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Seven years later: Contradictory responses to Fukushima

Nuclear safety is an oxymore, shut them all down!
On March 11, 2011, the one-two punch from the Great East Japan Earthquake and the tsunami wave it triggered left workers at the Fukushima Daiichi nuclear plant in Japan powerless to prevent three reactors from melting down. In March 2017, the Japan Center for Economic Research estimated that the cleanup cost could range from $470 billion to $658 billion.
The conclusions Japanese and U.S. institutions made about why the Fukushima facility was so vulnerable to such an accident were strikingly similar. The commission created by Japan’s National Diet concluded that its “root causes were the organizational and regulatory systems that supported faulty rationales for decisions and actions.”
The U.S. National Academy of Sciences (NAS) committee that investigated the accident similarly concluded “that regulatory agencies were not independent and were subject to regulatory capture.” According to the NAS report, regulatory capture is “the processes by which regulated entities manipulate regulators to put their interests ahead of public interests.” It found that the plant’s owner “manipulated the cozy relationship with the regulators to take the teeth out of regulations.”
In response to the accident, Japan established an agency, the Nuclear Regulation Authority. The NRA is not a clone of the U.S. Nuclear Regulatory Commission (NRC), but it clearly is patterned after the U.S. agency, adopting many of its principles and policies to safeguard public health and safety.
Now, in an odd nuclear safety yin and yang, while Japan’s NRA strives to beef up its role as an effective, independent regulator, the NRC is backsliding towards becoming a cozy captive enforcing toothless regulations.
After the 9/11 terrorist attacks, the NRC upgraded nuclear plant security. The upgrades included increasing the frequency of “force-on-force” tests, which determine whether security staff can thwart an assault on a plant. A team of mock intruders visited each operating nuclear plant at least once every three years and simulated four sabotage attempts against the plant’s gates, guards and guns.
The force-on-force tests either demonstrated security was sufficient or identified weaknesses for correction before actual intruders could exploit them. But plant owners complained about the cost, so the NRC has reduced the number of force-on-force exercises from four to one and is even considering allowing the plant owners to conduct the tests themselves.
Plant owners also complain about the high cost of NRC safety inspections and have targeted some of the NRC’s most important inspections, such as of fire protection measures, for replacement with self-assessments.
Nuclear dentistry last year involving the Palo Verde nuclear plant in Arizona removed teeth from regulatory requirements. One of the two backup emergency power supplies for Palo Verde’s Unit 3 reactor blew up during a test. The plant’s NRC license allowed the reactor to continue operating for as long as 10 days with its backup power capability diminished. The repairs would take considerably longer than 10 days, however, so the plant owner asked the NRC for permission to continue operating for as long as 62 days. Despite the fact that NRC safety protocols prevent the agency from even considering requests for longer than 14 days, the NRC not only considered it, it granted it.
Granting the request also contradicted a formal agreement between the NRC and industry limiting how long a reactor can operate with less than the minimum amount of safety equipment specified in its operating license to 30 days. The agreement termed the 30-day limit a safety backstop, but it did not stop the agency from allowing the Palo Verde reactor to operate unsafely for twice that long.
It is admirable that the new Japanese nuclear power regulator is seeking to improve its safety oversight capability. But it is unfathomable that in the United States, the NRC is retreating from the regulatory front. There’s no doubt that uncompromising, effective regulation is not cheap. But Fukushima reminded the world of what was already well-known — that ineffective safety oversight can cost far more.
Americans deserve — and need — the nuclear regulator toward which Japan is striving.

April 9, 2018 Posted by | Fukushima 2018 | , | Leave a comment

Time to transform Japan’s nuclear plant inspection system

Japan lies at the middle of 4 tectonic plates. The pressure of the plates has produced 113 active fault lines in Japan’s crust. It has also 118 active volcanoes. 10% of the world earthquakes occur in Japan.

To talk about nuclear safety there is like taking bets with people lives, is like talking about a death wish.

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The government has submitted to the Diet a bill to revise the Act on the Regulation of Nuclear Source Material, Nuclear Fuel Material and Reactors. The bill includes the introduction of surprise inspections at nuclear plants by inspectors from the Secretariat of the Nuclear Regulation Authority, which would allow them to enter any part of a nuclear plant at any time, as well as a system where the state gives an overall evaluation to each plant based on the results of the inspections and other factors and release the data. These new systems are expected to come into operation in fiscal 2020.
With surprise inspections, it will be difficult for power companies to hide problems at their nuclear plants. And since evaluation results will be published and comparison among nuclear plants will be possible, the principle of competition comes into play, which is expected to encourage utilities to voluntarily develop safety measures at their own plants.

