S has located a chapter in Japan's history that is surprising. That Japan developed and utilised "dual-use" nuclear reactor propulsion to power the ship Mutsu in the 1970s to 1992.
In Comments in mid June 2016 S identified Japan’s one public example of a nuclear propulsion for a ship.
But Mutsu had a second life - after its reactor was removed in 1995 it was renamed the (non-nuclear) Mirai.
Next week S and Pete will complete Japanese Nuclear Propulsion 2 - further down the technological track towards a Japanese submarine reactor capability.
S and Pete