Ironically, another “poor choice” of candidate is the IAEA’s proposed Generation IV reactor the modular lead cooled fast reactor. This reactor is remarkably similar to the BM-40A used on the Soviet Alfa class submarines of the cold war. The Alfa class was one of the best submarines the soviets ever built, small, capable of going much deeper than any Western boat, highly manoeuvrable and blisteringly fast – so fast and manoeuvrable that they could actually out run and out turn a number of allied torpedoes of the era!
However, the US navy Admirals slept quietly in their beds over the Alfa as it has two drawbacks, they were noisy (thus easily tracked) and it got this performance from its Lead-cooled reactor. The Lead had to be kept heated at above 125 °C or the core froze solid. In practical terms this meant keeping the reactor running 24/7 which made maintenance a nightmare. Of 7 Alfa class boats, 4 had problems with their cores freezing solid, in one case while the boat was at sea! For most of the boats this meant decommissioning and after it happened to the final boat in service, K-123, it seems that even the Soviet navy ran out of patience with the Lead-cooled reactor as they cut it out of the sub and replaced it with a standard PWR type.
While the developers of the LCFR claim to have solved this “freezing” core problem, the experience of the Russian navy suggests that this is not the sort of reactor we want to be putting in the hands of amateurs. Also, as it relies on running on highly enriched uranium, there are a number of potential proliferation issues which means we don’t want to be handing them out willy nilly… not without them drawing terrorists to them like moths to a flame!