Aircraft carrier nuclear power is a funny one because they have been built for many years but never once used as a commercial source of electricity, I wonder why that is?

Actually the whole SMR thing is kind of funny. In the last ten fifteen years France and Finland as well as the UK have been building much larger next generation plants, and suffering huge cost overruns and delays (thinks tens of billions and decades late in France and Finland). The nuclear industry wanted everyone to believe these huge complicated plants were the answer to making nuclear cost competitive in the future by getting economies of scale, stranglely that never worked out ... so now the nuclear industry wants us to think the exact opposite - much smaller and easier to build plants are the future of making nuclear competitive. Obviously this is a joke, the fact that after maybe 50 years of fission power, the industry has not figured out whether bigger or smaller plants offer better value for money just points to the industry basically just being a massive graft which will never be economically competitive. The simple answer is that if they offered value for money people would build them but it's wind, solar and batteries that are actually being built at scale.