Just so you all know what happened: russia made a nuclear powered cruise missile using a stolen 50s american design using a fuel cycle invented by japs in the 80s, wherein molten sodium is passed through the reactor as a working fluid that operates the missile engine/turbine. This was a great design except for the fact that the molten sodium combusts explosively if it's exposed to oxygen, so any leak becomes a fatal one.

The accident was thus: missile launched and successfully ran for about 20 seconds before having a leak and partially exploding, falling into the ocean. Russians then went to recover it, without containing it in anything. As soon as the exposed fluid (not reactor) was raised to the surface and touched air, it exploded destroying the barge and killing the scientists. This also explains Russia's previous submarine accident wherein material from another (similar) missile test exploded when brought into the presence of the submarine's atmosphere, causing a catastrophic explosion.