In the meantime, the Nuclear Regulation Authority (NRA) should work on boosting the number of nuclear plant inspectors and training such officials so that the revisions will lead to the improvement of nuclear plant safety.

The NRA was established in the wake of the March 2011 nuclear disaster at the Fukushima No.1 Nuclear Power Plant and new safety standards subsequently came into effect. Restarts of idled nuclear reactors based on the new standards are underway. At the same time, reviews on nuclear plant inspection systems had been put on the back burner.

The pillars of nuclear plant inspections conducted by the government and power companies are regular checkups, which are carried out about once every 13 months, and security examinations done four times a year. With regular inspections, facilities with higher levels of importance are screened, while security examinations mainly judge whether a nuclear plant is operated safely.

The dates and contents of these checks are set prior to the actual inspections, however, and the system lacks flexibility, preventing the government from acting on a case-by-case basis to check problems at each plant.

NRA Chairman Shunichi Tanaka has said that there is corporate culture within power companies where they think their nuclear plants are fine as long as they pass safety checks by government regulators. The International Atomic Energy Agency has also pointed out that this way of thinking is problematic and the agency recommended Japanese authorities improve nuclear plant inspection systems in the pre-disaster year of 2007 and again in January 2016.

Under the proposed bill, the division of roles shared by the government and power companies will be clarified. Utilities would be solely responsible for making sure that facilities at their nuclear plants meet safety standards, while the government would take the role of a watchdog, monitoring power companies’ safety measures and how inspections are being carried out to give an overall evaluation for each plant. The results of surprise inspections will be included in a nuclear plant’s overall grade, which will be reflected in the next inspection.

The new inspection system was inspired by those employed in the United States and other countries with nuclear power. While Japan will catch up with those countries in terms of the system after the law is revised, that alone is not enough.

In the United States, where around 100 nuclear reactors are in operation, there are some 1,000 inspectors at the U.S. Nuclear Regulatory Commission, and they undergo a two-year training program. In Japan, on the other hand, there are only around 100 inspectors for more than 40 reactors, and they receive a mere two weeks of training.

Unless the quality and quantity of the nuclear plant inspectors are secured, the effectiveness of the new system would become questionable.

Furthermore, the overall grades for each nuclear plant should be released in a way to make it easier for the public to understand. The government should also consider ways to make good use of the system such as changing the premiums of liability insurance policies for potential nuclear accidents depending on the nuclear plants’ safety grades.

February 28, 2017 Posted by | Japan | | Leave a comment

Nuclear watchdog to require waterproofing measures at facilities


nuclear safety is an oxymoron.jpg


The Nuclear Regulation Authority (NRA) is set to require power companies and other operators to complete waterproofing measures of their nuclear facilities within the next year, following an incident in which tons of rainwater flowed into the No. 2 reactor building at the Shika nuclear plant last fall, it has been learned.

The NRA conducted a survey on nuclear plant operators across the country to detect possible similar problems and released the results on Feb. 8. The survey found that measures to shut off the influx of water into reactor buildings had not been carried out on at least 655 parts of such structures at 10 nuclear facilities.

The facilities mentioned in the survey are: the No. 1 and 2 reactors at the Shika nuclear plant in Ishikawa Prefecture, the No. 2 reactor at Tohoku Electric Power Co.’s Onagawa nuclear plant in Miyagi Prefecture, the No. 1 through 4 reactors at Tokyo Electric Power Co. (TEPCO)’s Fukushima No. 2 nuclear plant in Fukushima Prefecture, the No. 1 through 7 reactors at TEPCO’s Kashiwazaki-Kariwa nuclear plant in Niigata Prefecture, the No. 3 through 5 reactors at Chubu Electric Power Co.’s Hamaoka nuclear plant in Shizuoka Prefecture, the No. 1 and 2 reactors at Chugoku Electric Power Co.’s Shimane nuclear plant in Shimane Prefecture, the No. 1 reactor at the Japan Atomic Power Co.’s Tsuruga Power Station in Fukui Prefecture, the Monju prototype fast-breeder reactor also in Fukui Prefecture, the Tokai Reprocessing Plant in Ibaraki Prefecture and the Rokkasho Reprocessing Plant in Aomori Prefecture. The Shimane nuclear plant’s No. 1 reactor and the Tsuruga Power Station’s No. 1 reactor are under decommissioning work, while the Monju reactor and the Tokai Reprocessing Plant are set to be dismantled.

