日本地震毁坏的核反应堆麻烦增加

An explosion blew the roof and outer walls off of the number 3 unit Monday at the Fukushima nuclear power plant in earthquake-stricken northern Japan.

A similar explosion struck the number 1 unit on Saturday at the plant, where cooling systems were knocked out by Friday's devastating earthquake and tsunami. Officials said the inner containment vessel remained intact after Monday's explosion and they did not believe there had been a major release of radiation.

However engineers were still struggling to gain control of a new threat at the number 2 unit, where officials reported a total failure of the cooling system. The operators of the plant, Tokyo Electric Power Company, said the coolant had evaporated exposing the fuel rods, raising the risk of them melting down.

If the heat from a meltdown ruptures the containment vessel, that could permit a major release of radiation with serious health consequences. Engineers were desperately pumping sea water into all three units at Fukushima in an effort to cool them down.

Engineers have also vented steam from the plants to release a build-up of pressure. Hydrogen in the steam is believed to have mixed with oxygen, causing the two explosions.

Almost 200,000 people have already been evacuated from areas around Fukushima and other troubled nuclear power stations. About 600 people still in homes near the Fukushima plant were advised to remain indoors.

The commander of the aircraft carrier USS Ronald Reagan, which has been assisting in relief efforts from about 160 kilometers offshore, said the American fleet had moved away from the Fukushima plant after low levels of radiation were detected on 17 crewmen. He said the radiation was easily washed off.

The nuclear crisis has diverted attention away from a massive rescue and relief effort. The total death toll from the quake and tsunami is expected to reach more than 10,000. 

日本北部遭受地震的福岛核电站星期一发生爆炸，炸毁了3号机组的外墙和屋顶。

这个核电站的1号机组星期六发生了类似的爆炸。星期五毁灭性的地震和海啸导致这个核电站的冷却系统失灵。官员们说，星期一的爆炸发生后，1号反应堆内部安全罩仍完好无损。他们相信没有释放出大量的辐射。

但是，工程师们仍在努力控制2号反应堆面临的新威胁。那里的官员们报告说冷却系统已经完全失灵。这个核电站的运营商东京电力公司表示，冷却剂已经挥发，导致燃料棒暴露在外，增加了燃料棒熔化的危险。

如果溶化时产生的热量使安全罩出现破裂，可能会导致一次严重危害人体健康的重大辐射。工程师们正竭力地向福岛核电站的3个反应堆注入海水，努力使它们降温。

工程师们还排放了核电站产生的蒸汽，以释放积聚的压力。据信，蒸汽中的氢气混合了氧气，导致了这两次爆炸。

将近20万人已经从福岛核电站以及其它被毁坏的核电站周围地区撤离。仍住在福岛核电站附近的大约600人被劝告呆在户内。

从距离海岸约160公里的海域前来救灾的美国“里根号”航空母舰的舰长说，在17名船员身上发现了低水平的放射性辐射后，这个美国舰队已经驶离福岛核电站。他表示，这种放射性辐射很容易就能冲洗掉。

这次核危机分散了人们对大规模救援和救灾工作的注意力。地震和海啸造成的总死亡人数预计将超过一万人。