In-reactor and post-reactor studies on the foundations of performance of the cluster-type absorber assemblies in WWER-type reactors. 3

In connection with the Soviet WWER 1000 type reactor post-irradiation studies have been performed on samples of Soviet made absorber rods which had been irradiated in the WWER-2 reactor of the Rheinsberg nuclear power plant. The following absorber systems have been studied: (1) boron carbide in the form of both pellets and powder compacted in the cladding; (2) dysprosium titanate and a concentrate of various rare earth element titanates; (3) nickel base alloy containing fractions of samarium, indium and hafnium; (4) europium oxide with aluminium. The alloy 00X20H40B was used as canning material. The studies on size and mass density, hardness, mechanical strength and elongation as well as metallographic and X-ray examinations did not reveal any critical irradiation effects on the absorber and canning materials at neutron fluences of 1020 up to 1021 n/cm2. (author)