Tokyo Electric Power Co. (TEPCO)'s then President Masataka Shimizu instructed staff not to use the term "core meltdown" when describing the disaster at the Fukushima No. 1 Nuclear Power Plant in 2011, according to a report by a third-party investigative committee of TEPCO that was made public on June 16.
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The report acknowledged that the instructions were conveyed widely within TEPCO by telephone and other means. It hinted that there had been "pressure" from the prime minister's office through a request for TEPCO to provide the content of announcements in advance, but it remained unclear whether the office had any involvement in clamping down on the use of "core meltdown."
What, then, prompted TEPCO to seal off the term? According to the report, the move was triggered by a hydrogen explosion at the building of the Fukushima nuclear plant's No. 1 reactor on the afternoon of March 12, 2011, the day after the plant was crippled by the massive Great East Japan Earthquake and tsunami.
The prime minister's office was aware of the explosion from TV images. But when TEPCO went ahead and held a news conference, publicly releasing a photograph of the explosion without contacting the prime minister's office for many hours, then Prime Minister Naoto Kan and other government officials got furious. Shimizu was called to the prime minister's office on March 13 and was told to contact the office in advance when announcing important accident information.
The removal of a senior official of the then Nuclear and Industrial Safety Agency from a public relations position on March 13 after he acknowledged a core meltdown in a news conference without first contacting the prime minister's office is also thought to have influenced TEPCO.
On the evening of March 14, when then TEPCO vice president Sakae Muto was giving a news conference, a memo from Shimizu was passed to him by a company employee, saying, "By instruction of the prime minister's office, don't use 'core meltdown.'" Hints of pressure from the prime minister's office had emerged during a teleconference beforehand, with Shimizu saying reports to the prime minister's office should be made "properly, in advance."
Shimizu's position was conveyed within the company by phone and other means. The report concluded that "an understanding was shared within TEPCO that statements acknowledging a meltdown should be avoided."
After that Muto and TEPCO employees switched to the term "core damage." The report pointed out, "If the memo had not been passed over, vice president Muto may have responded differently."
The third-party investigative committee searched for the memo, which was said to be handwritten, but did not find it. The committee questioned Shimizu on two occasions over a period of about four hours, but the report concluded, "His memory has faded and clear facts could not be confirmed."
However, it quoted a TEPCO employee who was summoned in April by then Minister of Economy, Trade and Industry Banri Kaieda as saying that Kaieda had told him, "There doesn't appear to be a clear definition of a core meltdown, so let's make it the melting of fuel pellets." After that, a fax was distributed within the company saying, "'Melting of fuel pellets' is to be used. This is because 'core meltdown' conveys the image that the whole core has melted, like the China syndrome."
This was in spite of a manual that was "discovered" at TEPCO in February this year, nearly five years after the meltdowns. The manual defined a core meltdown as having occurred when over 5 percent of the reactor core had been damaged. This being the case, TEPCO could have judged as early as March 14, 2011, three days after the outbreak of the disaster, that core meltdowns had occurred.
The third-party panel report stated that quite a few of some 55 TEPCO employees in charge of TEPCO external reports had checked the manual, and rejected TEPCO's claim that "nobody had noticed" it until its "discovery."
"It would have been natural to list 'core meltdowns' in reports, but the company avoided this," the report stated.
On June 16, Democratic Party Secretary-General Yukio Edano, who was Chief Cabinet Secretary at the time of the meltdowns, told reporters in Yokkaichi, Mie Prefecture, on June 16 that he had never issued any orders to avoid use of the phrase "core meltdown."
"Neither I or then Prime Minister Kan made any such request to TEPCO," he said, adding, "During news conferences at the time I myself acknowledged core meltdowns. Putting the brakes on (the use of the term) would have been out of the question."