High levels of radioactive material migrating down into soil around Fukushima

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High levels of radioactive cesium remain in the soil near the Fukushima Daiichi nuclear power plant and these radionuclides have migrated at least 5 centimeters down into the ground at several areas since the nuclear accident five years ago, according to preliminary results of a massive sampling project being presented at the JpGU-AGU joint meeting in Chiba, Japan.

In 2016, a team of more than 170 researchers from the Japanese Geoscience Union and the Japan Society of Nuclear and Radiochemical Sciences conducted a large-scale soil sampling project to determine the contamination status and transition process of radioactive cesium five years after a major earthquake and tsunami caused a nuclear accident at the Fukushima Daiichi plant.  

The team collected soil samples at 105 locations up to 40 kilometers (25 miles) northwest of the Fukushima Daiichi nuclear power plant in the “difficult-to-return” zone where entry is prohibited. The project seeks to understand the chemical and physical forms of radionuclides in the soil and their horizontal and vertical distribution.

The Japanese government has monitored the state of radioactive contamination in the area near the plant since the 2011 accident by measuring the air dose rate, but scientists can only determine the actual state of contamination in the soil and its chemical and physical forms by direct soil sampling, said Kazuyuki Kita, a professor at Ibaraki University in Japan, who is one of the leaders of the soil sampling effort.

Understanding the radionuclides’ chemical and physical forms helps scientists understand how long they could stay in the soil and the risk they pose to humans, plants and animals, Kita said. The new information could help in assessing the long-term risk of the radionuclides in the soil, and inform decontamination efforts in heavily contaminated areas, according to Kita, one of several researchers will present the team’s preliminary results at the JpGU-AGU joint meeting next week.

Preliminary results show high levels radioactive cesium are still present in the soil near the plant. The levels of radiation are more than 90 percent, on average, of what was found immediately following the accident, according to Kita.

Most of the radiocesium in the soil was found near the surface, down to about 2 centimeters, immediately following the 2011 accident. Five years later, at several sampling points, one-third to one-half of the radiocesium has migrated deeper into the soil, according to Kita. Preliminary results show the radiocesium moved about 0.3 centimeters per year, on average, deeper into the soil and soil samples show the radiocesium has penetrated at least 5 centimeters into the ground at several areas, according to Kita.

The team plans to analyze samples taken at greater depths to see if the radiocesium has migrated even further, he said.  

Most of the radioactive cesium remains after five years, but some parts of the radioactive cesium went from the surface to deeper soil,” he said.

Knowing how much radioactive contamination has stayed on the surface and how deep it has penetrated into the soil helps estimate the risk of the contaminants and determine how much soil should be removed for decontamination. The preliminary results suggest decontamination efforts should remove at least the top 6 to 8 centimeters of soil, Kita said.  

The preliminary data also show there are insoluble particles with very high levels of radioactivity on the surface of the soil. Debris from the explosion fused with radiocesium to form small glass particles a few microns to 100 microns in diameter that remain on the ground, according to Kita. The team is currently trying to determine how many of these radiocesium glass particles exist in areas near the nuclear plant, he said.

We are afraid that if such high radioactive balls remain on the surface, that could be a risk for the environment,” Kita said. “If the radioactivity goes deep into the soil, the risk for people in the area decreases but we are afraid the high radioactive balls remain on the surface.”

Nanci Bompey is the manager of AGU’s public information office. This research is being presented Thursday, May 25 at the JpGU-AGU joint meeting in Chiba, Japan. 

http://blogs.agu.org/geospace/2017/05/19/high-levels-radioactive-material-migrating-soil-around-fukushima/

Test to recycle some screened soil from Fukushima

 

Japan’s Environment Ministry is studying the possibility of using some screened soil cleared from Fukushima Prefecture after the 2011 nuclear power plant accident in public works projects.

The Japanese government says, within the next 30 years, it plans to dispose of some 22 million cubic meters of soil and other waste that will be removed from the prefecture as part of the decontamination effort.

To make the job easier, the Ministry hopes to use soil with acceptable levels of radioactive material to build roads, embankments and parks.

The ministry began testing the feasibility of such projects last month at a temporary storage site in Minami Soma, Fukushima Prefecture. The process was shown to the media on Wednesday.
The experiment involves sifting the soil to remove rocks, leaves and branches, then entering it into a machine that measures the level of radioactive substances. The soil is then piled into mounds.

Ministry officials will monitor radiation levels in the air and groundwater around the mounds.

They plan to draw up guidelines for local governments and construction workers by April next year.

The ministry says it aims to use soil with up to 6,000 becquerels per kilogram of radioactive substances in roads and embankments, and up to 4,000 becquerels in parks.

