it's 35% of the fission energy released by totally fissioning 1g of U-235!
i.e. I don't know whether this it's feasible to just have a heavy water & lead shield, as 0.1g is fairly optimistic to be the heaviest particle hitting you. Already at this size we're in range of tactical nuclear weapons.
https://www.wolframalpha.com/input/?i=1%2F2+*+10%5E-4kg+*+(0...
it's 35% of the fission energy released by totally fissioning 1g of U-235!
i.e. I don't know whether this it's feasible to just have a heavy water & lead shield, as 0.1g is fairly optimistic to be the heaviest particle hitting you. Already at this size we're in range of tactical nuclear weapons.