Fukushima Daiichi NPS Prompt Report 2013

This is follow-up information regarding the water leak from the underground reservoirs at Fukushima Daiichi NPS.

The sampling result of all β detected in the drain hole (southwest) of the underground reservoir No.1 in the afternoon today (April 28) is announced. The density is equivalent to that of this morning.

- Drain hole (southwest) of the underground reservoir No.1
[All β detected in the afternoon on April 28] 4.8×10^-2Bq/cm³
[All β detected in the morning on April 28] 7.4×10^-2Bq/cm³ (Previously announced)
[All β detected in the afternoon on April 27] 1.1×10⁰Bq/cm³ (Previously announced)
[All β detected in the morning on April 27] 1.1×10⁰Bq/cm³ (Previously announced)
[All β detected in the afternoon on April 26] 4.1×10^-2Bq/cm³ (Previously announced)
[All β detected in the morning on April 26] Below the detection limit (2.6×10^-2Bq/cm³) (Previously announced)

As a result of using a new sampling bottle to collect water sample from the drain hole (southwest) of the underground reservoir No.1 in the morning and afternoon today in order to prevent contamination of collected sample, the all β density was equivalent with that on the day before yesterday (April 26). Thus, the sample obtained yesterday (April 27) from the drain hole (southwest) of the underground reservoir No.1 is assumed to have been contaminated when sampled.

The results of sampling performed in the underground reservoirs this morning are also announced.
- Drain holes of the underground reservoirs No.1-7
- Leakage detection holes of the underground reservoirs No.1-4 and 6

No significant change was found with the results obtained today compared to the previous day (except for the drain hole (southwest) of the underground reservoir No.1).

Please refer to our web page for the sampling results.
http://www.tepco.co.jp/en/nu/fukushima-np/f1/smp/2013/images/chosui_13042803-e.pdf

The water level, etc. of the underground reservoirs will continue to be intensively monitored.