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Evaluating Different Radiocesium Decontamination Practices In A Forest Plantation Near The Fukushima Nuclear Power Plant

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June 25, 2018
Owing to an earthquake and the resulting tsunami that occurred on March 2011 in central-eastern Japan, the Fukushima Dai-ichi Nuclear Power Plant was damaged by several hydrogen explosions.
This accident released a vast amount of radionuclides, including caesium 134 and 137 (ca. ratio 1:1). Initial fallout contaminated cultivated soils (mainly paddy fields), forests, water bodies, residential areas, asphalt and concrete surfaces. Since then, a variety of decontamination practices have been completed, reducing the ambient dose rates.
In a recent study, published in Environmental Pollution (available online since April 19, 2018) and conducted by Prof. Yuichi Onda (University of Tsukuba, Japan), Dr. Manuel López-Vicente (EEAD-CSIC, Soil Management and Global Change Group), and staff of Onda’s Laboratory and Asia Air Survey Co., eight decontamination practices were evaluated in a forest plantation located 16 km southwest of the power plant and within the exclusion area. The stand is composed of a forest plantation of Japanese cedar (Cryptomeria japonica) and natural understory vegetation. This plantation has an age of 58 years (in 2017) and is located on a steep hillslope (average slope gradient of 25⁰) near Kawauchi village, in the Fukushima Prefecture. Ten runoff plots were installed and managed by the Fukushima Prefectural Forestry Research Centre.
B
Radiocesium (Cs-137) concentrations and activities were calculated in soil and litter samples over 27 months (May 2013 – July 2015) and after decontamination practices. One plot was devoted to litter removal; two plots to tree thinning without litter removal (Th_1 with logged area, and Th_2 under remnant trees); two plots to tree thinning with litter removal (Th + LR_1 with logged area, and Th + LR_2 under remnant trees); and three plots to clearcutting with litter removal (CC + LR_1 without matting, CC + LR_2 matting with seeds, and CC + LR_3 matting without seeds). Finally, two plots (Co_1 and Co_2) remained as control plots without application of any decontamination practice.
Differences were statistically significant, and researchers distinguished four homogeneous groups. Tree thinning and litter removal greatly reduced the radioactivity. Tree thinning, clearcutting with litter removal, and litter removal also had higher discharge rates than those rates in the control plots. We only observed low rates in the two plots with matting (soil conservation practice). The temporal variability was explained by (i) the different rainfall depths registered during the measurement intervals (with heavy rainfall events and typhoons: accumulated precipitation from 14 to 361 mm during the measurement intervals); and (ii) the fluctuations of the total ground coverage (canopy and surface).
The vegetation recovery after the countermeasures triggered a reduction of hydrological connectivity in all compartments of the forest plantation. This fact explained the decreasing trend in radiocesium concentration that was very high in 2013, high in the first half of 2014, moderate in the second half of 2014, and low in 2015. This tendency will reduce the possibility of secondary pollution of the neighboring residential and/or agricultural areas. The average proportions of the contribution of Cs-137 discharge by soil and leaf fraction were 96.6% and 3.4%.
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These findings are described in the article entitled Radiocesium concentrations in soil and leaf after decontamination practices in a forest plantation highly polluted by the Fukushima accident, recently published in the journal Environmental Pollution. This work was conducted by Manuel López-Vicente, Yuichi Onda, Junko Takahashi, and Hiroaki Kato from the University of Tsukuba, and Shinya Chayama and Keigo Hisadome from Asia Air Survey Co.
This research was funded by the project “Development of techniques for migration control against radioactive substances in forests (2012-2016)” of the Japanese Forestry Agency; and was carried out by Dr. Manuel López-Vicente during his postdoctoral stays at the University of Tsukuba (Prof. Onda Laboratory) in 2015 (Research Fellowships Program of the Canon Foundation in Europe, call 2014) and 2016.
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June 26, 2018 Posted by | Fukushima 2018 | , , , | Leave a comment

Fire crews finally extinguish Fukushima blaze in no-go zone as officials battle “radiation rumors”

The official line is don’t you worry about radiation, it is only radiation rumors!!!

n-fukufire-a-20170512-870x650Ground Self-Defense Force personnel work on putting out fire in a forest in Namie, Fukushima Prefecture on May 4

 

FUKUSHIMA – A wildfire near the Fukushima No. 1 nuclear plant has finally been extinguished after a 12-day battle waged by firefighters and Self-Defense Force troops in special protective gear left 75 hectares of tainted forest scorched, and local officials scrambling to quash radiation rumors.

