Estimates of highly radioactive cesium-rich microparticles released by Fukushima disaster

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August 14, 2018

Scientists have for the first time been able to estimate the amount of radioactive cesium-rich microparticles released by the disaster at the Fukushima power plant in 2011. This work, which will have significant health and environmental implications, is presented at the Goldschmidt geochemistry conference in Boston.
The flooding of the Fukushima Daiichi Nuclear Power Plant (FDNPP) after the disastrous earthquake on March 11 2011 caused the release of significant amounts of radioactive material, including cesium (Cs) isotopes 134Cs (half-life, 2 years) and 137Cs (half-life, 30 years). Initially scientists thought that all Cs was released in soluble form. Now however, they have realized that a part of the released Cs was in the form of glassy microparticles, formed at the time of the reactor meltdown; these particles were thrown over a wide area, but until now there has been no reliable estimate of how much radioactive cesium-rich microparticles was deposited in the surrounding area, and how this material was distributed.

Now a group of international scientists, led by Dr. Satoshi Utsunomiya (Associate Professor of Kyushu University, Fukuoka, Japan) has been able to give the first accurate estimates of the amount of the radioactive microparticles in the environment. This work describes the significance of the microparticles to current radiation levels, and provides fundamental data for a future re-evaluation of health risks from the highly radioactive microparticles which remain in the local environment.

“Most of the glassy microparticles are only a few microns in size, and were spread alongside the soluble cesium. The soluble cesium is generally bound to clay minerals after wet deposition, with the clay minerals also forming particles, so it was difficult to distinguish the cesium-rich microparticles from cesium absorbed on clay.” said Dr. Utsunomiya, “However, we realized that the cesium-rich microparticle has an extremely high radioactivity ~1011 Bq/g compared with the much lower radioactivity for cesium-sorbing clay particles, and this can be used to distinguish the two types. So we have established a novel procedure to quantify the cesium-rich microparticles by applying a quantitative autoradiography method”.

Autoradiography exposes a photographic film or detector to a radioactive source, which causes the radiation to show up on the film (medical X-rays is the most common autoradiography technique). The team determined the threshold radioactivity for Cs-rich microparticles in the sieved fraction based on the relation between photostimulated luminescence signal and radioactivity. They applied this method to soil samples from 20 affected areas.

Dr. Utsunomiya continued “In certain areas, these glassy particles are highly concentrated, so they are a major concern. We have found up to 318 of these particles in just 1 gram of soil, near the Fukushima Daiichi power plant. Most of these particles are still in the ambient environments, indicating the high stability.

Since the Fukushima accident we have been gradually coming to understand how the microparticles were distributed, and what this might mean to health and the environment. As you would expect, there are more radioactive particles nearer the reactor: we believe that there was a proportion of cesium released as soluble material, but we have found that the area south of the reactor contains a higher proportion of glassy particles. Our estimate is that around 78% of radioactive cesium was released as glassy particles. Many of the microparticles have been washed down from roofs and from plants, and have now gathered in radioactive hot spots.

Now that we have a better idea of the quantities involved and how the radiation has been distributed, it gives our team a better idea of how to approach the effect on health, which is obviously a major concern. This work does not imply that there is any additional radiation which has been missed—the total amount of cesium released at Fukushima remains the same. However, the glassy particles have concentrated the radiation, which means that there is still much new work to be done to understand how this concentrated radiation might affect health”

Commenting on the work, Dr. Ken Buesseler (Woods Hole Oceanographic Institution) said:

“The idea of microparticles has not been ‘missed’ in the assessment of total cesium levels in soil after Fukushima; it has been included, although this work highlights the fraction found in cesium microparticles. So we shouldn’t think that there is additional radiation to worry about, but nevertheless in this highly concentrated form it may have different health impacts. These researchers have done a fine job of developing new tools to quantify these microparticles, and that is an important story to tell”

More information: Ryohei Ikehara et al. Novel Method of Quantifying Radioactive Cesium-Rich Microparticles (CsMPs) in the Environment from the Fukushima Daiichi Nuclear Power Plant, Environmental Science & Technology (2018). DOI: 10.1021/acs.est.7b06693

Read more at: https://phys.org/news/2018-08-reliable-highly-radioactive-cesium-rich-microparticles.html#jCp

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Regulator urges release of treated Fukushima radioactive water into sea

