High-priced Fukushima ice wall nears completion, but effectiveness doubtful

 

A subterranean ice wall surrounding the nuclear reactors at the stricken Fukushima No. 1 Nuclear Power Plant to block groundwater from flowing in and out of the plant buildings has approached completion.

Initially, the ice wall was lauded as a trump card in controlling radioactively contaminated water at the plant in Fukushima Prefecture, which was crippled by meltdowns in the wake of the March 2011 Great East Japan Earthquake and tsunami. But while 34.5 billion yen from government coffers has already been invested in the wall, doubts remain about its effectiveness. Meanwhile, the issue of water contamination looms over decommissioning work.

In a news conference at the end of July, Naohiro Masuda, president and chief decommissioning officer of Fukushima Daiichi Decontamination & Decommissioning Engineering Co., stated, “We feel that the ice wall is becoming quite effective.” However, he had no articulate answer when pressed for concrete details, stating, “I can’t say how effective.”

The ice wall is created by circulating a coolant with a temperature of minus 30 degrees Celsius through 1,568 pipes that extend to a depth of 30 meters below the surface around the plant’s reactors. The soil around the pipes freezes to form a wall, which is supposed to stop groundwater from flowing into the reactor buildings where it becomes contaminated. A total of 260,000 people have worked on creating the wall.

This photo shows pipes to freeze soil for the ice wall next to the No. 4 reactor at TEPCO’s Fukushima No. 1 Nuclear Power Plant, in Okuma, Fukushima Prefecture, on June 1, 2016. (Mainichi)

 

The plant’s operator, Tokyo Electric Power Co. (TEPCO) began freezing soil in March last year, and as of Aug. 15, at least 99 percent of the wall had been completed, leaving just a 7-meter section to be frozen.

Soon after the outbreak of the nuclear disaster, about 400 tons of contaminated water was being produced each day. That figure has now dropped to roughly 130 tons. This is largely due to the introduction of a subdrain system in which water is drawn from about 40 wells around the reactor buildings. As for the ice wall, TEPCO has not provided any concrete information on its effectiveness. An official of the Secretariat of the Nuclear Regulation Authority (NRA) commented, “The subdrain performs the primary role, and the ice wall will probably be effective enough to supplement that.” This indicates that officials have largely backtracked from their designation of the ice wall as an effective means of battling contaminated water, and suggests there is unlikely to be a dramatic decrease in the amount of decontaminated groundwater once the ice wall is fully operational.

TEPCO ordered construction of the ice wall in May 2013 as one of several plans proposed by major construction firms that was selected by the government’s Committee on Countermeasures for Contaminated Water Treatment. In autumn of that year Tokyo was bidding to host the 2020 Olympic and Paralympic Games, and the government sought to come to the fore and underscore its measures to deal with contaminated water on the global stage.

Using taxpayers’ money to cover an incident at a private company raised the possibility of a public backlash. But one official connected with the Committee on Countermeasures for Contaminated Water Treatment commented, “It was accepted that public funds could be spent if those funds were for the ice wall, which was a challenging project that had not been undertaken before.” Small-scale ice walls had been created in the past, but the scale of this one — extending 1.5 kilometers and taking years to complete — was unprecedented.

At first, the government and TEPCO explained that an ice wall could be created more quickly than a wall of clay and other barriers, and that if anything went wrong, the wall could be melted, returning the soil to its original state. However, fears emerged that if the level of groundwater around the reactor buildings drops as a result of the ice wall blocking the groundwater, then tainted water inside the reactor buildings could end up at a higher level, causing it to leak outside the building. Officials decided to freeze the soil in stages to measure the effects and effectiveness of the ice wall. As a result, full-scale operation of the wall — originally slated for fiscal 2015 — has been significantly delayed.

A worker makes checks with a hammer on an impermeable wall near TEPCO’s No. 4 reactor in the town of Okuma in Fukushima Prefecture on Feb. 24, 2017. (Mainichi)

 

Furthermore, during screening by the NRA, which had approved the project, experts raised doubts about how effective the ice wall would be in blocking groundwater. The ironic reason for approving its full-scale operation, in the words of NRA acting head Toyoshi Fuketa, was that, “It has not been effective in blocking water, so we can go ahead with freezing with peace of mind” — without worrying that the level of groundwater surrounding the reactor buildings will increase, causing the contaminated water inside to flow out.

