes during which fast and intermediate neutrons slow down. When neutrons reach thermal energies, they are absorbed during neutron capture.

Due to the implementation of the distinguishing features of the independent claim of the utility model formula, a technical result is achieved consisting in providing sufficiently effective protection against neutron radiation from the SFA container. The effectiveness of this protection is enhanced by the implementation of dependent paragraphs 2, 3 of the utility model formula.

Claims (5)

1. A container for transporting and long-term storage of spent fuel assemblies (SFA) of a nuclear power plant, comprising an outer casing 1 with a cover 2, an inner casing 3 with a cover 4, a cover 5 with sockets 6 for the SFA 8, and shock absorbers 9, characterized in that that in the outer casing along its longitudinal axis there are channels 10 that are filled with neutron-absorbing hydrogen-containing material. 2. The container according to claim 1, characterized in that a cavity 11 is made in the bottom of the outer casing, filled with a neutron-absorbing hydrogen-containing material. 3. The container according to claim 1, characterized in that in the lid 4 of the inner case there is a cavity 12 filled with a neutron-absorbing hydrogen-containing material. 4. The container according to claims 1 to 3, characterized in that hydrogen-containing polymers are used as a neutron-absorbing hydrogen-containing material. 5. The container according to claims 1 to 3, characterized in that as a neutron-absorbing hydrogen-containing material used a compound containing, wt.%: dimethylsiloxane rubber 98-99 ethyl silicate 0.1-0.2 tin octoate rest