Japan’s bomb in the basement

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Under the guise of a civil nuclear program, Japan has become a de-facto nuclear weapons state without so far having to take that next fateful step.

On Thursday, a shipment of 700 kilograms of plutonium arrived in Japan after a journey by sea from the French port of Cherbourg. That’s enough material for more than 100 nuclear weapons.

The plutonium – in the form of atomic fuel known as MOX, a mix of uranium and plutonium oxide – is for use in the Takahama-4 reactor, owned by Kansai Electric Power Co. and located on Wakasa Bay, in western Japan near Osaka.

There have been six shipments of such highly toxic cargoes since 1999, the result of an agreement to send radioactive spent fuel in Japan for reprocessing in France and the UK, and then to be shipped back as plutonium MOX fuel for use in Japan’s reactors.

Putting aside the reactor fuel issue for the moment, Japan’s plutonium program must be seen in the context of the nuclear arms proliferation dynamic that has existed for decades in Northeast Asia, but which today has taken on even greater urgency owing to North Korea’s nuclear weapon program.

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Map of Japan’s nuclear plants. Photo: Japan Atomic Industries Forum, 2016.

 

There is no question that Japan has the technical capability to build an advanced nuclear weapons arsenal.

There have been over the decades multiple references to it taking less than six months for Japan to build an atomic weapon – a credible timeframe if it’s true as reported more 20 years ago that a design or designs already exist in the country.

However, to build a ‘credible’ arsenal of weapons would require several years at least.

More important than any actual timeframe are the external factors that would lead a Japanese government to move to nuclear weaponization.

This debate is stirring in Japan. In a TV Asahi program on September 6, former Defense Minister Shigeru Ishiba suggested a review was needed of Japan’s so-called three non-nuclear principles: Not producing, possessing, or allowing nuclear weapons into Japan.

Ishiba asked the question if Japan is under the US nuclear umbrella then isn’t it necessary to allow US nuclear weapons into the country to deter threats from North Korea?

It’s clear that without a peaceful resolution to the underlying security threats in the region, there is an increasing possibility that policy makers in Tokyo – backed by Washington – will decide that Japan should weaponize its plutonium stockpile.

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We have not reached that point yet, but without a fundamental change in thinking and policy, Japan’s nuclear bomb in the basement may not remain there for very much longer.

But back to Japan’s plutonium stockpiles and the question of why the only country attacked by a nuclear weapon and one that espouses the three non-nuclear principles has large amounts of the bomb-making material.

To answer that question requires looking back to the 1950s and a policy that was spearheaded by the United States, but soon adopted by Japan’s Science and Technology Agency established by former Prime Minister Yasuhiro Nakasone.

The policy was to build new types of nuclear power plants, or so-called Fast Breeder Reactors (FBRs), worldwide that would be fueled with plutonium reprocessed from spent uranium fuel. As FBRs produce more fuel than they burn  – hence the name “breeder” – they would in turn generate plutonium to fuel yet more FBRs.

The procedure was known as “closing the nuclear fuel cycle.”

While the idea seems a solution for processing spent fuel and producing more fuel for FBRs, the problem is fast breeder reactor programs failed worldwide, including in Japan.

Japan’s principle FBR started up in 1994 and was called Monju – named after a Buddhist deity for wisdom. However, a fire broke out at Monju 18 months after it opened, which shut the plant down for 14 years.

4Monju nuclear reactor. Photo: IAEA Energy/Flickr

 

It restarted in May 2010, but weeks later a 3.3 metric-ton fuel exchange device fell into the reactor, which shut it down again for good, though to add to the fiasco its computers were later hacked and data stolen.

This effectively ended Japan’s FBR ambitions, though it took two decades and a total investment of more than US$10 billion for the government to finally make the wise decision to terminate Monju in December 2016.

However, Tokyo had other motives for commitment to a plutonium fuel cycle.

By the late 1960’s and early 1970’s, plans to build commercial light water reactors across Japan, such as at Takahama and Fukushima, faced strong opposition from local communities and activists.

To appease the opposition, the government and utilities said the new reactors would not become nuclear waste sites because the spent fuel would be shipped for reprocessing in the UK and France. This solved, temporarily, a major nuclear waste problem at least for Japan.

In total over 7,000 tons of such fuel went off to Europe during the decades up to the mid 1990’s.

