Target for radiation at site boundary attributed to water tanks will be met by end of March as scheduled, lowering risk for workers and surrounding community
TOKYO, March 16, 2015 A revised schedule for the treatment of the remaining contaminated water at Fukushima Daiichi was announced today by the Tokyo Electric Power Co. The new schedule will achieve the goal of reducing the radiation dose at the site boundary attributed to water tanks to under 1 millisievert per year by the end of March.
"We are re-evaluating the risks of not just contaminated water, but all factors including solid waste, liquid and airborne risks," Chief Decommissioning Officer Naohiro Masuda said. "Even if some contaminated water remains, I feel that we can reduce a substantial amount of risk."
TEPCO said it focused on the goal of meeting the site boundary dosage target because it reduces the overall risk created at the premises, something it recognizes as being very important to the site workers and people of the surrounding communities.
The company had originally projected it would treat all contaminated water on the site by the end of March, but in January it announced that it would need more time. The company attributed the longer time frame to the challenges of implementing new technologies to clean the water, and to a "safety first" approach that, at the urging of both domestic and international advisors, places safety and reliability ahead of meeting arbitrary deadlines. At the time, the company said it would announce a revised schedule in March, and it is now doing so.
The new targets call for most of the remaining water to be treated by the end of May. This includes:
・Water which has had strontium and other contaminants removed through the multi-nuclide removal system.
・Contaminated water treated in the days when the multi-nuclide removal systems had encountered performance issues and which needs to be treated again to further remove contaminants.
・Strontium-removed contaminated water which requires treatment through the multi-nuclide removal system to further remove contaminants.
The remainder is water containing relatively high levels of seawater components. (In the days immediately following the accident, the reactors were being cooled with water pumped directly from the sea until a freshwater system could be put in place.)
The latest findings showed that this type of water must be put through the treatment system more slowly than the other types of water to ensure that strontium is removed effectively.
Several additional months will be needed to complete the treatment of the water with relatively high seawater components. The company cautioned that safety must always come first and that a pause in treatment activity remains possible if necessary to protect workers or in the event of unforeseen technical reasons.
Groundwater entering the reactor buildings on a daily basis (approx. 300 tons) and water drawn up from well points and transferred to the reactor buildings on a daily basis (approx. 100 tons) will continue to be treated as part of the overall process.
TEPCO also said residual water at the bottom of the storage tanks that cannot be pumped out using conventional means will be removed and treated as each storage tank is dismantled in the future. This water is not included in the treatment target amount, but every precaution would be taken in the dismantling of the tanks to ensure that workers are not exposed to radiation and that the environment is protected, the company said.
For detail, please go to http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2015/images/handouts_150316_02-e.pdf
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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