 The Kashiwazaki-Kariwa Nuclear Power Plant, the largest nuclear generating station in the world by net electrical power rating, happened to be near the epicenter of the strongest Mw 6.6 July 2007 Chūetsu offshore earthquake.This initiated an extended shutdown for structural inspection which indicated that a greater earthquake-proofing was needed before operation could be resumed.On May 9, 2009, one unit (Unit 7) was restarted, after the seismic upgrades.