Ilkovych V. Development of Scientific and Technical Fundamentals of Additional Surveillance Program for VVER-1000 Reactors

The thesis is devoted to the development of scientific and technical fundamentals of additional surveillance program for VVER-1000 reactor based on modernization of one-floor container assemblies. Technique to determine optimal unloading terms of regular one-floor container assemblies for the modernization and the modernized container assemblies for tests of the irradiated surveillance specimens is developed. Dosimetry experiment for determination of neutron field characteristics at the places of surveillance specimen locations of the concrete reactor is developed. Orientation determination technique of pipes intended for container assemblies installation with respect to central axis of the reactor is developed and validated. Terms of realization start of additional surveillance programs for some Ukrainian NPP units with VVER-1000 reactors is estimated using pressure vessel and surveillance specimen dosimetry results. The detailed stage-by-stage plan of modernization of one-floor container assemblies is developed for unit 1 of South-Ukrainian NPP. According to this plan the one-floor container assembly 5L2 was modernized and loaded into reactor. At the same time realization of the dosimetry experiment was begun. Irradiation during one fuel cycle of three metrological container assemblies with extended sets of the neutron activation detectors is carrying out in this experiment.