Investigation on iodine release behavior during the operation of high temperature engineering test reactor (HTTR)

高温工学試験研究炉(HTTR)運転中におけるヨウ素放出挙動の研究

植田 祥平   ; 猪井 宏幸; 水谷 義隆; 大橋 弘史 ; 岩月 仁 ; 坂場 成昭 ; 沢 和弘

Ueta, Shohei; Inoi, Hiroyuki; Mizutani, Yoshitaka; Ohashi, Hirofumi; Iwatsuki, Jin; Sakaba, Nariaki; Sawa, Kazuhiro

核分裂生成物のヨウ素は甲状腺被ばく評価上極めて重要な核種であるが、その複雑な放出・沈着挙動に伴う測定・評価の困難さから、ヨウ素の事故時ソースタームが保守的に評価されていると考えられる。本研究では、実炉のHTTRを用いた原子炉出力急停止並びに一次冷却材喪失試験を通じて、ヨウ素の娘核種である一次冷却材中のキセノン核種を測定する方法でヨウ素の放出挙動を評価することを目的とした試験計画並びに予備解析の結果について述べる。

Japan Atomic Energy Agency (JAEA) has planned to investigate on iodine release behavior from fuel through the testing operation of High Temperature Engineering Test Reactor (HTTR) in order to contribute to the reasonable estimation of the radiation exposure necessary for the realization of HTGR in the future. In this test, the fractional release of iodine will be measured and evaluated by measuring xenon isotopes, the daughter nuclides of iodine isotopes, in the primary coolant sampling under the loss-of-forced cooling (LOFC) test by which the primary coolant circulator is shut down and/or the manual scram test of HTTR. In parallel, the local area of primary coolant circuit where iodine is plated-out will be evaluated. This paper describes the testing plan and the preliminary analytical study on the release behavior of iodine and xenon isotopes through the operation of HTTR.