Maintaining the ice wall will cost over a billion yen a year, and the radiation exposure of workers involved in its maintenance is high. Meanwhile, there are no immediate prospects of being able to repair the basement damage in the reactor buildings at the crippled nuclear plant.

Nagoya University professor emeritus Akira Asaoka commented, “The way things stand, we’ll have to keep maintaining an ice wall that isn’t very effective. We should consider a different type of wall.”

In the meantime, TEPCO continues to be plagued over what to do with treated water at the plant. Tainted water is treated using TEPCO’s multi-nuclide removal equipment to remove 62 types of radioactive substances, but in principle, tritium cannot be removed during this process. Tritium is produced in nature through cosmic rays, and nuclear facilities around the world release it into the sea. The NRA takes the view that there is no problem with releasing treated water into the sea, but there is strong resistance to such a move, mainly from local fishing workers who are concerned about consumer fears that could damage their businesses. TEPCO has built tanks on the grounds of the Fukushima No. 1 plant to hold treated water, and the amount they hold is approaching 800,000 metric tons.

In mid-July, TEPCO Chairman Takashi Kawamura said in an interview with several news organizations that a decision to release the treated water into the sea had “already been made.” A Kyodo News report on his comment stirred a backlash from members of the fishing industry. TEPCO responded with an explanation that the chairman was not stating a course of action, but was merely agreeing with the view of the NRA that there were no problems scientifically with releasing the treated water. However, the anger from his comment has not subsided.

Critical opinions emerged in a subsequent meeting that the Ministry of Economy, Trade and Industry held in the Fukushima Prefecture city of Iwaki at the end of July regarding the decontamination of reactors and the handling of contaminated water. It was pointed out that prefectural residents had united to combat consumer fears and that they wanted officials to act with care. One participant asked whether the TEPCO chairman really knew about Fukushima.

The ministry has been considering ways to handle the treated water, setting up a committee in November last year that includes experts on risk evaluation and sociology. As of Aug. 15, five meetings had been held, but officials have yet to converge on a single opinion. “It’s not that easy for us to say, ‘Please let us release it.’ It will probably take some time to reach a conclusion,” a government official commented.

https://mainichi.jp/english/articles/20170816/p2a/00m/0na/016000c

 

 

Radioactive Hot Particles in Japan: Full Radiation Risks not Recorded

 

Radioactively-Hot Particles in Japan; New Study Shows Full Radiation Risks are not Recorded

The article details the analysis of radioactively hot particles collected in Japan following the Fukushima Dai-ichi meltdowns. Based on 415 samples of radioactive dust from Japan, the USA, and Canada, the study identified a statistically meaningful number of samples that were considerably more radioactive than current radiation models anticipated. If ingested, these more radioactive particles increase the risk of suffering a future health problem…

http://www.fairewinds.org/newsletter-archive//press-release-radioactively-hot-particles-in-japan

 

Radioactively-hot particles detected in dusts and soils from Northern Japan by combination of gamma spectrometry, autoradiography, and SEM/EDS analysis and implications in radiation risk assessment

by Marco Kaltofen (Nuclear Science and Engineering Program, Department of Physics, Worcester Polytechnic Institute) and Arnie Gundersen (Fairewinds Energy Education), Dec 2017 :

Radioactively-hot particles detected in dusts and soils from Northern Japan… Radioactive particles from Fukushima are tracked via dusts, soils, and sediments; Radioactive dust impacts are tracked in both Japan and the United States/Canada; Atypically-radioactive particles from reactor cores are identified in house dusts… After the March 11, 2011, nuclear reactor meltdowns at Fukushima Dai-ichi, 180 samples of Japanese particulate matter (dusts and surface soils) and 235 similar U.S. and Canadian samples were collected and analyzed… Samples were collected and analyzed over a five-year period, from 2011 to 2016.

 

Detectable levels of 134Cs and 137Cs were found in 142 of 180 (80%) Japanese particulate matter samples… U.S. and Canadian samples had detectable 134Cs and 137Cs in one dust sample out of 32 collected, and four soils out of 74… The mean in Japan was skewed upward due to nine of the 180 (5%) samples with activities > 250 kBq kg− 1 [250,000 Bq/kg]… 300 individual radioactively-hot particles were identified in samples from Japan; composed of 1% or more of the elements cesium, americium, radium, polonium, thorium, tellurium, or strontium.

