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

On June 1, 2011, we conducted sampling surveys regarding sub-drains 
(subsurface water obtained and managed in the site) near the turbine
buildings of Fukushima Daiichi Nuclear Power Station. Today, we reported
to NISA and the government of Fukushima Prefecture, since, as the results
of nuclide analyses, radioactive materials were detected as shown in the
attachment.

Regarding the sample collected on May 18, Plutonium 238, 239, 240 were not
detected as a result of the analysis of water in the sub-drains. 

Appendix1: Results of Nuclide Analyses of Sub-drains (PDF 11.1KB) 
Appendix2: Result of Plutonium measurement analysis on Sub-drain water in Fukushima 
           Daiichi nuclear power plant(PDF 7.52KB) 
Appendix3: Radioactivity Density of Sub-drain (PDF 23.9KB)