JCO臨界事故の終息作業と反省点

JCO Criticality Accident Termination Operation

金盛 正至

Kanamori, Masashi

平成11年9月30日10時35分頃、茨城県東海村にあるJCOにおいて臨界事故が発生した。本資料は平成13年12月17日の水戸地裁の証言等をもとに整理し,関係者のコメントを修正したものである。JCOでは臨界事故の発生を想定していなかったため、中性子測定機器がなく、臨界を終息させる器材もなかった。サイクル機構には国等から通報と派遣専門家の派遣の要請があった後、速やかに専門家を派遣した。事故対策上の課題が4点あり、これらの課題についてJCOサイト内で検討を行い、臨界事故を終息させることができた。これらの活動の過程で、種々の反省点があったので今後の対応のためにとりまとめた。

On September 30 at around 10:35 AM, criticality accident occurred at the JCO's conversion building in Tokai-mura. Since criticality accident had not been anticipated, neither devices for termination of criticality accident nor neutron detectors were available. Immediately after the information of the accident, our emergency staff (Japan Nuclear cycle development institute staff) went to JCO site, to measure the intensity of neutrons and gammas. There were four main tasks, first one was to measure the radiation intensity, second one was to terminate the criticality accident, third one is to alert the residents surrounding the JCO site, fourth one is to evacuate the employees in the site. These tasks were successfully performed until October 1. This paper describes about how these operations were performed by the relevant staff. And also pointed out related reviewed points for the futer.