Uranium vs Thorium -- past decisions
I recall reading an argument to the effect that the Uranium fuel source was favoured in the 60's and 70's because it was believed to be impractical to develop a thorium-based ballistic missile submarine. The 'boomer' was an important development as a strategic weapon because of it's stabilizing effect on the arms race. Nuclear deterrence was assured because neither side could win by launching a first strike. There would always be a boomer or two surviving a first strike and this would ensure the destruction of the instigator.
There was an adequate supply of Uranium for bomb-making and I have been told that there are better ways of making weapons-grade Plutonium than harvesting it from power stations. The vast number of weapons maintained during the cold war included large numbers of obsolete weapons that were retained only for their use in arms-reduction talks. This is supported by the very small number of weapons (less than 300) now held in European NATO countries by the United States.
