Fukushima plant reactor #3 gets new roof cover


Workers at the crippled Fukushima Daiichi nuclear power plant have finished installing a new roof covering for the No.3 reactor building.
The work started last August to set up a dome-shaped cover. It is part of preparations for removing nuclear fuel from the reactor’s storage pool. A total of 566 spent and unused fuel units remain in the storage pool of the No. 3 reactor.
On Wednesday, workers installed the last part of the cover, which is 17 meters high and 22 meters wide, and weighs 55 tons.
The cover will prevent radioactive materials from spreading, and shield the building from winds.
Reactors at the Fukushima plant suffered meltdowns after a quake-triggered tsunami hit the plant on March 11th, 2011. The fuel units left in storage pools need to be removed as part of decommission work at the plant.
The plant’s operator, Tokyo Electric Power Company, will clear the pool of rubble and provide workers with training on remotely handling devices for the fuel removal.
Then, it plans to start removing nuclear fuel units from the No.3 reactor’s storage pool in autumn this year, ahead of those of other damaged reactors.
21 feb 2018 reactor 3 roof.jpg



Key figures for the seventh anniversary



February 17, 2018

Translation by Herve Courtois from the ACRO article


All the figures quoted in this article are from TEPCO and the Japanese government. We can safely assume the true figures to be somehow higher, as we know from the past 7 years that TEPCO and the Japanese government have never been straightforward with their figures.


As we approach the seventh anniversary of the nuclear disaster at the Fukushima Daiichi nuclear power plant, here are some key figures as they appear in the media and official websites. This article will be updated as they appear.

Situation of the reactors

The work is aimed primarily at securing the damaged reactors that are still threatening. Nearby, the dose rates are such that the work time of the workers must be very limited, which complicates the work.

Reactor # 4

The reactor vessel was empty on March 11, 2011 so there was no core melting, but a hydrogen explosion destroyed the reactor building. Since December 2014, the reactor fuel pool has been emptied and work is stopped because it is no longer threatening. http://www.tepco.co.jp/en/press/corp-com/release/2014/1246703_5892.html

The few dose rates available inside the reactor building are here expressed in mSv / h, knowing that the limits are in mSv / year. They date from 2016. www.tepco.co.jp/en/nu/fukushima-np/f1/surveymap/images/sv-u4-20160630-e.pdf

Reactor # 3

There was a core meltdown and a hydrogen explosion destroyed the reactor building. All top debris were removed using remotely controlled gear. A new building is being finished. Fuel removal is expected to begin this year and end in 2019.

The first images taken inside the containment led to a revision of the core fusion scenario.




The few dose rates available inside the reactor building are here expressed in mSv / h, knowing that the limits are in mSv / year. They date from 2016.


There would be between 188 and 394 tonnes of corium in this reactor, with a nominal value of 364 tonnes for reactor No. 3. The latter contains MOx fuel, which contains plutonium. To know more:


Reactor # 2

There was a melting of the core, but the reactor building is whole. TEPCO has not started removing used fuel from the pool. The company sent several robots into the containment to locate the corium, the mixture of molten fuel and debris.

Several series of images have been put online by the company. Those taken in January 2017 were analyzed and put back online in December 2017. There is a gaping hole just below the vessel, most likely due to the passage of molten fuel.


Those obtained in January 2018 at the bottom of the containment enclosure show what TEPCO thinks is corium and fragments of fuel assembly.




Dose rates inside the containment enclosure are lethal within minutes. The latest results published following the January 2018 exploration are quite surprising: not higher near what TEPCO thinks is corium, but higher outside.


The few dose rates available inside the reactor building are here expressed in mSv / h, knowing that the limits are in mSv / year. They date from 2016.


There would be between 189 and 390 tonnes of corium in this reactor, with a nominal value of 237 tonnes. To know more:


Reactor # 1

There was a core meltdown and a hydrogen explosion destroyed the reactor building. This building was covered by a new structure in 2011, which was completely dismantled in November 2016. TEPCO began removing the debris from the upper part of the reactor, then rebuilding a new structure to empty the pool. fuels.

