You flatter me.
This actually brings up my personal favorite potential PoD of all time: in the late '50s, Alvin Weinberg was offered a seat on the Atomic Energy Commission - that is, the five guys who are the actual Commission. Not the chairmanship, but who knows what that could lead to in years to come? IOTL, he turned it down because he wanted to remain as director of ORNL.
It's not a perfect PoD - a perfect PoD would prevent the Great Bandwagon Market in LWR's, which this probably won't - but it's the best I've got.
I've been doing some research for a paper and also for my timeline, and many authors point to Rickover having an undue influence on the course of nuclear power development. One even claims that Rickover had decided in favor of light water reactors as early as 1946. Even if he was only leaning that way or truly neutral, the problems with the S1G and S2G reactors and
Seawolf definitely didn't endear the Navy to alternative reactor technologies.
When the United States decided to start developing commercial nuclear reactors in the 1950s, the Navy aircraft carrier reactors were used as a starting point. In 1958 the European market apart from France and the United Kingdom opened up to American PWR technology through the EURATOM Cooperation Act. That preceded the Bandwagon Market in the United States, but certainly contributed to it, as many experts thought European gas cooled reactors were superior to American PWR designs. By the 1970s Canadian heavy water technology was the only alternative to American PWR designs, apart from those developed by the Soviets. General Atomics sold a few high temperature reactors prior to the 1973 Energy Crisis (I think they were gas cooled), but ironically they were canceled afterwards due to a decline in energy demand, despite concern over the use of fossil fuels.
One paper argues that a lock in was inevitable, and that PWR won out because of its early advantages, but it also argues that in the early development of a technology the decision to pursue technologies can be essentially random. A small advantage or advancement along the curve of a technology can lead to something that works better early in development beating out a technology that is superior at a later stage of development.
I think there might still have been a chance for an alternative design to have become popular for the second generation nuclear reactors onwards, but the United States made mistakes in the development of technologies and in forecasting resource demands. Specifically, sodium cooling was developed for too long after major questions were raised about cost and reliability, and breeder reactors turned out not to be required.
Having read into it more, I'm wondering if gas cooled designs might have been able to take the place of PWR in the early history of nuclear power (Chicago Pile 1 was itself graphite moderated, although not with a gas). It was essentially a toss-up between the two technologies in the 1950s, but gas cooled designs can potentially achieve thermal efficiencies of 40% to 50%. They can even use pressure chambers built out of concrete with stringers, allowing them to be built with less specialized industry while having a reduced probability of sudden catastrophic failure.
Heavy water reactors would have been another interesting route, although they don't have potential power densities as high as gas cooled designs. They were less expensive then PWR designs in the 1970s, although I think they had to undergo expensive repairs in the 1980s. I'm not that familiar with gas cooled reactors, but I know the heavy water designs produce significant quantities of plutonium, as well as tritium, critical for the construction of thermonuclear weapons. Perhaps the British could have taken advantage of the heavy water facilities in Canada and Europe for a heavy water reactor program?
That gets to molten salt reactors. They were projected to be cost competitive with PWR designs in the 1970s, after several test reactors had been built and operated without incident. One fluid designs were successfully operated, and a two fluid design would have been usable as a breeder reactor, if developed. MSR designs can do online refueling and chemical processing of their fuel to allow for long term operation, and there was even a design for a one-through MSR capable of operating for thirty years without refueling. The technology seems to have had promise for both conventional and breeder operation (it was also multi-fuel capable), and could have been part of the second generation of commercial reactors had it been pursued or even alongside of the breeder reactor design favored by the Atomic Energy Commission.
Essentially, I'm wondering if gas cooled reactors (perhaps with heavy water reactors as a niche, similar to today) and MSR reactors could have become an industry standard instead of the PWR, and what effect that might have had on nuclear power. Also, would a gas cooled design (or even a heavy water design) be useful for a nuclear powered warship?