 

Some particles reached specific activities in the MBq μg− 1 level and higher [1,000,000,000,000,000 Bq/kg]… Some of the hot particles detected in this study could cause significant radiation exposures to individuals if inhaled. Exposure models ignoring these isolated hot particles would potentially understate human radiation dose.

 

http://www.sciencedirect.com/science/article/pii/S0048969717317953?np=y&npKey=ae4b9f4116b6874eaa549d53528bc26460935d9178063240f633554071f1b295

http://audioslides.elsevier.com/viewersmall.aspx?doi=10.1016/j.scitotenv.2017.07.091&source=0

7 summers later, weeds engulf Fukushima’s abandoned areas

 

The startling effects of the passage of time come into sharp focus in aerial images taken of Fukushima’s “difficult-to-return zones” in the seventh summer since the March 2011 nuclear disaster.

The bird’s-eye view pictures were captured in abandoned areas near the crippled Fukushima No. 1 nuclear power plant in Okuma and Futaba in Fukushima Prefecture.

The disaster unfolded after the magnitude-9.0 Great East Japan Earthquake spawned a tsunami that devastated coastal areas of the Tohoku region, including Tokyo Electric Power Co.’s Fukushima No. 1 plant.

The Okuma outlet of Plant-4, a large shopping mall located 3 kilometers away from the nuclear plant along National Route No. 6, had been bustling with visitors before the disaster.

Today, weeds grow from the cracks of the asphalt-surfaced mall parking lot, slowly creeping through the expanse of space.

One striking image shows the exterior of the TEPCO-owned condominium building, which housed its employees in Futaba, is becoming covered with rampant weeds that have reached the second floor.

Another photo shows cars that cannot be recovered are partially buried, appearing as if they are sinking into a sea of green.

http://www.asahi.com/ajw/articles/AJ201708010034.html

Blast from the Past: Plutonium Contamination from Fukushima Daiichi Unit 3

From Majia’s blog

I was reviewing my notes regarding plutonium found at Fukushima and I found this news story worth remembering:

Amina Khan (of the Los Angeles Times). (March 8, 2012). Plutonium near Fukushima plant poses little risk, study says Published: Thursday, March 8, 2012 http://www.heraldnet.com/article/20120308/NEWS02/703089849

The levels of radioactive plutonium around Japan’s Fukushima Daiichi nuclear power plant aren’t much higher than the amount of plutonium remaining in the environment from Cold War-era nuclear weapons tests, and it probably poses little threat to humans, a new study indicates.

The paper, published Thursday in the journal Scientific Reports, provides the first definitive evidence of plutonium from the accident entering the environment, the authors say. It examines the area within a roughly 20-mile radius of the plant and details the concentration of plutonium isotopes deposited there after explosions ripped open multiple reactors.

At the three sites examined, the levels for certain isotope ratios were about double those attributed to residual fallout from above-ground nuclear tests conducted by the U.S. and former Soviet Union at the dawn of the Cold War….

Robert Alvarez, who has served as a senior policy adviser in the U.S. Energy Department, said he would have been surprised if researchers had not found evidence of plutonium contamination near the plant. “They were irradiating plutonium in Unit 3, which experienced the biggest explosion,” he said. In fact, the explosion was so massive that investigators found fuel rod fragments a mile away, leading to speculation that a supercritical fission event may have also occurred, Alvarez said.

The article is referring to a study by Zheng et al. Here is my synopsis of the study’s findings:

A study released in Scientific Reports published by Nature titled ‘Isotopic evidence of plutonium release into the environment from the Fukushima DNPP accident’ by Zheng et al found that a wide array of highly volatile fission products were released, including 129mTe, 131I, 134Cs, 136Cs and 137Cs, which were all found to be ‘widely distributed in Fukushima and its adjacent prefectures in eastern Japan.’[i]

The study also found evidence of actinides, particularly Pu isotopes, on the ground northwest and south of the Fukushima DNPP in the 20–30 km zones. The study called for long-term investigation of Pu and 241Am dose estimates because of findings of ‘high activity ratio of 241Pu/239+240Pu (> 100) from the Fukushima DNPP accident.’

The study concluded that in comparison to Chernobyl, the Fukushima accident ‘had a slightly higher 241Pu/239Pu atom ratio, but lower ratio of 240Pu/239Pu.’ Unit 3 was seen as the likely source for the high Pu detections.

