[hunter-2]

I'm no expert on the subject, but do you think the plutonium being buried under several tons of ice could cause it to explode?

[manwe150]

My layman’s understand is you need a neutron trigger to destabilize it rapidly, as well as a shell to contain it to get a stable chain reaction going. I think you typically need to be at the center of a an exploding star to see that happen just from pressure.

[AareyBaba]

"Radioisotope thermoelectric generator" is what you want to understand. There are plenty of youtube videos on this topic.