In-reactor and post-reactor studies on the foundations of performance of the cluster-type absorber assemblies in WWER-type reactors. 2

Novel absorber assemblies of the cluster type have been tested in the Rheinsberg reactor WWER-2. In addition to results obtained from mechanical and physical tests, those of post-irradiation studies are given. The mechanical tests consisted in movement checks performed according to a given programme. The physical tests provided for measurements of both the differential and integral efficacy of the clusters and the axial distribution of the thermal neutron flux density close to the clusters. The post-irradiation studies in the Rheinsberg nuclear power plant included: visual inspection, check of cluster finger tightness, measurement of gas pressure, determination of gas composition and cladding diameter, and preparation of samples for further post-irradiation studies of the cladding and absorber materials. (author)