Kerncentrales Japan #31

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Fukushima power plant operator 'knew of need to protect against tsunami' | Environment | The Guardian

Revelation casts doubt on Tepco’s claim that it had taken every possible action to protect the plant which suffered meltdown in 2011 disaster

The operator of Japan’s ruined Fukushima Daiichi nuclear power plant was aware of the need to improve the facility’s defences against tsunami more than two years before the March 2011 disaster but failed to take action, according to an internal company document.

The revelation casts doubt on claims by Tokyo Electric Power (Tepco) that it had done everything possible to protect the plant, which suffered a triple meltdown after being struck by a towering tsunami.

The nuclear accident, the world’s worst since Chernobyl 25 years earlier, caused massive radiation leaks and forced the evacuation of more than 150,000 people, most of whom have yet to return to their homes.

Tepco executives agreed that building coastal defences to defend the plant against tsunami higher than those previously recorded in the region was “indispensable”, according to the document, which was discussed at a meeting at the plant in September 2008 – two and a half years before the disaster.

The utility disclosed the document this week during a lawsuit brought by more than 40 Tepco shareholders who are demanding damages totalling 5.5 trillion yen from company executives.

Tepco has always insisted that it was powerless to take precautions against a tsunami of the size that struck Japan’s north-east coast in March 2011, killing almost 16,000 people.

In April 2012, for instance, the company said that based on expert knowledge of previous tsunami in the region, the March 2011 disaster “could not have been foreseen, and Tepco also considers the height [scale] of the tsunami that followed this earthquake to have been unpredictable ”.

The company has voiced similar claims during the ongoing damages case at Tokyo district court, but Kyodo News quoted lawyers for the plaintiffs as saying that the internal document proved that Tepco “had clearly recognised as of [2008] that measures against tsunami were inevitable, contradicting the company’s explanations so far”.

The document showed Tepco recognised the need to improve tsunami defences as “inevitable, as we cannot help but expect bigger tsunami than currently projected”, Japanese media said.

Plaintiffs cited a government report showing that Tepco had predicted in June 2008 that the Fukushima Daiichi plant could be hit by tsunami waves of up to 15.7 metres in height following a major offshore earthquake. Tepco failed to act on that prediction, and on concerns raised in the internal report, which was discussed by executives at Fukushima three months later.

In response, Tepco told the court that it was wrong to conclude that the 2008 tsunami estimate would have prompted the firm to improve the plant’s defences, “because there were differences of opinion, even among experts, on how to estimate [the size] of an earthquake”, the newspaper Asahi Shimbun said.
Bron: www.theguardian.com

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Melting of Key Parts Blamed for Fukushima Meltdown - Nuclear Watch - News - NHK WORLD - English

Officials at Tokyo Electric Power Company believe the loss of those components made it difficult to stop the Number 2 reactor from melting down and spewing out large amounts of radioactive substances following the March 2011 accident.

Four days after the onset of the accident, the emergency cooling system at the reactor stopped working.

In an attempt to cool fuel inside the reactor, the workers had no choice but to pour in water from a fire engine.

But they were unable to inject water as planned because of the high pressure that had built up inside the reactor.

The officials also could not use safety relief valves to release pressure. Those valves were designed to open when hit by high-pressure gas from a tank.

The TEPCO analysis determined that key parts of the gas feeding system may have melted, leading to a gas leak. The analysis says the temperature inside the reactor exceeded 200 degrees Celsius, far beyond the limit of the parts' durability.

Those parts are present in all other reactors in the model line used at the Fukushima Daiichi plant. The utility plans to replace the parts at its other nuclear power plant in central Japan with heat-resistant ones.

Bron: www3.nhk.or.jp

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TEPCO to tackle removal of molten nuclear fuel - News - NHK WORLD - English

The operator of the crippled Fukushima Daiichi nuclear power plant is expected to take on the challenge of removing the molten fuel from reactors that suffered meltdowns in 2011.

Soon it will be nearly five years since the massive earthquake and tsunami triggered a nuclear accident at the plant.