But residents in Minami Soma have requested that for the experiment, the Ministry only use soil with up to 3,000 becquerels per kilogram.
As a result, the officials are unable to test whether soil with higher levels of contamination is safe for recycling.

The project also raises questions about the long-term monitoring of public works built with contaminated soil, and how the Ministry will win the support of people who live nearby.

https://www3.nhk.or.jp/nhkworld/en/news/20170517_23/

 

Japan ponders recycling Fukushima soil for public parks & green areas

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Workers move big black plastic bags containing radiated soil. Fukushima prefecture, near Fukushima Daiichi nuclear power plant.

Soil from the Fukushima prefecture may be used as landfill for the creation of “green areas” in Japan, a government panel has proposed, facing potential public backlash over fears of exposure to residual radiation from the decontaminated earth.

The advisory panel of the Environment Ministry on Monday proposed reusing soil that was contaminated during the Fukushima nuclear meltdown of 2011 as part of future landfills designated for public use, Kyodo news reported

In its proposal, the environmental panel avoided openly using the word “park” and instead said “green space,” apparently to avoid a premature public outcry, Mainichi Shimbun reported.

Following an inquiry from the news outlet, the Ministry of the Environment clarified that “parks are included in the green space.”

In addition to decontaminating and recycling the tainted earth for new parks, the ministry also stressed the need to create a new organization that will be tasked with gaining public trust about the prospects of such modes of recycling.

To calm immediate public concerns, the panel said the decontaminated soil will be used away from residential areas and will be covered with a separate level of vegetation to meet government guidelines approved last year.

In June last year, the Ministry of the Environment decided to reuse contaminated soil with radioactive cesium concentration between 5,000 to 8,000 becquerels per kilogram for public works such as nationwide roads and tidal banks.

Under these guidelines, which can now be extended to be used for the parks, the tainted soil shall be covered with clean earth, concrete or other materials.

Such a landfill, the government said at the time, will not cause harm to nearby residents as they will suffer exposure less than 0.01 mSv a year after the construction is completed.

The Fukushima Daiichi nuclear power plant suffered a blackout and subsequent failure of its cooling systems in March 2011, when it was hit by an earthquake and a killer tsunami that knocked out the facility, spewing radiation and forcing 160,000 people to flee their homes. Three of the plant’s six reactors were hit by meltdowns, making the Fukushima nuclear disaster the worst since the Chernobyl catastrophe in 1986.

https://www.rt.com/news/382515-japan-recycling-fukushima-soil/#.WNoJ3cpBs98.facebook

Gov’t proposes reusing Fukushima’s decontaminated soil on green land

The Environment Ministry on Monday proposed reusing decontaminated soil from disaster-hit Fukushima Prefecture as landfill for parks and green areas.

At a meeting of an advisory panel, the ministry also called for launching a new organization to map out plans on how to gain public understanding about the reuse of decontaminated soil, ministry officials said.

The proposals come at a time when Fukushima Prefecture faces a shortage of soil due to the decontamination work following the 2011 nuclear meltdown.

http://english.kyodonews.jp/news/2017/03/465656.html

 

Radiation limit for contaminated soil in reuse experiment lowered after local opposition

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Black bags containing radioactively contaminated soil are seen piled up at a temporary storage site in Minamisoma, Fukushima Prefecture, in this June 2016 file photo. (Mainichi)
 
The radiation limit for soil contaminated by the Fukushima nuclear disaster in an experiment to reuse it in construction was lowered from 8,000 becquerels per kilogram to 3,000 becquerels per kilogram after strong opposition from a local mayor, it has been learned.

The experiment is to be carried out at a temporary storage site in Minamisoma, Fukushima Prefecture, where around 1,000 bags of contaminated soil will be opened, made into construction foundations, and their radiation levels measured. The experiment will be done to check, among other things, whether the radiation exposure dose remains at the yearly limit of 1 millisievert or less. The experiment will cost around 500 million yen. The results are expected to be put together next fiscal year or later.

From soon after the Great East Japan Earthquake in 2011, municipalities including Minamisoma asked the national government to separate out lower-radiation level concrete and other debris for reuse in things like groundwork for coastal forests used to defend against tsunami. At first, the Ministry of the Environment was negative about this, but in December 2011 the ministry allowed such reuse for debris with a limit of 3,000 becquerels per kilogram. According to documents released in response to a release of information request made by the Mainichi Shimbun, some 350,000 metric tons of this kind of debris have been used in Minamisoma and the towns of Namie and Naraha in projects such as groundwork for coastal forests.

Then in June last year, the Ministry of the Environment decided on a policy of reusing contaminated soil with 8,000 becquerels or less per kilogram in structures such as soil foundations for public works projects.

