nuclear cycle

例句：

1. 1. The nuclear power plant is undergoing a major upgrade.
   核电站正在进行一次重大升级。
2. 2.The nuclear cycle is crucial for the functioning of the reactor.
   核循环对于反应堆的运行至关重要。
3. 3. During the nuclear cycle, the reactor heats up and cools down.
   在核循环过程中，反应堆加热并冷却。