NRA Confirms Additional Effective Dose Reduction at Fukushima Daiichi Boundaries

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At its regular meeting on June 17, Japan's Nuclear Regulation Authority (NRA) confirmed that the additional effective doses from radioactive waste had been reduced to less than 2mSv/year at the boundaries of the Fukushima Daiichi Nuclear Power Station.

In accordance with an implementation plan that the Tokyo Electric Power Co. (TEPCO) had submitted to the NRA on June 8, the company evaluated additional effective doses stemming from radioactive waste in light of the treatment of contaminated water as of the end of March 2015, and found it to be 1.44mSv/year at maximum.

The NRA secretariat then measured the concentration of radioactive materials by sampling contaminated water from various groups of tanks. Doing so, it confirmed the amounts of contaminated water stored, then carried out further analysis. As a result, it concluded that the evaluation by TEPCO was appropriate.

According to the revised medium-and-long-term roadmap for decommissioning for Fukushima Daiichi’s Units 1-4, released on June 12, water that has already been treated will undergo additional treatment by multi-nuclide removal equipment to reduce the additional effective dose to less than 1mSv/year at the boundaries of station by the end of FY15 (i.e., by March 31, 2016). (For further details, see the article entitled “Government Revises Roadmap for Medium-term and Long-term Decommissioning of Fukushima Daiichi.”)