On March 28 2011, we were advised from Nuclear Safety Commission of Japan
to enhance sampling surveys regarding water accumulated in underground
floor of the turbine buildings of Fukushima Daiichi Nuclear Power Station.
In order to verify any leakages to underground and sea, and safety, we
have been implementing the sampling surveys of subsurface water and
seawater.

Regarding sampling surveys of sub-drains, per the instruction from Nuclear
and Industry Safety Agency (NISA) on April 14th, we will continue the same
kind of sampling surveys three times a week, and inform the result on the
next day of the survey.
                                                    (Previously announced)

As a result of Nuclide analysis from the sample regarding sub-drains
 (subsurface water obtained and managed in the site) near the turbine
buildings of Fukushima Daiichi Nuclear Power Station collected on July 25,
radioactive materials were detected as shown in the attachment and today,
we reported to NISA and the government of Fukushima Prefecture. 

Appendix1: Nuclide Analysis Results of Sub-drains(PDF 10.8KB) 
Appendix2: Radioactivity Density of Sub-drain (PDF 24.1KB)