All the reactors in question are boiling-water reactors. Meanwhile, waterproofing measures have been completed on all of the country’s pressurized-water reactors — including the No. 1 and 2 reactors at Kyushu Electric Power Co.’s Sendai nuclear plant in Kagoshima Prefecture, which were reactivated amid much controversy.

Following heavy rainfall in late September last year, approximately 6.6 metric tons of rainwater flowed into the building housing the No. 2 reactor at the Shika nuclear plant by way of cracks and gaps around plumbing, causing short circuits in lighting switchboards. The crisis occurred as the amount of precipitation surpassed the capacity of makeshift drainage pumps, raising the risk that a storage battery for cooling the reactor in emergencies and other key safety equipment would become submerged and unusable.

The NRA’s new safety regulations introduced in the wake of the 2011 meltdowns at the Fukushima No. 1 nuclear plant call on power companies and other plant operators to take measures to prevent an influx of rainwater and tsunami in reactor buildings from affecting key facilities. However, the regulations do not oblige plant operators to take such measures as fill in the gaps in pipes that penetrate reactor buildings. In response to the recent incident at the Shika plant, which the NRA views seriously, the agency has decided to effectively mandate plant operators to implement waterproofing measures at all nuclear facilities.

February 10, 2017 Posted by | Japan | , | Leave a comment

Pipe checks at Japan’s nuclear control rooms conducted without removing insulation

The vast majority of Japan’s 42 viable commercial nuclear reactors have not had detailed checkups performed on the air conditioning and ventilation systems of their central control rooms, it has been learned.

According to Japan Atomic Power Co. and nine utilities that manage nuclear power plants, the checkups — conducted at only two of the plants so far — are carried out without removing the insulation on the pipes.

Last month, Chugoku Electric Power Co. found extensive corrosion and holes, including one measuring 30 cm by 100 cm, in the ventilation pipes of the No. 2 reactor at the Shimane nuclear plant in Matsue, Shimane Prefecture. It was the first time the utility had removed the covering on the pipes since the reactor booted up in 1989.

Concluding the pipes were not functioning properly, Chugoku Electric reported the degradation to the Nuclear Regulation Authority.

In the event of a accident, control rooms, which are staffed around the clock, must be self-contained to prevent outside air from entering.

Five reactors at the three nuclear plants that have been reactivated since 2015 have not undergone pipe inspections in which their insulation was removed. Of the five, the No. 1 reactor at Kyushu Electric Power Co.’s Sendai plant in Kagoshima Prefecture and the No. 3 reactor at Shikoku Electric Power Co.’s Ikata plant in Ehime Prefecture are currently in operation.

Following the discovery of the pipe degradation at the Shimane No. 2 reactor, the NRA plans to check conditions at all of the nation’s nuclear plants, sources said.

Hokuriku Electric Power Co. detected rust in the ventilation pipes of the No. 1 reactor at its Shika nuclear plant in Ishikawa Prefecture in 2003. After removing the covers and conducting further inspections, the company replaced the equipment in 2008.

The NRA suspects that the pipe corrosion at the Shimane No. 2 reactor may violate nuclear regulatory standards, an official said.

As the plant is located near the sea, salt-containing air may have flowed into the pipes and hastened corrosion,” a Chugoku Electric official said.

Most of the nation’s nuclear plants are in coastal areas because they use seawater to cool their turbines.

January 15, 2017 Posted by | Japan | , , | Leave a comment

Japan earthquakes: Nuclear regulator refuses to shut down station on Kyushu Island

Japan’s atomic regulator will not shut down the nation’s only operating nuclear plant on earthquake-hit Kyushu island, despite concerns of a repeat of the Fukushima crisis.

The Nuclear Regulation Authority’s (NRA) decision came to light as the race to rescue survivors of the deadly earthquakes in southern Japan continued, with 10 still missing and the death toll rising to 42.

The Kumamoto region of Kyushu island was first hit last Thursday by a major tremor claiming nine lives which proved to be a foreshock to a bigger 7.3 magnitude earthquake striking early Saturday, killing a further 33.

