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What safety problems can occur if molten metal leaks from a liquid-metal-cooled reactor?

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nuclear engineering Installation of the dome of a containment structure at the Taishan nuclear power plant, Guangdong province, southern China, 2012.

In liquid-metal-cooled reactors (LMRs), the primary safety concern regarding a coolant leak involves the chemical reactivity of the coolant, most commonly sodium.

If molten sodium leaks from the system, it poses a significant hazard because it reacts exothermically with air and water. These reactions release large amounts of heat, which can exacerbate the thermal stress on the reactor beyond the decay heat already present in the core.1

Specific risks include:
* Fire: Liquid sodium is highly reactive in air and can ignite at temperatures as low as 125 °C (257 °F). Once ignited, the fire can reach temperatures exceeding 800 °C (1,500 °F) and is notoriously difficult to extinguish, requiring specialized dry-powder agents rather than standard fire extinguishers.2
* Explosive Hazards: While sodium-water reactions generally do not produce the shock waves associated with high explosives, they are highly exothermic and generate hydrogen gas, which presents a significant explosion risk.2

Because of these chemical risks, maintaining the integrity of the coolant system is a critical safety priority in LMR design.1