At around 9:30 am on April 2nd, 2011, we detected water containing 
radiation dose over 1,000 mSv/h in the pit* where power supply cables are 
stored near the intake channel of Unit 2. Furthermore, there was a crack 
of about 20 cm length on the concrete lateral of the pit, from where the 
water in the pit was outflowing to the ocean. At around 12:20 pm on April 
2nd, we reaffirmed the event at the scene.
We have implemented sampling of the water in the pit, together with the 
seawater in front of the bar screen near the pit. These samples were sent 
to Fukushima Daini Nuclear Power Station for analyses.

At around 5:38 am on April 6th, we have observed stoppage of spilling of 
water to the ocean from the crack on the concrete lateral of the pit. For 
the sake of completeness, we put further reinforcement for the stoppage of 
leakage and consider countermeasures including continuous injection of 
coagulant. We also note the water level of the turbine building of Unit 2 
remains unchanged. We will further investigate if there is any other 
leakage.

Since April 5th we have been conducting sampling surveys of the water in 
the pit and the seawater in front of the bar screen near the pit. Regarding 
the survey results of the detection of three nuclides (iodine 131, 
cesium 134, cesium 137), we report those as definite results. As for other 
nuclides, we will revaluate in accordance with the preventive measures 
formulated after receiving a warning from Nuclear and Industrial Safety 
Agency (NISA) on April 1st.

On April 12th, due to the installation of silt fences, we changed the 
sampling points from the front of the bar screen of Unit 4 to the north 
and the south of the inside of the water intake canal of Units 1 to 4. 
Since April 17th, we have been conducting an additional sampling survey 
outside the silt fence in front of the bar screen of Unit 2, in order to 
assess the effect of the installation of the silt fence.
                                                    (Previously announced)

On April 28th, 2011, we conducted sampling survey of the water in the pit 
and the seawater in front of the bar screen near the pit, and conducted 
nuclide analysis of radioactive materials in the water. As a result, some 
radioactive materials were detected as described in the exhibit. 
Accordingly, we have reported the result of the analysis to NISA and the 
government of Fukushima Prefecture.

* pit: a vertical shaft made of concrete 

 
Appendix: Result of Nuclide Analysis of the seawater at the shallow draft 
          quay, Unit 2 screen, and the water intake canal of Unit 1-4 
                                                         (PDF 11.3KB) 
Appendix: Radioactivity density of seawater(PDF 21.2KB)