The containment structure surrounds the nuclear reactor.

安全壳包围着核反应堆。

The company has been sending robots inside the Unit 1 main containment structure since last year.

自去年以来，该公司一直派遣机器人在1号机组主安全壳内勘察。

The material piled as high as 40 to 50 centimeters from the bottom of the containment structure, Matsuo said.

松尾说，这些材料堆积在距离安全壳底部40到50厘米的地方。

Based on data collected from earlier studies, experts have said most of the melted fuel inside Unit 1 fell to the bottom of the main containment structure.

根据早期研究收集的数据，专家表示，1号机组内熔化的燃料大部分都落到了主安全壳的底部。