Kumamoto city is located around 72 miles from Sendai nuclear power station, the only nuclear power plant which is currently in operation in Japan, operated by Kyushu Electric Power.

Last weekend, a group of writers and journalists joined forces to ask operators to immediately suspend operations at the Sendai plant in the aftermath of the earthquake, to avoid a repeat of the Fukushima crisis.

“Based on the experience at the Fukushima No. 1 nuclear power plant, it is clear to everyone that it would be too late if you waited for some abnormality to occur,” the group said in its request faxed to Kyushu Electric Power, according to the Asahi Shimbun.


However, the NRA on Monday held a special meeting with its commissioners, which resulted in Shunichi Tanaka, the chairman, to concluding that the Sendai plant, which has two reactors, was not endangered and should remain open.

The NRA announced plans to closely monitor the Sendai plant alongside three other nuclear power stations, including Genkai and Ikata on Kyushu island and Shimane, located further away on the main Honshu island.

The decision is likely to be greeted with widespread disappointment and protest in the disaster-hit region, with opposition to nuclear power running at an all time high in Japan.

The Kumamoto disaster comes five years after a major earthquake struck the northern Tohoku region of Japan on March 11, 2011, triggering a major tsunami, the world’s worst nuclear crisis in decades at Fukushima power plant.

News of the nuclear reactor situation came as rescue efforts continued across the Kumamoto region, which has been rattled by more than 500 aftershocks since last week’s earthquakes.

The United States military was due to join the relief efforts of 30,000-plus rescue service personnel who were rushing to provide food, water and shelter to more than 100,000 people who remained in shelters yesterday.

“There are still missing people,” Shinzo Abe, the prime minister, told parliament, as he outlined plans to declare the region a disaster zone as soon as possible. “We want to make further efforts to rescue and save people and prioritise human lives.”

Infrastructure was hit badly in the quakes, with the widespread destruction of roads and bridges, plus at least one mountain highway reportedly severed into two, causing concrete to tumble into a green valley below.

Around 1,000 homes were damaged in the two earthquakes, which also left around 80,000 households without electricity and 400,000 with no running water.

Transport is another challenge across the mountainous region, which suffered extensive mudslides in the earthquakes, with commercial flights to damaged Kumamoto airport cancelled and bullet train services suspended.

In addition to the race to find missing residents believed to be trapped under the rubble of collapsed buildings, food shortages were a key concern among rescue workers.

“Yesterday, I ate just one piece of tofu and a rice ball. That’s all,” the mayor of one of the areas affected told Reuters. “What we’re most worried about now is food. There’s no electricity or water, either.”

In a reflection of Kumamoto’s status as a manufacturing hub, the earthquakes have forced a string of major companies to temporarily close factories, resulting in parts shortages causing halted production elsewhere in Japan.

Toyota, the world’s biggest selling automaker, will suspend much of its plant production across Japan this week due to shortages of parts, while Honda also stopped production at its motorcycle plant near Kumamoto city.

Sony, the electronics giant, also halted production at its Kumamoto plant producing image sensors – used in Apple’s iPhone camera – as the damage was assessed, although there were full operations at other Kyushu plants making the sensors.

April 21, 2016 Posted by | Japan | , | Leave a comment

600 plus earthquakes in 5 days,nuclear plants said to be safe

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From April 14th to April 19th 2016, 665 earthquakes : 72 were above magnitude 4, 10 above magnitude 5, 6 above magnitude 6, 1 above magnitude 7. But the Japan Nuclear Regulation Authority tells us that the 3 nuclear plants in Southern Japan,  the Sendai nuclear power plant, the Genkai nuclear power plant and the Ikata nuclear power plant, are safe depite more than 600 earhquakes within 5 days, out of which 89 were above magnitude 4.

The Japan Nuclear Regulation Authority tells us that the 3 nuclear plants in Southern Japan,  the Sendai nuclear power plant, the Genkai nuclear power plant and the Ikata nuclear power plant, are safe depite more than 600 earhquakes within 5 days, out of which 89 were above magnitude 4.

Questions and answers: The Kumamoto earthquakes

The series of huge earthquakes and aftershocks that have been rattling wide parts of Kumamoto and Oita prefectures since Thursday have raised fears that other regions in the nation might be struck by similar jolts in the near future.

Here are some questions and answers on seismic activity in Japan:

What type of earthquakes struck Kumamoto?

