Primary-to-secondary leak monitoring using information obtained from measurement of reference radionuclides in NPP water

Detection of heat-exchange equipment failures in the primary circuit is one of the problems to be solved by radiochemical monitoring during operation of nuclear power installations. A series of experimental and numerical studies were performed in a low-power installation with a water-cooled water-moderated reactor where sequential failure of heat exchangers in two reactor water cleanup and cooling units occurred and progressed. The mechanism of transport of radionuclide impurities from the primary to secondary circuits was determined, and data for different radionuclides were obtained to compare how valuable each radionuclide was as information source for leak detection and monitoring.