Another radiation exposure accident (Oarai, Ibaraki Prefecture, Japan)

japantimes.co.jp ^ | JUN 18, 2017 | no byline

[ransomnote]

A radiation accident earlier this month at the Japan Atomic Energy Agency’s facility in Oarai, Ibaraki Prefecture, underlines the need for operators of facilities handling radioactive substances to make sure there are no flaws in their safety systems and procedures. Such caution is all the more important since Japan will have to manage large amounts of radioactive substances in decommissioning nuclear power reactors, including the agency’s fast-breeder reactor Monju, which the government decided last December to take out of service.

The accident occurred when five workers were taking stock of 300 grams of uranium oxide and plutonium oxide put in a cylindrical stainless steel container at the Plutonium Fuel Research Facility in the agency’s Oarai Research and Development Center. The powdery substances had been encased in a double-wrapped plastic bag placed inside the container, whose lid was fastened with six bolts. When one of the workers opened the lid, the black powder sprayed out under pressure, exposing the men to radiation. The fiver workers were admitted to the National Institute of Radiological Sciences’s hospital in Chiba for treatment.

The fiasco brings to mind the 1999 criticality accident at a nuclear fuel processing facility operated by JCO Co. in Tokai, Ibaraki Prefecture, which killed two workers — the worst nuclear radiation accident in Japan prior to the 2011 meltdowns at the Fukushima No. 1 power plant. The fatal accident occurred when three workers were preparing a small batch of nuclear fuel using uranium enriched to 18.8 percent. They were handling the nuclear fuel in stainless steel buckets. The company apparently failed to give workers proper safety training, and sloppiness was the clear cause of the accident.

[ransomnote]

More at link. THere aren't any rules for how often stored radioactive materials are inspected. This container had not been opened in 26 years and radioactive decay probably resulted in helium, pressurizing the container. Reading the whole thing, it's just sad that the public is at the mercy of the nuclear industry. Protection offered by government to rebut regulation and oversight by the public has produced an industry lacking professional standards and knowledge and it shows. The recent Hanford (WA) "accident" reflects similar backward thinking and management.

[ransomnote]

A few months ago, a 400 foot hole opened up in a tunnel containing rail cars filled with radioactive waste (Hanford, WA). But it’s not the only problem there and just glancing around I found this from 2 years ago:
“On Dec. 10, radioactive contamination was found on the elbow of a worker after the suit had been removed. It was one of several incidents at the Plutonium Finishing Plant during the past six months, including incidents of skin contamination.”
http://www.tri-cityherald.com/news/local/hanford/article50600355.html

[Carl Vehse]

"The powdery substances had been encased in a double-wrapped plastic bag placed inside the container, whose lid was fastened with six bolts. When one of the workers opened the lid, the black powder sprayed out under pressure, exposing the men to radiation."

Sounds like there may have been some residual moisture and/or nitric acid left in the powder, and radiolysis of the moisture by the plutonium's alpha radiation resulted in the production of hydrogen or nitrogen oxide gas. The gas pressure in the sealed container caused some of the radioactive powder to blow out when the lid of the container was unbolted. The main danger is worker inhalation of the plutonium dust as blew out of the container. External radiation is minor for that amount of plutonium or uranium.

[chajin]

That makes more sense than the explanation in the article.

[VTenigma]

There is so much wrong with that story as posted by the Tri City Herald it’s hard to know where to start. First the tunnel is 400’ long not the cave in, that was 20’. Next, this was a tunnel used to transfer plutonium and enriched uranium between points within the finishing plant. The waste in the tunnel system is not what most would know as waste, it is actually the equipment used in shuttling the nuclear material within the tunnel system, the rail cars and such.

This equipment is highly radioactive and has been out of service for decades. At this point most of the finishing plant has been dismantled, raised to the ground, and decontaminated. There is one building left that is currently being decontaminated and equipment removed. That building had the highest radioactive contamination and new technologies had to be developed to provided improved health and safety protections for the workers.

The tunnel areas are a challenge and those are slated to be addressed after the above ground facility dismantling is complete. More than likely Hanford is now reassessing the timeline since the cave in. Cleaning up Hanford is a monumental project that is already in it’s third decade. Only the U.S. has made a commitment like this to restore one of the most contaminated places on earth.

[Carl Vehse]

The generation of gases by alpha radiolysis of plutonium has been known for some time:

Radiolytically Generated Hydrogen and Oxygen from Plutonium Nitrate Solution (1964)
Radiation chemistry of nitric acid solutions (1969)
The storage behavior of plutonium metal, alloys, and oxide: A review (1971)
Matrix Effects on Radiolytic Gas Generation in Plutonium Residues (1999)
The Scientific Basis for Plutonium Stabilization with Particular Emphasis on Gas Generation (2000)
Evaluation of Moisture Limits for Uranium and Plutonium Mixed Oxides to Support On-Site Transportation Packaging (2000)
Hydrogen yields from plutonium alpha-radiolysis of nitrate solutions (2015)

[ransomnote]

“Fifty-three dump trucks full of soil filled the 400-square foot hole over the tunnel containing radioactive waste stored on the former plutonium production site near Richland in southern Washington.”
https://www.theatlantic.com/science/archive/2017/05/hanford-tunnel-collapse/526041/
There’s a picture (twitter) on that page that shows the 20’ x 20’ opening. The article says that the millions of gallons leaking out the massive radioactive sludge tanks are a bigger concern at Hanford. :(

[ransomnote]

The waste in the tunnel system is not what most would know as waste, it is actually the equipment used in shuttling the nuclear material within the tunnel system, the rail cars and such.
______________________________________________
Actually, those rail cars were filled with radioactive material:
“ Eight flatbed railroad cars loaded with radioactive material were parked inside when the entrance was sealed in 1965.”
https://www.usatoday.com/story/news/nation-now/2017/05/12/sinkhole-collapsed-hanford-nuke-site/319098001/

[ransomnote]

They were warned that the wood beams supporting the tunnels had lost 1/3 of their strength by 1980 but did nothing. Then:
“A group of academic experts, working under contract to the department, said more alarmingly in a 1,969-page report in August 2015 that the roof of the tunnel in question had been seriously weakened and that a “partial or complete failure” could expose individuals even 380 feet away to dangerous levels of radiation.”
And still they did nothing. The story of nuclear energy. Same with Fukushima.
https://www.publicintegrity.org/2017/05/12/20862/repeated-warnings-preceded-collapse-hanford-tunnel-storing-deadly-wastes

[21twelve]

https://www.washingtonpost.com/news/post-nation/wp/2017/05/09/tunnel-collapses-at-hanford-nuclear-waste-site-in-washington-state-reports-say/?utm_term=.c695c09fecc1

The Energy Department said it activated its emergency operations protocol after reports of a “cave-in” at the 200 East Area in Hanford, a sprawling complex about 200 miles from Seattle where the government has been working to clean up radioactive materials left over from the country’s nuclear weapons program.

The agency said in a statement that the 20-foot section is part of a tunnel that is hundreds of feet long and is “used to store contaminated materials.”

************************************

Adjacent to the Hanford Project is the running nuclear power plant. I’m not positive, but the spent fuel for that looks to be stored right on-site near the power plant and offices. There is a fenced-off area with radiation warning signs, and tall cylinders sitting vertical in racks.

I was in one building that is a lab of some type with numerous “hot” working areas with the mechanical arms and stuff inside the shielded work areas (3-foot cube) with the big glass(?) fronts. One of the working areas looked like it was still in use. The dozens of others were filled with contaminated stuff of all types and of all ages. Was like some weird museum - but really just a safe place to store contaminated stuff.