During that time, the plants reprocessing Japan’s spent fuel at la Hague in France and Sellafield in the UK became synonymous with accidents, nuclear waste discharges into the ocean and atmosphere, and public health concerns.

While the Japanese contracts were lucrative for the two state owned companies that operated the Sellafield and la Hague plants –Cogema/AREVA in France and British Nuclear Fuels Limited (BNFL) in the UK – both were to become failed entities.

The Sellafield site is now managed by a UK government agency and absorbs most of the nation’s nuclear decommissioning budget estimated well in excess of US$100 billion.

5.jpgSellafield nuclear reprocessing site. Image: Sellafield Ltd.

 

There is another large wrinkle in this tale.

As failures engulfed Japan’s Monju fast-breeder reactor and shut it down, the government had to figure out what to do with the thousands of kilograms of plutonium that would be returning to Japanese shores to fuel a fleet of FBR’s that didn’t exist.

The answer, which brings us back to the cargo that arrived in Japan this week, was plutonium MOX fuel that could be used in existing commercial light water reactors.

The first MOX shipments in 1999 were for use in Fukushima and Takahama reactors.

However, in the case of the MOX delivered to Takahama, activists revealed that the fuel had been manufactured with falsified quality certification, leading to its return shipment to the UK.

In the case of the Fukushima plant, citizens from the prefecture, supported by evidence from Greenpeace, took Tokyo Electric Power Co., or TEPCO the plant owner, to court over the quality control of the fuel.

While the citizens group lost the case, AREVA was instructed to release vital safety data, which they refused to do. The ensuing controversy led the then Fukushima Governor Eisaku Sato to refuse to permit loading of the plutonium fuel.

It sat in the cooling pool at the Fukushima Daiichi reactor until August 2010 when TEPCO finally loaded the 32 assemblies of 235 kilograms of plutonium into reactor unit 3.

This was just six months before the Fukushima plant was hit by the strongest earthquake ever recorded in Japan and flooded by a tsunami that caused triple reactor meltdowns on March 11, 2011, including reactor unit 3.

Worker wearing protective suit and mask works on roof of No.4 reactor building of TEPCO's tsunami-crippled Fukushima Daiichi nuclear power plant in Fukushima prefectureA worker in protective suit works on the roof of the No.4 reactor building of the  crippled atomic plant in Fukushima prefecture February 20, 2012. Reuters/Issei Kato

 

Without the actions of Japanese citizens and others around the world, TEPCO would almost certainly have spent the past decade through to 2011 loading many tons of plutonium MOX fuel into the Fukushima Daiichi reactors.

The meltdown of this fuel would have been far more severe and with greater onsite and offsite radiological consequences than the reality at the accident site today, which itself will take decades and tens of billions of dollars to clean up.

Worse still, tons of high temperature spent MOX fuel would have been sitting in Fukushima’s spent fuel pools.

If the Fukushima reactors had been loaded with plutonium MOX, then the warning from the Atomic Energy Commission to then Prime Minister Naoto Kan in late March 2011 that the loss of control at the spent fuel pools at the plant may require the evacuation of Tokyo, may well have become a reality.

Of the five reactors now operating in Japan, three are loaded with plutonium MOX fuel. However, the threat from Japan’s plutonium obsession could be about to get a lot worse.

Japan has built its own US$21 billion nuclear spent fuel reprocessing facility in Rokkasho-mura in Aomori prefecture, near Hokkaido. (Yes, the same Hokkaido North Korea has recently taken to firing missiles over.)

7The Rokkasho nuclear fuel reprocessing plant in Japan’s Aomori prefecture. Wikimedia Commons.

 

The Rokkasho story sounds more than a little similar to Monju, just more expensive.

Rokkasho was supposed to be completed in 1997, but due to multiple construction and equipment failures, it was delayed and has since missed repeated start up dates. It’s now 20 years behind schedule and has a new opening set for 2018.

Assuming Rokkasho does eventually open, it was built to process spent fuel to produce plutonium primarily for use in fast-breeder reactors.

As pointed out, Japan’s only fast-breeder reactor, Monju, has been permanently shut so what happens to the 8,000 kilograms of plutonium Rokkasho was to produce each year?

The answer it appears lies in an atomic power plant being built at the northern tip of Aomori prefecture that will contain the Ohma Advanced Boiling Water reactor.

