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Hydrogen sulfide present in Fukushima contaminated water tanks

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January 7, 2019
Mako Oshidori reported from a recent TEPCO press conference that the company has admitted to finding hydrogen sulfide in some of the contaminated water tanks at Fukushima Daiichi.
 
The instances of hydrogen sulfide was found in newer welded tanks in the G3 tank farm in August.
TEPCO found levels up to 50 ppm in some of the tanks.
If it oxidizes to sulfuric acid it can corrode steel and concrete storage equipment including the water tanks.
 
TEPCO claims that the cause of the hydrogen sulfide gas was due to anaerobic bacterial decomposition. Hydrogen sulfide gas is a corrosion concern for the contaminated water tanks.
 
This is a problem from a human health standpoint for workers in the area. TEPCO cites a level of at least 50 ppm. They do not report the exact concentrations over 50 ppm. Health effects can happen at doses lower than 50 ppm. As exposure doses increase so do the health dangers. High concentrations can cause rapid death. With tanks creating this gas byproduct the risk exists of a worker accidentally coming in contact with a concentrated amount of this gas. Workers in the tank farms do not wear respirators, only paper particle filtration masks.
 
TEPCO stated they would continue to investigate the conditions in the on site tanks for gas and corrosion.
 
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January 9, 2019 Posted by | fukushima 2019 | , , | Leave a comment

Fukushima Daiichi H4 Tank Farm Dismantled, Contents Transferred

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On May 26 Tepco finished dismantling the 56 tanks from the H4 tank farm. Tepco mentioning some soil remediation having being done, but providing no details about it.

Those tanks were used to contain contaminated water and sludge from the reactors and the contaminated water treatment systems.

Those tanks panels having not been welded but only bolted with rivets, caused numerous leals in 2013. Those tanks panels were removed and sent to an automated cutting system for further dismantling and storage as radioactive waste. Their content was transfered to other more recent tanks, those welded.

http://www.tepco.co.jp/cc/press/2013/1232456_5117.html

http://www.tepco.co.jp/nu/fukushima-np/handouts/2017/images1/handouts_170526_03-j.pdf

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June 2, 2017 Posted by | Fukushima 2017 | , , | 1 Comment

Fukushima nuclear plant still plagued by tainted water 6 years after meltdowns

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Workers bring in a new water tank, right, as a replacement for an old contaminated water tank at TEPCO’s No. 1 nuclear power plant in the town of Okuma in Fukushima Prefecture on Feb. 24, 2017

OKUMA, Fukushima — With two weeks to go until the sixth anniversary of the disaster at Tokyo Electric Power Co. (TEPCO)’s Fukushima No. 1 Nuclear Power Plant here, the Mainichi Shimbun visited the plant on Feb. 24, obtaining a first-hand view of working conditions and the persisting problem of tainted water.

The number of areas on the plant site requiring full face masks has decreased considerably, and the overall working environment has improved greatly. However, the issue of having to replace the tanks that hold radioactively contaminated water lingers.

Dealing with contaminated water requires significant manpower. According to TEPCO, about half of the approximately 6,000 people working daily at the No. 1 nuclear power plant are involved in handling contaminated water.

There are roughly 1,000 tanks of contaminated water inside the No. 1 plant site, forming a forest of containers with nowhere else to go.

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

During the immediate aftermath of the nuclear disaster in 2011, a considerable number of tanks known as flanges were placed within the site. However, as concerns continue to grow about contaminated water leaking from these tanks due to dilapidation, TEPCO has taken action and is working on dismantling them.

Although covering the ground at the No. 1 plant with concrete has made it possible to work in about 90 percent of the site without a protective uniform, all those working near the old tanks must wear full face masks and Tyvek suits as the tanks once held highly contaminated water. Wearing this kind of protective clothing makes the work much harder to perform — as it can be difficult to breathe — and it is physically exhausting, even in the middle of winter.

Hiroshi Abe, 55, of Shimizu Corp. — the company overseeing the dismantling work — states, “As we work toward recovery from the disaster, we want to ensure that all workers are protected from radiation exposure and injuries.”