The dose rates inside the reactor building are here expressed in mSv / h, knowing that the limits are in mSv / year. They date from 2016.


There would be between 232 and 357 tons of corium in this reactor, with a nominal value of 279 tons. To know more:


Reactors 5 and 6

Reactors 5 and 6 were partially unloaded on March 11, 2011, and a backup diesel generator was still functional, which prevented the core from melting. These reactors are now fully unloaded and will be dismantled.

Contamination of the plant

The last dose rates on the plant site published by TEPCO are from February 2017:

Groundwater also remains contaminated. Figures to come.



Contaminated water

The fuel that has melted and drilled the vessels must always be cooled. To this end, TEPCO injects 72 m3 of water per day into each of the reactors 1, 2 and 3 for this purpose. This makes a total of 216 m3 per day. This water is highly contaminated by contact with the molten fuel and infiltrates the basements of the reactor and turbine buildings where it mixes with the groundwater that infiltrates it.


At the beginning of the disaster, the infiltration amounted to about 400 m3 per day, which became contaminated and had to be stored in tanks. Inversely, the water of the basements, highly contaminated, leaked towards the groundwater then the ocean.

To reduce groundwater seepage, TEPCO pumps upstream of reactors before this water is contaminated and releases it directly into the ocean. It has also built a barrier all along the shoreline and pumps groundwater at the foot of the reactors. Part of this is partially decontaminated and released into the ocean. Another part, too contaminated, is mixed with the pumped water in the basements of the reactors to be put in tanks after treatment, waiting for a better solution.

The last barrier put in place is the freezing of the ground all around the 4 accidented reactors, on 1.4 km in order to stop the infiltrations. After many setbacks, the ice wall is finished since November 2017, but the effect remains limited. Even the Nuclear Regulatory Authority, the NRA, seriously doubts the effectiveness of this technique, which it now considers secondary.

A year ago, during our previous assessment, TEPCO pumped 135 m3 of contaminated water daily in the basements of reactor and turbine buildings, in addition to the one it injected for cooling and 62 m3 of groundwater, which made a total of 197 m3 which accumulated daily in tanks after treatment. It’s more in case of rain, or even more during typhoons.


Now that the soil freeze is over, these flows have been reduced. According to the latest report published by the company, 75 m3 of groundwater infiltrate daily in the basements of reactors to which must be added 15 m3 per pumped groundwater too contaminated to be treated directly before discharge to sea. therefore makes a total of 90 m3 per day. These values correspond to a week without rain. In case of heavy rainfall, it is much more, even if TEPCO has paved and concreted all soils to limit infiltration.


The water pumped into the basements is treated and stored in tanks at the plant site. TEPCO removes 62 radioelements, but it remains notably tritium, radioactive hydrogen, which is difficult to separate. The company announces that it has already treated 1,891,070 m3 of contaminated water, which generated 9,219 m3 of highly radioactive liquid waste and 597 m3 of radioactive sludge. Part of this is used for cooling and the rest is stored in tanks. According to the company, the stock of treated or partially treated water amounts to 1,037,148 m3 plus 35,010 m3 of water in the basements of the reactor and turbine buildings. There are nearly a thousand tanks to keep this water that occupy almost the entire site of the plant.


What to do with this treated water? After considering several unrealistic solutions, there remains only the rejection at sea. The concentration in tritium would be one to five million becquerels per liter, which is more than the authorized limit, set at 60 000 Bq / L. But, just dilute, as is done in normal operation. The problem is rather on the side of the total stock, estimated at 3.4 PBq (3.4 billion million becquerels), which represents about 150 years of rejection to the authorized limit.


By way of comparison, the discharge authorization at the Areva plant in La Hague is 18.5 PBq for tritium and the actual releases in recent years ranged from 11.6 to 13.4 PBq per year. The Fukushima tritium stock therefore represents 3 ½ months of discards at La Hague. What make the Japanese authorities jealous!


On the other hand, we do not know the concentration of other radioelements after filtering. This is important for an impact study before rejection. Toyoshi Fuketa, the president of the Nuclear Regulatory Authority, has asked for a decision to be made this year, saying that the rejection at sea is the only solution. The preparation of the rejection should take two to three years, according to him, and TEPCO will quickly run out of space.