Now planned to start up in 2024, this reactor is intended to have a full MOX core, which would contain over 5 tons of plutonium and an annual demand of around 1.7 tons.

The safety implications of what would be a unique reactor worldwide operating with a full plutonium MOX core are enormous.

One reason why citizens and the city of Hakodate over the Tsugaru straits in Hokkaido have filed court challenges seeking to halt the Ohma plant’s construction. A court judgement is expected later this year.

Like Monju before, the prospects for operation of Ohma are dire and unlikely to solve Japan’s self inflicted plutonium hangover. But that also may be the point – the strategic and national security rationale for the program remains central for a government increasingly nationalistic in tone and outlook.

Under the guise of a civil nuclear program, Japan has become a de-facto nuclear weapons state without so far having to take that next fateful step.

The MOX shipment this week is merely one further fig leaf for a plutonium and nuclear program that was always so much more than about energy.

How long can the Japanese government defend such a policy? We may be about to see in 2018 when the US Japan Peaceful

North Korean leader Kim Jong Un provides guidance on a nuclear weapons program in this undated photo released by North Korea's Korean Central News AgencyKim Jong-un with nuclear weapon engineers in this undated photo released by Korean Central News Agency in Pyongyang September 3, 2017. KCNA via REUTERS

 

Nuclear Cooperation Agreement, that provides sanction for Japan’s program, is up for renewal.

Given the incumbents in the Prime Minister office in Tokyo and the White House, don’t expect much deep reflection (or policy reversal) on what it means for a nation in a region on the edge of major conflict to possess the largest stockpile of nuclear weapons plutonium outside the declared nuclear weaponized states.

Instead, ending this decades long multi-billion dollar program will, as ever, be secured by the dedication of the people of Japan and their allies around the world concerned as they are with public safety and real security built on peace.

Shaun Burnie is a senior nuclear specialist with Greenpeace Germany, Tokyo. He is co-author of “Nuclear Proliferation in Plain Sight: Japan’s Plutonium Fuel Cycle–A Technical and Economic Failure But a Strategic Success” Japan Focus, March 2016, available at http://apjjf.org/2016/05/Burnie.html. He has worked on nuclear issues worldwide for more than three decades, including since 1991 on Japan’s plutonium and nuclear policy. sburnie@greenpeace.org

Nuclear physicist, Professor Frank Barnaby, is formerly of the UK Atomic Weapons Establishment and Director of the Stockholm International Peace Research Institute (SIPRI – from 1971-1981). Prof. Barnaby testified to the Fukushima District Court against TEPCO’s plans for MOX use in Fukushima Daiichi 3 in 2000, and is the author of multiple books on nuclear weapons design and policy.

http://www.atimes.com/article/japans-plutonium-proliferation-energy//

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Reprocessed nuclear fuel returned to Japan for reactor use

Japan has learned absolutely nothing from the Fukushima Daiichi nuclear plant disaster. This is not going to end well!

This is a mouthful, read this:

“Nuclear fuel reprocessed in France returned to Japan on Thursday for use in a reactor as the country tries to burn more plutonium amid international concerns about its stockpile.”

“The need to reduce its plutonium stockpile adds to Japan’s push to restart reactors, aside from also needing to generate power. It would require 16 to 18 reactors to burn MOX to keep Japan’s plutonium stockpile from growing when the Rokkasho plant starts up, according to government and utility officials.”

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TOKYO- Nuclear fuel reprocessed in France returned to Japan on Thursday for use in a reactor as the country tries to burn more plutonium amid international concerns about its stockpile.

Kansai Electric Power Co said the shipment arrived for use at the No. 4 reactor at its Takahama plant in Fukui Prefecture. The reactor is one of only five reactors currently operating in Japan.

A specialized ship, the Pacific Egret, was seen docked just outside one plant as the heavily protected shipment was brought inside under extremely tight security. The utility said it cannot provide details such as the amount of the fuel. The new fuel is expected to be loaded after the reactor’s regular safety check planned next year.

Japan has a stockpile of 47 tons of plutonium – 10 tons at home and the rest in Britain and France, which reprocess and store spent fuel for Japan as the country still lacks its own capacity to do so. Experts say the amount could be enough to make thousands of atomic bombs, although utility operators deny such risk, saying the material is stored safely and monitored constantly.

Japan plans to start up its Rokkasho reprocessing plant next year, but critics say that would only add to the stockpile problem and nuclear security concerns.

