ナトリウム冷却大型炉に適合する破損燃料位置検出器の開発

Development of failed fuel detection and location system in sodium-cooled large reactor

相澤 康介 ; 大嶋 淳*; 上出 英樹 ; 笠原 直人

Aizawa, Kosuke; Oshima, Jun*; Kamide, Hideki; Kasahara, Naoto

スリット付き炉上部機構を有するナトリウム冷却大型炉に適合する破損燃料位置検出器を開発するため、炉心上部機構を模擬した水流動試験及び濃度評価解析を実施し、スリット部に位置する燃料集合体に対するサンプリング手法の成立性を評価した。

JSFR adopts a Selector-valve method for the failed fuel detection and location (FFDL) system. A Selector-valve FFDL system identifies the failed fuel subassembly by sampling outlet sodium of each fuel subassembly. One of the JSFR design features is an upper internal structure (UIS) with a radial slit, in which an arm of fuel handling machine can move and access the fuel assemblies under the UIS. This UIS can simplify a fuel handling system, and can downscale the reactor vessel diameter. Thus, JSFR cannot place the sampling ports right above the fuel subassemblies located under the slit. So, it is necessary that the sampling ports will be set around the UIS slit so as to catch the sodium flow from the fuel subassemblies located under the slit. To demonstrate sampling performance of under-slit subassemblies, water experiments and numerical analyses have been conducted.