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This article is more than 2 years old

Extremely high radiation levels have been recorded inside a damaged reactor at the Fukushima Daiichi nuclear power station, almost six years after the plant suffered a triple meltdown.



The facility’s operator, Tokyo Electric Power (Tepco), said atmospheric readings as high as 530 sieverts an hour had been recorded inside the containment vessel of reactor No 2, one of three reactors that experienced a meltdown when the plant was crippled by a huge tsunami that struck the north-east coast of Japan in March 2011.

The extraordinary radiation readings highlight the scale of the task confronting thousands of workers, as pressure builds on Tepco to begin decommissioning the plant – a process that is expected to take about four decades.

Even if a 30-percent margin of error is taken into account, the recent reading, described by some experts as “unimaginable”, is far higher than the previous record of 73 sieverts an hour detected by sensors in 2012.

Tepco pointed out, however, that the camera had probed deeper inside the reactor than before and had focused on a single point. Radiation levels at other spots filmed by the camera are estimated to be much lower, it added.



A single dose of one sievert is enough to cause radiation sickness and nausea; 5 sieverts would kill half those exposed to it within a month, and a single dose of 10 sieverts would prove fatal within weeks.

Tepco also said image analysis had revealed a hole in metal grating beneath the same reactor’s pressure vessel. The one-metre-wide hole was probably created by nuclear fuel that melted and then penetrated the vessel after the tsunami knocked out Fukushima Daiichi’s back-up cooling system.

“It may have been caused by nuclear fuel that would have melted and made a hole in the vessel, but it is only a hypothesis at this stage,” Tepco’s spokesman Tatsuhiro Yamagishi told AFP.

“We believe the captured images offer very useful information, but we still need to investigate given that it is very difficult to assume the actual condition inside.”

The presence of dangerously high radiation will complicate efforts to safely dismantle the plant.

A remote-controlled robot that Tepco intends to send into the No 2 reactor’s containment vessel is designed to withstand exposure to a total of 1,000 sieverts, meaning it would survive for less than two hours before malfunctioning.

The firm said radiation was not leaking outside the reactor, adding that the robot would still prove useful since it would move from one spot to the other and encounter radiation of varying levels.

Tepco and its network of partner companies at Fukushima Daiichi have yet to identify the location and condition of melted fuel in the three most seriously damaged reactors. Removing it safely represents a challenge unprecedented in the history of nuclear power.

Quantities of melted fuel are believed to have accumulated at the bottom of the damaged reactors’ containment vessels, but dangerously high radiation has prevented engineers from accurately gauging the state of the fuel deposits.

Earlier this week, the utility released images of dark lumps found beneath reactor No 2 that it believes could be melted uranium fuel rods – the first such discovery since the disaster.

In December, the government said the estimated cost of decommissioning the plant and decontaminating the surrounding area, as well as paying compensation and storing radioactive waste, had risen to 21.5tn yen (£150bn), nearly double an estimate released in 2013.

This article was amended on 9 February to explain that the camera had probed deeper inside the No 2 reactor – and closer to the damaged nuclear fuel – than before, hence the high radiation estimate.</s>Radiation levels inside a damaged reactor at the Fukushima Daiichi nuclear power station are at their highest since the plant suffered a triple meltdown almost six years ago.The facility’s operator, Tokyo Electric Power (Tepco), said atmospheric readings as high as 530 sieverts an hour had been recorded inside the containment vessel of reactor No 2, one of three reactors that experienced a meltdown when the plant was crippled by a huge tsunami that struck the north-east coast of Japan in March 2011.</s>The level of nuclear radiation detected at the troubled Fukushima nuclear plant in Japan spiked on Thursday to its highest level since the triple core meltdown in 2011.

In March 2011, multiple reactors at the Fukushima Daiichi power plant spiraled out of control after a 42-foot tsunami overwhelmed the plant’s sea walls, rendering the vital systems used to cool the plant’s six reactors inoperable. Ultimately, fuel meltdowns occurred at three reactors, releasing vast amounts of radioactive matter and resulting in the world’s worst nuclear disaster since Chernobyl.

On Thursday, the Tokyo Electric Power Company (TEPCO), the investor owned utility that operates the Fukushima reactors, reported that it detected a radiation level of 530 sieverts per hour in the containment vessel of reactor 2 at the Fukushima No. 1 power plant.

A sievert is a measure of the health effect of low levels of ionizing radiation on the human body.

Even a brief exposure to 530 sieverts of radiation would kill a person. Exposure to only one sievert is enough to result in infertility, loss of hair and cataracts. According to the National Institute of Radiological Sciences, exposure to a mere four sieverts of radiation would typically be lethal for one out of every two people. The highest level of radiation detected previously at the Fukushima reactor was 73 sieverts per hour.