Without the prospect of achieving a plutonium-burning fast reactor in near future, Japan has resorted to burning MOX, a mixture of plutonium and uranium fuel, in conventional reactors.

The need to reduce its plutonium stockpile adds to Japan’s push to restart reactors, aside from also needing to generate power. It would require 16 to 18 reactors to burn MOX to keep Japan’s plutonium stockpile from growing when the Rokkasho plant starts up, according to government and utility officials.

Only three reactors, including two at Takahama, use MOX, with a fourth one expected to start up next year. Restarts come slowly amid persistent ant-nuclear sentiment among the public since the 2011 Fukushima nuclear accident and stricter standards under the post-Fukushima safety requirement.

https://japantoday.com/category/national/reprocessed-nuclear-fuel-returned-to-japan-for-reactor-use

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

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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

Possible safety regulation violations at Ibaraki Pref. nuclear facility led to accident: NRA

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In this photo provided by the JAEA, the stainless steel radioactive material container involved in the June 6, 2017 accident is seen soon after the plastic bags inside burst, exposing five workers to powdered plutonium and uranium oxides, at the Oarai Research & Development Center in Oarai, Ibaraki Prefecture.

Staff likely failed to follow safety regulations at a nuclear research facility in Ibaraki Prefecture where five workers were exposed to radioactive materials in June, a Nuclear Regulation Authority (NRA) inquiry has revealed.

While just after the accident the Japan Atomic Energy Agency (JAEA) stated that there was no way that such a serious incident could have been predicted, the NRA’s on-site investigation has revealed that, regardless of whether the accident could have been predicted, the facility staff were working without conducting proper safety procedures.

The accident occurred at the JAEA Oarai Research and Development Center in Oarai, Ibaraki Prefecture, at roughly 11:15 a.m. on June 6, when a worker opened a stainless steel container to inspect the powdered nuclear fuel materials within. The plastic bag inside the container ruptured, exposing the worker and four other staff to plutonium and other radioactive materials. The container had been sealed in 1991, and not opened once since.

“There was no way to know the state of the vessel’s contents, so the work was done extremely carefully,” the JAEA had initially explained. It had also stated that the workers had been aware that the plastic bag around the materials had degraded over the 26 years it was in storage. The JAEA had also been aware since January of a similar case at another facility where the plastic bag in a container had swelled up.

However, the recent inquiry found that the workers at the Ibaraki facility decided that the item on the inspection safety checklist stating “risk of explosion, rupture or dispersal” was non-applicable before beginning their task, which their supervisor also approved. Furthermore, though there were five sealed workstations in the room, the workers chose to open the container at a simple, unsealed workstation instead. No work plan had been put together prior to the task.

“If the workers had used a sealed workstation, it is clear that this accident could have been prevented,” lamented a JAEA representative.

Also, after the accident, it took three hours to set up a temporary decontamination tent for the effected workers. The survey found that the building where the incident occurred was not equipped with the materials necessary to construct the decontamination tent, and no drills for the setup had ever been carried out. In addition, a shower meant to wash away radioactive materials was also found to be broken.

“When handling plutonium, we cannot afford to make inexperienced or groundless decisions,” declared NRA Chairman Shunichi Tanaka at a regular meeting of the authority on July 5. “(The JAEA’s) safety culture is lacking.”

https://mainichi.jp/english/articles/20170707/p2a/00m/0na/013000c

 

Rotten resin gas ‘most likely’ cause of Ibaraki nuclear accident

oarai, ibaraki.jpgThe fuel research building of the Japan Atomic Energy Agency’s Oarai Research and Development Center in Oarai, Ibaraki Prefecture, where the accident occurred June 6

 

The Japan Atomic Energy Agency (JAEA) now considers the most likely cause of last month’s nuclear contamination accident at its Oarai research center to be gas produced by decomposing resin containing plutonium and other radioactive substances.

The June 6 incident at the facility in Ibaraki Prefecture, northeast of Tokyo, exposed five workers to plutonium when they handled 26-year-old radioactive waste stored there.

Resin was used to stick the radioactive waste on an aluminum sheet and stored in a tightly sealed polyethylene container, which was wrapped in plastic bags and placed in a stainless steel container.

The accident occurred when the workers opened the steel container and were exposed to radioactive particles that seeped out of the polyethylene container in gas that ruptured the plastic coverings and escaped into the room they were in.