The wildfire, which was started by lightning, broke out in the town of Namie on April 29 and spread to the adjacent town of Futaba, which co-hosts the meltdown-hit power plant. It was declared extinguished on Wednesday.

Since the area has been a no-go zone since the March 2011 nuclear crisis, residents are basically banned from returning to large portions of the two irradiated towns.

A local task force said that no one was injured by the wildfire and that there has been no significant change in radiation readings.

Because a large swath of the area scorched hadn’t been decontaminated yet, firefighters donned protective gear in addition to goggles, masks and water tanks. They took turns battling the blaze in two-hour shifts to avoid heatstroke.

Ground Self-Defense Force troops and fire authorities mobilized close to 5,000 people while nine municipalities, including the Tokyo Metropolitan Government, provided helicopters.

The Fukushima Prefectural Government denied online rumors saying the fire was releasing radioactive material into the air from trees and other plant life that absorbed fallout from the power plant, which also lies partly in the town of Okuma. It published data on its website showing no significant change in radiation readings.

We will let people not only in the prefecture, but also in other parts of Japan know about the accurate information,” a prefectural official said.

The Kii Minpo, a newspaper based in Wakayama Prefecture, said in its May 2 edition that once a fire occurs in a highly contaminated forest, “radioactive substances are said to spread the way pollen scatters,” explaining how radiation can get blown into the air.

The publisher said it received around 30 complaints, including one from a farmer in Fukushima, who criticized the evening daily for allegedly spreading an unsubstantiated rumor.

The daily issued an apology a week later in its Tuesday edition.

We caused trouble by making a large number of people worried,” it said.

Atsushi Kawamoto, head of the news division, said that while story may have caused some people anxiety, the newspaper will continue to report on matters of interest to its readers.

That there’s public concern about the spread of radiation is true,” Kawamoto said.

On Tuesday, reconstruction minister Masayoshi Yoshino emphasized that unspecified radiation readings have been unchanged since before the fire.

We will provide accurate and objective information,” he said.

Commenting on the fact that there are no fire crews in the no-go zone, Yoshino said the Reconstruction Agency will consider what kind of support it can offer there the next time a major fire breaks out.

http://www.japantimes.co.jp/news/2017/05/11/national/fire-crews-finally-extinguish-fukushima-blaze-no-go-zone-officials-battle-radiation-rumors/

May 17, 2017 Posted by | Fukushima 2017 | , , , , | Leave a comment

Multiple wildfires hit Tohoku, approaching near residential areas

9 may 2017

A wildfire continues to burn in a mountain forest in Kamaishi, Iwate Prefecture, on the morning of May 9, 2017.

Helicopters were dispatched to the Iwate Prefecture city of Kamaishi and the Fukushima Prefecture town of Namie on the morning of May 9 as wildfires continue to spread in those areas. Particularly in Kamaishi, a fire apparently came within roughly 300 meters to the closest residential community as of the morning of the same day.

A total of 12 helicopters dispatched from the Self-Defense Forces (SDF) as well as the Iwate, Aomori and Akita prefectural governments started dumping water over mountain forests in the Heita district of Kamaishi at around 5 a.m. An evacuation order has been issued for nearby areas, and as of 10:30 a.m., 71 people had evacuated from their homes. According to the Kamaishi Municipal Government, an area approximately 400 hectares in size has burned down.

Meanwhile, the wildfire in Namie, Fukushima Prefecture, has been burning for over 10 days, and the SDF and Fukushima Prefectural Government have continued efforts to put out the fire.

At the same time, a fire that started in the prefectural town of Aizubange, which burned down eight buildings on May 8 and spread to a nearby forest, was put out on the morning of May 9. The local fire department said a man was cooking wild vegetables in front of his house and rice straw caught on fire.