According to the Japan Times, the reading was taken near the entrance to the space just below the pressure vessel, which contains the reactor core. The extremely high radiation levels suggest that some of the melted fuel that escaped the pressure vessel is nearby.

TEPCO had planned to deploy a remote-controlled robot to assess conditions inside the containment vessel. But, considering the extreme radiation levels, it is unclear whether it will be able to do so.

The robot is designed to withstand exposure of up to 1,000 sieverts. Based on the calculation of 73 sieverts per hour, the robot could run for more than 10 hours, but 530 sieverts per hour means it would be rendered inoperable in less than two hours.

William Pentland is a Partner at Brookside Strategies, LLC, a consulting firm in Portland, Maine that focuses on issues in utility regulation, market strategy and energy policy.</s>Leaked fuel in a reactor containment vessel is believed to be releasing deadly radiation within the Fukushima Daiichi Nuclear Power Plant, the Nikkei Asian Review reported Friday.

The discovery was made in January when plant operator Tokyo Electric Power Company (Tepco) conducted an inspection of the containment vessel in the No. 2 reactor, Nikkei added. A camera used in the inspection captured images of a 1-square meter hole melted into a walkway below the pressure vessel.

The Fukushima Daiichi plant was badly damaged after a massive quake struck the north-eastern coast of Japan in March, 2011, knocking out its cooling systems and causing a meltdown. However, a recent study showed that radiation levels at the plant were lower than previously expected and plenty continue to live in close proximity to the disaster site.</s>The Fukushima nuclear power plant’s (NPP) operator has detected extremely high radiation levels at a damaged reactor at the Fukushima power plant in Japan.

Radiation levels that are lethal after brief exposure were found inside the second reactor on Thursday

Tokyo Electric Power Company also found a hole which was likely caused by melted nuclear fuel was also discovered at the reactor.

Radiation levels of up to 530 Sieverts per hour were detected inside an inactive Reactor 2 at the Fukushima Daiichi nuclear complex damaged during the 2011 earthquake and tsunami catastrophe, Japanese media reported on Thursday citing the plant operator, Tokyo Electric Power Company (TEPCO).

A dose of about 8 Sieverts is considered incurable and fatal.

A hole of no less than one square meter in size has also been discovered beneath the reactor’s pressure vessel, TEPCO said. According to researchers, the apparent opening in the metal grating of one of three reactors that had melted down in 2011, is believed to be have been caused by melted nuclear fuel that fell through the vessel.

The iron scaffolding has a melting point of 1500 degrees, TEPCO said, explaining that there is a possibility the fuel debris has fallen onto it and burnt the hole. Such fuel debris have been discovered on equipment at the bottom of the pressure vessel just above the hole, it added.

The latest findings were released after a recent camera probe inside the reactor, TEPCO said. Using a remote-controlled camera fitted on a long pipe, scientists managed to get images of hard-to-reach places where residual nuclear material remained. The substance there is so toxic that even specially-made robots designed to probe the underwater depths beneath the power plant have previously crumbled and shut down.

However, TEPCO still plans to launch further more detailed assessments at the damaged nuclear facility with the help of self-propelled robots.

Earlier this week, hopes for a more efficient cleanup at Fukushima were high, as the plant operator announced a portion of nuclear fuel debris responsible for a lot of the lingering contamination from six years ago may have finally been found.</s>An area of the Fukushima Daiichi nuclear plant is showing record levels of radiation, the highest since the complex suffered a nuclear meltdown initiated by a tsunami in 2011. The plant operator Tokyo Electric Power Company (Tepco) announced that the containment vessel of the No 2 reactor showed radiation levels of up to 530 sieverts per hour, which can kill a human in under a minute.

Previous analysis of the area back in 2012 showed records of 73 sieverts per hour in the same area. The new discovery, which was made on 30 January, is based on images captured by three manned cameras which were mounted on a robot to gather information about the state of the reactor.

Images also indicated a hole below the pressure vessel, Nekkei Asian Review reported. According to Tepco, the hole may have been the result of nuclear fuel that entered the vessel as it overheated. Loss of reactor cooling functions in the days following the tsunami could have led to the melting of the walkway.

"It may have been caused by nuclear fuel that would have melted and made a hole in the vessel, but it is only a hypothesis at this stage," Tepco spokesman Tatsuhiro Yamagishi told AFP on 3 February.

"We believe the captured images offer very useful information, but we still need to investigate given that it is very difficult to assume the actual condition inside."

The radiation levels could effectively shut down TEPCO's robots that are being used for the investigation in under two hours, AFP reported. However, the operators plan to extend the probe and check conditions by sending a robot to the bottom of the reactor containment vessel.

