Fukushima Daiichi NPS Prompt Report 2013

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

Sampling was performed in the drain hole (southwest) of the underground reservoir No.1 in the afternoon of April 26 and April 27 in response to the increase of all β in the sample collected in the drain hole (southwest) of the underground reservoir No.1 in the morning of April 27. The results are as follows.

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

The all β detected in the sample collected in the afternoon on April 27 was equivalent to that of the sample analyzed in the morning on April 27.

No significant increase in all β was found with the sample collected in the afternoon on April 26.

Though an increase of all β in the sample collected in the drain hole (southwest) of the underground reservoir No.1 was confirmed, no significant increase was found with the chloride concentration of the drain hole and the leakage detection hole and with the all β of the leakage detection hole located in the inside of the drain hole.

Please refer to our web page for the sampling results.
http://www.tepco.co.jp/en/nu/fukushima-np/f1/smp/2013/images/chosui_13042706-e.pdf

The cause of the increase in all β in the drain hole (southwest) of the underground reservoir No.1 will be investigated while intensively monitoring the water level, etc. of the reservoirs.