Editer l'article Suivre ce blog Administration + Créer mon blog
Le blog de fukushima-is-still-news

information about Fukushima published in English in Japanese media info publiée en anglais dans la presse japonaise

Radioactive waste - update Feb 11, 2012

February 11, 2012

Radioactive waste site opened to media in Okuma

OKUMA, Fukushima--The government, for the first time, has allowed the media to cover operations to move waste contaminated by radioactive substances to a baseball stadium being used for temporary storage in the Ottozawa district in Okuma, Fukushima Prefecture.

The contaminated waste was collected in the government-led model decontamination project conducted in the town.

On Thursday, the bags containing the waste were moved to the site and piled in two designated areas at the town-run stadium, about three kilometers away from the power plant.

Radiation levels exceeded 70 microsieverts per hour in certain areas of the Ottozawa district, the highest level among the government-monitored locations.

Workers in protective clothing and masks used cranes to pile up bags with the contaminated soil and grass, each weighing about a ton.

A worker said, "Protective clothing hampers our breathing and it's tough to work because my hands are freezing in these rubber gloves."

Before placing the bags, four layers of sheeting, including a water-resistant sheet, were spread on the ground to block radiation leaks. [since when has water-resistant material been able to block radiation ?]

Later, the pile will be covered by three layers of sheets and soil.

An official at the Japan Atomic Energy Agency, which handled the operation, said, "It's possible to block 98 percent of radiation [using this system]."

February 09, 2012

Radioactive waste disposal site unveiled to reporters


A temporary storage site for radioactive waste generated under a model decontamination project around the disaster-struck Fukushima No. 1 nuclear plant was unveiled to reporters on Feb. 9.

To prevent radioactive materials from contaminating groundwater, temporary disposal sites are lined with waterproof sheets. Materials produced in the decontamination operation -- including earth and plant matter -- are categorized, packed into thick bags and lifted into the disposal site by crane.

"We are building these (temporary disposal) sites in such a way that, even when full of waste, radiation levels won't rise in the surrounding area," a Japan Atomic Energy Agency official in charge of the operation stated.

The model decontamination project started in November last year in 12 municipalities in and around the exclusion zone to find the most effective decontamination and disposal techniques.


February 08, 2012

Nuke dangers nowhere near resolved: Kan's crisis adviser


By REIJI YOSHIDA - http://www.japantimes.co.jp/text/nn20120208f1.html

In December, Prime Minister Yoshihiko Noda announced the "conclusion" of the meltdown crisis at the Fukushima No. 1 nuclear plant, saying Tokyo Electric Power Co. was managing to keep the three crippled reactors cool, as well as the facility's spent fuel pools.

But a former special adviser to Naoto Kan, who was prime minister when the crisis started, warned that the situation is far from resolved and said Fukushima has exposed a raft of serious nuclear problems that Japan will have to confront for years.

"I would say (the crisis) just opened Pandora's box," Hiroshi Tasaka, who has a doctorate in nuclear engineering and is now a professor at Tama University, said in a recent interview with The Japan Times.

He was one of a select group who glimpsed the secret worst-case scenario document written up by the Japan Atomic Energy Commission on March 25 that was later reportedly quashed by the government.

According to the scenario, the biggest risk during the meltdown crisis wasn't the reactors themselves but the spent fuel pools sitting atop them, particularly the one above reactor 4, which still contains about 1,500 nuclear fuel assemblies, Tasaka said.

Unlike reactors 1, 2 and 3, the No. 4 unit was offline for regular checks when disaster struck on March 11 and thus didn't suffer a meltdown. But its fuel rods were in the pool outside the reactor, and its coolant water fell dangerously low.

Adding to the danger is that the fuel pool is now directly exposed to the outside environment after a hydrogen explosion blew off the upper part of the reactor building on March 15, Tasaka noted.

The potential heat from the pool was also much higher than other pools because 204 of the 1,535 assemblies were still "new ones" that had been temporarily removed from reactor 4 for regular checks.

The Fukushima crisis has highlighted the dangers of spent fuel pools, which are outside the robust primary containment vessels of the reactors themselves, Tasaka said.

Under the current circumstances, the nation has no prospect of starting up the experimental high-level nuclear waste processing facility in Rokkasho, Aomori Prefecture, because of both technical difficulties and the sentiments of antinuclear activists.

This means utilities must store their spent fuel assemblies in cooling pools at their respective reactor sites as a "temporary measure." This situation greatly increased the danger at Fukushima No. 1 on March 11.

