Development of failed fuel detection and location technique using resonance ionization mass spectrometry

Rapid detection of fuel failures as well as failed fuel location are quite important for safety in fast reactor operation. As one of the failed fuel d etection and location (FFDL) techniques, a tagging method has been adopted, where a tag Gas with different isotopic abundance of krypton (Kr) and xeno n (Xe) is loaded into each fuel pin, and analyzed when leaked into cover ga s with fuel failure. On the other hand, with recent improvement of laser pe rformance, resonance ionization mass spectrometry (RIMS), which can detect specific atoms with high sensitivity and elemental selectivity, has been pr acticable in engineering application. We propose a new FFDL technique for fast reactor safety instrumentation bas ed on monitoring of a very small amount of the Kr/Xe tag gas leaked into th e cover gas by RIMS. Here are discussed the basic performance necessary to the design of RIMS-FFDL such as the detection limit and the elemental selec tivity of Kr and Xe through basic experiments and numerical analyses. The a pplicability of the RIMS system to FFDL for fast reactors is also demonstra ted through the detection and isotopic analysis of ppb level Kr/Xe tag gas in the cover gas sampled from the fast experimental reactor "JOYO".