At the Fukushima daiichi nuclear power plant

From March 11, 2011 to March 31, 2016, 46,956 workers were exposed to ionizing radiation at the site of the Fukushima daï-ichi power station, including 42,244 subcontractors. It is the subcontractors who take the highest doses, with an average that varies from 0.51 to 0.56 mSv per month between January and February 2016. It is between 0.18 and 0.22 for employees of TEPCO.
There are also 1,203 people who have a higher limit to continue to enter the site. Their average cumulative dose since the beginning of the accident is 36.49 mSv and the maximum value of 102.69 mSv.


On April 1, 2016, TEPCO reset all meters. For example, 174 workers who exceeded the dose limit of 100 mSv over 5 years may return. Since then, until December 31, 2017, 18,348 people have worked in controlled areas, including 16,456 subcontractors (90%). It is impossible to know how many of them have been exposed in the first five years. During this period, subcontractors took a cumulative average dose of 4.29 mSv, with a maximum of 60.36 mSv, while TEPCO employees took a cumulative average dose of 1.79 mSv with a maximum of 22.85 mSv. Subcontractors thus took 95.4% of the cumulative collective dose of 74 men.sieverts.



TEPCO has put online many other data on the doses taken, with distributions by age, year …


TEPCO reduced the risk premiums paid to workers because dose rates decreased on the site. This subject would be one of the main complaints of the staff engaged on the site. It could reach 20,000 yen (150 €) per day, even if, for the subcontractors, this premium was punctuated at each level of subcontracting, to be reduced, sometimes, to less than half. In March 2016, TEPCO divided the site of the accident site into 3 zones, red, yellow and green, depending on the level of risk. But for many workers, this zoning is meaningless: debris from the red zone is transferred to the green zone. The dust raised by the machines does not respect the boundaries … Thus, subcontractors wear protective equipment such as masks in the green zone, even if TEPCO does not require it.


About the decontamination sites

In the evacuated areas, it is the government that is prime contractor for the decontamination sites and in the areas not evacuated, it is the communes. The monthly report of the Ministry of the Environment (source, page 16) states:

13 million decontaminators in the evacuated areas and

17 million decontaminators in the areas not evacuated according to the data transmitted by the communes.


These numbers are completely unrealistic. This is probably the number of contracts signed. This means that the authorities do not know the number of decontaminators and therefore do not know the individual doses.

An individual dosimetric follow-up was introduced in November 2013 for the decontaminators (source in Japanese) who work in the evacuated zone and who are subject to the same dose limits as the nuclear workers. Data for 2016 show 36,000 decontaminators. We are far from the millions of decontaminators reported by the Ministry of the Environment. The majority (87%) received a dose of less than 1 mSv / yr and the highest dose was 7.5 and 10 mSv. There is also data by number of sites or by zone.



The most recent data in English, dated January 8, 2018, covers the period October 2016 – September 2017. Doses are reported by period of 3 months while the limits are annual. It is difficult to interpret these numbers. If it appears that the vast majority of decontaminators received less than 1 mSv over 3 months, it is not known how much below this limit over one year. The average annual dose is 0.5 mSv.


Other people exposed

I did not find any official data on the doses taken by those who continued to work in the evacuated area or the many police officers who guard and patrol the restricted areas.


Mapping of radioactive pollution

The latest aerial mapping of radioactive pollution around the Fukushima daiichi nuclear power station was made in November 2016 and is available online at the dedicated site.
The immediate vicinity of the nuclear power plant has not been recontrolled, it seems.




Decontamination of evacuated areas is the responsibility of the government. Elsewhere, where the external exposure could exceed 1 mSv / year, it is the municipalities that have to deal with it. See the latest report published by the Ministry of the Environment:


In the evacuated zone, decontamination is complete, except in the parts classified as “difficult return zones” where the external exposure could exceed 50 mSv / year. Decontamination took place only in populated and agricultural areas, not in forests. The ministry announces 22,000 decontaminated homes, 1,600 ha of roads, streets, lanes …, 8,500 ha of agricultural land and 5,800 ha of forest near residential areas.

