– TEPCO concealed radiation data before explosion at No. 3 reactor (Asahi, May 14, 2011):
Tokyo Electric Power Co. concealed data showing spikes in radiation levels at the Fukushima No. 1 nuclear power plant in March, one day before a hydrogen explosion injured seven workers.
The Asahi Shimbun obtained a 100-page internal TEPCO report containing minute-to-minute data on radiation levels at the plant as well as pressure and water levels inside the No. 3 reactor from March 11 to April 30.
The data has never been released by the company that operates the stricken plant.
The unpublished information shows that at 1:17 p.m. on March 13, 300 millisieverts of radiation per hour was detected inside a double-entry door at the No. 3 reactor building. At 2:31 p.m., the radiation level was measured at 300 millisieverts or higher per hour to the north of the door.
Both levels were well above the upper limit of 250 millisieverts for an entire year under the plant’s safety standards for workers. But the workers who were trying to bring the situation under control at the plant were not informed of the levels.
When the Great East Japan Earthquake struck on March 11, the No. 1, No. 2 and No. 3 reactors all automatically shut down. But the tsunami crippled the emergency generators, leading to a total power failure that prevented the cooling systems from functioning.
The TEPCO data also showed high levels of hydrogen may be emitting from the damaged core of the No. 3 reactor on March 13, when TEPCO started injecting seawater to cool the reactor.
The following day around 11 a.m., a hydrogen explosion destroyed the upper part of the No. 3 reactor building. Seven TEPCO workers were injured in the blast.
TEPCO’s public relations department said the company has informed the public that significant levels of radiation have been detected at the plant, but it disclose specific data after a thorough review of the figures is completed.
Keiji Miyazaki, professor emeritus of nuclear reactor engineering at Osaka University, criticized TEPCO’s policy.
He said such important data should be immediately released to ensure the safety of the public and workers at the plant, especially in an emergency like the Fukushima nuclear accident.
Miyazaki said TEPCO’s decision to conceal the data must be scrutinized.
Failure to release radiation data in the early stages of the crisis is said to have delayed the evacuations of communities near the plant.
Kiyoshi Sakurai, another nuclear power expert, said a thorough examination is needed not only on TEPCO’s unpublished data, but also verbal communications of those involved, instructions issued by the central government and TEPCO, and the communication structure between management and workers at the plant.
(This article was written by Kamome Fujimori, Tatsuyuki Kobori and Yo Noguchi.)