South Korea has shut down operations at two nuclear reactors due to their having unauthorized parts, although the government insisted that there was no public-safety threat. Openings at two other reactors were delayed. The shutdown comes just months after a scandal late last year that exposed that nuclear reactors had fake security certificates. South Korea uses about 23 nuclear reactors to supply about one third of all its power. Meanwhile, it appeared that tensions with North Korea could be easing as leaders from the North invited factory owners from the South to visit a shuttered industrial complex near the border—although it appeared unlikely that the South would agree.