In the non-evacuated areas, 104 communes were initially concerned, in Fukushima, Iwate, Miyagi, Ibaraki, Tochigi, Gunma, Saïtama and Chiba prefectures and it went down to 92 by simple radioactive decay. The decontamination work is completed in 89 of them and remains to be done in 3 others. The ministry announces 418,582 homes decontaminated in Fukushima and 147,656 in other provinces, 11,958 public facilities in Fukushima and 11,803 in other provinces. There are also 18,403 km of roads, streets, roads in Fukushima and 5,399 in other provinces, 31,043 ha of agricultural land in Fukushima and 1,588 ha in other provinces.

For so-called difficult return zones, the government will decontaminate a center in Futaba and Okuma in order to be able to affirm that it has not abandoned any commune. The end of the work is scheduled for 2022. Who will come back after 11 years of evacuation? This work in a highly contaminated zone will generate exposure of the decontaminators to ionizing radiation. As there is no threshold of safety, the first principle of radiation protection requires the justification of these exposures and this has not been done.



The Ministry of the Environment has budgeted 2.6 trillion yen (24.79 billion dollars) until 2016 to finance the decontamination work. Half is for evacuated areas, without taking into account the so-called difficult return zone and the other half for non-evacuated areas.

Radioactive waste from decontamination

See our summer 2016 report on the problem of waste from decontamination. Organic waste is incinerated and ash must be stored as industrial waste. Soils, for their part, must be stored for 30 years on a site of 16 km2 around the Fukushima daï-ichi plant, the time to find a final solution.


According to the Ministry of the Environment, the decontamination of the evacuated areas has generated 8,400,000 m3 of waste containing radioactive soils to which are added approximately 7,200,000 m3 in the areas not evacuated (6,800,000 m3 in Fukushima and 400,000 m3 in the other provinces concerned).


• Regarding the 16-square-kilometer (1,600-hectare) contaminated soil storage site with a capacity of 22 million cubic meters, the government has only been able to lease or purchase 48.4% of the surface area , knowing that 21% of the land already belonged to the government or municipalities. That was 18% a year ago.


This site will only accept Fukushima waste. The ministry announces that it has transferred 404,773 bags of about one cubic meter to this site in 2017. It is still far from the millions of cubic meters, but it required 67,146 truckings. And it will take as much transport to resume in 30 years … The total volume stored for the moment is 633 889 m3.

To learn more about this storage site.
• For radioactive waste from other provinces, the authorities prefer landfill even if they are struggling to find sites (source).

http://josen.env.go.jp/en/storage/ josen.env.go.jp/en/pdf/progressseet_progress_on_cleanup_efforts.pdf

In the meantime, there is waste everywhere, as far as the eye can see. See the Greenpeace videos.




Evacuated areas

The last evacuation orders were lifted on April 1, 2017 and it remains mostly so-called back difficult areas where access is prohibited.


Cost of the disaster

Official figures for the cost of the disaster were revised upwards in December 2016 to 21.5 trillion yen (216.88 billion dollars) and have not changed since. This includes the dismantling of the Fukushima daï-ichi reactors, worth 8 trillion yen (80.56 billion dollars), 7.9 trillion yen (79.32 billion dollars) for compensation, nearly 4 trillion yen (40.28 billion dollars) for decontamination and 1.6 trillion yen (16.11 billion dollars) for the temporary radioactive waste storage center.

This sum does not include the cost of storing the waste resulting from the dismantling of the damaged power station nor the creation of a decontaminated island in the so-called “difficult return” zones whose sole purpose is the non-disappearance of the villages concerned.

The bill for the nuclear disaster could be 50,000 to 70 trillion yen (520.67 to 719.02 billion dollars), which is 3 times higher than the government estimate, according to a study by the Japan Center for Economic Research.

TEPCo has already received a total of 8,032.1 billion yen (73.76 billion dollars at the current rate) in advance for compensation. This money is loaned without interest.


