A new method for the localisation of gas leaker fuel subassemblies in fast breeder reactors

摘要

In Fast Breeder Test Reactor, increase in reactor vessel cover gas (RVCG) activity was detected during reactor operation. However, delayed neutron detection system did not show increase in reading above background. Gamma spectrometric analyses of RVCG sample confirmed the presence of gas leaker fuel subassembly (GLFSA). Detection of Xe-133m, Xe-135m and Kr-85 in RVCG are indicators for a fuel clad failure and the specific activity of Xe-133 is observed to be three orders higher compared to baseline data. Reactor was operated after shuffling the suspected FSAs and RVCG samples were analysed to confirm the removal of GLFSA. Detection of Xe-133, Xe-138 and Xe-135m in the RVCG samples during short duration operation is an indicator for the presence of GLFSA in core. Comparison of specific activity of Xe-133, Xe-138, Xe-135m and Kr-87 with baseline data facilitates the localisation of the GLFSA in the absence of delayed neutron detection counts. (C) 2019 Elsevier Ltd. All rights reserved.