The same month, Minamisoma’s Mayor Katsunobu Sakurai visited then vice-minister of the environment Soichiro Seki, where he questioned Seki about the 3,000 becquerel limit that had been used until being replaced by the 8,000 becquerel limit. Sakurai reportedly called for the 3,000 becquerel limit to be used in the upcoming experiment in Minamisoma.

Sakurai says, “If they don’t use the 3,000 becquerel limit it is inconsistent. It doesn’t make sense for a ministry that is supposed to protect the environment to relax the standards it has set.”

The ministry confirmed to the Mainichi Shimbun that the experiment will only use soil up to the 3,000 becquerel limit, and said that the soil used will on average contain about 2,000 becquerels per kilogram.

http://mainichi.jp/english/articles/20170206/p2a/00m/0na/009000c

Nuclear watchdog questions Environment Ministry’s plan to reuse radioactive soil

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Bags containing contaminated soil and other materials produced through decontamination work are seen at a provisional storage site in Tomioka, Fukushima Prefecture.

The Nuclear Regulation Authority (NRA) has raised questions about the Environment Ministry’s proposal to reuse radioactive soil resulting from decontamination work around the crippled Fukushima No. 1 Nuclear Power Plant due to the insufficiency of information on how such material would be managed, it has been learned.
As the ministry has not provided a sufficient amount of information, the nuclear watchdog has not allowed the ministry to seek advice from its Radiation Council — a necessary step in determining standards for radiation exposure associated with the reuse of contaminated materials.

The Ministry of the Environment discussed the reuse of contaminated soil in closed-door meetings with radiation experts between January and May last year. The standard for the reuse of such materials as metal produced in the process of decommissioning nuclear reactors is set at 100 becquerels of radioactive cesium per kilogram. Materials with a contamination level topping 8,000 becquerels are handled as “designated waste” requiring special treatment. In examining the reuse of contaminated soil, the ministry in June decided on a policy of reusing soil containing up to 8,000 becquerels of radioactive cesium per kilogram as a base for roads with concrete coverings.

According to sources close to the matter, the ministry sounded the NRA out on consulting with the Radiation Council over the upper limit of 8,000 becquerels and other issues. An official from the NRA requested the ministry to provide a detailed explanation on how such soil would be handled, including the prospect of when the ministry would end its management of the reused soil, and how it would prevent illegal dumping. The official then told the ministry that the rule of 100-becquerel-per-kilogram rule would need to be guaranteed if contaminated soil were reused without ministry oversight.

The official is also said to have expressed concerns over the ministry plan, questioning the possibility of contaminated soil being used in somebody’s yard in a regular neighborhood. Since the ministry failed to respond with a detailed explanation, the NRA did not allow the ministry to consult with the Radiation Council.

Government bodies are required to consult with the council under law when establishing standards for prevention of radiation hazards. It was the Radiation Council that set up the 8,000-becquerel rule for designated waste.

An official from the NRA’s Radiation Protection and Safeguards Division told the Mainichi Shimbun, “We told the ministry that unless it provides a detailed explanation on how contaminated soil would be used and on how it will manage such material, we cannot judge if its plan would be safe.”

http://mainichi.jp/english/articles/20170109/p2a/00m/0na/012000c

 

 

Environment Ministry deleted some of its remarks from minutes on contaminated soil meet

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The Ministry of the Environment deleted some of its remarks made in closed-door meetings on reuse of contaminated soil stemming from the Fukushima nuclear disaster from the minutes of the meetings, it has been learned.

When the ministry posted the minutes on its website, it said it had “fully disclosed” them. The deleted remarks could be taken to mean that the ministry induced the discussions. The remarks led the meetings to decide on a policy of reusing contaminated soil containing up to 8,000 becquerels of radioactive cesium per kilogram. An expert on information disclosure lashed out at the ministry’s handling of the minutes, saying, “It is extremely heinous because it constitutes the concealment of the decision-making process.”

The meetings were called the “working group to discuss safety assessments of impacts of radiation.” The meetings were attended by about 20 people, including radiation experts, officials of the Environment Ministry and the Japan Atomic Energy Agency (JAEA) and others. The meetings were held six times from January to May in 2016.

The meetings discussed the reuse of radioactively contaminated soil generated when areas affected by the Fukushima nuclear crisis were decontaminated.

Initially, the meetings themselves were unpublicized. But because requests for information disclosure on the meetings were filed one after another, the Environment Ministry posted the minutes and relevant data on its website in August. As a matter of clerical procedures, the ministry said at that time that everything was disclosed.

The minutes that were disclosed contain “draft minutes” that were prepared before becoming official documents, but the Mainichi Shimbun obtained an “original draft” that was prepared even before then. Comparing the disclosed minutes with the original draft, the Mainichi found multiple cases of remarks being deleted or changed. According to the original draft, an Environment Ministry official said at the fourth meeting on Feb. 24, “With the assessments of soil with 8,000 becquerels, there have been cases in which the annual radiation dose slightly exceeds 1 millisievert in times of disasters and the like. But it will be good if it stays within 1 millisievert.” But the remark was deleted from the disclosed minutes.

