There have been 3 fairly dangerous and catastrophic meltdowns rendering partial or whole plants inoperable within 4 decades. These meltdowns have caused long term environmental damage, killed people, etc.
If you're averaging almost a meltdown a decade, and where each time we have been lucky it hasn't been worse, I reject any claims that this is a safe technology that we have under sufficient control for it to make sense, especially when we have such cheaper and less dangerous ways to get the power we need now.