Gas absorbing device for fuel element

Abstract

The invention relates to the technical field of fuel elements, and particularly discloses a gas absorbing device for a fuel element. The gas absorbing device for the fuel element comprises a fuel element coating material adopting a cylindrical case structure as well as a gas absorbing structure which is fixed in the fuel element coating material and can absorb hydrogen and isotopes of hydrogen, wherein the gas absorbing structure is located at the upper or lower part of a fuel pellet zone of the whole fuel element. With the adoption of the gas absorbing device for the fuel element, the content of gases such as the hydrogen, the isotopes of the hydrogen and the like in the fuel element can be decreased, risks of hydrogenation and damage to the cladding of the fuel element are reduced, emission of the isotopes of the hydrogen and pollution are reduced, and meanwhile, adverse effects on the performance of the fuel element can be avoided.

Description

technical field [0001] The invention belongs to the technical field of fuel elements, and in particular relates to a gas absorbing device for fuel elements. Background technique [0002] Typical pressurized water reactor fuel assemblies work under harsh conditions such as high temperature, high pressure, high boron water, strong neutron irradiation, corrosion, erosion and hydraulic vibration in the core for a long time, so the performance of the fuel assembly is directly related to the reactor Safety, reliability, economy and advancement. Pressurized water reactors generally use low-enriched uranium fuel, spring grids, and boxless bundled rod fuel assemblies. The fuel assembly is composed of fuel elements, positioning grids, assembly skeletons and other components, among which the components used to generate nuclear fission and release heat are fuel elements. A typical fuel element is about 3 to 4 meters in length and 9 to 11 mm in outer diameter. It is composed of uranium...

AI Technical Summary

Problems solved by technology

Through analysis and calculation, and a lot of operating experience, it is shown that the commonly used tubular support structure can meet the strength requirements, but when the catalyst is coated on its surface to make it have the ability to absorb hydrogen and tritium, due to a large amount of hydrogen absorption, the resulting structure Loose hydrides, which lead to a decrease in the strength of the support structure and therefore may cause instability of the support structure

Moreover, the structure is a tubular structure. If the catalyst is only coated on the inner surface of the tubular structure, the catalyst coating is difficult and difficult to process due to the small inner wall space of the tubular structure, and the surface area of ​​the structure for absorbing hydrogen and tritium is relatively small.

If the catalyst is coated on the outer surface of the structure, the above-mentioned problems can be avoided, but because the gap between the outer surface of the structure and the inner surface of the fuel element coating material is small, and no effective isolation device is provided, the outer surface of the structure may be in contact with the fuel element. If the inner surface of the coating material is in contact, the catalyst coated on the outer surface may diffuse to the inner surface of the fuel element coating material, causing hydrogen absorption damage to the fuel element coating material

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