[i] J. Zheng, K. Tagami, Y. Watanabe, S. Uchida, T. Aono, N. Ishii, S. Yoshida, Y. Kubota, S. Fuma and S. Ihara (8 March 2012 ) ‘Isotopic Evidence of Plutonium Release into the Environment from the Fukushima DNPP Accident,’ Scientific Reports, 2, http://www.nature.com/srep/2012/120308/srep00304/full/srep00304.html.

http://majiasblog.blogspot.fr/2017/07/blast-from-past-plutonium-contamination.html

No human rights in terrifyingly contaminated Namie in Fukushima

The evacuation orders of the most populated areas of Namie, Fukushima were lifted on March 31, 2017.

We are publishing the most recent soil surface density map of Namie created by a citizen’s measurement group named the “Fukuichi Area Environmental Radiation Monitoring Project“(http://www.f1-monitoring-project.jp/index.html). Their members are mainly from Tokyo metropolitan region.

 

Their map is simply terrifying. This is far much higher level of radio-contamination than in the Radiation Control Zone. Any area becomes designated as such when the total effective dose due to external radiation and that due to radioactive substances in the air is likely to exceed 1.3mSv per quarter – over a period of three months, or when the surface density is likely to exceed 40,000Bq/m2. In the Radiation Control Zone, it is prohibited to drink, eat or stay overnight. Even adults, including nuclear workers, are not allowed to stay more than 10 hours. To leave the zone, one has to go through a strict screening.

Namie’s radio contamination is far over these figures! The average soil contamination density of the total of 314 points where the soil was collected and measured is 858,143Bq/m². The maximum value was 6,780,000Bq/m², and the minimum was only 31,400Bq/m²!

And people, including infants and pregnant women, are told to go back to these areas to live, because it is supposed to be safe. Basically the Japanese government does not recognize the fundamental human right to live in a healthy environment. The population is facing a tough future, for the compensation will be cut off soon, and the housing aid by the central government finishes at the same time. As for the auto-evacuees who fled from areas which are not classified as evacuation zones but are nevertheless radio-contaminated, they had only very little compensation and the housing aid was cut off at the end of March 2017. Continuing to live as nuclear refugees is becoming more and more difficult. We consider that this is a violation of basic environmental human rights.

Let us not forget to thank the members and volunteers of the Fukuichi Area Environmental Radiation Monitoring Project team. They are mostly elderly people over 60 years old. However, that doesn’t mean that they can be exposed to radiation. We thank them and pray for their health.

Measurement devices

 

Kit for soil collection

 

Kit carried on the back

 

 

 

Collected soil samples

 

Analysing the soil samples

 

You might think that Japanese just endure their fate without complaining. This is not true. Many people are fighting and protesting. Let us cite, among numerous on-going trials, the one called the “Trial to require the withdrawal of the 20mSv dose as the limit for evacuation” filed by residents of Minamisoma city in Fukushima, who are against the lifting of the evacuation order when the radiation dose decreases below 20mSv/year. Let us remind you that the Japanese government has adopted 1mSv/year, the internationally recognized dose limitation for public recommended in 1990 by ICRP (International Commission on Radiological Protection), and this is still the limit for the public all over Japan EXCEPT in Fukushima. This is one of the reasons why many people from Fukushima ask themselves: “Is Fukushima really a part of Japan?” or “Are we the people abandoned by the State?”

Related articles of this site :

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

The scandalous deficiency of the health scheme in Fukushima

Incredible contamination in Namie, Fukushima

New data show massive radiation levels in Odaka, Minamisoma

Source: https://fukushima311voices.wordpress.com/2017/07/31/no-human-rights-in-terrifyingly-contaminated-namie-in-fukushima/

An election campaign in an unknown town

31/7/2017 by Mayumi MATSUMURA

Yesterday morning, while I was waiting with my mother-in-law the pickup bus from the Day Care Center for the Elderly, I heard voices approaching. They seemed to say “Good morning” using a loudspeaker attached to an advertising car.

 

However, the voices were weak, considering that they came from a loudspeaker. They also seemed very reserved and embarrassed to disturb people. (Translator’s note: In Japan during the election time, candidates and their teams roam the streets in vehicles shouting their names and asking for support). I listened. The voices said: “Good morning, I am XXXX, candidate for the election of the mayor of Tomioka”.

 

The voices were really reserved, weak …

They made me so sad. Profoundly moved, I opened the kitchen window and waved my hands.

The first car stopped.

The voice said, “Oh, thank you, thank you. ”

 

“Courage and good luck! I’m sorry, I’m not from Tomioka, but … ” I said.

