> It might be since it's so bad at penetrating anything solid This isn't the case! Plutonium 239 is relatively safe, merely an alpha emitter which is what you

> It might be since it's so bad at penetrating anything solid This isn't the case! Plutonium 239 is relatively safe, merely an alpha emitter which is what you're talking about. But that isn't where the danger comes from. The danger comes from the Plutonium 240, which is present as a contaminant in all plutonium weapons cores. Plutonium 240 spontaneously undergoes fission, releasing neutron radiation which is very penetrating. If you bring two halves of a core together, neutrons from the spontaneous fusion of Pu-240 can cause a chain reaction; this is the reason gun-type bombs don't work with Plutonium cores; they give off too much neutron radiation and would react prematurely if you tried to build a Plutonium bomb like that.