company:tokyo electric power co.

Six Years After Fukushima, Robots Finally Find Reactors’ Melted Uranium Fuel - The New York Times
▻https://www.nytimes.com/2017/11/19/science/japan-fukushima-nuclear-meltdown-fuel.html

https://static01.nyt.com/images/2017/11/21/science/21SCI-FUKUSHIMA4/21SCI-FUKUSHIMA4-facebookJumbo.jpg

Now that engineers say they have found the fuel, officials of the government and the utility that runs the plant hope to sway public opinion. Six and a half years after the accident spewed radiation over northern Japan, and at one point seemed to endanger Tokyo, the officials hope to persuade a skeptical world that the plant has moved out of post-disaster crisis mode and into something much less threatening: cleanup.

“Until now, we didn’t know exactly where the fuel was, or what it looked like,” said Takahiro Kimoto, a general manager in the nuclear power division of the plant’s operator, Tokyo Electric Power Co., or Tepco. “Now that we have seen it, we can make plans to retrieve it.”

Tepco is keen to portray the plant as one big industrial cleanup site. About 7,000 people work here, building new water storage tanks, moving radioactive debris to a new disposal site, and erecting enormous scaffoldings over reactor buildings torn apart by the huge hydrogen explosions that occurred during the accident.

C’est beau la com’ du nucléaire

At the plant’s entrance, a sign warned: “Games like Pokemon GO are forbidden within the facility.”

“We have finished the debris cleanup and gotten the plant under control,” said the guide, Daisuke Hirose, a spokesman for Tepco’s subsidiary in charge of decommissioning the plant. “Now, we are finally preparing for decommissioning.”

In September, the prime minister’s office set a target date of 2021 — the 10th anniversary of the disaster — for the next significant stage, when workers begin extracting the melted fuel from at least one of the three destroyed reactors, though they have yet to choose which one.

#Nucléaire #Fukushima #Propagande #Robots

Japan’s 17,000 Tons of Nuclear Waste in Search of a Home - Bloomberg Business
▻http://www.bloomberg.com/news/articles/2015-07-10/japan-s-17-000-tons-of-nuclear-waste-in-search-of-a-home

http://assets.bwbx.io/images/iOMkrxWDNlRA/v2/-1x-1.jpg

It will need billions of dollars and technology not yet invented to clean up Fukushima. How long that will take is disputed. The operator, Tokyo Electric Power Co., estimates 40 years. Greenpeace says it could take twice that time. (...)

Now facing the accelerated shutdown of some reactors post-Fukushima, NUMO in May ditched the idea of waiting for a volunteer. Instead, scientists will nominate suitable regions.

(...) It would contain about 40,000 canisters, each weighing half a ton and holding waste at temperatures above 200 degrees Celsius (392 Fahrenheit). The contents would give off 1,500 sieverts of radiation an hour, a level that would instantly kill a human being.

The canisters need to cool in interim storage for as long as 50 years before heading 300 meters below ground. Their stainless steel inner layer is wrapped in bentonite clay to make sure water can’t leak inside.

je sais pas pourquoi, cette histoire m’évoque Le Salaire de la peur

#nucléaire #pollution #Fukushima

Japan utility admits nuclear crisis avoidable - World - CBC News
►http://www.cbc.ca/news/world/story/2012/10/12/japan-nuclear-tokyo-electric.html

Tokyo Electric Power Co. said in a statement issued Friday that it had known safety improvements were needed before last year’s tsunami triggered three meltdowns, but it had feared the political, economic and legal consequences of implementing them.

#nucléaire #japon #fukushima

Japan’s ’nuclear gypsies’ face radioactive peril at power plants - latimes.com
►http://www.latimes.com/news/nationworld/world/la-fg-japan-nuclear-gypsies-20111204,0,347252.story

Temporary workers at the #Fukushima plant in 2010 also faced radiation levels 16 times higher than did employees of the plant’s owner-operator, Tokyo Electric Power Co., because contractors are called in for the most dangerous work, according to the government’s industrial safety agency.

“This job is a death sentence, performed by workers who aren’t being given information about the dangers they face,” said Hiroaki Koide, an assistant professor at Kyoto University’s Research Reactor Institute and author of the book “The Lie of Nuclear Power.”

#nucléaire #japon #travail

TEPCO: Radioactive substances belong to landowners, not us - AJW by The Asahi Shimbun
►http://ajw.asahi.com/article/behind_news/social_affairs/AJ201111240030

During court proceedings concerning a radioactive golf course, Tokyo Electric Power Co. stunned lawyers by saying the utility was not responsible for decontamination because it no longer “owned” the radioactive substances.

“Radioactive materials (such as cesium) that scattered and fell from the Fukushima No. 1 nuclear plant belong to individual landowners there, not TEPCO,” the utility said.

