もんじゅ廃止措置第2段階の状況,2; ナトリウムリスクの低減に向けた取り組みと保全の合理化

Status of Monju decommissioning Phase 2, 2; Efforts to reduce sodium risk and rationalize conservation

福島 翼; 大野 史靖; 倉本 新平; 西野 友貴; 西野 一; 内橋 昌也

Fukushima, Tsubasa; Ono, Fumiyasu; Kuramoto, Shimpei; Nishino, Yuki; Nishino, Hajime; Uchihashi, Masaya

「もんじゅ」はナトリウムを用い炉心を冷却する原子炉施設である。廃止措置のリスク低減のため、漏えいの恐れのある液体ナトリウムの保有範囲を縮小すべく冷却系配管内の液体ナトリウムを全てタンクへ移送・固化した。本件は初めての試みであったため、関連設備への影響評価、専用手順書の策定及び種々の運用変更等の課題に対処するとともに、液体ナトリウムの保有範囲縮小に伴う設備保全の合理化を図り、その成果を纏めた。

"Monju" is a nuclear reactor facility that uses sodium to cool the reactor core. In order to reduce the risk of decommissioning, all liquid sodium in the cooling system piping was transferred to the tank and solidified in order to reduce the range of liquid sodium that may leak. Since this was the first attempt of this project, we dealt with issues such as the assessment of the impact on related equipment, the formulation of dedicated procedure manuals, and various operational changes, and streamlined equipment maintenance due to the reduction of the range of liquid sodium ownership, and summarized the results.