Tokyo Electric Power Co. faces new accusations that it withheld critical information from regulators in the early hours of the Fukushima Daiichi crisis, including the likely presence of hydrogen that caused explosions in reactor buildings.
A report from the country's Nuclear and Industrial Safety Agency says TEPCO detected 290 millisieverts of radiation per hour in unit 1 – indicative of the kind of fuel damage that would also produce hydrogen – at 9:51 p.m. on March 11. The utility waited two hours to inform NISA that a radiation leak was possible, and it did not confirm the presence of a leak until 5:14 a.m. on March 12 – some six hours hours after further tests confirmed radiation levels in the unit were rising.
A hydrogen explosion blew the roof off the unit's external building at 3:36 p.m. that day. The report also suggests TEPCO delayed reporting similar conditions in unit 3 before an explosion there March 14, the Asahi Shimbun reported Tuesday.
The newspaper quoted a TEPCO spokesman as saying the delay was allowed by government regulations that did not require the company to report all data regarding possible radiation leaks to regulators.