The government still holds a 50.1% stake in TEPCO.

Source: http://fukushima.eu.org/chiffres-cles-septieme-anniversaire/


Media reports de-romanticize the cleanup work on the Fukushima nuclear power plant

Front-line fight: Workers remove protective clothing after a shift at the Fukushima No. 1 nuclear plant in November 2011.
Most of the reliable reporting about the clean-up of the Fukushima No. 1 nuclear power plant since it suffered three meltdowns in March 2011 has been from on-site workers. Even when articles appear in major media outlets about the situation at the crippled reactor, it’s usually presented through the anonymous or pseudonymous firsthand experiences of the men on the front lines.
Some have become famous. The public would not know much about the situation without Kazuto Tatsuta’s manga series, “Ichiefu” (or “1F” — shorthand for “Fukushima No. 1”), the writings of former letter carrier and cleanup worker Minoru Ikeda, or the books and tweets of a man known as “Happy” who has been working as an employee at the plant.
Because these individuals directly address what they and their colleagues have gone through on a daily basis, the work they do has been de-romanticized. It’s not as heroic as initial foreign media reports made it out to be. If anything, it’s tedious and uncomplicated.
Workers are concerned about those matters that all blue-collar laborers worry about — pay and benefits — which isn’t to suggest they don’t think about the possible health risks of radiation exposure. Last October, Ikeda talked to the comedy duo-cum-nuclear power reporters Oshidori Mako & Ken on the web channel Jiyu-na Radio about potential false reports on radiation levels around Fukushima, although also touching on health issues that have not been reported by the mainstream media. His main point was that serious illnesses may not manifest themselves until years after workers quit the site and thus no longer qualify for worker’s compensation. In other words, the workers understand the risk. They just want to be fairly compensated for it.
In that regard, one of the most common gripes from on-site reporters is the “hazard compensation” (kiken teate) workers are supposed to receive. Recently, Tokyo Electric Power Company Holdings Inc. (Tepco), which is both responsible for the accident and in charge of the cleanup, announced a reduction in outlay associated with the hazard compensation, which is paid as a supplement to wages. This compensation can add as much as ¥20,000 a day to a worker’s pay, but now that Tepco says radiation levels have dropped, they will no longer provide the compensation, or, at least, not as much as they have been paying.
A special report in the Jan. 22 Tokyo Shimbun attempted to explain how this change will affect workers and the work itself. In March 2016, Tepco divided the work area into three zones: red, for high radiation levels; yellow, for some radioactivity; and green, for areas that had no appreciable radioactivity. Workers interviewed by Tokyo Shimbun say they’ve never liked this system because they feel it “has no meaning.” Rubble from the red zone is routinely transferred to the green zone, where heavy machinery kicks up a lot of dust, so there’s no physical delineation between zones when it comes to radiation levels. On the ground, this reality is addressed by subcontractors who make their employees in the green zone — which constitutes 95 percent of the work site — wear extra protective gear, even though Tepco doesn’t require it.
But the workers’ main gripe about the zone system is that most of them ended up being paid less and, as on-site workers have often explained, they weren’t getting paid as much as people thought they were. Contractors advertise high wages to attract workers, but then subtract things like room and board, utility fees, clothing and equipment. And it’s been known for years that the hazard compensation was more or less a racket gamed by the contractors standing between Tepco, which distributes the compensation, and the workers, who are supposed to be the beneficiaries. There can be up to six layers of contractors between Tepco and a worker, and each layer may take a cut of the compensation. In 2014, four workers sued Tepco for ¥62 million, saying they worked at the site but received none of the promised hazard compensation.
That situation still seems to be in play, according to Tokyo Shimbun. Several subcontractors told the newspaper they receive the compensation for their workers not from Tepco directly but from the contractor that hired them, and in most cases the compensation has been reduced, sometimes by more than half. One subcontractor said that a company above them actually apologized for the paucity of the compensation they were handing down because their “revenues had decreased.” The man known as Happy told Tokyo Shimbun that Tepco is ordering less work at the site, which means existing subcontractors may cut wages in order to compete for these dwindling jobs. Some contractors have even invested in the robots that are used to inspect the reactor, because they want the work to continue without interruption.
It was common practice to rotate out workers toiling in the highly radioactive areas regularly and quickly and then re-assign them to low-radiation areas. After some time they may have been rotated back into the high-radiation area, where pay is more. The man known as Happy says this sort of system now seems to be on the way out, and that makes sense if radiation is actually decreasing. However, he’s afraid that if there is another emergency that requires a sudden influx of workers, they won’t be available.
Tepco is obviously thinking of its bottom line, and the man known as Happy thinks the work should be managed by the government, which is contributing tax money to the cleanup. However, it seems only the Japan Communist Party is reading the dispatches from the plant. Last May, Japanese Communist Party lawmaker Taku Yamazoe questioned Tepco President Naomi Hirose about the hazard compensation in the Diet, and why the structure of payments to workers wasn’t clear.
Hirose said that while his company intends that the money goes to workers, he cannot say for sure that is the case because of the circumstances surrounding Tepco’s relationships with contractors. With work on the wane, it seems unlikely that those workers will see any of the money that’s owed to them, retroactively or otherwise.