The Fukushima plant suffered three meltdowns as a result of the tsunami on 11 March, 2011 which destroyed the emergency generators which provided power to cool the reactors. The accident led to one of the worst nuclear disasters since Chernobyl in 1986, and last year, researchers were able to detect radiation from the site all the way in Oregon, USA.</s>A crisis at Tokyo Electric Power's Fukushima Daiichi nuclear plant, where an earthquake and tsunami in March last year triggered radiation leaks, has hammered public faith in nuclear power and prevented the restart of reactors shut down for regular maintenance checks.

Hokkaido Electric said it started lowering output from the 912-megawatt No.3 unit at Tomari nuclear plant in northern Japan at 5 p. m. (0800 GMT).

The maintenance on the unit is set to begin at around 11 p.m. (1400 GMT) when power generation falls to zero, with the unit to be shut down completely by the early hours of Sunday.

The shutdown means all of Japan's 50 reactors have been taken off line, marking the country's first nuclear power-free day since May 1970.

Trade Minister Yukio Edano and three other ministers have been trying to win the support of communities to reactivate two idled reactors at Kansai Electric Power's Ohi nuclear plant to help ease expected power shortages of nearly 20 percent in coming hot-weather months.

The two Ohi reactors are the first to be considered for reactivation by the central government, but it faces an uphill battle of winning public support.

Kansai Electric's expected deficit for this summer was the highest among four Japanese nuclear plant operators that forecast shortfalls when demand peaks in the summer.

The last time Japan was nuclear power-free was for five days to May 4, 1970, when the two reactors then existing were shut for maintenance, according to the Federation of Electric Power Companies of Japan. (Reporting by Osamu Tsukimori; Editing by Jeremy Laurence)</s>Three former executives from Tokyo Electric Power (Tepco) have been charged with contributing to deaths and injuries stemming from the triple meltdown in 2011 at the Fukushima Daiichi nuclear power plant.

Their indictment on Monday marks the start of the first criminal action to be taken in connection with the disaster, which forced the evacuation of 160,000 residents, many of whom are still unable to return to their homes.

Tsunehisa Katsumata, who was Tepco’s chairman at the time, has been charged with professional negligence resulting in death, along with two former vice-presidents, Sakae Muto and Ichiro Takekuro.

The men, who have not been taken into custody, allegedly failed to take measures to defend Fukushima Daiichi, despite being aware of the risk from a tsunami.

Three of the plant’s six reactors went into meltdown after a magnitude-9 earthquake triggered a tsunami along the north-east coast of Japan on 11 March 2011. The waves flooded the facility’s back-up power supply and crippled the reactors’ cooling systems, causing massive radiation leaks.

Experts say prosecutors could struggle to prove criminal responsibility for failing to prevent the meltdown. The trial, which is not expected to begin until next year, could reveal information about the disaster that Tepco has yet to make public.

Japan’s public broadcaster, NHK, said the three former executives would plead not guilty to the charges and argue that it was impossible to predict the size of the tsunami.

An independent judicial panel of citizens ruled last July that the men should go on trial, after public prosecutors had twice decided not to pursue the case.

The 11-member panel, which has the power to compel prosecutors to act, said Katsumata, 75, Muto, 65, and Takekuro, 69, should be held criminally responsible for the deaths of 44 elderly hospital patients during and soon after the evacuation, and injuries to Tepco staff and members of the self-defence forces.

Campaigners called the indictments “a major step”, and called on Japan to abandon nuclear power.

“The people of Fukushima and Japan deserve justice,” said Hisayo Takada of Greenpeace Japan. “The court proceedings that will now follow should reveal the true extent of Tepco’s and the Japanese regulatory system’s enormous failure to protect the people of Japan.

“Tepco and the Japanese regulator continue to ignore demands to disclose key details of what they know about the causes of the accident. The 100,000 people who still can’t return home deserve to have all the facts.”

Of the country’s 43 working reactors, four have been restarted since last year, while the remainder are undergoing repairs and checks under stricter post-Fukushima safety regulations.

Reports by the government and MPs have been strongly critical of the safety culture at Tepco, and of lax oversight by the government and regulators.



Last year, the International Atomic Energy Agency pointed to a misguided faith in the safety of nuclear power as a key factor in the Fukushima accident. A 2012 parliamentary report said Fukushima was a “manmade disaster” caused by poor regulation and collusion between the government, Tepco and the industry’s watchdog.

Tepco has insisted it was impossible to anticipate a tsunami of the size that struck the plant almost five years ago. The judicial panel said, however, that the executives ignored a 2008 internal report predicting that the plant could be struck by tsunami as high as 15.7 metres, adding that they had “failed to take pre-emptive measures, knowing the risk of a major tsunami”.