A voice replied, “Thank you, thank you for your words of support.”

 

I waved my hands and shouted words of encouragement to the second and third vehicle where the candidate was seated.

My eyes were filled with tears.

They run an election campaign in an unknown city, without knowing where the residents of Tomioka are, where their voters took refuge.

 

If it were their own town, they would campaign with dignity from the electoral car in a loud voice. But they were belittling themselves, roaming through the unknown streets.

 

Tears have troubled the visions.

However, I continued to wave my hands until the vehicles disappeared.

It has been 6 years and 4 months since we left our home.

There will never be a restful end to our journey.

 

___

On July 28, 2017 published on Facebook by Mrs. Mayumi MATSUMURA, evacuee from the town of Namie, Fukushima prefecture.

http://nosvoisins311.wixsite.com/voisins311-france/single-post/2017/07/31/Une-campagne-%C3%A9lectorale-dans-une-ville-inconnue

Study: Radioactive Hot Particles Still Afloat Throughout Japan Six Year After Fukushima Meltdowns

Radioactive particles of uranium, thorium, radium, cesium, strontium, polonium, tellurium and americium are still afloat throughout Northern Japan more than six years after a tsunami slammed into the Fukushima Daiichi Power Plant causing three full-blown nuclear meltdowns. That was the conclusion reached by two of the world’s leading radiation experts after conducting an extensive five-year monitoring project.

Arnie Gundersen and Marco Kaltofen authored the peer reviewed study titled, Radioactively-hot particles detected in dusts and soils from Northern Japan by combination of gamma spectrometry, autoradiography, and SEM/EDS analysis and implications in radiation risk assessment, published July 27, 2017, in Science of the Total Environment (STOLEN).

Gundersen represents Fairewinds Associates and is a nuclear engineer, former power plant operator and industry executive, turned whistleblower, and was CNN’s play-by-play on-air expert during the 2011 meltdowns. Kaltofen, of the Worcester Polytechnic Institute (WPI), is a licensed civil engineer and is renowned as a leading experts on radioactive contamination in the environment.

415 samples of “dust and surface soil” were “analyzed sequentially by gamma spectrometry, autoradiography, and scanning electron microscopy with energy dispersive X-ray analysis” between 2011 and 2016. 180 of the samples came from Japan while another 235 were taken from the United States and Canada. The study further clarifies, “Of these 180 Japanese particulate matter samples, 57 were automobile or home air filters, 59 were surface dust samples, 29 were street dusts (accumulated surface soils and dusts) and 33 were vacuum cleaner bag or other dust samples.”

108 of the Japanese samples were taken in 2016, while the other 72 were gathered in 2011 after the meltdowns. Gundersen and Kaltofen tapped 15 volunteer scientists to help collect the dust and soil — mostly from Fukushima Prefecture and Minamisouma City. “A majority of these samples were collected from locations in decontaminated zones cleared for habitation by the National Government of Japan,” the study revealed. For the 108 samples taken in 2016, an “International Medcom Inspector Alert surface contamination monitor (radiation survey meter) was used to identify samples from within low lying areas and on contaminated outdoor surfaces.”

A Fairewinds Associates’ video from 2012 features Gundersen collecting five samples of surface soil from random places throughout Tokyo — places including a sidewalk crack, a rooftop garden, and a previously decontaminated children’s playground. The samples were bagged, declared through Customs, and brought back to the U.S. for testing. All five samples were so radioactive that according to Gundersen, they “qualified as radioactive waste here in the United States and would have to be sent to Texas to be disposed of.” Those five examples were not included as part of the recently released study, but Gundersen went back to Tokyo for samples in 2016. Those samples were included, and were radioactive, and according to Gundersen were “similar to what I found in Tokyo in [2012].”

 

Furthermore, 142 of the 180 samples (about 80 percent) contained cesium 134 and cesium 137. Cesium 134 and 137, two of the most widespread byproducts of the nuclear fission process from uranium-fueled reactors, are released in large quantities in nuclear accidents. Cesium emits intense beta radiation as it decays away to other isotopes, and is very dangerous if ingested or inhaled. On a mildly positive note, the study shows that only four of the 235 dust samples tested in the United States and Canada had detectable levels of cesium from Fukushima.

