> a result of extremely inefficient solid fuel reactors cooled by water
, a design which was chosen over thorium reactor designs because thorium reactors do not produce any significant amount of "waste" plutonium required for nuclear weapons production.
Fixed that incomplete thought for you.
That is not accurate. Thorium breeder reactors produce weapons-grade U-233. And a reactor designed to use liquid fuel with on-site reprocessing can very easily extract this weapons grade material. It is even easier to do so than a U-238 breeder reactor cause you don't have to worry about burnup requirements limiting Pu-240 production.
The reason why we went with UO2 based reactors instead of thorium ones is simply because that is where our knowledge base stemmed from. UO2 worked and thorium didn't offer any significant advantage worth starting over from scratch on.