The Mysterious Explosion of a Russian Nuclear Missile Engine
However, the jump in radioactivity in the air near the blast site reduces the likelihood that the nuclear reactor installed in the Burevestnik missile is fueled with enriched uranium, or even highly enriched. It is therefore reasonable to conjecture that the nuclear fuel of the reactor is plutonium-239, which, in addition to being toxic, is radioactive. It is also more suitable for refueling a miniature reactor because its critical mass is five times lower than that of uranium-235, which makes it possible to reduce the reactor’s dimensions.
Moreover, it is possible that the plutonium fuel in the reactor was not metallic but in a saline state, which would further reduce the amount of plutonium needed to fuel it. This hypothesis might explain Rosatom’s reference to “an isotopic source of energy for a liquid-fueled rocket engine.” Rosatom conducts many activities related to the development of molten salt reactors (MSR). These are nuclear fission reactors in which the primary reactor coolant and/or nuclear fuel is a molten salt mixture, and they use plutonium-239 as fuel.
The August 8 rocket engine explosion appears to have been caused by a rapid jump in reactor criticality beyond the permitted level. Nuclear missiles use a liquid-fueled booster rocket to accelerate to a speed that will enable their reactors to operate. There is thus a high probability of failure during the launch phase due to an obstacle hindering synchronization between the rocket’s acceleration and the nuclear reactor system, or – either alternatively or in addition – a failure of the reactor’s criticality control system.
via besacenter The Mysterious Explosion of a Russian Nuclear Missile Engine
What could be worse than dumping liquid plutonium into the ocean and into the air? Nothing!