Fukushima Daiichi NPS Prompt Report 2013

Following the water leakage from the drain valve at the H4 area tank dike, we have been conducting enhanced patrols of the tanks. During a patrol today (on September 1), we found a location showing a high dose equivalent rate, which is at the same tank as one announced yesterday as having a location that showed a high dose equivalent rate, and which is on the opposite side to the location that previously showed the high rate.
·H3-Tank No.4 (north side): 1700mSv/h (β-ray 70μm dose equivalent rate)
Additionally, rates obtained today by remeasurement in the following high dose equivalent rate locations as announced yesterday are as follows.

·H3-Tank No.10: 80mSv/h (β-ray 70μm dose equivalent rate)
·H3-Tank No.4 (south side): 1100mSv/h (β-ray 70μm dose equivalent rate)
* The values of γ ray were below 1mSv/h (the needle of the measurement instrument did not move), and the rates were attributable mainly to β ray radiation. Since a β-ray radiation dose decreases considerably as the distance increases, the above rates do not represent the atmosphere dose rates in the whole surroundings at the sites.

No water dropping was found in the above 3 locations. We will conduct detailed investigations as to whether there has been water leakage, etc., and announce the investigation results as soon as they are available.

Note that no location other than the above 3 locations showed a high dose equivalent rate not less than 10mSv/h in the measurement (conducted within 1m from the outer surface of the tank, at the height of approx. 50cm from the ground, along the entire circumference of each tank) during the patrol.
* The recording criteria of "10mSv/h" was as reported in "The 5th Meeting of the Working Group for Review on Contaminated Water Countermeasures of the Supervision and Evaluation Committee for the Specified Nuclear Power Facilities" of the Nuclear Regulation Authority.