福島第一原子力発電所14号機使用済燃料プールの水環境履歴に関する調査

Temperature and chemical history for spent fuel pools in Fukushima Dai-ichi Nuclear Power Station; Units 1 through 4

井上 賢紀 ; 浅賀 健男

Inoue, Masaki; Asaka, Takeo

福島第一原子力発電所廃止措置における直近の最重要課題の一つに、14号機の使用済燃料プール保管燃料集合体の共用プールへの移送がある。使用済燃料プールは事故によって冷却機能と補給水機能を失い、応急処置的に注入された淡水や海水、水素爆発によって混入した瓦礫等により、保管燃料集合体は熱的にも化学的にも厳しい水環境に曝された。そこで、保管燃料集合体の共用プール移送後における長期健全性評価に必要な腐食試験計画検討に資するため、14号機の使用済燃料プールにおける事故事象の時系列を水環境に着目して調査した。

Integrity of fuel assemblies (FAs) stored in the spent fuel pools (SFPs) of Fukushima Dai-ichi Nuclear Power Station (units 1 through 4) is one of the most important issues to transport the FAs to the common pool for long term storage. The SFPs had lost their functions of decay heat removal and water supply due to the station blackout. Since fresh and sea waters were injected into and concrete fragments by hydrogen explosions fell into the SFPs, the FAs have been exposed to much more corrosive environments than usual ones. In this report, many events during the accidents were investigated from a view point of temperature and chemical constituents in the SFPs in order to evaluate integrity for fuel assemblies during long term storage in the common pool by means of corrosion tests.