However, there are some points you miss:
- There is a lot of space for smaller accidents which can happen, including nuclear fuel leaks. Belarusian Power Plant is very close to River Neris and, as far as I know, uses its water for cooling. River Neris goes through Lithuanian capital Vilnius and there is a great concern that accidents can contaminate the water.
- See my point in a post bellow about the nuclear power plants not being built equal, even if they use the same reactor technology.
- Both political systems produced nuclear disasters, but accidents above INES Level 5 only occurred in the Soviet Union; I am not including Fukushima, because its cause was a natural disaster: earthquake followed by tsunami (and their 1960s tech was still holding in the immediate aftermath). Poor quality standards, general attitude to safety, disregard to procedures, etc -- these are the common problems in such political systems like the Soviet one. Also, many of the accidents in the West occurred in 1950s when the nuclear technology was still in its early days. So, no, I don't draw the equality between different political systems in the context of nuclear safety, although perhaps it shouldn't be overestimated either.