Cesium, due to its molecular structure, mimics potassium once inside the body, and is often transported to the heart where it can become lodged, thereafter mutating and burning heart tissue which can lead to cardiovascular disease. Other isotopes imitate nutritive substances once inside the body as well. Strontium 90 for example mimics calcium, and is absorbed by bones and teeth.

“Different parts of the human body (nerves, bones, stomach, lung) are impacted differently,” Kaltofen told EnviroNews in an email. “Different cells have radio-sensitivities that vary over many orders of magnitude. The body reacts differently to the same dose received over a short time or a long time; the same as acute or chronic doses in chemical toxicity.”

In contrast to external X-rays, gamma, beta or alpha rays, hot particles are small mobile pieces of radioactive elements that can be breathed in, drunk or eaten in food. The fragments can then become lodged in bodily tissue where they will emanate high-intensity ionizing radiation for months or years, damaging and twisting cells, potentially causing myriad diseases and cancer. The study points out, “Contaminated environmental dusts can accumulate in indoor spaces, potentially causing radiation exposures to humans via inhalation, dermal contact, and ingestion.”

The study also explains, “Given the wide variability in hot particle sizes, activities, and occurrence; some individuals may experience a hot particle dose that is higher or lower than the dose calculated by using averaged environmental data.” For example, a person living in a contaminated area might use a leaf blower or sweep a floor containing a hefty amount of hot particle-laden dust and receive a large does in a short time, whereas other people in the same area, exposed to the same background radiation and environmental averages, may not take as heavy a hit as the housekeeper that sweeps floors for a living. People exposed to more dust on the job, or who simply have bad luck and haphazardly breathe in hot radioactive dust, are at an increased risk for cancer and disease. High winds can also randomly pick up radioactive surface soil, rendering it airborne and endangering any unsuspecting subject unlucky enough to breath it in.

Hot particles, or “internal particle emitters” as they are sometimes called, also carry unique epidemiological risks as compared to a chest X-ray by contrast. The dangers from radiation are calculated by the dose a subject receives, but the manner in which that dose is received can also play a critical factor in the amount of damage to a person’s health.

“Comparing external radiation to hot particles inside the body is an inappropriate analogy,” Gundersen told EnviroNews in an email. “Hot particles deliver a lot of energy to a very localized group of cells that surround them and can therefore cause significant localized cell damage. External radiation is diffuse. For example, the weight from a stiletto high heal shoe is the same as the weight while wearing loafers, but the high heal is damaging because its force is localized.”

Kaltofen elaborated with an analogy of his own in a followup email with EnviroNews saying:

Dose is the amount of energy in joules absorbed by tissue. Imagine Fred with a one joule gamma dose to the whole body from living in a dentist’s office over a lifetime, versus Rhonda with exactly the same dose as alpha absorbed by the lung from a hot particle. Standard health physics theory says that Fred will almost certainly be fine, but Rhonda has about a 10 percent chance of dying from lung cancer — even though the doses are the same.

External radiation and internal hot particles both follow exactly the same health physics rules, even though they cause different kinds of biological damage. Our data simply shows that you can’t understand radiation risk without measuring both.

Some isotopes, like plutonium, only pose danger to an organism inside the body. As an alpha emitter, plutonium’s rays are blocked by the skin and not strong enough to penetrate deep into bodily tissue. However, when inhaled or ingested, plutonium’s ionizing alpha rays twist and shred cells, making it one of the most carcinogenic and mutagenic substances on the planet.

“Measuring radioactive dust exposures can be like sitting by a fireplace,” Dr. Kaltofen explained in a press release. “Near the fire you get a little warm, but once in a while the fire throws off a spark that can actually burn you.”

“We weren’t trying to see just somebody’s theoretical average result,” Kaltofen continued in the press release. “We looked at how people actually encounter radioactive dust in their real lives. [By] combining microanalytical methods with traditional health physics models… we found that some people were breathing or ingesting enough radioactive dust to have a real increase in their risk of suffering a future health problem. This was especially true of children and younger people, who inhale or ingest proportionately more dust than adults.”

“Individuals in the contaminated zone, and potentially well outside of the mapped contaminated zone, may receive a dose that is higher than the mean dose calculated from average environmental data, due to inhalation or ingestion of radioactively-hot dust and soil particles,” the study says in summation. “Accurate radiation risk assessments therefore require data for hot particle exposure as well as for exposure to more uniform environmental radioactivity levels.”

https://www.environews.tv/072917-study-plutonium-hot-particles-still-afloat-throughout-japan-six-year-fukushima-meltdowns/