#nucléaire #propriété

Inside Japan’s Fukushima Nuclear Power Station
►http://blogs.denverpost.com/captured/2011/11/14/inside-japans-fukushima-nuclear-reactor/5085

Associated Press photographer David Guttenfelder, along with other reporters, was allowed inside the Fukushima nuclear power station to witness the devastation, for the first time, caused by Japan’s March 12th earthquake and tsunami.

http://denverpost.slideshowpro.com/albums/001/496/album-281158/cache/powerplant043.sJPG_950_2000_0_75_0_50_50.JPG

The Unit 4 reactor building at the crippled Tokyo Electric Power Co. (Tepco) Fukushima Dai-Ichi nuclear power station is seen through a bus window in Okuma Town, Fukushima Prefecture, Japan, on Saturday, Nov. 12, 2011. Tepco is struggling to contain the worst nuclear disaster in 25 years. Photographer: David Guttenfelder/Pool via Bloomberg

#Fukushima Desolation Worst Since Nagasaki as Residents Flee - Bloomberg
►http://www.bloomberg.com/news/2011-09-26/fukushima-desolation-worst-since-nagasaki-as-population-flees.html

What’s emerging in Japan six months since the nuclear meltdown at the Tokyo Electric Power Co. plant is a radioactive zone bigger than that left by the 1945 atomic bombings at Hiroshima and Nagasaki. While nature reclaims the 20 kilometer (12 mile) no-go zone, Fukushima’s $3.2 billion-a-year farm industry is being devastated and tourists that hiked the prefecture’s mountains and surfed off its beaches have all but vanished.
(...)
The bulk of radioactive contamination cuts a 5 kilometer to 10 kilometer-wide swath of land running as far as 30 kilometers northwest of the nuclear plant, surveys of radiation hotspots by Japan’s science ministry show. The government extended evacuations beyond the 20-kilometer zone in April to cover this corridor, which includes parts of Iitate village.

voir aussi la #carte de la radioactivité :
►http://radioactivity.mext.go.jp/ja/distribution_map_around_FukushimaNPP/0002/11555_0830.pdf

#nucléaire #cartographie #japon

Two Other Nuclear Reactors Suffer Serious Damage - WSJ.com

By MITSURU OBE

TOKYO—Substantial damage to the fuel cores at two additional reactors of Japan’s Fukushima Daiichi nuclear complex has taken place, operator Tokyo Electric Power Co. said Sunday, further complicating the already daunting task of bringing them to a safe shutdown while avoiding the release of high levels of radioactivity. The revelation followed an acknowledgment on Thursday that a similar meltdown of the core took place at unit No. 1.

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0515tepco
European Pressphoto Agency

Junichi Matsumoto, an official of Tokyo Electric Power Co. listens to questions during a press conference regarding the meltdown of Fukushima Daiichi nuclear power plant at the company headquarters in Tokyo, Japan, May 13, 2011.
0515tepco
0515tepco

The operator of Japan’s stricken nuclear plant is using remote-controlled robots inside reactor buildings damaged by a hydrogen explosions to gauge radiation and temperature levels. Video courtesy of AFP and image courtesy of Associated Press.

Workers also found that the No. 1 unit’s reactor building is flooded in the basement, reinforcing the suspicion that the containment vessel is damaged and leaking highly radioactive water.

The revelations are likely to force an overhaul of the six- to nine-month blueprint for bringing the reactors to a safe shutdown stage and end the release of radioactive materials. The original plan, announced in mid-April, was due to be revised May 17.

The operator, known as Tepco, said the No. 1 unit lost its reactor core 16 hours after the plant was struck by a magnitude-9 earthquake and a giant tsunami on the afternoon of March 11.

The pressure vessel a cylindrical steel container that holds nuclear fuel, “is likely to be damaged and leaking water at units Nos. 2 and 3,” said Junichi Matsumoto, Tepco spokesman on nuclear issues, in a news briefing Sunday.

He also said there could be far less cooling water in the pressure vessels of Nos. 2 and 3, indicating there are holes at the bottom of these vessels, with thousands of tons of water pumped into these reactors mostly leaking out.

Tepco found the basement of the unit No. 1 reactor building flooded with 4.2 meters of water. It isn’t clear where the water came from, but leaks are suspected in pipes running in and out of the containment vessel, a beaker-shaped steel structure that holds the pressure vessel.

Additional nuclear evacuations begin outside a 30 kilometer exclusion zone on fears of high levels of accumulated radiation. Video courtesy of Reuters and photo courtesy of Getty Images.

The water flooding the basement is believed to be highly radioactive. Workers were unable to observe the flooding situation because of strong radiation coming out of the water, Tepco said.

A survey conducted by an unmanned robot Friday found radiation levels of 1,000 to 2,000 millisieverts per hour in some parts of the ground level of unit No. 1, a level that would be highly dangerous for any worker nearby. Japan has placed an annual allowable dosage limit of 250 millisieverts for workers.

