The passive systems? They all depend on large groups of people doing their job perfectly during the manufacturing and another group of people doing their jobs perfectly at maintaining these systems and not disabling them when inconvenient. I don't trust people doing everything right every single time.
The fission reaction is a kind of a reaction that can go out of control very fast spontaneously.
Don't get me wrong, I'm not against nuclear energy but I think it must be treated as something we can do until we switch to something sustainable.
I tried to find marketing material for Chernobyl and Fukushima but I did not find anything, I wanted to see if they explained the risks or did they described these plants as perfectly safe. People now claim that those designs were flawed and that everyone knew about it but I don't believe it, I will be shocked if people were promised anything less than perfect safety.
As we stand today, we built 667 nuclear power reactors and 2(actually more as fukushima lost multiple reactors) of those went bust with significant damage to the communities close to the reactors. The body count is hard to pinpoint but large communities had their lives uprooted and everything could have went worse if we lacked heroes.
With currently %10 of our electricity is coming from Nuclear, in 60 years we had 2 regions becoming uninhabitable practically forever due to incidents that could have been much worse. If our track record remains in line, with %100 nuclear we can expect to have 20 more places ruined within the lifetime of a junior developer who just started today.
I don't know, maybe we can have nuclear power plants close to photovoltaic production facilities to offset the energy need when building those far away from densely populated places and ramp up our efforts to switch to the fusion reactor in the sky? Turn off the last nuclear power plant when we have enough solar energy equipment?