What specifically triggered a meltdown in the fukushima daiichi nuclear power plant?

What specifically triggered a meltdown in the fukushima daiichi nuclear power plant?
Show captionThe Fukushima Daiichi plant as the tsunami approached. Seawater flooded power lines, causing a meltdown in three of the six reactors. Photograph: Reuters

Japan

Tokyo Electric Power rejected report warning the nuclear plant could be at risk from 10-metre high tsunami, media claim

The operator of the Fukushima Daiichi nuclear power plant ignored warnings that the complex was at risk of damage from a tsunami of the size that hit north-east Japan in March, and dismissed the need for better protection against seawater flooding, according to reports.

Tokyo Electric Power (Tepco) officials rejected "unrealistic" estimates made in a 2008 internal report that the plant could be threatened by a tsunami of up to 10.2 metres, Kyodo news agency said.

The tsunami that crippled backup power supplies at the plant on the afternoon of 11 March, leading to the meltdown of three reactors, was more than 14 metres high.

Evidence that the utility was unprepared for the tsunami, despite previous warnings, came as the firm announced that the manager of the Fukushima plant, Masao Yoshida, was being treated for an unspecified illness and would leave his post on Thursday.

The company refused to disclose the nature of Yoshida's illness, but said it was not related to his exposure to radiation during the nine months since the crisis began. "On doctors' advice, I have no choice but to be hospitalised for treatment," Yoshida, 56, reportedly said in a message to staff. "It breaks my heart to have to bid farewell in this way to all of the people with whom I have worked since the disaster."

Yoshida, who led the department overseeing the plant's management when the 2008 report was submitted, has been credited with preventing a more serious accident in March.

In the immediate aftermath of the tsunami, he approved the continued injection of seawater into one of the damaged reactors, despite being told to abandon the measure by Tepco officials. He was later reprimanded, but won praise from experts who said he had helped cool overheating fuel rods and prevent a worse disaster.

Yoshida had not spoken publicly about the accident until earlier this month, when he told reporters that the situation at Fukushima Daiichi had improved considerably and that the reactors would be brought to a safe state, known as cold shutdown, by the end of the year. But he added: "Several times during the first week of the crisis, I thought I was going to die."

The accident was triggered when seawater flooded power supply lines, disabling cooling systems and triggering a meltdown in three of Fukushima Daiichi's six reactors.

The 40-year-old plant was built on the assumption that the biggest tsunami that could be expected on the Fukushima coast would be 5.7 metres high. Even at that height, the 2008 report said, water levels onsite could exceed 15 metres.

Kyodo quoted Tepco sources as saying the plant might have been better prepared for the disaster had it taken the report seriously.

Greenpeace, meanwhile, called on Japan not to restart nuclear reactors taken offline for stress tests and maintenance checks until it improves its disaster-response plans. It said simulation maps of potential accidents being used to devise emergency response efforts did not take into account accidents of the severity of the Fukushima disaster.

Greenpeace said Japanese government officials had conceded that the Speedi simulations were inadequate, as they are confined to low-level releases of radiation over a six-mile radius. Contamination from the Fukushima accident has spread over a much wider area.

The emergency response effort was "slow, chaotic and insufficient, and it appears that the government has learned nothing from it", said Junichi Sato, executive director of Greenpeace Japan. "These maps show that there is a strong risk of reactor restarts being pushed through without a proper, science-based assessment on the real risks being conducted, and without proper precautions being taken to protect the communities around the plants."

More than 80% of Japan's nuclear reactors will lie idle once Kansai Electric Power suspends operation of a reactor for inspection at a plant in western Japan on Friday. The move will leave all but 10 of the country's 54 reactors out of service.

The danger contamination poses to food supplies was underlined this week when officials in Fukushima confirmed that 9kg of a batch of contaminated rice had been sold to consumers this month. The discovery came soon after they banned shipments of another batch of rice containing excessive levels of radioactive caesium.

The rice, grown at three farms in the town of Date, contained up to 1,050 becquerels of caesium per kg, compared with the government-set upper limit of 500 becquerels. In response, the government imposed a ban on Tuesday on rice shipments from the area, while local officials said they were trying to trace the consumers.

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Topics

  • Japan disaster
  • Asia Pacific
  • Nuclear power
  • Energy
  • Fukushima
  • Tsunamis
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A Japanese parliamentary panel has delivered a damning verdict after investigating the accident at the Fukushima nuclear plant which followed an earthquake and tsunami on 11 March 2011.

Although such an event should have been predicted and planned for, the panel said, it found gaping holes in safety standards and emergency procedures.

Here is an outline of key quotes, findings and recommendations from the 88-page executive summary of the Nuclear Accident Independent Investigation Commission's report.

Image caption,

The disaster was natural but the panic and confusion were manmade

The earthquake and tsunami of March 11, 2011 were natural disasters of a magnitude that shocked the entire world. Although triggered by these cataclysmic events, the subsequent accident at the Fukushima Daiichi Nuclear Power Plant cannot be regarded as a natural disaster. It was a profoundly manmade disaster - that could and should have been foreseen and prevented...

Our report catalogues a multitude of errors and wilful negligence that left the Fukushima plant unprepared for the events of March 11. And it examines serious deficiencies in the response to the accident by Tepco, regulators and the government.

For all the extensive detail it provides, what this report cannot fully convey - especially to a global audience - is the mindset that supported the negligence behind this disaster. What must be admitted - very painfully - is that this was a disaster "Made in Japan."