Only last week, the utility admitted it had failed to announce that meltdowns had occurred in three Fukushima Daiichi reactors until two months after the accident.

Tepco said it had been unaware of a company emergency manual that defined a meltdown as damage to more than 5% of the fuel inside a reactor. For weeks, the firm said the reactors had sustained less serious “core damage”.

The nuclear and industrial safety agency, the industry watchdog at the time, also refused to describe the accident as a meltdown.

Tepco only started using the word meltdown May 2011, after a computer simulation showed fuel in one reactor had almost entirely melted and fallen to the bottom of the primary containment chamber, and that two other reactor cores had melted significantly.

The firm conceded its initial wording had been misleading, but insisted it had responded appropriately.

“Core damage or meltdown, it didn’t make any difference in how we responded to the emergency, which was to cool the cores no matter what,” said Tepco spokesman Shinichi Nakakuki.</s>Japanese power wholesaler Electric Power Development Co , known as J-Power, said on Friday that it is shelving a planned November 2014 start date for commercial operation at its Ohma nuclear plant.

J-Power said it does not know when commerical operation will begin at the plant in Aomori prefecture, northern Japan. The power wholesaler stopped construction work on the nuclear plant on March 12, 2011, the day after a magnitude 9.0 quake and tsunami hit Japan's northeast. (Reporting by Risa Maeda; Editing by Edmund Klamann)</s>A record radiation level has been detected inside the No. 2 reactor at the damaged Fukushima Daiichi nuclear complex, with the estimated reading of up to 530 sieverts per hour, the plant operator said Thursday.

The reading means a person could die from even brief exposure, highlighting the difficulties ahead as the government and Tokyo Electric Power Company Holdings Inc grope their way toward dismantling all three reactors that melted down in the March 2011 nuclear disaster.

The plant operator also announced that based on an image analysis, a 1-square-meter hole has been found on a metal grating beneath the reactor pressure vessel, likely caused by melted nuclear fuel that fell through the vessel.

The new radiation level, described by some experts as “unimaginable,” far exceeds 73 sieverts per hour, the previously highest radiation reading monitored in the interior of the reactor.

An official of the National Institute of Radiological Sciences said medical professionals have never considered dealing with this level of radiation in their work.

According to TEPCO, the extremely high radiation level was detected inside the containment vessel, in the space around 2.3 meters away from the base of the reactor pressure vessel.

According to the institute, 4 sieverts of radiation exposure would kill one in two people.

Experts say 1,000 millisieverts, which equals 1 sievert, could lead to infertility, loss of hair and cataracts, while exposure to radiation doses above 100 sieverts increases the risk of cancer.

The latest discovery spells difficulty in removing the fuel debris as part of decommissioning work at the plant. The government and TEPCO hope to locate the fuel and start removing it from a first reactor in 2021.

The debris is believed to have been created as nuclear fuel inside the reactor pressure vessel overheated and melted due to the loss of reactor cooling functions.

In the coming weeks, the plant operator plans to deploy a remote-controlled robot to check conditions inside the containment vessel, but the utility is likely to have to change its plan.

For one thing, it will have to reconsider the route the robot is to take to probe the interior because of the hole found on the grating.

Also, given the extraordinary level of radiation inside the containment vessel, the robot would only be able to operate for less than two hours before it is destroyed.

That is because the robot is designed to withstand exposure to a total of up to 1,000 sieverts of radiation. Based on the calculation of 73 sieverts per hour, the robot could have operated for more than 10 hours, but 530 sieverts per hour means the robot would be rendered inoperable in less than two hours.

The latest analysis follows TEPCO’s discovery Monday of a black mass deposited on the grating directly beneath the pressure vessel, possibly melted fuel after the unit suffered a meltdown along with two other reactors at the six-reactor plant.

Images captured using a camera attached to a telescopic arm on Monday also showed part of the grating has gone.

If the deposits are confirmed as fuel debris, it would be the first time the utility has found any at the three units that suffered meltdowns.

Following the world’s worst nuclear disaster since the 1986 Chernobyl catastrophe, the plant’s No. 1 to 3 reactors suffered fuel meltdowns.

Portions of the fuel in the reactors are believed to have accumulated at the bottom of the containment vessels. But the actual condition of the melted fuel remains unknown due to high radiation levels.
According to Tokyo Electric Power Company, radiations levels within one of the reactors of Fukushima Daiichi Nuclear Power Plant, damaged by an earthquake and tsunami in 2011, are at its highest level since experiencing a meltdown, with a reading of 530 sieverts an hour.