Meanwhile, Miyagi Prefectural Police detected traces of a bonfire near a forest believed to be the source of the wildfire on May 8 in the prefectural city of Kurihara. The fire burned down roughly 5 hectares, including 11 buildings.

According to the Japan Meteorological Agency, the air on the Pacific side of the Tohoku region has been very dry, with less than 10 percent of an average year’s rainfall recorded over the 10-day period through May 8.

https://mainichi.jp/english/articles/20170509/p2a/00m/0na/019000c

May 17, 2017 Posted by | Fukushima 2017 | , , | Leave a comment

Forest fire in the exclusion zone in Fukushima: Why monitoring the radiation dose is not enough for radioprotection

It was announced that the forest fire in Namie was reduced on May 6. Today, on May 7, we still do not have confirmation of the fire’s extinction. Meanwhile, surfing on the internet, we have noticed that many people were looking for radiation dose information, and relied on it for radioprotection.

Since we also received several questions and comments, we have decided to publish additional comments of M.Yoichi Ozawa of “Fukuichi (Fukushima Daiichi) Area Environmental Radiation Monitoring Project”, seen below.

In order to protect yourself from radiation, you must take into account both the radiation dose and the contamination. In the case of the radiation dose, you can imagine something like fixed paint. It requires radioprotection measures against external exposure. For example, in a high-dose place, you control the amount of exposure by staying a shorter period of time. The dose is expressed by units like Sv/h.

Contamination is like a floating powder, which can enter the body by breathing, eating and drinking, and cause internal irradiation. The radioprotection requires equipment such as clothes and masks. Contamination is taken into account in terms of the surface contamination density and the concentration of radioactive substances in the air.

The surface contamination density is the radioactivity per unit area, where radioactive materials are deposited or absorbed on the surface of the material. It is expressed by units such as Bq/cm2 and Bq/m2.

The concentration of radioactive material in the air is expressed by units such as Bq/cm3 or Bq/m3.

The following is a table in the radioprotection training textbook used in the crippled TEPCO Fukushima Daiichi nuclear power plant. The radioprotection is staged according to the classified areas. The lines in the table show the radiation dose, whereas the columns show contamination (in terms of the surface contamination density and the concentration of radioactive substances in the air). The combination gives 12 areas from 1A to 3D areas, and the radioprotection measures for workers are adapted accordingly.
For example, in the D areas workers are provided with a full mask and an oxygen cylinder.

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Similarly, in the regions affected by the TEPCO Fukushima Daiichi nuclear power plant accident, we must consider the means of radioprotection by taking into account both the radiation dose and contamination.

In the case of environmental contamination, the air contamination density changes according to conditions such as fire, wind, and rain. Therefore, to protect ourselves, we need to monitor continuously not only during but also after the fire.

Furthermore, it has to be noted that monitoring post and air dust sampling show only gamma rays represented by cesium 137. Strontium 90 and plutonium 239 which emit beta and alpha rays that are most damaging in cases of internal irradiation are not measured. Aside from the question of the amount, these are certainly floating, and the risk of internal exposure cannot be ignored.

Please refer to the contamination map of the areas where the evacuation orders were lifted from last year to this year.
In light of this map and the TEPCO manual, you can see that there are many places in the area where you can return, and where you should wear heavy equipment with a full mask if you were a worker in a nuclear power plant.

The scandalous deficiency of the health scheme in Fukushima

Incredible contamination in Namie, Fukushima

New data show massive radiation levels in Odaka, Minamisoma

In such an environment, ordinary people without a manual, nor professional radioprotection training are allowed to return, including babies and pregnant women.

In addition, whereas the workers are protected by the radiation protection standards shown in the table, in the context of minimization of the accident, residents are exposed to highly radio-contaminated environments without equipment.