Inside a meltdown-hit Fukushima reactor building

February 17, 2018
Seven years on, Tepco aims to pull fuel out of Unit 3’s rubble-strewn pool
A crane and dome-shaped roof have been erected on the top floor of Fukushima Daiichi’s No. 3 building, in preparation for removing rods and rubble from the spent fuel pool
FUKUSHIMA, Japan — As the Fukushima Daiichi nuclear disaster unfolded in March 2011, a hydrogen explosion ripped through the No. 3 reactor unit. Nearly seven years on, steel framing and other debris still litter the spent fuel pool, along with 566 fuel rods.
The painstaking process of removing the rods is expected to begin sometime in the fiscal year that starts in April. The fuel extraction will be a first for reactor Nos. 1-3 at the Tokyo Electric Power Co. Holdings facility, which was crippled by the earthquake and tsunami that hit northeastern Japan.
On Feb. 8, reporters from The Nikkei were allowed into the No. 3 building to get a sense of the work that awaits. 
A 20-minute bus ride from the town of Tomioka took us to Fukushima Daiichi. After donning masks and protective clothing, we walked toward Unit 3. An elevator slowly lifted us to the top floor of the building, about 36 meters up. There, a crane for moving the spent rods stood ready, wrapped in plastic sheeting. We peered down into the pool but could not see the fuel, which lies under 4 to 5 meters of water.
Large slabs of rubble that fell into the pool have been removed, but smaller pieces remain.
Other decontamination work is proceeding gradually. Radiation on the top floor was measured as high as 2,000 millisieverts per hour in the disaster’s immediate aftermath, but now it is less than 1 millisievert.
Still, caution is a must. Near the pool, our dosimeters displayed relatively high readings of up to 0.7 of a millisievert per hour. “The reading has climbed, so let’s leave for now,” a Tepco supervisor said. As we moved on, we frequently checked to ensure our exposure would not exceed 0.1 of a millisievert a day. 
Spent fuel has been removed from reactor No. 4, which was not operating when the tsunami hit the plant. But the job will be a challenge at the meltdown-stricken Unit 3. The rods and rubble will be extracted with heavy equipment operated remotely, from a separate administrative building. 
While it normally takes about two weeks to remove spent fuel, Tepco intends to proceed carefully over the course of two years.

NOAA research plane flying over Alaska has detected enriched U-235


An aerosol particle containing enriched uranium encountered in the remote upper troposphere
• We describe a highly unusual aerosol particle containing a very small amount of enriched uranium.
• The bulk of the particle probably came from combustion of heavy fuel oil.
• The particle was encountered when we were making no special attempt to sample radioactive material.
• We don’t know the source for this particle. It may indicate a novel source where enriched uranium was dispersed.
We describe a submicron aerosol particle sampled at an altitude of 7 km near the Aleutian Islands that contained a small percentage of enriched uranium oxide. 235U was 3.1 ± 0.5% of 238U. During twenty years of aircraft sampling of millions of particles in the global atmosphere, we have rarely encountered a particle with a similarly high content of 238U and never a particle with enriched 235U. The bulk of the particle consisted of material consistent with combustion of heavy fuel oil. Analysis of wind trajectories and particle dispersion model results show that the particle could have originated from a variety of areas across Asia. The source of such a particle is unclear, and the particle is described here in case it indicates a novel source where enriched uranium was dispersed.