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The chief of Japan’s nuclear regulator said Thursday water at the crisis-hit Fukushima Daiichi nuclear plant that contains radioactive tritium even after being treated should be released into the sea after dilution.
“We will face a new challenge if a decision (about the release) is not made within this year,” Nuclear Regulation Authority Chairman Toyoshi Fuketa told a local mayor, referring to the more than 1 million tons of coolant water and groundwater that has accumulated at the facility crippled by the 2011 disaster triggered by a devastating quake and tsunami.
As local fishermen are worried about the negative impact from the water discharge, the Japanese government and Fukushima plant operator Tokyo Electric Power Company Holdings Inc. have not made a final decision on the treated water, which is currently stored in tanks.
In his meeting with Yukiei Matsumoto, mayor of Naraha town near the Fukushima plant, Fuketa said, “It is scientifically clear that there will be no influence to marine products or to the environment” following the water release.
The nuclear regulator chief underlined the need for the government and Tepco to quickly make a decision, saying, “It will take two or three years to prepare for the water release into the sea.”
At the Fukushima plant, toxic water is building up partly because groundwater is seeping into the reactor buildings to mix with water made radioactive in the process of cooling the damaged reactors.
Such contaminated water is treated to remove radioactive materials but tritium, a radioactive substance considered relatively harmless to humans, remains in the filtered water as it is difficult to separate even after passing through a treatment process.
At other nuclear power plants, tritium-containing water is routinely dumped into the sea after it is diluted. The regulator has been calling for the release of the water after diluting it to a density lower than standards set by law.
With limited storage space for water tanks, observers warn tritium could start leaking from the Fukushima plant.
On March 11, 2011, tsunami inundated the six-reactor plant, located on ground 10 meters above sea level, and flooded the power supply facilities.
Reactor cooling systems were crippled and the Nos. 1 to 3 reactors suffered fuel meltdowns in the world’s worst nuclear catastrophe since the 1986 Chernobyl disaster.

Tepco chairman’s remark on water release goes radioactive

Comment draws ire from Fukushima residents, fishermen and watchdog

0721N_TEPCO_article_main_imageTakashi Kawamura, a former Hitachi chairman, took up his current post just last month.

 

TOKYO — Comments by Tokyo Electric Power Co. Holdings’ chairman about releasing nuclear wastewater into the ocean are being met with anger from fisheries groups and many others.

Tepco Chairman Takashi Kawamura told news outlets earlier this month that the utility “has made its decision” on the release of tritiated water from the crippled Fukushima Daiichi power plant to the ocean. Tritiated water is a radioactive form where the usual “light” hydrogen atoms are replaced with tritium.

Kyodo News reported the following day that the company shares the view of Shunichi Tanaka, chairman of the Nuclear Regulation Authority, that spilling the water into the sea would not cause any problem, scientifically speaking.

Tepco immediately released a statement saying Kawamura’s comments “did not intend to announce the concluded policy of the company on the matter.”

Nonetheless, the national cooperative of fishermen has protested. And rather unexpectedly, Tanaka criticized Kawamura for using his name to promote the company’s agenda. This is a worrying development for Tepco, since increased mistrust by the NRA could affect the utility’s medium- to long-term strategies, including restarting nuclear power plants.

Tritiated water is also released from normally functioning nuclear power plants. In Japan, water meeting official standards can be dumped into the sea.

But local residents have protested the idea, out of concern that rumors and misunderstandings could damage their community. At the Industry Ministry, a special committee has been considering the matter. Kawamura’s remarks were seen as getting ahead of that process, hence the backlash.

The wastewater in question still sits inside a number of storage tanks at the Fukushima power plant, with nowhere to go. Tepco and the government want to find a solution quickly, but the latest controversy shows that skipping careful and thoughtful communication with various stakeholders could end up costing them more time.

http://asia.nikkei.com/Business/Companies/Tepco-chairman-s-remark-on-water-release-goes-radioactive

Potential releases of 129I, 236U and Pu isotopes from the Fukushima Dai-ichi nuclear power plants to the ocean during 2013 to 2015

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After the Fukushima Dai-ichi Nuclear accident, many efforts were put into the determination of the presence of 137Cs, 134Cs, 131I and other gamma-emitting radionuclides in the ocean, but minor work was done regarding the monitoring of less volatile radionuclides, pure beta-ray emitters or simply radionuclides with very long half-lives.