If you think about it, it just does not make sense.

https://fukushima311voices.wordpress.com/2017/05/07/forest-fire-in-the-exclusion-zone-in-fukushima-why-monitoring-the-radiation-dose-is-not-enough-for-radioprotection/

 

 

May 17, 2017 Posted by | Fukushima 2017 | , , , | Leave a comment

Mount Juman forest fire in Namie

Namie-Fire-Nippon-TV.jpg

 

A forest fire has been burning in the no-entry zone of Namie in Fukushima since April 29th, and is now in its fourth day. This has been the subject of many news reports of varying quality, and we are following the situation closely.

The site is among the most highly-contaminated by the Fukushima disaster, well within the “difficult-to-return” zone. Clicking this link will center the Safecast web map on the site of the fire at Juman-yama, which we derived by comparing terrain in news videos and in Google Earth.

To summarize what has been reported so far:

The fire is in a mountainous area of Namie Town called Juman-yama, about 10 km from the Fukushima Daiichi plant. The Daiichi plant itself is not at risk from this blaze.

The fire appears to have begun on Sat. April 29, caused by a lightning strike.

Fire-fighters used helicopters to dump water on it, and it appeared to have largely died out on the morning of April 30, but high winds revived it shortly after.

The burned and burning area has been growing, and as of May 2 was approximately 20 hectares.

We don’t have much information about wind direction, which is variable, but predominant winds would blow the smoke eastward towards the ocean (generally over the Daiichi plant site and the towns of Okuma and Futaba).

The most informative news report we’ve seen so far is from Fukushima Chuo TV, on May 1. Prof. Kenji Namba from Univ. of Tokyo notes that the fire can be expected to spread radioactive cesium from the trees in smoke and ash, a general risk pointed out by many experts in the past. He also notes that a monitoring post at Tomioka Station, about 15 km to the southeast of the fire site, has shown what appears to be a very small increase in radiation levels there since the start of the fire. We believe that data from many more points should be examined before ascribing any significance to this kind of reading.

Our closest Pointcast fixed sensor in the area is in Namie, about 7.8 km to the east-northeast of the fire. Its readings have remained relatively constant since the start of the fire, with no appreciable change in radiation levels detected. The time series graph for this sensor showing the change in radiation over the past 30 days can be accessed here.

We also have Pointcast sensors in the nearby towns of Tomioka and Odaka. Neither these nor any other Pointcast sensors show any appreciable increase in radiation levels so far.

Examining readings from government radiation monitoring posts shows what appear to be noticeable “bumps” at some locations around May 1. But these are not large spikes, and in general appear to be within the range of the variation seen in recent months. However, any detection at all would depend on the direction the wind is blowing the smoke plume.

Though any increases in radiation dose rates seen so far appear to be very small, inhaling the smoke from this fire could lead to an internal dose of radioactive cesium. We strongly suggest that people avoid inhaling this smoke. The area surrounding the fire where such risks would be highest are in fact closed to the public and therefore inaccessible, but the additional radiation risk to firefighters is making it difficult to send adequate personnel to battle the blaze.

News videos here:

NHK, Sun. April 30, 2017

Nippon Television, Tues. May 2, 2017

http://blog.safecast.org/2017/05/mount-juman-forest-fire-in-namie/

May 3, 2017 Posted by | Fukushima 2017 | , , , , | 2 Comments

Wildfires in Namie

Wildfire is raging in the highly radio-contaminated area in Namie, Fukushima prefecture. Japanese authorities are minimizing the radiation risk. It is time to provide information from civil movement point of view. We are publishing here the translation of an article by Suzuki Hiroki, a freelance journalist.

What is happening in Namie, the 74th month after the Fukushima Daiichi accident?

There is a wildfire in the forest in the “difficult-to-return zone” causing rising concerns about the secondary dispersion of radioactive substances.
“Is it safe?” Voices of rage from the townspeople towards the central and local governments that hurried the evacuation order lifting.

A forest fire broke out on 29 April in Namie Town, Fukushima Prefecture, where one month had passed since the evacuation orders were lifted from a large part of the town. Moreover, it happened in the “difficult-to-return zone” where radio-contamination is especially high even in Namie town. Strong winds and high concentrations of contamination have made it difficult to fight against the fire and the fire has not been extinguished as of the night of May 1. Although the evacuation orders have been lifted as “the environment for everyday life is sufficiently in order”, it has been made clear that Namie has a perpetual risk of secondary dispersion of radioactive materials in the future. The fact that there is no means to prevent internal irradiation of firefighters as well as of returning residents brought home again the “reality” of the nuclear power plant accident.

