The Three Mile Island Accident 美国三里岛事故.pptVIP

* Introduction Main reason Process Emergency measures Aftermath Influence Lessons learned The Three Mile Island accident was a partial nuclear meltdown which occurred in one of the two United States Three Mile Island nuclear reactors in Dauphin County, Pennsylvania, on March 28, 1979. It was the worst accident in U.S. commercial nuclear power plant history. The partial meltdown resulted in the release of small amounts of radioactive gases and radioactive iodine into the environment. Unit?2 (二号反应堆) The power plant was owned and operated by General Public Utilities and Metropolitan Edison (Met Ed). The reactor involved in the accident, Unit?2, was a pressurized water reactor manufactured by Babcock Wilcox. Consequences of stuck valve Human factors – confusion over valve status The design of the PORV(减压阀) indicator light was fundamentally flawed .And the operators had not been trained to use it. The operators did not correctly diagnose the problem Nuclear leak alarm did not attract the attention of operators 主水泵停转 辅助回路中 隔离阀门未打开 辅助水泵未正常开启 二号回路冷却水 蒸汽发生器 反应堆热量聚集 堆芯压力上升 稳压器减压阀开启 一号回路冷却水流出 堆芯温度过热 47%的堆芯和部分燃料元件烧毁 放射性物质泄漏 Schools were closed and residents were urged to stay indoors. pregnant women and pre-school age children were emergency evacuation. Farmers were told to keep their animals under cover and on stored feed Cleanup started in August 1979 and officially ended in December 1993, with a total cleanup cost of about $1 billion *