In this study we document the temporal evolution of 129I, 236U and Pu isotopes (239Pu and 240Pu) in seawater sampled during four different cruises performed 2, 3 and 4 years after the accident, and compare the results to 137Cs collected at the same stations and depths.

Our results show that concentrations of 129I are systematically above the nuclear weapon test levels at stations located close to the FDNPP, with a maximum value of 790 x107 at·kg-1, that exceeds all previously reported 129I concentrations in the Pacific Ocean.

Yet, the total amount of 129I released after the accident in the time 2011-2015 was calculated from the 129I/137Cs ratio of the ongoing 137Cs releases and estimated to be about 100 g (which adds to the 1 kg released during the accident in 2011).

No clear evidence of Fukushima-derived 236U and Pu-isotopes has been found in this study, although further monitoring is encouraged to elucidate the origin of the highest 240Pu/239Pu atom ratio of 0.293±0.028 we found close to FDNPP.

http://pubs.acs.org/doi/abs/10.1021/acs.est.7b03057

New TEPCO executives tripping over their tongues

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TEPCO Chairman Takashi Kawamura, right, receives a formal letter of complaint from an executive member of JF Zengyoren, a nation-wide federation of fishery associations, over his comment about dumping contaminated water to the sea on July 19 in Tokyo’s Chiyoda Ward.
Hoping to restore trust in embattled Tokyo Electric Power Co., the company’s new chairman and president have instead generated unwanted criticism and hostility in their first gaffe-filled month on the job.
They have added to the problems facing the operator of the crippled Fukushima No. 1 nuclear power plant, which also is hoping to bring its idled reactors back online.
On July 19, TEPCO Chairman Takashi Kawamura, who is also honorary chairman of Hitachi Ltd., was apologizing at the headquarters of JF Zengyoren, a nationwide federation of fishery associations, in Tokyo’s Chiyoda Ward. He was forced to explain “the true intention” of remarks he made last week regarding the release of diluted radiation-contaminated water into the sea.
On July 12, during a collective media interview session, Kawamura said “the decision has been made” to do so.
On the Fukushima plant premises, nearly 780,000 tons of water used to cool the reactors are stored, which had been decontaminated of radioactive cesium and plutonium but not tritium. Legally, the tritium-tainted water can be released into the sea, if diluted enough so the concentration of tritium is below a set standard.
However, as the release would add further adversity to the struggling fishing industry in Fukushima and neighboring prefectures, the central government has not made any clear decision on what to do with it.
Kawamura, however, also said, “I am on the same line as the opinion of chair Shunichi Tanaka (of Japan’s Nuclear Regulation Authority) that it is scientifically safe (to discharge water into the sea).”
On July 14, disaster reconstruction minister Masayoshi Yoshino expressed concerns that releasing the water now would “definitely affect public sentiment” over catches from Fukushima Prefecture, where full-scale fishing had been stalled.
At the July 19 meeting with the fishery federation, Kawamura retracted his comment, saying, “As a company or personally, no decision has ever been made whether to release contaminated water to the sea. The true intention of my comments were not properly understood by some media agency.” The TEPCO chairman apologized to Hiroshi Kishi, chairman of the federation, and others at the meeting.
Kishi, in return, submitted a letter of protest stating that they “strongly demand not to release radiation-contaminated water to the sea” and it is “unacceptable to the fishery industry and other Japanese people.”
On the same day, Kawamura admitted to the media what he said a week earlier, explaining that he meant “it cannot be independently decided by TEPCO.”
On July 19, in another part of Tokyo, NRA Chairman Tanaka told the media at a regular news conference that he is “boiling with anger” with Kawamura for including him in his comment. He also said Kawamura’s remark symbolizes his reluctance to face Fukushima residents.
“He used me as an excuse,” said Tanaka, who has suggested releasing water before the storage of contaminated water on the site reaches full capacity. “I have told him he needs to confront Fukushima issues as the first party to resolve them even if he faces a backlash. Despite that, he is still looking for an escape.”
On July 10, Kawamura and TEPCO President Tomoaki Kobayakawa attended a meeting with NRA members, including Tanaka, in Tokyo.
There, Kawamura said, “TEPCO has a responsibility to show that it can operate a nuclear power plant,” and he was warned by an NRA member for being “overly forward-looking.” Currently, none of TEPCO’s nuclear power plants are on-line.
On June 27, Kobayakawa also landed in hot water after referring to the town of Futaba, which co-hosts the Fukushima No. 1 nuclear plant, as “where the evacuation order is partially lifted” in a comment to a group of reporters. However, the town has been in a “difficult-to-return zone” since the accident, and no residents are allowed to return to their homes.
At a regular news conference on July 18, a disgruntled Fukushima Governor Masao Uchibori said, “I would like TEPCO to fulfill its responsibility as the operator that caused a severe accident.”