Workers have not been able to determine the extent of damage or find the molten fuel at the No.1, 2 and 3 reactors. Experts believe some of the fuel penetrated the reactor cores and is sitting at the bottom of the respective containment vessels.

TEPCO officials will bring in a remote-controlled robot that can withstand extremely high radiation levels to capture images of the fuel at the No. 2 reactor as early as next month. A similar undertaking is to take place at the No. 1 reactor.

The officials will then decide ways to remove the fuel. Filling the reactor containment vessels with water before extracting it is one option to shield workers from the intense radiation.

TEPCO's Chief Decommissioning Officer Naohiro Masuda says removing the fuel is their final goal.
He added that finding its whereabouts would be a big step toward decommissioning the plant.

Bron: www3.nhk.or.jp

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Rechter sluit twee van de vier actieve Japanse kernreactoren

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Ex-Japan PM: nuclear power remains unsafe and too costly | Environment | The Guardian

Naoto Kan, who presided over country during Fukushima disaster in 2011, cautions over plans to build new UK plants


Nuclear power is unsafe and too expensive to justify building new plants anywhere in the world, according to the Japanese prime minister at the time of the Fukushima nuclear accident.

Related: Hinkley Point C: what you need to know about the nuclear power project

Speaking on the fifth anniversary of the disaster, Naoto Kan said he was against the idea of Japanese manufacturers such as Hitachi and Toshiba building plants in the UK.

“Nuclear power is not safe. In the worst case scenario up to 50 million people would have had to be evacuated. Nuclear power is not a suitable technology and renewable power is much better,” Kan told the Guardian.

The former prime minister insisted he did not want to tell other countries such as Britain what to do but he said he did not support the reactors being switched back on in Japan.

His warning came as Britain’s nuclear plans are hanging in the balance because of delays over the go-ahead for EDF Energy’s Hinkley Point C project in Somerset and concerns about the project’s financial viability.

While the French company EDF is at the centre of the Hinkley scheme, Hitachi and Toshiba are behind similar intiatives being developed for new reactors at Wylfa on Anglesey, Oldbury in South Gloucestershire, and Sellafield in Cumbria.

Related: After Fukushima: faces from Japan's tsunami tragedy, five years on

Kan said it “did not make sense” to construct new atomic plants because of the cost, especially in those countries where there were no long-term storage facilities for high level radioactive waste. This includes Britain and Japan.

“What I experienced as prime minister made me feel that it does not make sense to rely on nuclear. New generation plant designs are supposed to increase safety but all these do is increase the cost.”

Tom Greatrex, chief executive of Britain’s atomic lobby group, the Nuclear Industry Association (NIA), said he was comfortable that Hinkley and the other reactors being planned in Britain would be safe because they would go through the UK’s most rigorous regulatory scrutiny.

“The process of assessing the reactor design is done in a different way in the UK and that gives confidence that the reactor design (EDF’s European pressurised reactors) will be safe and that is what we need to see.”

Asked about Kan’s wider concerns, Greatrex said: “Since that time [of the Fukushima accident], four reactors have come back on line in Japan … the reality of Fukushima was that all of the casualties were to do with the tsunami and then the evacuation process, not to do with radioactive material being released. In that respect it was a climatic catastrophe rather than a nuclear catastrophe.

“But the most important thing in the UK context of Fukushima is what the UK government did five years ago which was to pause, to reflect, for Mike Weightman [chief inspector of nuclear installations] to do his assessments of what the implications of what Fukushima were for the UK.”

A spokesperson from the Department of Energy and Climate Change also said the safety of British reactors would be paramount. “Any nuclear power station built in the UK will need to comply with our world-leading nuclear safety regulation.

“The British government is backing new nuclear. It is an important part of our plan to give hardworking families and businesses clean, affordable and secure energy that they can rely on now and in the future.”

The £18bn Hinkley Point C nuclear project was thrown into doubt this week after after EDF’s finance director, Thomas Piquemal, resigned after opposing the deal. He believes the costly agreement threatens the company’s future.

Bron: www.theguardian.com