Decomposition of resin by a radioactive substance is considered as the most likely cause of the gas’s formation,” said Toshio Kodama, JAEA president, at a July 3 meeting with the science and technology ministry’s special investigation team that was set up to determine the cause of the accident.

JAEA found that the polyethylene container inside the plastic bags contained powdered plutonium set in pieces of epoxy resin.

The agency is looking at other possibilities, but now considers decomposition of the resin as the most likely cause.

On the same day, the National Institute of Radiological Sciences in Chiba announced that three of the five workers have been admitted to its facility for the third time to receive medication via an intravenous drip that speeds the excretion of radioactive substances from their bodies as urine.

The health of the five workers has not changed, according to NIRS.

http://www.asahi.com/ajw/articles/AJ201707040020.html

Plutonium in Workers’ Urine


The Asahi Shimbun is reporting that, contrary to the reassurances made a few days ago by the Japan Atomic Energy Agency (see here), workers at JAEA’s Oarai Research and Development Center, WERE internally contaminated by Plutonium:

Plutonium found in urine of 5 workers in Ibaraki accident. THE ASAHI SHIMBUN, June 20, 2017 http://www.asahi.com/ajw/articles/AJ201706200039.html

Minute amounts of plutonium have been detected in the urine samples of all five workers who were accidentally exposed to radioactive plutonium at Japan Atomic Energy Agency (JAEA)’s Oarai Research and Development Center in Oarai, Ibaraki Prefecture, on June 6…. While maintaining the level of exposure the five workers experienced “would not have immediate effect on their health for a few months,” Akashi said their internal exposure levels are “relatively high for cases occurring in Japan as far as I know.”… 

…In urine testing, NIRS said it can detect smaller amounts of plutonium as the measurement time is much longer, while the smallest radiation doses the dosimeter for lungs can detect is between 5,000 and 10,000 bequerels.

I shouldn’t be too critical of these oscillating reports given the US won’t even admit when its workers are contaminated with Plutonium, as the recent tunnel collapse at Hanford reminds us:

Tia Ghose. May 10, 2017. Hanford Disaster: What Happens to Someone Who’s Exposed to Plutonium? Live Science, https://www.livescience.com/59042-how-does-plutonium-damage-the-body.html

Workers at a nuclear-waste site in Washington state were recently told to hunker down in place after a tunnel in the nuclear finishing plant collapsed, news sources reported yesterday (May 9)…

The tunnel was part of the plutonium and uranium extraction facility (PUREX) said to be holding a lot of radioactive waste, including railway cars used to carry spent nuclear fuel rods, news agency AFP reported. At least some of the radioactive waste at the Hanford facility contains radioactive plutonium and uranium, according to the DOE, although at least some of it is also radioactive “sludge” composed of a mixture of radioactive substances. Right now, authorities have not revealed whether radioactive substances have been released or whether people have been exposed any of these contaminants

Governments don’t want to talk too much to the public about plutonium. Every dimension of knowledge about this element seems to be weaponized. Despite the desire for secrecy, plutonium always seems to be out of bounds, contaminating some people or environment, or perhaps all people, especially men’s testes (see here).

Plutonium’s astonishing level of chemical toxicity and atomic instability are fetishized by the atomic priesthood, but the priesthood cannot control their Frankensteinan creation, as these stories and ongoing atmospheric emissions at Fukushima Daiichi demonstrate:

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http://majiasblog.blogspot.fr/2017/06/plutonium-in-workers-urine.html

Plutonium in workers’ urine at Oarai Research and Development Center

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Traces of plutonium in workers’ urine

Doctors say extremely small quantities of radioactive substances have been detected in the urine of 5 workers who were accidentally exposed to the materials early this month at a research facility north of Tokyo.

The incident took place on June 6th at a facility of the Japan Atomic Energy Agency in Oarai Town, Ibaraki Prefecture. The workers were inspecting a nuclear fuel container when a bag inside suddenly burst, expelling radioactive powder.

The agency initially said as much as 22,000 becquerels of plutonium-239 were detected in the lungs of one of the workers. But they were discharged from hospital by Tuesday of last week after repeated examinations at the National Institute of Radiological Sciences detected no plutonium in their lungs.

On Monday, the institute said checks of the 5 workers’ urine later revealed extremely small amounts of plutonium and other radioactive materials.