The 2016 Kumamoto Earthquake is actually a series of quakes that are being caused by two plates slipping against each other along an active inland fault. The events take place at a relatively shallow depth and cause the destruction of bedrock.

It is the same type as the Great Hanshin Earthquake of 1995 that hit Kobe and surrounding cities, killing over 6,000 people.

In contrast, the Great East Japan Earthquake that hit the Tohoku region in 2011, was caused by accumulated stress resulting from one tectonic plate being forced underneath another, resulting in what is called a “megathrust quake.”

What is unique about the 2016 Kumamoto Earthquake?

Whereas often a huge temblor hits first, followed by smaller aftershocks, a number of strong quakes have occurred following the first magnitude-6.5 quake on Thursday. The shaking has affected much wider areas than other quakes in the past, experts said.

The magnitude-7.3 quake that according to the Meteorological Agency was the main tremor struck the region 1½ days after the first one.

Why did we see such big quakes in relatively rapid succession?

Experts say the reason is not entirely known.

Of the 2,000 active faults around Japan, some 100 are designated by the government as key active faults. The Futagawa and Hinagu faults, along which the recent quakes occurred, are among the 100 most active and dangerous faults in the country.

The central government has conducted research on these 100 active faults over the past decade or so but was not able to predict the quakes that took place in Kumamoto, said Hiroyuki Fujiwara, a seismologist at National Research Institute for Earth Science and Disaster Prevention.

Are the focal points of quakes moving or expanding?

Fujiwara said the magnitude-7.3 quake on Saturday caught seismologists by surprise as they thought the initial quake — which turned out to be a precursor for Saturday’s — was an isolated tremor in a small section of the Futagawa fault.

Other quakes then took place further east. Some researchers say quakes may take place in succession along the lines of long faults, but no solid theory to explain such a scenario has been found, Fujiwara said.

Are these quakes precursors for others, especially along the Median Tectonic Line — the largest fault running from central Honshu to Kyushu?

Experts are not sure.

“We can explain what has happened, but it’s really hard to say what will happen,” Fujiwara said.

Takeshi Sagiya, a professor at Nagoya University’s Disaster Mitigation Research Center and an expert on crustal movement, said it is too early to worry about such a scenario.

Sagiya said he is more concerned about the southwestern side of the Hinagu fault in Kumamoto, where seismic activities appear to have been spreading in recent days.

A level-6 quake on the Japanese intensity scale of 7 may hit the fault in the near future, Sagiya said.

Is the small eruption of Mount Aso on Saturday related to the quake?

The view of volcanologists, as well as the Meteorological Agency, has been that the eruption was not triggered by the Kumamoto quakes, as its characteristics are no different from small-scale eruptions that have taken place before.

“There is probably no causal connection” between the earthquakes and the eruption, Chief Cabinet Secretary Yoshihide Suga told a news conference Saturday. “But we will keep monitoring (the volcano).”

Are the quakes in Kyushu and the magnitude-7.8 quake that hit Ecuador over the weekend — the largest since 1979 — related?

Fujiwara said they are not.

“The two locations are so far away from each other it’s impossible to suspect a link,” he said.

Are nuclear power plants in Kyushu safe?

Many citizens and anti-nuclear activists have expressed concern over the nuclear power facilities in Kyushu, in particular the two reactors running at the Sendai power plant in Kagoshima Prefecture, the only commercial nuclear plant now in operation in Japan.

The Nuclear Regulation Authority, however, has maintained that the Sendai plant does not need to be shut down because the strongest temblor registered at the plant since Thursday night was 8.6 gal (a unit used in seismology to express the acceleration of an earthquake), far lower than the safety level that would trigger an automatic reactor shutdown.

The criteria was set between 80 to 260 gal, depending on the direction of a shake and the strength of key components in the Sendai reactors.

All other reactors have been stopped in the wake of the 2011 Fukushima meltdown crisis, while power companies have applied for the NRA’s safety checks to restart many other reactors under the new safety standards drawn up after the Fukushima crisis.

At the Genkai nuclear power plant in Saga Prefecture, the strongest of the recent shakes was 20.3 gal. The reactors at the plant have long been shut down, but had they been active, they would be automatically shut down with a temblor of between 70 and 170 gal.

The Ikata nuclear power plant in Ehime Prefecture, which is also undergoing safety checks, is right by the Median Tectonic Line. The three reactors there have not shown abnormal activity since the quakes, according to Shikoku Electric Power Co. and the Ehime Prefectural Government.


