Experimental and analytical study of failed fuel detection and location system in JSFR

JSFRに適合する破損燃料位置検出器の試験・解析研究

相澤 康介 ; 大嶋 淳*; 上出 英樹 ; 笠原 直人

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

本検討では、スリット付き炉心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 mechanism for the failed fuel detection and location (FFDL) system. The Selector-Valve FFDL system identifies failed fuel subassemblies by sampling sodium from each fuel subassembly outlet and detecting fission product or delayed neutron. One of the JSFR design features is employing 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. Thus, JSFR cannot place sampling nozzles right above the fuel subassemblies located under the slit. To overcome above diffculties, we have developed the sampling method for indentifying the failed fuel subassemblies located under the slit by numerical simulations and water experiments.