The fallacy here is that any reactor that you initiate for planning even immediately at this very moment will come years or decades too late to affect our power composition and keep us under 1.5°C, which means that such projects distract society from the importance of green/renewable energy solutions like wind or solar, which we CAN expand very quickly and which WILL have a measurable effect on mitigating the effects of climate change. Solar and wind are the only things that can replace fossil in time.