Feasibility study of PGAA for boride identification in simulated melted core materials

Tsuchikawa, Yusuke ; Abe, Yuta  ; Oishi, Yuji*; Kai, Tetsuya   ; Toh, Yosuke   ; Segawa, Mariko   ; Maeda, Makoto  ; Kimura, Atsushi   ; Nakamura, Shoji  ; Harada, Masahide   ; Oikawa, Kenichi   ; Matsumoto, Yoshihiro*; Parker, J. D.*; Shinohara, Takenao   ; Nagae, Yuji ; Sato, Ikken 

In the decommissioning of the Fukushima-Daiichi (1F) Nuclear Power Plant, it is essential to understand characteristics of the melted core materials. The estimation of boride in the real debris is of great importance to develop safe debris removal plans. Hence, it is required to investigate the amount of boron in the melted core materials with nondestructive methods. Prompt gamma-ray activation analysis (PGAA) is one of the useful techniques to determine the amount of borides by means of the 478 keV prompt gamma-ray from neutron absorption reaction of boron. Moreover, it is well known that the width of the 478 keV gamma-ray peak is typically broadened due to the Doppler effect. The degree of the broadening is affected by coexisting materials, and can be recognized by the width of the prompt gamma-ray peak. As a feasibility study, the prompt gamma-ray from boride samples were measured using the ANNRI, NOBORU, and RADEN beamlines at the Materials and Life Science Experimental Facility (MLF) of Japan Proton Accelerator Complex (J-PARC).