The high level of radioactivity means even more challenges for Tepco’s bid to set up a continuous cooling system that won’t threaten radiation leaks into the environment.
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Tepco separately released its analysis on the timeline of the meltdown at unit No. 1. According to the analysis, the reactor core, or the nuclear fuel, was exposed to the air within five hours after the plant was struck by the earthquake. The temperature inside the core reached 2,800 degrees Celsius in six hours, causing the fuel pellets to melt away rapidly.

Within 16 hours, the reactor core melted, dropped to the bottom of the pressure vessel and created a hole there. By then, an operation to pump water into the reactor was under way. This prevented the worst-case scenario, in which the overheating fuel would melt its way through the vessels and discharge large volumes of radiation outside.

The nuclear industry lacks a technical definition for a full meltdown, but the term is generally understood to mean that radioactive fuel has breached containment measures, resulting in a massive release of fuel.

“Without the injection of water [by fire trucks], a more disastrous event could have ensued,” said Mr. Matsumoto.

Tepco also released its analysis of a hydrogen explosion that occurred at unit No. 4, despite the fact that the unit was in maintenance and that nuclear fuel stored in the storage pool was largely intact.

According to Tepco, hyrogen produced in the overheating of the reactor core at unit 3 flowed through a gas-treatment line and entered unit No. 4 because of a breakdown of valves. Hydrogen leaked from ducts in the second, third and fourth floors of the reactor building at unit No. 4 and ignited a massive explosion.

►http://online.wsj.com/article/SB10001424052748703509104576325110776621604.html

Core of reactor 1 melted 16 hours after quake | The Japan Times Online
►http://search.japantimes.co.jp/cgi-bin/nn20110516a1.html

Monday, May 16, 2011

Core of reactor 1 melted 16 hours after quake
New analysis shows damage to fuel rods was surprisingly quick
Kyodo

The meltdown at reactor No. 1 in Fukushima happened more quickly than feared, Tokyo Electric Power Co. said Sunday in a new analysis.

The core of the heavily damaged reactor at the Fukushima No. 1 power plant is believed to have melted 16 hours after the March 11 mega-quake and tsunami rocked the complex in northeastern Japan.

Preliminary analysis shows that No. 1 had already entered a critical state by 6:50 a.m. on March 12, with most of its fuel having melted and fallen to the bottom of the pressure vessel, the plant operator said. Tepco released data Thursday showing some of the fuel rods had melted.

The reactor automatically halted operations immediately after the 2:46 p.m. quake, but the water level in the reactor dropped and the temperature began rising at around 6 p.m. The damage to the fuel rods had begun by 7:30 p.m., with most of them having melted by 6:50 a.m. the following day, the utility said.

While the utility had planned to bring the nation’s worst nuclear accident under control in around six to nine months from mid-April, it now has no choice but to abandon a plan to flood the containment vessel of reactor 1 because holes have been created by the melted fuel, an adviser to Prime Minister Naoto Kan said earlier Sunday.

Nevertheless, Goshi Hosono, the top official tasked with handling the nuclear crisis, told TV programs the government had yet to revise the timetable for bringing the crisis to an end.

Asked about initial plans to completely submerge the 4-meter-tall fuel rods by entombing the vessel in water, Hosono said, “We should not cause the (radioactive) water to flow into the sea by taking such a measure.”

Hosono said the government will instead consider ways to decontaminate the water being used to cool the fuel so that it can be recirculated instead of letting it flood the facility.

Hosono made the remarks after Tepco discovered a pool of water more than 4 meters deep and exceeding 3,000 tons in the basement of reactor No. 1. This suggests that the water, which is likely highly radioactive, is seeping through the holes after being injected into the reactor core.

From there, it is probably leaking from either the containment vessel or the suppression pool, which enclose the pressure vessel, and into the piping.

In a related revelation concerning a major mixup after the six-reactor complex lost power, Tepco and other sources said the same day that the utility had assembled 69 power supply vehicles at the plant by March 12 but that these proved virtually useless.

The inability to use the vehicles delayed the damage control work at the plant, significantly worsening the emergency.

Tepco earlier said it had tried to connect the vehicles to power-receiving equipment needed to operate the water pumps intended to cool down the reactors. But this failed because the equipment was submerged in seawater from the tsunami, which posed the risk that the equipment would short out.

Tepco’s account conflicts with the one detailed by the Nuclear and Industrial Safety Agency, which mentioned the first arrival of such a vehicle on the evening of March 11 but stopped mentioning it the following day, as the focus of attention had shifted to the need to release radioactive steam to relieve pressure that had built up inside the containment vessel of reactor 1.

The different versions of the story given by Tepco and the agency might come to a head as investigations progress to determine why efforts to immediately contain the crisis failed.