Japan's Fukushima nuclear disaster a year ago caught the nation's government leaders, nuclear regulators and the plant operator grossly unprepared, an independent investigation of the accident concludes. Officials feared that focusing on nuclear accident risks would undermine public confidence in nuclear power, the investigators said.
"This lack of preparation was caused, in part, by a public myth of 'absolute safety' that nuclear power proponents had nurtured over decades," according to the authors of the investigative report by the Rebuild Japan Initiative Foundation.
The posture of confidence was required to overcome Japan's postwar resistance to nuclear power spawned by the atomic bombing of Hiroshima and Nagasaki, according to the authors, Yoishi Funabashi, the foundation chairman and former editor-in-chief of the Asahi Shimbun news organization, and Kay Kitazawa, staff director of the foundation's Fukushima investigation commission.
"Since the 1970s, disaster risk has been deliberately downplayed by what has been called Japan's nuclear mura ['village' or 'community'] -- that is, nuclear advocates in industry, government, and academia, along with local leaders hoping to have nuclear power plants built in their municipalities. The mura has feared that if the risks related to nuclear energy were publicly acknowledged, citizens would demand that plants be shut down until the risks were removed," the report's authors say in an article published today by the Bulletin of the Atomic Scientists.
The foundation's investigation commission released a 420-page report in Japan yesterday. An English-language version will be published this summer, it said. The commission is chaired by Koichi Kitazawa, former chairman of the Japan Science and Technology Agency.
The Bulletin article describes the particular environment for nuclear power in Japan that compromised a forthright safety attitude by industry and regulators and bred an inadequate disaster management command structure that broke down at critical junctures, the authors say.
But the investigation also cites vulnerabilities in Japan's nuclear power sector that were separately highlighted by the U.S. Nuclear Regulatory Commission's Fukushima task force last year in its assessment of the U.S. industry's accident preparedness.
A worker's mistake accelerated failures
The Japanese investigation, like the task force report, pointed to the dangers that could erupt if crises struck several nuclear reactors at the same site, as happened at Fukushima Daiichi. NRC regulations do not adequately address that threat, the task force said.
Both the investigation and the task force report noted the threat that extreme natural disasters could create "cliff-edge" emergencies that could unexpectedly overwhelm multiple safety systems -- again, Fukushima's fate. And the foundation authors and the task force warned about the potential weakness of voluntary safety standards. The task force said that the NRC's acceptance of voluntary industry safety practices, which were not backed up by regular safety inspections, was linked to inconsistent compliance by plant operators.
The Bulletin article authors say the investigation documents a profound lack of preparation for the emergency by Tokyo Electric Power Co. (TEPCO) workers and executives, a consequence of failures to plan adequately for worst-case scenarios.
"At the outset of the accident, a Tepco worker misjudged the backup cooling situation at Unit 1. He failed to notice that the valve of the unit's isolation condenser, or IC -- a battery-powered emergency cooling system -- was either fully or partially closed after the plant lost power. Steam usually spews out when the IC is activated; because there was no sign of steam, the worker hastily assumed that the IC system had lost its cooling water. For fear of the mechanical damage that could occur if the system were run without water, the worker removed the IC from service for about three hours, starting at around 6:30 p.m. on March 11."
The loss of this primary emergency cooling system accelerated a chain of events that led to uncovering of the reactor core, core melting and generation of high-pressure hydrogen gas that leaked from the containment structure into the Unit 1 outer building, and exploded on March 12.
"But the role of human error in the Fukushima nuclear accident was not limited to the misjudgment of any one worker. ... The technical chief, the plant director, and the nuclear energy section of Tepco's headquarters all failed to ascertain the true operational situation of the IC system at Unit 1," the authors said.
Planning and training voids
TEPCO's most recent emergency operating plan, created in 1994, does not "address the possibility of a prolonged, total loss of power, the authors said. "When on-site workers referred to the severe accident manual, the answers they were looking for simply were not there." Moreover, workers had never been trained to use the emergency system, they said.
Japan's Nuclear Safety Commission, one of the industry regulators, concluded that the possibility of a prolonged loss of electric power at a nuclear plant did not need to be considered.
Funabashi and Kitazawa say the reluctance to address safety issues -- the "safety myth" they call it -- was illustrated in 2010 when Niigata prefecture initially planned to conduct a joint earthquake and nuclear disaster drill. In 2007, an offshore earthquake temporarily shut down the Kashiwazaki- Kariwa nuclear power plant there.
But Japan's Nuclear and Industrial Safety Agency (NISA), another regulator, advised that a nuclear accident drill premised on an earthquake would cause "unnecessary anxiety and misunderstanding" among residents. Instead, the prefecture based its drill using a heavy snowfall scenario, the authors said.
Regulators were aware of the possibility of an extreme tsunami that could overwhelm the Fukushima Daiichi plant, and encouraged TEPCO to take precautions, but did not require those measures, the report authors say.
The uses of misinformation
"Making such changes, the nuclear community felt, would be an admission that existing safety precautions and regulations were insufficient and that nuclear plants did not possess 'absolute safety'. In this way, power companies found themselves caught in their own trap."
The emergency injection of seawater to try to halt core melting provoked a confused, dysfunctional debate between top government officials and TEPCO executives, the two authors said. Former Prime Minister Naoto Kan -- who by then was personally and deeply involved in emergency response -- had been informed that seawater injection could cause the damaged nuclear fuel to become critical, restarting the chain reaction process.
In a conference call, TEPCO's president told the plant's director to hold up further seawater injections until the government had decided what to do. The plant director, Masao Yoshida, was determined to continue the injections. During the conference call, he called an assistant to him and said in a side voice that while the assistant would hear Yoshida order injections halted for the conferees' benefit, the assistant should ignore that order and continue the injections, to prevent the catastrophe from escalating.
"Thereupon, Yoshida loudly declared to all teleconference participants that water injections would be interrupted. Yoshida's kabuki play successfully helped Tepco avoid further confrontations with the government, while ensuring that the cooling of the reactors would continue; at this point, the company's Fukushima Daiichi plant team was working independently of their headquarters," the authors wrote.
"When it comes to nuclear disasters, no two are exactly the same," the authors said. "At Fukushima Daiichi, the problems were not with the law or the manual, but with the humans who formulated the 'anticipated' risks that fell in line with corporate and political will -- but did not represent the actual risks the nuclear plant faced and posed."
Like what you see?
We thought you might.
Start a free trial now.