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。

youdao

The pools, which sit atop the reactor buildings and are meant to keep spent fuel submerged in water, have lost their cooling systems.

乏燃料池位于反应堆建筑的顶部，它们本应浸泡在冷却水中，但是它们的冷却系统已经损坏。

youdao

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。

youdao

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

As of 14:00 local time (05:00 GMT) on Friday, the temperature of water inside the cooling pool at reactor 3 was 15.1C, well below the safety limit of 65C, Tepco said.

BBC: Fukushima nuclear plant: Cooling system power restored

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

WSJ: New Leak at Japan Reactor Threatens Ocean