 As of 27 March 2012, Japan had only one out of 54 nuclear reactors operating; the Tomari-3, after the Kashiwazaki-Kariwa 6 was shut down.The Tomari-3 was shut down for maintenance on 5 May, leaving Japan with no nuclear-derived electricity for the first time since 1970, when the country's then only two reactors were taken offline for five days for maintenance.On 15 June 2012, approval was given to restart Ōi Units 3 and 4 which could take six weeks to bring them to full operation.