Performance confirmation of MONJU failed fuel detection and location system, 1

Morohashi, Yuko ; Suzuki, Satoshi

The failed fuel detection and location (FFDL) system collects the tagging gas that migrates into the reactor cover gas from a failed pin. The tagging gas is made of stable isotopes of Kr and Xe. The isotopic composition of the tagging gas can be made specific to each assembly. The assembly containing a failed fuel pin can be identified by analyzing the isotopic composition. The FFDL system is comprised of two tagging gas concentration devices. The concentration rate is designed to be higher than 200. Past examinations demonstrated that the concentration rate meets the requirement with a noble gas concentration of 1ppm. However, the actual noble gas concentration emitted from a failed fuel is assumed to be much lower. In the present study, the performance of FFDL system was investigated by measuring low concentration gas of the actual fuel failure level. As a result, the concentration rate was confirmed to be more than tens of thousands, which sufficiently satisfies the design demand.