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NASA wants a nuclear reactor on the Moon. What would happen during a meltdown?

With NASA announcing plans to build a nuclear reactor on the Moon, what would happen if a meltdown strikes?

Hayley Bennett, BBC Science Focus, February 7, 2026 

NASA has announced plans to build a nuclear reactor on the Moon – a milestone that could power future lunar bases and long-term missions. But it also raises some big questions.

How much will it cost? Will someone need to stay up there to operate it? And, for the doom-mongers among us, what happens if it fails?……………………………………………………………………

its demise is a fascinating hypothetical.

What if it blew up?

We’ve really no idea what a nuclear meltdown on the Moon would look like – and, with current plans, there’s no indication it would even be big enough to be considered a meltdown.

But we can speculate, of course. It’s not just the size of the reactor that determines what happens if it blows – it’s the environment.

A reactor accident on the Moon would unfold very differently to one on Earth.

As the Moon has no atmosphere, no weather and one-sixth of Earth’s gravity, we might expect that instead of the explosion, mushroom cloud and aftershock (triggered by reactions with molecules in the Earth’s atmosphere) it would be something somewhat less dramatic. 

Instead, the reactor might simply overheat, perhaps producing an initial flash, then a glowing pool of molten metal that cools and solidifies in silence.

That’s not to say that such an event wouldn’t be dangerous for anyone manning the station. They would still be exposed to a strong surge in radiation.

That radiation would still be dangerous nearby, but without air or wind to carry radioactive dust, fallout would remain largely local.

A near miss

Thankfully, we don’t have a better answer to the question, though we might have done if certain US scientists had got their way back in the 1950s.

Project A119 was a secret plan to drop a hydrogen bomb on the Moon as part of the escalating ‘space race’ between the US and the Soviet Union.

Fortunately, it never really got beyond the planning stage. https://www.sciencefocus.com/space/moon-nuclear-reactor-meltdown

February 13, 2026 - Posted by Christina Macpherson | space travel