シビアアクシデント時の原子炉内におけるセシウム分布・性状の予測,2; Cs化学吸着挙動の評価

Estimation of Cs distribution and characteristics in the reactor under severe accident, 2; Evaluation of Cs chemisorption behavior

中島 邦久  ; 鈴木 恵理子   ; 井元 純平 ; 三輪 周平  ; 逢坂 正彦  

Nakajima, Kunihisa; Suzuki, Eriko; Imoto, Jumpei; Miwa, Shuhei; Osaka, Masahiko

化学吸着生成物の一つであるCsFeOは、鉄の酸化状態によっては、463K程度でも生成することから、873Kよりも低い温度領域で化学吸着再現実験を行った。その結果、ラマン分光測定により673KでもCsFeOが生成することが確認され、Csの化学吸着は、気水分離器や蒸気乾燥器といった福島第一原子力発電所(1F)事故時比に較的温度が高かった圧力容器内の上部構造材領域だけでなく、格納容器鋼表面も含んだもっと広い領域で起きる可能性があることが分かった。

Since CsFeO, which is one of the chemisorption products, is formed even at about 463 K depending on the oxidation state of iron, simulation tests of Cs chemisorption were conducted in a temperature region lower than 873 K. As a result, it was confirmed by Raman spectroscopy that CsFeO was formed even at 673 K. Therefore, it was suggested that the Cs chemisorption could occur not only in the upper region of reactor pressure vessel, where the steam separator and the steam dryer were located and the temperature was relatively high at the Fukushima accident, but also in a wider area including the steel surface of the primary containment vessel.