Chernobyl Disaster Learning Path

Decay heat and need for continued cooling

After a nuclear reactor shuts down, it continues to generate heat due to radioactive decay of fission products. This decay heat can damage fuel cladding if coolant flow is not maintained for a considerable time, potentially leading to core overheating and, in the worst case, full core meltdown. In the Chernobyl context, the disaster sequence occurred during a test meant to simulate reactor cooling under accident conditions. Because decay heat removal still requires continued coolant circulation, any loss or interruption of cooling—especially during power loss or system failures—creates a critical risk of overheating. The accident involved loss of coolant and subsequent overheating, showing why continued cooling after shutdown is essential even when fission has stopped.

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RBMK reactor design and coolant dependence

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