It says the workers have so far suffered no damage to their health, but that they have reentered hospital to take medicines that will purge the plutonium from their bodies. They will take the drug for 5 days, after which doctors will decide if further medication is necessary.

An official related to the institute says the radioactive materials in the workers’ bodies are at levels that will not immediately affect their health.

Meanwhile, the Japan Atomic Energy Agency, which employs the 5 workers, on Monday submitted to the country’s nuclear regulator an interim report on how the accident unfolded.

The agency’s president, Toshio Kodama, told reporters that he apologizes to the public for the incident. Kodama added that his organization may have problems sensing and foreseeing risks.

Kodama said the agency has to work on organizational issues, including worker awareness.

The agency says it plans to conduct a detailed investigation into the cause of the accident. It says it will consider measures to prevent recurrences and report to the regulator.

https://www3.nhk.or.jp/nhkworld/en/news/20170619_27/

Tokyo, June 19 (Jiji Press)–Trace amounts of plutonium have been detected in the urine of all five workers exposed to radioactive materials at a nuclear research facility in eastern Japan earlier this month, a radiological research center treating them said Monday.
The radioactive substances detected in the urine were plutonium-239, plutonium-238 and americium-241, the National Institute of Radiological Sciences, or NIRS, said.
The results showed that the workers at the Japan Atomic Energy Agency’s Oarai Research and Development Center in Ibaraki Prefecture, northeast of Tokyo, suffered internal radiation exposure, the NIRS said.
The NIRS plans to continue examining the five workers for about a month to estimate levels of exposure.
The exposure is unlikely to reach levels that cause symptoms, said Makoto Akashi, a senior official at the National Institutes for Quantum and Radiological Science and Technology, which oversees the NIRS.

http://jen.jiji.com/jc/eng?g=eco&k=2017061901238

Plutonium found in urine of 5 workers in Ibaraki accident

Minute amounts of plutonium have been detected in the urine samples of all five workers who were accidentally exposed to radioactive plutonium at Japan Atomic Energy Agency (JAEA)’s Oarai Research and Development Center in Oarai, Ibaraki Prefecture, on June 6.

The test results were announced June 19 at a news conference by the National Institute of Radiological Sciences (NIRS) within National Institutes for Quantum and Radiological Science and Technology (QST).

The revelation marks the latest twist in the changing assessment of severity of the health risks in the accident. Initially JAEA announced on June 7 that one of the five workers had suffered an internal exposure of 22,000 bequerels during an inspection at the nuclear energy research center. On June 9, JAEA said no plutonium was detected in any of the five workers’ lungs in further testing by NIRS.

Makoto Akashi, an executive of QST, said at the news conference the latest finding confirmed that the workers did “suffer an internal exposure.”

While maintaining the level of exposure the five workers experienced “would not have immediate effect on their health for a few months,” Akashi said their internal exposure levels are “relatively high for cases occurring in Japan as far as I know.”

He also added that long-term observation may be necessary depending on the level of internal exposure.

JAEA’s initial “internal exposure of 22,000 bequerels” assessment was hastily done on the night of the accident on June 6. The five workers were examined using a dosimeter that can detect small traces of X-rays emitted by plutonium particles inhaled into the lungs.

However, the next day, NIRS staff discovered that four of the workers did not have all the plutonium on their bodies completely removed. After thorough decontamination efforts, they were retested for plutonium in the lungs, which was “not detected.”

It is believed the initial assessment came back with a high reading, as the dosimeter also picked up the radiation from the plutonium residue on their bodies.

In urine testing, NIRS said it can detect smaller amounts of plutonium as the measurement time is much longer, while the smallest radiation doses the dosimeter for lungs can detect is between 5,000 and 10,000 bequerels.

The latest test result suggests the possibility that some plutonium particles inhaled into the workers’ lungs have been absorbed into the bloodstream, then discharged into the urine.

The five workers had been discharged and are in stable condition, but were readmitted to the institution for further treatment on June 18. They started receiving medication via intravenous drip injections to speed the excretion of radioactive substances in their bodies from June 19, according to NIRS.

It is the second time they have received this medication. NIRS confirmed the treatment’s effectiveness as the amount of plutonium in their urine increased after the first round of injections compared to the amount found prior to receiving the drug.

http://www.asahi.com/ajw/articles/AJ201706200039.html