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Increasing amounts of contaminated water at Fukushima I NPS at issue

Jan. 22, 2013

The multi-nuclide removal equipment whose operation is being delayed (January 17)

TOKYO --A point at issue at the Fukushima I nuclear power station (NPS) is treatment of increasing amounts of water contaminated by radioactivity. As a year and 10 months has passed since the onset of the accident, the amount of contaminated water stored has amounted to about 220,000 metric tons. Contaminated water is still being generated as much as 40 tons per day, and additional storage tanks are being constructed. While Tokyo Electric Power Company (TEPCO) planned to start operating the multi-nuclide removal equipment (ALPS), which can remove 62 nuclides from the contaminated water, in September last year, its startup is delayed by about four months as of now.

At Fukushima I units 1 to 3, approximately the same amount of water is recirculated a number of times to cool the reactors. Groundwater flows into the recirculation system every day. Because of this incremental amount of contaminated water, TEPCO is using a water treatment system called SARRY to remove cesium and storing treated water in tanks. The ALPS can remove all the nuclides except cesium to less than the corresponding statutory levels. The water treated by the ALPS can be handled almost as ordinary water, although it cannot be discharged freely because of the persistence of tritium, the only radionuclide remained.

The operation of the ALPS is significantly delayed because the Nuclear Regulation Authority staff is requiring stricter safety measures. This poses a serious effect. According to TEPCO's calculation, a delay of one day means additional four days required to treat all the contaminated water with the ALPS. Therefore, a delay of about a year and half is currently expected by now. If the ALPS remains unavailable, the period required for treatment, expected to be about three years if everything goes well, will be extended to four to five years or more.


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