Enhancement of reactor coolant leakage measurement using radiation instrumentation

The detection of reactor coolant system (RCS) leakage inside containment with sampling radiation monitors located outside containment is reviewed. The target for the radiation monitor response is the clear indication of a one gpm increase in RCS leakage within one hour. The limitations of present methods using beta sensitive detectors are discussed. The limitations are often due to the detection of interfering radioactive materials not related to RCS leakage. Modeling of radioactive material buildup from leakage is used to predict the response of gamma sensitive detectors operated in spectral modes. This would allow isolating isotopes responsive from leak detection considerations from isotopes unresponsive and from isotopes unrelated to RCS leakage.