Modification of STACY for the study of criticality characteristics of fuel debris, 20; Pre-service inspections for the core using debris structural material rods

Kamikawa, Yutaka; Arakaki, Yu; Yoshikawa, Tomoki ; Hasegawa, Kenta; Aizawa, Eiju; Seki, Masakazu; Ishii, Junichi; Araki, Shohei   ; Izawa, Kazuhiko ; Gunji, Satoshi  

JAEA resumed Static Experiment Critical Facility (STACY) operation in August 2024 after the renewal of the core to a light-water moderated heterogeneous critical assembly for the criticality experiments to clarify the criticality characteristics of the fuel debris. JAEA is currently proceeding the test operation along with pre-service inspections of the core loaded with debris structural material rods to study the nuclear characteristics of the fuel debris. In addition, for experiments simulating the properties of fuel debris, assuming the mixture of core internals and fuels, JAEA manufactures Stainless steel rods (debris structural material rods (iron)), Aluminum alloy rods which are filled with concrete pellets (debris structural material rods (concrete)), which are processed into the same shape as the fuel rods, Refillable fuel rods which have cylindrical shapes, made of zirconium alloy with a detachable end stopper, and Loading tubes which are made of aluminum alloy or zirconium alloy. In this presentation, we report on the fabrication of the experimental loadings such as debris structural material rods and the status of the pre-service inspections.