Presently, the level of radiation in the vicinity of the buildings housing the No. 1, No. 2, and No. 3 reactors is high. During the Mainichi Shimbun’s visit to the site on Feb. 24, the radiation level near the No. 3 reactor was found to be more than 300 microsieverts per hour, and near the No. 2 reactor building, it was discovered to be 137.6 microsieverts per hour.

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A radiation measuring device shows a reading of 137.6 microsieverts per hour near TEPCO’s No. 2 reactor in the town of Okuma in Fukushima Prefecture on Feb. 24, 2017.

Furthermore, an “ice wall,” which was built to restrict the flow of contaminated water underground, has not been as effective as initially expected.

A spokesman for TEPCO, Takahiro Kimoto, who accompanied the Mainichi Shimbun on this visit, said, “Nearly six years have passed since the disaster. Our decommissioning work is now about to enter the main stage of extracting melted fuel.”

However, with TEPCO and the government’s decommissioning work set to continue until around 2041-2051, there is still a long way to go until they can reach the “main stage.”

http://mainichi.jp/english/articles/20170225/p2a/00m/0na/010000c

 

 

 

February 26, 2017 Posted by | Fukushima 2017 | , , , , | Leave a comment

TEPCO Delays Replacing Tainted Water Tanks

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Tokyo, Sept. 28 (Jiji Press)–Tokyo Electric Power Company Holdings Inc. <9501> has effectively given up replacing tainted water storage tanks at its Fukushima No. 1 nuclear power station with safer ones at an early date, it was learned Wednesday.


It is believed to be the first time that the power firm has abandoned a deadline in its decommissioning work timetable, revised in June last year.


TEPCO now expects to finish the work in June 2018 at the earliest, according to documents submitted to a panel of the Nuclear Regulation Authority.


TEPCO initially planned to finish replacing the storage tanks with welded low-leakage ones early in the current business year through March 2017.


TEPCO remains unable to stop increases in the amount of radioactive water. The amount of contaminated water stored in the current tanks with a higher risk of leakage stood above 110,000 tons as of Thursday.

http://jen.jiji.com/jc/eng?g=eco&k=2016092800865

September 29, 2016 Posted by | Fukushima 2016 | , , | Leave a comment

TEPCO to reuse tanks holding radioactively contaminated water at Fukushima plant

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Tokyo Electric Power Co. (TEPCO) will reuse highly contaminated tanks at the crippled Fukushima No. 1 Nuclear Power Plant to store radioactively contaminated water after treatment, company sources said.

The company will return contaminated water to flange-type tanks that had held such water after removing radioactive materials from the water using the Advanced Liquid Processing System (ALPS). This is because TEPCO has failed to prevent contaminated water from being generated on the premises of the plant or to secure enough storage tanks to hold treated water.

TEPCO had submitted the reuse plan to the Nuclear Regulation Authority, which approved it on July 6 or earlier. TEPCO is set to begin reusing contaminated tanks as early as this month.

Flange-type tanks are assembled by tightening multiple steel plates with bolts. Since such tanks have higher risks of leaking contaminated water, TEPCO is gradually replacing them with tanks assembled by welding steel plates together.

TEPCO is trying to freeze underground soil to surround reactor buildings at the Fukushima power plant to prevent underground water from flowing beneath them and becoming contaminated with radioactive materials.

However, as the efforts have proven ineffective, the utility has decided to reuse flange-type tanks, which it had initially planned to dismantle.

Massive amounts of water are flowing onto the premises of reactor buildings at the atomic power station, generating some 400 tons of radioactively contaminated water a day. TEPCO uses ALPS to purify contaminated water, but the system cannot remove radioactive tritium.

The power company has stored the treated water mainly in welded-type tanks. There are already 1,000 water tanks on the premises of the power station.

http://mainichi.jp/english/articles/20160707/p2a/00m/0na/003000c

July 7, 2016 Posted by | Fukushima 2016 | , , , | 1 Comment