

The headline is a lie. Not only did they not cut into the roof of the reactor, but the reactor was also offline when they replaced the steam generators
Bruce Power cut into the roof of an operating nuclear station, hauled eight steam generators weighing 100 metric tons each (about 110 US tons) out through the top, and lowered brand-new ones into the same hole. Then it brought the reactor back online on June 8

The comment by ksymph sums up my thoughts exactly: