noun
cold shutdown (nuclear reactor)
Technical term used in nuclear engineering and safety contexts. Refers to a state where the reactor coolant temperature is below the boiling point and the reactor is subcritical.
事故後、原子炉は冷温停止状態に達した。
After the accident, the reactor reached a cold shutdown state.
Compound of 冷温 (れいおん, 'cold temperature') and 停止 (ていし, 'stoppage'). A technical term likely coined in the nuclear industry.