[Firefighters cannot get close to the scene]

At the Sports Center near Japan Railway Joban Line Namie station fire-fighting helicopters in Fukushima and Miyagi prefecture land in the parking lot every few minutes. Water is put in the tanks with the hose connected to the fire hydrant. In the direction where the helicopter flew, smoke was still rising from the ridge of the mountain. Only the sound of the propeller echoes in the city empty of its population. Since April 29, the day when “Namie Town Security Watch Corps” rushed to the fire station, the feared forest fire is still ongoing 2 days later. The concern of secondary dispersion of radioactive materials is heightened.

The burned area has exceeded 10 hectares. Although the fire is weakening, the fire department is cautious in declaring the judgment of “repression” and “extinguishing” of fire, for the fire became strong once again after it was judged being “repressed”. On May 2, since 5:00 am, BABA Tamotsu, the mayor of Namie, and OWADA Hitoshi, head of the headquarters of the Futaba Regional Communities Area Union Fire Department, have been busy inspecting the area from the sky by helicopter.

Jyumanyama” (altitude 448.4 meters), where lightning caused the fire, is located in the Ide district, which is designated as a “difficult-to-return zone”. Although the evacuation orders were partially lifted on March 31 from Namie, the “difficult-to-return zone” is still severely restricted from entering. The town’s fire brigade was called up, but its members cannot go close to the scene. It takes two hours on foot from the entrance of the mountain trail to the site, according to the headquarters of the Futaba Regional Communities Area Union Fire Department. The spot could not be specified easily. As soon as it was localized from the sky by the helicopter, firefighters climbed the steep slopes without trails while receiving the guidance of the Forestry agency and Iwaki Forest management office staff. In the meantime, smoke fueled by strong winds reduced visibility like a dense fog. But it’s not just smoke that is dangerous – there is the danger of radioactivity as well The effect of the absorption can attached to the protective mask only functions up to three hours. The exchange in the contaminated smoke is accompanied by the irradiation risk. Considering the health hazards of the members, it is not a good idea to enter the virgin forest without a discussed plan. On April 30 at noon, UCHIBORI Masao, the governor of Fukushima Prefecture requested to dispatch the 6th Division of the JGSDF (Yamagata Prefecture) for the disaster. The amount of water spray exceeds 400 tons by GSDF alone.

However, it is not possible to stop the secondary dispersion of the radioactive material even by the SDF. This is the specificity and danger of this forest fire.

photo-1.jpeg(Top) At the Namie Regional Sports Center parking lot, fire-fighting helicopters came back one after another for water supply. The extinguishing activity from air is scheduled again on May 2 in the morning.

photo-2(Middle) From Jyumanyama mountains there was still smoke.
Secondary dispersion of radioactive materials is concerned. (Taken on May 1 around 11 a.m.)

photo-3(Bottom) Firefighters entered the field in protective gear and masks, but ” practically, there are no means to prevent the exposure to the radiation”.

 

The radiation of the firefighters is unavoidable”.

The secondary dispersion of radioactive materials is an alarming thing, but it has been expected. Judging that ‘the living environment is generally in order’, evacuation orders have been lifted, but once the wildfire starts, this is what happens. Did the government lift the evacuation orders after presenting these risks to the townspeople? I do not have any confidence in the central government nor in the local administration. They are good at appealing that everything is going well in this country. It was the same during the war. In that sense, it is a system of ‘self-responsibility’. I have no choice but to take care of myself”, said a man in his 40s, who was evacuated from the Hiwatari-Ushiwata administrative district. No active effort to announce the secondary dispersion of radioactive materials associated with forest fires was made by the town. It was delivered at last in the Mail magazine of the town at 10:00 a.m. on May 1. The following warning sentence was diffused: “Please do not approach carelessly, for it is dangerous”. It was not known to the townspeople for more than a full day because the fire report is dated Saturday evening. “The administration is difficult to move on Saturdays and Sundays,” said the General Affairs Disaster Security Division. On May 1 at 7:00 a.m., the same content was announced to the entire neighborhood by the disaster prevention radio, and “Notice of forest fire conditions” was published on the town homepage. However, there was no call for wearing a mask related to secondary dispersion of radioactive materials.

