Nine months have passed since the Great East Japan Earthquake triggered the crisis at the Fukushima No. 1 nuclear power plant. This is the first installment in a two-part series that looks into problems facing the Nuclear and Industrial Safety Agency, among other issues, and what is required to create a new nuclear safety agency in April.
When did a meltdown occur at the Fukushima No. 1 nuclear power plant after the March 11 disaster?
"It's a core meltdown. We believe the fuel has started to melt [in the No. 1 reactor]," Koichiro Nakamura of the Nuclear and Industrial Safety Agency said at a press conference at 2 pm the following day.
But the agency quickly reversed itself and expressed doubt whether a meltdown had occurred. The agency finally admitted on June 7 there had been a meltdown.
On Nov 30, the plant's operator, Tokyo Electric Power Co., issued a statement on the No. 1 reactor: "Almost all of the [68 tons of] nuclear fuel [rods] melted, fell through a pressure vessel and eroded the concrete bottom of the containment vessel by up to 65 centimeters."
Therefore, a meltdown had advanced in the reactor core and this fact was hidden from the public for about three months.
Nakamura, deputy director general for nuclear safety at the Economy, Trade and Industry Ministry's agency, was the first to touch on the possibility of a meltdown of the No. 1 reactor.
His statement was based on the fact that radioactive cesium, which normally is only found in the fuel rods in theory, had been detected outside the nuclear power plant.
Ahead of his press conference, Nakamura asked then agency Director General Nobuaki Terasaka, 58, whether he could say a meltdown had occurred.
Terasaka gave him the green light, saying, "We have no choice but to mention it."
An hour after the press conference, staffers at the Prime Minister's Office were taken aback by Nakamura's remarks when they watched live coverage of the press conference on TV.
"What's this media coverage [of the press conference]?" shouted Keisuke Sadamori, then secretary to the prime minister and a former METI bureaucrat.
He telephoned the agency and demanded that it inform the Prime Minister's Office in advance whenever it had important information.
"It's wrong for the prime minister to get such information via TV," Sadamori said over the phone.
Thereafter, the Prime Minister's Office established a rule that it would hold a news conference on important findings and other information ahead of the agency.
"As we couldn't get the necessary information, our distrust in the agency knew no bounds. I had to phone the agency," Sadamori said as he recalled the tense atmosphere at the Prime Minister's Office that day.
At 3.36 pm on March 12, a hydrogen explosion destroyed the upper part of the building housing the No. 1 reactor at the Fukushima plant. TV stations broadcast white smoke rising from the damaged building.
While the government struggled to gather information on the explosion, the agency clammed up and refused media's requests to explain what is happening.
"We're unable to get approval [for a press conference] from the Prime Minister's Office," an agency official told the media.
Finally at 5:45 p.m., then Chief Cabinet Secretary Yukio Edano, 47, held a press conference, followed by an agency news conference at 6 pm Neither Edano nor the agency provided much information.
On March 13, Edano admitted at a press conference there was a possibility of a meltdown. In contrast, the agency had backed down from its initial assertion.
The following day, Nakamura did an about-face only two days after his initial statement. "We can't say for certain whether there's been a meltdown," he said.
Finally on June 7, the agency itself admitted a meltdown had occurred at the No. 1 reactor.
According to research results announced by TEPCO in May, however, most of the fuel at the No. 1 reactor had melted by the morning of March 12. This means Nakamura's initial explanation was correct.
Explaining why the agency's information had undergone such a change, Terasaka said: "After the Prime Minister's Office's instruction, we became very cautious about using the term 'meltdown.' We felt our statements should not exceed what the Prime Minister's Office said at press conferences."