> other nuclear reactors in britain(and in fact across the world) operate with the same fractures in their vessels and it's not considered a reason to shut them

> other nuclear reactors in britain(and in fact across the world) operate with the same fractures in their vessels and it's not considered a reason to shut them down This should be viewed as "corrupted regulators" rather than "magically strong materials". In 1986, the Challenger blew up. We learned that although originally good safety standards had existed, over time a series of small exceptions had been made, each one on the theory that "hey it never blew up yet, a small change won't matter". Reactor licensing works like that. Sure, the reactor vessel is cracking which was never expected to happen. Sure, the graphite bricks are cracking which was never expected to happen. The important thing is, it never blew up yet, and that means it's perfectly safe to ignore the problems. At some future point there will be a Problem and it will be dutifully explained that a series of small deviations from safe practices became normalized, blah-blah, and everyone will nod and take the lesson to heart, until it happens the next time.