短语词组短语melt -through 全部熔化Reactor Vessel Melt -Through 压力容器的熔融贯通core melt through 堆芯全熔化core melt through accident 堆芯全部溶化事故melt through accident 全部熔化事故through melt 通过熔融Gas blows through melt front 吹破 返回 melt through