Tepco ‘s response to the article about the release of tritiated water into the ocean

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A certain article reported today, “TEPCO decided to release tritiated water into the ocean” quoting the comment of TEPCO’s chairman Mr. Kawamura about the release of tritiated water into the ocean. The comment intended to say that TEPCO shares the same recognition with Nuclear Regulation Authority Chairman Dr. Tanaka, et al. that in accordance with the current regulation and standard based on scientific and technical ground, there should not be an impact of releasing tritiated water into the ocean. The comment did not intend to announce the concluded policy of the company on the matter.

We need to give our full attention to the satisfaction of both peace of mind of local residents and reconstruction of Fukushima, as well as the safety requirement to meet regulation and standard for the final decision. We will carefully examine our policy on the matter with the government and local stakeholders from such a perspective.

http://www.tepco.co.jp/en/announcements/2017/1444608_10494.html

Will Tepco Dump 770,000 tons of Tritiated Water Into the Pacific Ocean???

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Massive amounts of radiation-contaminated water that has been processed and stored in hundreds of tanks at the plant are hindering decommissioning work and pose a safety risk in case another massive quake or tsunami strikes.

“TEPCO needs to release the water — which contains radioactive tritium that is not removable but considered not harmful in small amounts — into the Pacific Ocean”, de lared Tokyo Electric Power Co.’s new Chairman Takashi Kawamura during an interview at the TEPCO headquarters in Tokyo on Thursday, July 13, 2017.

The method is favored by experts at the International Atomic Energy Agency and Japan’s Nuclear Regulation Authority as the only realistic option. Earlier, TEPCO had balked at calls by NRA chairman Shunichi Tanaka for controlled release of the water, now exceeding 770,000 metric tons, into the sea, fearing a public backlash.

Tepco’s intention to release more than 770,000 metric tons of tritiated water into the sea was relayed by many media, the Japan Times adding to  the volume number of  770,000 metric tons, that it was contained in 580 tanks. The volume number is right, to be precise it concerns 777,647 metric tons of tritiated water, but the 580 tanks number is wrong.

Knowing that those tanks have a capacity of 1000 metric tons each, 777,647 metric tons can only be stored in 780 tanks and not in 580 tanks only.

Of course in that 777,647 metric tons, are not included the other 202,565 metric tons of  only partially decontaminated water, in which Cesium and Strontium are been already filtered out but the other 62 radionuclides have not been yet filtered by the Multi-nuclides Removal System (ALPS). Those 202,565 metric tons stored in some additional 202 tanks more in the Storing Tank Area.

Bringing the total of contaminated water, Cesium/Strontium partially decontaminated water plus the 62 radionuclides decontaminated water (Tritiated water) to a total of 980,212 metric tons stored in 980 tanks.

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Of course it is not question to release the partially decontaminated water (202,565 metric tons) into the sea, only the fully decontaminated water (all radionuclides removed to the exception of tritium), the tritiated water, the 777,647 metric tons.

On the Tepco Press Release on Jul 10,2017, Tepco indicates quite clearly the actual volume of the 2 types of water stored in those tanks. Knowing that all those tanks have a capacity of 1000 metric tons each, the maths are easy.

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Some media along the way, I suspect the Japan Times AGAIN, added the 580 tanks number into its article, maybe a typo from 5 to 7, then the error was copied on and on by the other media.

It is sad to see professionnal media not capable to get their numbers right.

Since that July 13, 2017 declaration from Tepco’s new chairman, Tepco is now backpedaling, saying that they have not yet reached that decision, fearing a public backlash and the ire of the local fishermen.

The radioactive half-life of Tritium is 12,3 years, its radioactive full life is 123 years to 184,5 years. Once inside the body, tritium can lead to internal exposure. Its biological half-life of 10 days, full life 100 to 150 days.

Tepco Press Release July 10, 2017 Nuclear Power Station (310th Release) Nuclear Power Station (310th Release): http://www.tepco.co.jp/en/press/corp-com/release/betu17_e/images/170710e0201.pdf