So that is the emergency core cooling system for a pressurised water reactor.

所以，那是紧急核心冷却系统，对于一个加压水反应堆而言。

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But even after shutdown, there is residual heat that needs to be drawn off by cooling water pumped through the reactor core, and that’s where the trouble came.

但是即便终止之后，依旧有余热存在，需要冷却水泵抽水注入反应堆芯将热量散去，这也是问题所在。

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This, we now know, is what "well prepared" looks like: total loss of power at the Fukushima Daiichi nuclear reactor, which deprived the reactor core and spent-fuel pools of cooling water.

现在我们都知道，所谓“准备地最充分”就是这样：在福岛大一针核反应堆完全丧失电力供应，使核反应堆中心装置和核废料池冷却水中断供应。

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For example, the Westinghouse AP 1000 reactor places cooling water at a level above the reactor unlike the Fukushima design so that it would naturally flow down.

WSJ: Nuclear Industry Likely to Reassess Safety Systems

That came alongside news that the volume of the reactor's cooling water had declined sharply.

WSJ: New Leak at Japan Reactor Threatens Ocean

That thinking changed on March 28, 1979, when a small valve stuck open, cooling water escaped and the reactor core of TMI's Unit 2 began to melt.

CNN: Three Mile Island, 20 years later