Monitoring Fission Gas in EBR-II by High-Resolution Gamma Spectrometry

High-resolution gamma spectrometry is routinely performed for fission product gases in Experimental Breeder Reactor II as a means of detecting and identifying fuel elements with leaks in the cladding. Detailed data accumulated for more than two years of operation has established background concentrations as well as the behavior of these fission products from eight different fuel elements. Different types of fuel have different “fingerprints.” It appears quite easy to distinguish a carbide leaker from either metal or oxide. The distinction between oxide and metal is less clear cut, but our results indicate that identification can be made with some confidence on the magnitude of the signal and on isotopic ratios, particularly the ratio ⁸⁸Kr/¹³⁸Xe. Further analysis has been made of the ²³Ne activation rate, which is expected to be much higher and far more troublesome in future sodium-cooled fast reactors.