Things I'd like to look into more (and would love to hear any thoughts if you have insights): are there anti-proliferation reasons that mean Chinese companies don't have access to the same level of nuclear technology as USA / France? Are domestic investors less willing to invest in these sort of projects in China (e.g. since there is a major construction boom)? Are international investors less able to invest in these sort of long-range and potentially sensitive projects in China, due to capital controls or other reasons?
But I agree, if China can't affordably build a nuclear plant, then that would at least suggest that the regulatory component isn't enough to explain why it's not cost effective.
Cost is a huge issue for nuclear power. It could sort-of compete with coal, but not with cheaper modern sources. This is a bitter pill for nuclear proponents to swallow. It's easier to blame irrational environmentalists and their unnecessary regulations than to accept that a fetish technology is not actually economically viable.
And yet, China is dominated by coal, and not building much much new nuclear capacity, really. That suggests that something other than treehugger political problems are causing the slow adoption. Meanwhile, they're building massive new wind and solar projects. Without checking the numbers, I expect those projects outstrip their planned nuclear in total capacity.
But the real cost of nuclear isn't the cost of safety. It's the cost of capital. And capital is sensitive to risk. So large scale projects with 30-50 year payoff schedules, in the face of new technologies that are already cheaper and continue to drop in cost, and don't have the political/social resistance nuclear does... well, that factors in to the risk. A little risk adds a great deal to long term capital cost.