[10p-N301-1~8] Decommissioning of Fukushima Dai-ichi Nuclear Reactors, and Fukushima's Rehabilitation -What and How We Can Contribute as JSAP Specialists?-

[10p-N301-7] Search of Red-emitting Oxide Scintillator Crystal for Dose Monitor under High-Dose Rate and its Optical Properties

〇(PC)Satoshi Ishizawa¹, Shunsuke Kurosawa^1,2, Yutaro Kurashima¹, Akihiro Yamaji^1,2, Shiori Ishikawa^1,2,3, Chihaya Fujiwara¹, Akira Yoshikawa^1,2,3, Hiroki Tanaka⁴ (1.IMR, Tohoku Univ., 2.NICHe, Tohoku Univ, 3.C&A Corporation, 4.Kyoto Univ)

Keywords:Red-emitting Oxide Scintillator, Decommissioning Nuclear Power Plant, optical property

Decommissioning of the Nuclear Power Plant should be operated with safety, and the distribution of high-dose radioactive debris (more than 10 Sv/h) in the reactor must be revealed. To estimate such high dose rate, a real-time remote radiation monitoring system has been proposed with scintillator and long silica optical fiber by a Japan Atomic Energy Agency research group. A scintillator with an emission wavelength in the range of 700-1100 nm and no hygroscopic nature was required in order to realize a dose monitor under high-dose rate.
Yb-doped La₂Hf₂O₇ (Yb:LHO) was grown by Core Heating (CH) Method as a red-emitting oxide scintillator with no hygroscopic nature. The optical properties for Yb:LHO were investigated, comparing with Cr:α-Al₂O₃ (ruby) as a typical red-emitting scintillator and Cs₂HfI₆ (CHI) . The results establish that Yb:LHO is a better red-emitting scintillator for the decommissioning than ruby and CHI from a point of signal to noise ratio.