This is crazy. Why on earth wouldn’t the respective government spend money to modernize a critical infrastructure like a nuclear power plant?
Safety and reliability come from understanding the system. Something that's old but that you know everything about is far safer than something new. This risk is that the people who know move on, or the sources of replacement parts stop working, or that other things around the system change. Then the risk curve inverts and you find the old system more of a liability than a asset.
Almost always people choose to update things either too early or too late. Knowing when to do something is hard.
That’s pure negligence. It’s not like the people that have the know how disappear suddenly . It’s the responsibility of the management to make sure the knowledge transferred to new generation.
I guess that kind of thinking is what led to the collapse of ancient civilisations like why even bother to improve anything and let everything decay and die out