12 Avril 2016
April 12, 2016
THE ASAHI SHIMBUN
A Tokyo Electric Power Co. senior official has admitted to knowing the criteria to assess reactor meltdowns during the onset of the 2011 Fukushima nuclear accident.
However, it took the company two months to make the declaration and another five years to "discover" its operational manual, which would have allowed it to declare a meltdown.
Until February this year, TEPCO had justified the delay in that it did not have the "basis to determine” such an occurrence. It announced Feb. 24 that it discovered a guideline in its operational manual.
TEPCO admitted that meltdowns had occurred in May 2011, two months after the disaster.
Yuichi Okamura, a senior director on nuclear power generation, said in a news conference on April 11 that he knew of the standard, although emphasizing it was only his “personal knowledge.” He did not elaborate on whether he knew the existence of the operational manual, or whether he shared his “personal knowledge” with other staff members.
“I, in fact, knew it (the criteria),” said Okamura. “I learned it while working in the field of nuclear technology with the company for over 20 years.”
According to Okamura, at the time of the accident at the Fukushima No. 1 nuclear power plant, he was directing the pumping of water into the cooling pool of spent nuclear fuel rods of the No. 4 reactor. He said he was not in a position to make a declaration whether a meltdown had occurred.
He made the admission in response to a question asking his personal understanding of the situation at the onset of the crisis.
Okamura declined to comment on whether he is being questioned by a third-party panel investigating the accident.
In February, TEPCO revealed that it did not realize for the past five years that there was a clear guideline in the operational manual to assess that a meltdown in a reactor had occurred. The standard requires the company to declare a meltdown when damage to a reactor core exceeds 5 percent.
TEPCO took two months to declare the triple meltdowns at the Fukushima plant, triggered by the Great East Japan Earthquake and tsunami on March 11, 2011. It had initially maintained that the reactors suffered "core damage" rather than meltdowns.