"The storage capacities of the spent fuel pools at the nation's nuclear power plants are reaching their limits," Tasaka wrote in a new book, "Kantei Kara Mita Genpatsu Jiko No Shinjitu" ("The Truth About the Nuclear Accident as Viewed From the Prime Minister's Office").

According to Tasaka, the utilities' fuel pools were about 70 percent full on average in 2010, but the figure was 80 percent at Fukushima No. 1.

The makeshift cooling systems set up at Fukushima No. 1 to stabilize the stricken reactors and fuel pools have greatly reduced the possibility of another catastrophe, Tasaka said, but the ad hoc system for decontaminating the coolant water is nevertheless generating large amounts of highly contaminated waste every day.

Making matters worse, the government doesn't have any place to permanently store it, he wrote.

Tasaka is also deeply concerned about the "groundless optimism" displayed by bureaucrats and business leaders as they rush to restart dozens of reactors that remain halted for safety checks since March 11.

"I understand quite well the intentions of the government, which now wants to send out a message of hope. But at this stage, all the risks should be put on the table," he said.

The nation's nuclear regulators must carry out drastic reforms to regain the people's trust. This is an imperative for the government if it wants to keep pushing nuclear power, Tasaka said.

He recalled viewing the government's worst-case scenario in late March. He was officially appointed special adviser to the prime minister on March 29.

The document detailed a hypothetical Fukushima crisis worst case: Eventual contamination from the plant would require the government to assist residents in the Tokyo area to evacuate if they wanted to voluntarily "migrate," based on the same evacuation protocols adopted for the 1986 Chernobyl accident.

The scenario assumed another hydrogen explosion would occur in the reactor 1 building and radiation would force all of the workers at the plant to evacuate.

All of the pools storing hundreds of nuclear fuel assemblies would eventually lose their cooling ability and the assemblies would melt down and breach the pools.

According to Kyodo News, the simulation was "so shocking" that top government officials decided to keep the paper secret by treating it as a mere personal document of Japan Atomic Energy Commission Chairman Shunsuke Kondo, who compiled the simulation. The government only gave it official recognition at the end of December, according to Kyodo.

More than 10 months after he saw the worst-case scenario paper, Tasaka is still not sure if such scary information should immediately be made public during a nuclear plant crisis.

The assumed worst case was extreme and people did not need to immediately flee the Tokyo area even in March or April, Tasaka said. Disclosing the simulation could have caused panic in the capital, he said.

Tasaka was obliged to keep secret what he learned through his work at the prime minister's office and was not in a position to decide what information was to be made public during the crisis.

He said he decided to start talking about the worse-case scenario only after Kan mentioned some of its highlights during an interview with the media in September.

Tasaka believes the media and government should lay some ground rules in advance on what sensitive information should be made clear in a nuclear crisis.


February 06, 2012

Govt to create more decontamination bases


The Environment Ministry plans to decontaminate more public facilities in Fukushima Prefecture to use them as bases for cleaning up radioactive substances.

The government wants to decontaminate no-entry and evacuation zones around the damaged Fukushima Daiichi plant. It hopes to create a safe environment so that residents can return to the area.

The ministry has designated 16 facilities, including schools and assembly halls, as bases for decontamination. Four municipal offices were cleaned up in December.

The operation is to be completed next month.

The government plans to begin radiation monitoring in these zones in a few months, and begin the decontamination process this summer.

February 04, 2012

Tokyo gov't unveils transport of incinerated radioactive sludge from sewage plant


Tokyo on Feb. 2 invited reporters to see how ash from incinerated sludge -- including some contaminated with radioactive substances -- is shipped from a sewage plant to be buried at a disposal site outside a breakwater in Tokyo Bay.

The Tokyo Metropolitan Government started burying ash from the incinerator at Akishima in the Tama region of suburban Tokyo in late October last year. In December, it procured gear to separate air from the incinerated sludge and load it into tanker trucks. The Bureau of Sewerage then started transporting the ash from the Tamagawa Joryu Water Reclamation Center to the disposal site.

During the press tour, journalists watched the material being loaded onto the tankers. Radioactive cesium levels in the ash are apparently far below national standards at 1,000 to 2,000 becquerels per kilogram.

The Akishima sewage plant stopped shipping the ash out in May last year and subsequently built up as much as some 420 metric tons of it. The plant will be completely rid of the ash by mid-February.

A total of about 2,600 tons of incinerated sludge are held at six other sewage plants in the Tama region, and the metropolitan government will send the separation gear to those plants to move the ash to the disposal site.

