Got any examples of any presently operating civil power reactors that don’t have their reactor cores in some kind of containment structure?

Others I guess the answer to your question is: fuckwit communists were running the place at the time.

Chernobyl happened while I was alive. It wasn’t that long ago. The leader of the Soviet Union who presided over the disaster (Gorbachev) died only 3 years ago.

Aside from that, “because communism” is not a serious answer.

Whether a deregulationist considers themselves communist or capitalist is a red herring: being in favor of dangerous deregulation spans many different national economic persuasions.