【摘要】 1999年 9月 3 0日 1 0 :3 5日本核燃料处理公司 ( JCO)的 3名工作人员在将约 1 6.6kg浓缩铀溶液直接倒入沉淀池内时引发临界事故。事故的核裂变总数为 2 .5× 1 0 1 8,释放出大量中子和 γ辐射 ,3名当事人都受到严重中子和 γ照射 ,表现出厌食、恶心、呕吐、腹泻等典型的急性辐射综合症。当天 1 5:0 0东海地方当局实施半径 3 50 m范围内 2 0 0人避迁撤离措施 ,1 0月 1日 6:0 0链式反应终止 ,1 0月 2日 1 8:3 0日本政府宣布解除对该地区的警戒。事故发生后日本有关部门和机构对事故处理、事故分析、应急监测、事故影响评价、公众沟通等方面做了大量工作。这次事故在国际核事故分级表上列为 4级 ,场外无明显放射性污染 ,临近公众受到轻微照射。本文介绍 JCO临界事故的事故序列、事故响应、事故监测和剂量估算。更多还原

【Abstract】 Criticality accident was caused at a Japan nuclear fuel processing plant JCO,Tokai mura,when three workers were pouring 16.6 kg concentrated uranium solution into precipitation tank at 10:35 on September 30th,1999.They were severely exposed to neutron and gamma radiation and developed acute radiation syndrome:nausea,vomiting and diarrhea.The Tokai village authority issued an evacuation advisory at 15:00 to 200 people living within a 350 meter radius of the plant.The criticality reaction was stopped at 6:00,October 1st.It was 18:30 on October 2nd that the Japan government announced that its order cordoning off the area was lifted.Many organizations were involved in the JCO criticality accident processing,accident analysis,emergency radiation monitoring,environmental and health effect evaluation and public communication.The number of total fission events were 2.5×10 18 ,and the accident is rated 4 on the international scale of 0 to 7 issued by the International Atomic Energy Agency.The aim of this paper is to report the JCO accident sequence,emergency radiological monitoring and dose determination.更多还原