April 21, 2016 Posted by | Japan | , | Leave a comment

End the nuclear ‘safety myth’

The International Atomic Energy Agency’s final report on the March 2011 triple meltdowns at Tokyo Electric Power Co.’s Fukushima No. 1 nuclear power plant puts the main blame on the then prevailing assumption that Japan’s “nuclear power plants were so safe that an accident of this magnitude was simply unthinkable.” Constant monitoring is needed to make sure the government, power companies and nuclear regulatory authorities aren’t falling into the same “safety myth” as they push to reactivate idled reactors that meet what is now touted as the “world’s most stringent” nuclear safety standards.

Last week, Kyushu Electric Power Co. began commercial operation of the No. 1 reactor of its Sendai nuclear power plant in Satsumasendai, Kagoshima Prefecture — a little over a month after it became the first reactor idled since 2011 to be reactivated on the basis of the safety standards that were tightened in response to the Fukushima disaster. The utility plans to restart the plant’s No. 2 reactor as early as next month, and the Abe administration and the power industry are pushing to bring more idled plants back online once they have cleared the Nuclear Regulation Authority’s screening.

The regulatory system for nuclear power generation has been reformed since the 2011 crisis. The old Nuclear and Industrial Safety Agency, which came under fire for the Fukushima debacle, has been replaced by the NRA, and new regulations introduced in 2013 require operators of nuclear power plants to beef up their defense against natural disasters such as major earthquakes and tsunamis. But while the NRA itself states that compliance with the new standards does not guarantee the plants’ safety, the government says the plants are ready for restart because they meet the NRA criteria. No one appears ready to take final responsibility for the plants’ safety.

The IAEA report, compiled by around 180 experts from 42 countries and submitted to an annual general conference of the United Nations nuclear watchdog this week, highlights the “assumption” held by Japan’s nuclear plant operators prior to 2011 that a crisis of that magnitude would not happen, which was never challenged by the government or regulatory authorities, leaving the nation unprepared for a severe accident.

The Fukushima power plant lost its emergency power supply after it was flooded by a 15-meter tsunami triggered by the magnitude-9 quake on March 11, 2011. The loss of power crippled its crucial core-cooling functions and led to the meltdowns in its three operating reactors. Citing Tepco’s failure to take precautionary action against such external hazards despite an estimate prior to the disaster that a powerful quake off Fukushima could cause a tsunami of roughly the same scale that hit the plant site, the report said “there was not sufficient consideration of low probability, high consequence external events,” partly because “of the basic assumption in Japan, reinforced over many decades, that the robustness of the technical design of the nuclear plants would provide sufficient protection against postulated risks.” This assumption led to “a tendency for organizations and their staff not to challenge the level of safety” and “resulted in a situation where safety improvements were not introduced promptly.”

The report also pointed to the deficiencies in Japan’s nuclear regulatory system behind the Fukushima disaster. “The regulation of nuclear safety in Japan at the time of the accident was performed by a number of organizations with different roles and responsibilities and complex interrelationships. It was not fully clear which organizations had the responsibility and authority to issue binding instructions on how to respond to safety issues without delay,” it said. “The regulations, guidelines and procedures in place at the time of the accident were not fully in line with international practice in some key areas, most notably in relation to periodic safety reviews, re-evaluation of hazards, severe accident management and safety culture.”

IAEA Director General Yukiya Amano, in his foreword to the report, says Japan’s regulatory system has since been reformed to meet international standards, with regulators given clearer responsibilities and greater authority. Whether the new plant safety standards are the world’s most stringent or not, plants that meet the standards are supposed to withstand much greater levels of external hazards and be better able to respond to emergencies than before.

Still, complacency under the new standards would risk reviving the same safety myth rebuked in the report. Questioning whether the tightened standards are sufficient could be branded as demanding zero tolerance of risks and thereby unrealistic. However, as the IAEA report points out, it was an “unlikely combination of events” that hit the Tepco plant, and the utility’s unpreparedness for such a situation that resulted in the 2011 disaster.

We need to consider whether the tendency to dismiss low-probability risks as “small enough” — as was, for example, the risk of Kyushu Electric’s Sendai plant being hit by a volcanic eruption when the go-ahead was given for its restart — is acceptable from the viewpoint of preventing severe accidents at nuclear plants in the future.

Source: Japan Times

September 18, 2015 Posted by | Japan | , , | Leave a comment