So... I reorganized my turbine setup and moved half of them above the reactors, also opened up more ways for the steam to enter the system, which is already seemingly solved the problem, and fixed the production on 480MW. After that, I redid how the water enters the system too, just to be on the ...

I have some trouble with my nuclear setup. I've built a 4 reactor setup, checked the ratios here on the wiki and on YouTube 4 reactors, 48 heat exchangers, 83 turbines, 6 water pumps. I have plenty of fuel, its produces around 480MW as it should be. But time to time it dips down under satisfaction ...