Analysis work report on removal of spent fuel sheared powder for decommissioning of main plant

Aoya, Juri; Mori, Amami; Sato, Hinata; Kono, Soma; Morokado, Shiori; Horigome, Kazushi; Goto, Yuichi; Yamamoto, Masahiko; Taguchi, Shigeo

JAEA-Technology 2023-008, 34 Pages, 2023/06

JAEA-Technology-2023-008.pdf:1.92MB

Flush-out, by which nuclear materials in the Tokai Reprocessing Plant process are recovered, has been started in June 2022 as the first step of decommissioning. Flush-out consists of removal of spent fuel sheared powder, plutonium solution, uranium solution, and the other nuclear materials. Removal of spent fuel sheared powder has been completed in September 2022. During removal of spent fuel sheared powder, uranium concentration, plutonium concentration, acid concentration, radioactivity concentration, and solution density have been analyzed for process control. For nuclear material accountancy, uranium concentration, plutonium concentration, isotope ratio, and solution density have been analyzed. Analysis work including sample pretreatment before transportation to IAEA analytical facility for safeguards, and the other operations related to Flush-out such as calibration of analytical instruments, education, and training of operators are reported.

Effect of the thermomechanical treatment conditions onto characteristics of chromium-zirconium copper after the solution treatment

Hada, Kazuhiko; Nishi, Hiroshi; Hirose, Takanori; Mori, Kensuke; Aoki, Shoji*; Wada, Masahiko*; Yamamichi, Tetsuo*

no journal, , 

Chromium-zirconium copper as precipitation hardened copper alloy is examined as one of the structural materials used for the ITER in vacuum vessel components. The process that consists of a thermomechanical treatments series of the solution treatment with rapid cooling to obtain the supersaturated solid solution and the aging treatment etc., is adopted in order to obtain the demanded high strength in manufacturing of this alloy material. However, as this alloy is precipitation hardened copper alloy, it is concerned that the great change in the strength characteristic is caused by the thermomechanical treatments conditions, especially the difference of the quenching cooling rate after the solution treatment in manufacturing. In this research, the influence of the quenching cooling rate condition after the solution treatment and the other conditions on this copper alloy was investigated by measuring the tensile test properties of the specimens that are prepared by treatments with some quenching cooling rate conditions after the solution treatment and aging treatment. One of the typical results from this study is that, for the quenching cooling rate after the solution treatment, it was understood that the cooling rate change from 1 to 10C/s causes the great growth in the tensile strength. Therefore, when this alloy component is manufactured by heat history process like HIP process and needed to be treated solution treatment to be use for the structural component, it is important to guarantee the strength of the product by checking the quenching cooling rate after the solution treatment.