January 31, 2012

Govt plans Fukushima decontamination test-run

NHK World English

Japan's Environment Ministry has unveiled a model project designed to decontaminate areas with high levels of radiation around the crippled Fukushima Daiichi nuclear plant.

In a test-run for a wider clean-up, the ministry will first try to decontaminate 3 closed sections of a national expressway running through the no-entry zone near the plant.

The ministry last week announced a 2-year plan to decontaminate by March 2014 some evacuation zones where radiation levels have dropped below 50 millisieverts per year.

Radiation levels over a total 5 kilometers of expressway slated for the new project have ranged from a little to substantially above 50 millisieverts a year.
The ministry plans to assess the project's effectiveness in a test-run from the middle of March through July.

January 28, 2012

Less polluted areas to come 1st / Govt releases decontamination schedule for Fukushima Prefecture

The government will prioritize decontamination work in areas of Fukushima Prefecture where the annual level of radiation exposure is 20 millisieverts or less, as part of efforts to allow residents of those areas to return home as soon as possible, according to a timetable released by the Environment Ministry.

The ministry on Thursday unveiled its timetable for decontamination operations in the no-entry and expanded evacuation zones in the prefecture. Entry is limited in these areas following the outbreak of the nuclear crisis at Tokyo Electric Power Co.'s Fukushima No. 1 nuclear power plant.

The no-entry and expanded evacuation zones have been deemed "decontamination special zones" to be decontaminated under the government's direct control. They are to be reorganized into three zones as of April 1 in accordance with their annual levels of radiation exposure.

The new categories will be:

-- Zones being prepared for residents' return. Annual radiation exposure is 20 millisieverts or lower, and residents are expected to be able to return following the completion of decontamination.

-- Zones with restricted residency. Annual radiation exposure is 20 millisieverts to 50 millisieverts, and residents are expected to be able to return in a few years.

-- Zones where residency is prohibited for an extended period. Annual radiation exposure is more than 50 millisieverts and it is expected to be more than five years before residents can return home.

The government plans to complete decontamination work in areas with annual radiation exposure of 20 millisieverts to 50 millisieverts by lowering the level to 20 millisieverts or less--a level at which residence is allowed--by March 2014.

However, the ministry did not present a concrete plan for the zones with annual radiation levels of more than 50 millisieverts.

Regarding the zones being prepared for residents' return, the government plans to proceed with decontaminating the areas with higher levels of radiation exposure. It will start decontaminating areas with the highest levels of radiation exposure, from 10 millisieverts to 20 millisieverts, starting around March and aims to complete the operation by the end of this year.

The government will start work in areas with annual radiation exposure of 5 millisieverts to 10 millisieverts once a number of conditions are fulfilled, such as gaining approval from residents. It plans to launch these operations on a full-scale basis around June, and continue through March 2013, according to the timetable.

Regarding the areas with the lowest levels of radiation--from 1 millisievert to 5 millisieverts--full-scale decontamination work will start from around summer, and is scheduled to be completed at the end of March 2014.

However, the government will prioritize decontamination at schools, parks and other places where children gather, and densely populated urban districts and hospitals.

Regarding the zones being prepared for residents' return, the government plans to urge people to return after lowering the radiation level as much as possible.

Meanwhile, the government plans to begin a full-scale decontamination operation in the zones with restricted residency starting around autumn and finish at the end of March 2014.

Based on the outcome of decontamination work conducted at the end of last year by the Self-Defense Forces, the government believes it is possible to reduce annual radiation exposure in the zones to 20 millisieverts or lower, according to the ministry.

However, the timetable did not indicate final target levels of radiation in the zones.

"We're conducting a model project to verify the effect of decontamination. After seeing the results, we plan to incorporate a target level of radiation in the timetable by March this year," an official of the ministry's Environmental Management Bureau said.

Regarding the zones where residency is prohibited for extended periods, the government said it plans to study decontamination measures and other steps.

"By conducting a model project for decontamination, we plan to establish efficient and effective decontamination technologies and measures to ensure safety of workers," the official said.

Carrying out decontamination operations in the zones is expected to be extremely difficult. The government is considering buying or leasing land from residents of these areas.

"A project to have residents return home following a nuclear crisis of this magnitude is unprecedented in the world, so we have to overcome quite high hurdles. We'll make a careful judgment about the timing for residents to return home after considering the opinions of local government heads and residents," Environment Minister Goshi Hosono said.


Partager cet article
Pour être informé des derniers articles, inscrivez vous :
Commenter cet article