Fukushima Daiichi NPS Prompt Report 2013

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

In relation to the leakage from the underground reservoir No.2, as a result of performing sampling in the leakage detection hole of the underground reservoir No.1 for the purpose of investigating the leakage location, all β nuclides were detected. (Previously announced at 6:07 PM on April 9)

Thus, it was judged that there is a possibility of a small amount of leakage from the sheet on the inside (double-layer impermeable sheet) to the sheet on the outside (bentonite sheet) although the water level of the underground reservoir No.1 has not decreased and the analysis results of the water in the drain hole of the underground reservoir No.1 has not yet been confirmed.

Though the incident has occurred in the controlled area, the condition has been judged to be subject to the application of Article 19-17, Item 10 of the Rule for the Installation, Operation, etc. of Commercial Nuclear Power Reactors (Rule for Commercial Nuclear Power Reactors) ("in the case that leakage of radioactive materials, etc. occurs in the controlled area due to a reactor facility failure or other unexpected incidents") at 4:34 PM on April 9.

This incident is reported in accordance with Article 168 of the Technical specification for nuclear reactor facility at Fukushima Daiichi Nuclear Power Station (Report).