Two worst-case scenarios
两种最坏的情况

If engineers are unable to cool a damaged fuel core, enriched uranium can melt into a pool of radioactive lava. The meltdown can burn its way out of the containment vessel or send radioactive steam out through cracks in the system.
如果工程师们无法成功冷却受损燃料核心，浓缩铀会像一滩具有放射性的熔岩，烧穿安全壳，或者让具有放射性的水蒸气从系统裂缝流入外界。

Cooling the spent fuel is critical, for if it becomes exposed, a zirconium fire can break out and spew massive amounts of radiation.
冷却用过的核燃料至关重要，因为一旦它暴露在外，就可能引发锆火灾，从而排放出大量放射物质。

According to nuclear analyst Kenneth D. Bergeron, the containment vessels at Daiichi are stronger than Chernobyl but not as robust as Three Mile Island.
据核分析师Kenneth D. Bergeron所言，日本福岛第一核电站的安全壳的结实程度比切尔诺贝利的好，却没三里岛的好。

关于切尔诺贝利、三里岛以及这次福岛的核泄漏事故对比，来引用微博网友“功夫猫”的一句经典总结：

举个例子来说，切尔诺贝利那是坐便器和厕所都炸了，溅人一身；三里岛那个是下水道里面冒个泡，厕所里面一股臭气，但是没跑到厕所外面；福岛这个是厕所里面不断冒泡硫化氢太多炸了，臭气大量外溢，但是屎还没出来。。。