The risk of a reactor meltdown there is awful enough .

日本核反应堆熔毁的风险已经够可怕的了。

During that period it became clear that a partial meltdown had taken place in at least one of the six reactors .

在此期间，很明显，6个反应堆中至少有一个会部分溶解。

A catastrophic meltdown is a sombre possibility .

灾难性的反应堆熔毁是一个令人沮丧的可能性。

The united states hasn 't had a meltdown since at any of its more than 100 reactors .

自那以来，美国本土上的100多座反应堆没有出现过熔毁事故。

If the cores cannot be cooled sufficiently , a total meltdown could ensue , exposing the fuel rods to the outside air and further spreading radiation .

如果内核不能得到充分冷却，恐其随后将完全熔毁，从而使能源棒暴露在空气中导致辐射进一步扩散。