No emergency calls have reached the town council members. A certain council member said, “It is a good thing that I happened to learn about it by the television news. Otherwise, I wouldn’t have been able to answer when questioned by the townspeople about this. I want to request to make a contact system because the forest fire in the “difficult-to-return zone” is an emergency situation.”

This council member says, “it is only a personal opinion, but it is natural to assume that radioactive cesium will scatter with smoke and ash, and the fire extinguishing activity should be carried out while measuring how much radioactive material there is in the one square meter. However, it is not realistic, and I have to say that it is not possible to prevent internal irradiation exposure after all.” Another council member also said, “the risk was not examined when the evacuation order was lifted. The danger has been proven by the forest fire this time.” He is ready to take the matter to the Town Council.

As for the irradiation risk of the fire brigade, the headquarters of the Futaba Regional Communities Area Union Fire Department admit that while they can make a point “not to carry out the contaminated materials from the area”, there is no means to prevent the exposure of the fire brigade member. They can only try to shorten the time of stay in the “difficult-to-return zone”, but in reality it takes time to reach the site, and it is difficult to reach it. We have to admit that the exposure is unavoidable.” I wonder if we can consider the situation as “nuclear accident is under control”?

 

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There was a warning about forest fires since even before the nuclear accident. The airborne radioactivity of Tsushima District, which is designated as “difficult-to-return zone” like Ide district, is still high. It is sad to say, but the risk of secondary dispersion of radioactive materials with a fire is high.

 

Difficulty to monitor fine particles

There is no significant fluctuation in the airborne radioactivity measured by the monitoring posts installed inside and outside the town. The local media also actively convey the point. However, Mr. Yoichi Ozawa of the citizen’s group in Minamisoma City, “Fukuichi Environmental Radiation Monitoring Project”, pointed out that “radioactive particulates cannot be caught by a dosimeter or monitoring post.” In response to the forest fire, the above Project and the Citizen Radioactivity Monitoring Center “Chikurin-sha” (Hinode Town, Nishitama County, Tokyo) put several linen cloths in the town of Namie. It is thought that the secondary dispersion situation can be estimated by examining the adhesion of the fine particles that cause the internal irradiation.

The central government also faces a cautious posture about the secondary dispersion of the radioactive materials by combustion. On April 20, at the meeting with the residents of Iitate village the person in charge of the Cabinet Office asked the villagers “not to burn the field until the results of experimentation and analyses about how much radioactive materials scatter and adhere to crops etc. come out.” It is a reality that even the bureaucrats of the central government who rushed the evacuation order lifting are not able to affirm that it is safe.

According to the research by Mr. Ozawa and his colleagues, radioactive cesium of 17,000 Bq/kg was found in the fallen leaves near the Ogaki dam last autumn in the “difficult-to-return zone”. “The radioactive material is concentrated by several dozen times by burning. Some experts have pointed out hundreds of times”, says Ozawa. However, neither the central government nor Fukushima prefecture nor the Namie town warn about the internal irradiation at all.

They lifted the evacuation order saying that it is safe and secure, but it’s not at all,” says a 70 year old resident angrily. A lot of worries about the exposure risk were voiced at the residents consultation meeting just before the lifting of evacuation orders. Some say, “it is useless to worry all the time. Since the nuclear power plant accident has happened, we have to think in a constructive way now”, but unfortunately many townspeople’s worries have become real. Moreover, it’s quite possible that the forest fire was caused by lightning. Namie will have to take the same risks in the future. The fire site continues smoldering. Radioactive materials are slowly spreading.

Published in Taminokoe shimbun, May 2, 2017.

https://fukushima311voices.wordpress.com/2017/05/02/wildfires-in-namie/

May 3, 2017 Posted by | Fukushima 2017 | , , , , | Leave a comment