Tagging-gas failed fuel detection and location system for sodium-cooled large reactors

Aizawa, Kosuke ; Chikazawa, Yoshitaka  

Failed fuel detection for an advanced loop-type sodium-cooled fast reactor has been studied as a conceptual design study of Japan Sodium cooled Fast Reactor (JSFR). A present JSFR design adopts a Selector-Valve (SV) failed fuel detection and location (FFDL) system. In this study, a Tagging-gas (Tag) FFDL system has been investigated as an alternative. One of major issues of the Tag-FFDL is isotope ratio change of tagging gas due to irradiation. It is expected that the isotope ratio change due to irradiation becomes larger than conventional ones, since JSFR adopts high burnup fuel. To identify a failed fuel subassembly, proper isotope content for JSFR tagging gas has been investigated. Tag gas isotope change in the JSFR condition has been evaluated regarding transmutation and fission gas release. In addition, an allowable background concentration of natural Kr and Xe in the cover gas has been evaluated.