Mysterious and ‘HIGHLY UNUSUAL’ radioactive substance detected in Alaska

Feb 15, 2018
SCIENTISTS have discovered an atmospheric aerosol particle enriched with uranium in Alaska which is used in nuclear fuel and bombs – and no-one can explain why the substance is there or how it arrived.
Experts from the US National Oceanic and Atmospheric Administration said they have found a “highly unusual aerosol particle containing a very small amount of enriched uranium” .
The substance with the uranium-235 have been found for the first time in 20 years of searches, say experts.
This particle can fuel nuclear reactions, are used in nuclear power plants, can damage organic material and cause mutations that lead to cancer.
The scientists said: “The bulk of the particle probably came from combustion of heavy fuel oil.
“The particle was encountered when we were making no special attempt to sample radioactive material.
“We don’t know the source for this particle. It may indicate a novel source where enriched uranium was dispersed.”
They believe the particle could have come from across Asia and was brought to the spot by the winds.
The researchers say the the sample was “definitely not from a natural source” but could have come from burnt nuclear fuel.
The scientists made the findings when their research plane was flying over the Aleutian Islands in 2016 and detected the uranium floating about four miles above Alaska’s far-western island chain.
Leader of the study, Dan Murphy, said to Gizmodo: “It’s not a significant amount of radioactive debris by itself. “But it’s the implication that there’s some very small source of uranium that we don’t understand.
One of the main motivations of this paper is to see if somebody who knows more about uranium than any of us would understand the source of the particle.”
The full findings have been published in the Journal of Environmental Radioactivity.
After the disaster at the Fukushima nuclear power plant in 2011 in Japan, experts became concerned about radiation impacts in Alaska as three reactors melted down. However, as the particle was found in 2016, the two are unlikely to be linked.

Photo collection shot inside Fukushima nuke plant to be released in March

The building housing reactor No. 3 of the Fukushima No. 1 Nuclear Power Plant still shows stark signs of the disaster in September 2016
Photographer Joe Nishizawa will offer a rare look inside the Fukushima nuclear plant damaged in the March 2011 earthquake and tsunami disaster with the release this March of a photo book recording of decommissioning work over a 3 1/2-year period.
Published by Misuzu Shobo, “Decommissioning Fukushima: A Photographer’s Journey into the Depths of the Fukushima Daiichi Nuclear Power Plant” will present roughly 150 photos of workers in protective gear and restorative efforts, arranged to show the passage of time. “I want to convey the scene exactly as it is,” the Takasaki, Gunma Prefecture-based photographer explains.
For the last 15 years, Nishizawa has taken photos of steel work factories, expressways and other construction scenes to cover Japan at various work sites. After the nuclear disaster occurred on March 11, 2011, plant operator Tokyo Electric Power Co. (TEPCO) released photos but they were blurred and difficult to make out. Nishizawa said he felt the need to document the state of the reactor for future generations. After negotiating with TEPCO, the photographer was granted access to the plant roughly once a month.
Wearing a mask and a protective suit covering his entire body, he first stepped foot on the grounds of the nuclear plant in July 2014. At the time, there was still debris on the premises scattered along the coastline and the destruction from the accident was still starkly evident. Once, a worker at whom he pointed his camera glared back and asked, “Just what are you photographing?”
Still, he continued to document the equipment used to purify water contaminated by radioactive materials, as well as the construction site filled with tanks of processed water. Along with the flow of time, Nishizawa also sensed the gradual progress of decommissioning efforts. Still, radiation levels around the reactor buildings are high, and the difficult labor conditions continue to this day.
“The decommissioning won’t end with this generation,” says Nishizawa. “We can’t afford to let the accident fade into the past, so I will continue taking photographs.”