Soil contaminated with radiation exceeding 8,000 becquerels is handled as “designated waste,” but discussions were held on reusing of contaminated soil containing 8,000 becquerels of radioactive cesium per kilogram during a series of meetings. In the Feb. 24 meeting, the JAEA showed an estimate that workers engaged in recovery work on a breakwater made of contaminated soil of 8,000 becquerels that has collapsed in a disaster would be exposed to radiation exceeding 1 millisievert per year — the maximum dose allowed for ordinary people. Based on the estimate, there was a possibility of the upper limit for reusing contaminated soil being lowered, but the Environment Ministry official’s remark promoted experts and others to call for s review to make a new estimate, with one attendee saying, “If it collapses, it will be mixed with other soil and diluted.”

A fresh estimate that the annual radiation dose will stay at 1 millisievert or lower was later officially presented, and the Environment Ministry officially decided in June on a policy of reusing contaminated soil containing up to 8,000 becquerels of radioactive cesium per kilogram.

http://mainichi.jp/english/articles/20170105/p2a/00m/0na/007000c

Temporary Radioactive Soil Storage Sites Hinder Fukushima Farmers

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Farmers harvest rice in one of Hisayoshi Shiraiwa’s paddies in Katsurao, Fukushima Prefecture, on Oct. 19, 2016. Another rice paddy in the foreground serves as a temporary storage site for piles of black plastic bags containing radioactive soil.

FUKUSHIMA — Wide swaths of temporary storage sites for radioactive soil and other waste generated from decontamination work in areas around the crippled Fukushima No. 1 Nuclear Power Plant are hampering locals from resuming farming, it has been learned.

The makeshift storage sites occupy roughly 1,000 hectares in total, or an area the size of 213 Tokyo Domes, across zones currently or formerly designated for evacuation in 11 municipalities in Fukushima Prefecture, according to the Ministry of the Environment. The high occupancy is the result of delayed work to develop interim storage facilities for contaminated soil.

Because slightly over 90 percent of those temporary storage sites lie on farmland, local governments are deprived of the very foundation for restoring farming — a key local industry — in those areas while farmers are concerned about possible damage caused by harmful rumors.

According to the Environment Ministry, there are about 280 temporary storage sites in areas designated as evacuation zones. Those storage sites — which are leased to the ministry by local farmers — accommodate over 7 million black plastic bags containing radioactive soil, grass and branches. Those flexible container bags — each capable of containing 1 cubic meter of soil and other waste — are commonly known as “flecon baggu” in Japanese.

Under the ministry plan, interim storage facilities will be built in areas totaling some 1,600 hectares in the so-called “difficult-to-return” zones in the prefectural towns of Futaba and Okuma around the Fukushima No. 1 plant. Under the scheme, radioactive soil temporarily stored at different locations in Fukushima Prefecture will be transported there for longer storage periods spanning up to 30 years before it is put to final disposal outside the prefecture.

While the ministry had initially sought to begin construction of interim storage facilities in July 2014, delays in negotiations with local residents and efforts to acquire land lots made it impossible to meet the schedule. The ministry aims to finish acquiring up to 70 percent of land necessary for the construction of interim storage facilities by the end of fiscal 2020, but the land it had managed to acquire by the end of October this year stood at a mere 170 hectares, or only 10 percent of the planned area.

The Environment Ministry estimates that up to 22 million cubic meters of contaminated soil and other waste will be generated across Fukushima Prefecture, but the interim storage facilities are expected to be able to accommodate no more than 12.5 million cubic meters of such waste by the end of fiscal 2020.

The Fukushima Prefecture village of Katsurao, where evacuation orders were lifted in most areas in June, has been pushing restoration of farming as a key policy measure. However, the total size of rice paddies in the village has dropped from some 130 hectares operated by roughly 270 households in 2010 — prior to the Fukushima meltdowns — to around 6 hectares operated by 11 households this year. Nearly 30 percent of the village’s rice paddies totaling some 220 hectares now serve as temporary storage sites for radioactive soil and other waste.

Hisayoshi Shiraiwa, a 70-year-old farmer in Katsurao, harvested rice in his paddy in October, which is adjacent to another paddy that serves as a temporary storage site for piles of black plastic bags containing radioactive soil. As the price of rice from the area hasn’t recovered to pre-disaster levels, local farmers are worried about prolonged reputational damage.

“As long as temporary storage sites remain here, farmers will lose their motivation and face a shortage of successors,” Shiraiwa said.

http://mainichi.jp/english/articles/20161120/p2a/00m/0na/004000c