'In practice, a “small” reactor brings all the big problems of a conventional reactor: dangerous radioactive fuel, complex safety systems, and the risk of catastrophic failure or sabotage. The only thing that’s truly small about SMRs is their inability to benefit from the economies of scale that, in theory, were supposed to make large reactors affordable — but never actually did.' - https://www.climateandcapitalmedia.com/the-nuclear-mirage-why-small-modular-reactors-wont-save-nuclear-power/
The nuclear mirage: why small modular reactors won’t save nuclear power

Don’t believe the hype, says a 50-year industry veteran

Climate and Capital Media
@bert_hubert Best argument against is that multiple navies have made small modular reactors, none of them are cheap. The US navy for instance, went hard for an all nuclear fleet, but gave up and now only do their carriers and subs. And this even though they don't need to budget anything for security, they already have armed soldiers anyway. And they can get the fuel for free as surplus weapons stock.
@trademark @bert_hubert Also, the enrichment levels of their fuel puts those designs out of reach for civilian use, because of proliferation risks. A compact reactor for low-levels of enrichment levels is much harder because of that.
@kastope @trademark @bert_hubert If anything, thoriusm is less fissible than uranium and comes with other technical risks. But look at Copenhagen Atomics, they are betting on a thorium SMR. Am wishing them luck.
@whvholst @kastope @bert_hubert Thorium can't be used by itself, you need at neutron source to breed it to U233 first. Then it becomes a high proliferation risk, since it is a simple chemical reaction to extract the uranium. E.g. Carlo Rubbia's design solves this by using an accelerator and pre-mixing the Thorium with U238 so you need isotopic separation. Which will certainly work, but I don't think it will be economical.
@whvholst @kastope @bert_hubert Mixing with U238 is purely added cost and makes the system less efficient, so there's a strong incentive to cheat and just drop that step.
@trademark @kastope @bert_hubert There are alternative neutron sources, like fusors. But it does not look like anyone is going down that route.