Fukushima Daiichi NPS Prompt Report 2013

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

Sampling was performed in the leakage detection hole (southwest) of the underground reservoir No.1 in the afternoon on 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.

- Leakage detection hole (southwest) of the underground reservoir No.1
[All β detected in the morning on April 26] 1.4×10^-1Bq/cm³ (Previously announced)
[All β detected in the afternoon on April 26] 1.9×10^-1Bq/cm³
[All β detected in the morning on April 27] 1.4×10^-1Bq/cm³ (Previously announced)
[All β detected in the afternoon on April 27] 1.3×10^-1Bq/cm³

No significant increase in all β was found in the leakage detection hole (southwest) of the underground reservoir No.1.

No significant increase in chloride concentration was found in the leakage detection hole (southwest) of the underground reservoir No.1 compared with the result obtained in the morning on April 27.

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. Thus, the possibility that the contaminated water in the underground reservoir No.1 has leaked from the west side of the reservoir to the outside is low. However, the cause of the increase in all β will continue to be investigated.

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

Please refer to our web page for the sampling results.
http://www.tepco.co.jp/en/nu/fukushima-np/f1/smp/2013/images/chosui_13042801-e.pdf