FUEL ELEMENT FOR A FAST NEUTRON REACTOR (VARIANTS) AND A CLADDING FOR THE PRODUCTION THEREOF

摘要

The invention relates to nuclear engineering, in particular to materials used for nuclear power engineering. The aim of said invention is to develop a fuel element for a fast neutron reactor and a cladding for the production thereof which exhibits the following properties: a lower induced activity level and the rapid loss thereof after a neutron exposure, a high embrittlement resistance within a temperature range of 270-400 DEG C at a neutron irradiation and a high heat resistance at temperatures up to 700 DEG C. The aim is achieved by that the fuel element cladding is made of a martensite-ferrite steel. The structure of said steel is embodied in the form of at least two areas through the height thereof, the steel structure ensures a high heat resistance in the upper area and a high low-temperature radiation embrittlement resistance in the lower area thereof. The inventive cladding for the fuel element is made of a steel having the following component ratio: 0.10-0.21 mass % carbon, 0.1-0.8 mass % silicium, 0.5-2.0 mass % manganese, 10.0-13.5 mass % chromium, 0.8-2.5 mass % tungsten, 0.05-0.4 mass % vanadium, 0.05-0.4 mass % titanium, 0.001-008 mass % boron, 0.001-0.01 mass % cerium (and/or yttrium in total), 0.05-0.2 mass % zirconium, 0.05-0.2 mass % tantalum, and 0.02-0.15 mass % nitrogen the rest, being iron at a ratio between a total vanadium, titanium, zirconium and tantalum content and a total carbon and hydrogen content ranging from 2 to 9. The steel structure through the height of the cladding is embodied in the form of at least two areas, ensures the high hear resistance thereof and comprises alpha -ferrite, delta -ferrite, sorbite, M23C6 and M6C chromium carbides, (V, Ta, Ti, Zr and other) steel component carbides and carbonitrides and Fe2 (W)-type intermetallides. The lower area structure ensures a high low-temperature radiation embrittlement resistance and consists of a sorbite, alpha -ferrite, delta -ferrite, retained austenite, (Cr, V, Ta, W and other) steel component carbides and carbonitrides, wherein grain high-angle boundaries are filled with M23C6 and M6C carbides, the sorbite and delta -ferrite grains are provided with separate precipitates of the VC, V(CN), Ti(CN) and Ta(CN) carbides and carbonitrides, the remaining (Fe, Mn, Mo, W, Si and other) elements being part of the complex M23C6 and M6C carbides or of a FeCr solid solution.