Top > Releases ・ Announcements > Fukushima Daiichi NPS Prompt Report > 2015 > Immediate release:ALMOST ALL WATER STORED AT FUKUSHIMA HAS BEEN TREATED, HELPING TO IMPROVE ENVIRONMENT AROUND THE PLANT

Fukushima Daiichi NPS Prompt Report 2015


Water treatment will help reduce radiation levels at the site boundary, and also help improve conditions for workers

FUKUSHIMA, May 26, 2015 -As of today, almost all stored water at Fukushima Daiichi NPS that was contaminated with radioactivity has been treated to remove Strontium, and in some cases even more nuclides, TEPCO has reported.

The achievement is expected to further contribute to lowering radiation levels within the facility. The treatment had achieved the goal of reducing the radiation dose at the site boundary attributed to water tanks to under 1 millisievert per year in March.

"This is a significant milestone for improving the environment for our surrounding communities and for our workers," said Chief Decommissioning Officer Naohiro Masuda. "It reduces risk and will make people inside and outside the facility more secure."

End-of-May Target Achieved

Today's announcement covers almost all stored contaminated water at the site. Some of the water includes high concentration of seawater (hereafter "high-percentage seawater" which occupied 3% of the whole volume as of March), which has been taking somewhat longer to treat because of its greater density, and the company expects to have it all treated soon. The finally remaining is water in the bottom of the storage tanks, which cannot be vacuumed up by the originally installed pumps. This water will be carefully removed when the tanks are disassembled etc., and then treated.

The company had originally hoped to have all the stored water treated by the end of March, but challenges in getting various technologically innovative treatment systems up to full capacity led the company to announce on March 16 that the new target for all but the "high-percentage seawater" and the residual water in the tanks would be May 31.

Though the "high-percentage seawater" represented only about 3 percent of the total quantity of contaminated water that had been stored on the site as of March, engineers originally expected it would take longer to treat because of the greater density of saltwater. But, they said, as they adjusted water flow inside the treatment facilities, they came to figure out the appropriate water flow which enables all "high-percentage seawater" to be treated within this month.

Some of the treated water will require further treatment to remove additional, less problematic, nuclides. But the removal of Strontium represents the removal of the substance most likely to contribute to radiation in the environment. The filters and related devices that now contain the strontium will be stored safely on the site in containers that shield radiation much more effectively than the tanks in which the contaminated water had been stored.


Tokyo Electric Power Company, Inc. (TEPCO) is Japan's largest power company, supplying energy to the greater Kanto area, including Japan's two most populous cities, Tokyo and Yokohama. Its 34,000 employees are committed to providing safe, reliable power to its 29.0 million customers, diversifying energy resources to ensure sustainability, and contributing to economic growth while fully meeting its responsibilities after the Fukushima Daiichi accident.
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