Its fundamental causes are to be found in the ingrained conventions of Japanese culture: our reflexive obedience; our reluctance to question authority; our devotion to 'sticking with the program'; our groupism; and our insularity.

(Chairman Kiyoshi Kurokawa)

Collusion and lack of governance

The Tepco Fukushima Nuclear Power Plant accident was the result of collusion between the government, the regulators and [private plant operator] Tepco, and the lack of governance by said parties. They effectively betrayed the nation's right to be safe from nuclear accidents. Therefore, we conclude that the accident was clearly "manmade"...

We believe that the root causes were the organizational and regulatory systems... rather than issues relating to the competency of any specific individual.

[All parties] failed to correctly develop the most basic safety requirements - such as assessing the probability of damage, preparing for containing collateral damage from such a disaster, and developing evacuation plans for the public in the case of a serious radiation release.

Organisational problems within Tepco

Had there been a higher level of knowledge, training, and equipment inspection related to severe accidents, and had there been specific instructions given to the on-site workers concerning the state of emergency within the necessary time frame, a more effective accident response would have been possible... Sections in the diagrams of the severe accident instruction manual were missing.

Emergency response issues

The government, the regulators, Tepco management, and the Kantei [prime minister's office] lacked the preparation and the mindset to efficiently operate an emergency response to an accident of this scope. None, therefore, were effective in preventing or limiting the consequential damage.

Image caption,

A rare public campaign against nuclear energy has sprung up in response to the Fukushima disaster

In the critical period just after the accident, the Kantei did not promptly declare a state of emergency. The regional nuclear emergency response team was meant to be the contact between the Kantei and the operator, responsible for keeping the Kantei informed about the situation on the ground. Instead, the Kantei contacted Tepco headquarters and the Fukushima site directly, and disrupted the planned chain of command.

The Commission concludes that the residents' confusion over the evacuation stemmed from the regulators' negligence and failure over the years to implement adequate measures against a nuclear disaster, as well as a lack of action by previous governments and regulators focused on crisis management. The crisis management system that existed for the Kantei and the regulators should protect the health and safety of the public, but it failed in this function.

The central government... failed to convey the severity of the accident... [O]nly 20% of the residents of the town hosting the plant knew about the accident when evacuation from the 3km zone was ordered at 21:23 on the evening of March 11.

There was great confusion over the evacuation, caused by prolonged shelter-in-place orders and voluntary evacuation orders. Some residents were evacuated to high dosage areas because radiation monitoring information was not provided.

Continuing public health and welfare issues

[R]esidents in the affected area are still struggling from the effects of the accident. They continue to face grave concerns, including the health effects of radiation exposure, displacement, the dissolution of families, disruption of their lives and lifestyles and the contamination of vast areas of the environment. ...

The Commission concludes that the government and the regulators are not fully committed to protecting public health and safety; that they have not acted to protect the health of the residents and to restore their welfare.

Approximately 150,000 people were evacuated in response to the accident... Insufficient evacuation planning led to many residents receiving unnecessary radiation exposure. Others were forced to move multiple times, resulting in increased stress and health risks - including deaths among seriously ill patients.

"If there had been even a word about a nuclear power plant when the evacuation was ordered, we could have reacted reasonably, taken our valuables with us or locked up the house before we had left. We had to run with nothing but the clothes we were wearing. It is such a disappointment every time we are briefly allowed to return home only to find out that we have been robbed again." (Comment by a resident of Okuma, from report appendices)

The regulators did not monitor or supervise nuclear safety... They avoided their direct responsibilities by letting operators apply regulations on a voluntary basis. Their independence from the political arena, the ministries promoting nuclear energy, and the operators was a mockery. They were incapable, and lacked the expertise and the commitment to assure the safety of nuclear power.

Tepco did not fulfil its responsibilities as a private corporation, instead obeying and relying upon the government bureaucracy of Meti, the government agency driving nuclear policy. At the same time... it manipulated the cosy relationship with the regulators to take the teeth out of regulations.

Shortcomings in laws and regulations

Laws and regulations related to nuclear energy have only been revised as stopgap measures, based on actual accidents. They have not been seriously and comprehensively reviewed in line with the accident response and safeguarding measures of an international standard. As a result, predictable risks have not been addressed.

The existing regulations primarily are biased toward the promotion of a nuclear energy policy, and not to public safety, health and welfare. The unambiguous responsibility that operators should bear for a nuclear disaster was not specified. There was also no clear guidance about the responsibilities of the related parties in the case of an emergency.

Replacing people or changing the names of institutions will not solve the problems. Unless these root causes are resolved, preventive measures against future similar accidents will never be complete...

The underlying issue is the social structure that results in "regulatory capture," and the organisational, institutional, and legal framework that allows individuals to justify their own actions, hide them when inconvenient, and leave no records in order to avoid responsibility.

  • Permanent committee in National Diet [parliament] to oversee the regulators, with regular investigations and hearings
  • Reform of the crisis management system, making boundaries between responsibilities of local and national governments and the operators clear, and establishing clear chain of command in emergency situations
  • Establishment of system to deal with long-term public health effects, including monitoring and decontaminating radiation-affected areas
  • Dramatic corporate reform of Tepco and new relationships established among the electric power companies built on safety issues, mutual supervision and transparency
  • New regulatory body established on independence, transparency, professionalism, and consolidation of functions
  • Reform of laws related to nuclear energy to meet global standards of safety, public health and welfare
  • Develop a system of independent investigation commissions