At around 9:30 am on April 2, 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 flowing out to the ocean. At around 12:20 pm on April 2, we reaffirmed 
the event at the scene. 
We have implemented sampling of the water in the pit of Unit 2, together 
with the seawater in front of the bar screen near the pit of Unit 2. These 
samples were sent to Fukushima Daini Nuclear Power Station for analyses.

At around 5:38 am on April 6, we observed stoppage of spilling of water to 
the ocean from the crack on the concrete lateral of the pit. 

Since April 5, we have been conducting sampling surveys of the water in 
the pit of Unit 2 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, and for 
the other nuclides, we will re-evaluate them.

On April 12, 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 17, 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.

On May 11, 2011, responding to out-flow leakage of contaminated water from 
the intake canal of Unit 3, from May 12th, we additionally conducted the 
sampling of the seawater inside and outside of the silt fence in front of 
the bar screen near the pit of Unit 1, 3 and 4. 
                                                    (Previously announced)

On November 23, 2011, we conducted sampling of the seawater near the intake 
canal of Units 1 to 4 of Fukushima Daiichi Nuclear Power Station and 
analyzed the samples. As a result, some radioactive materials were detected 
as described in the appendix. 

From November 15, in order to prevent performance degradation of pumps by 
suction of sand etc, we are cleaning the bottom of the pumping station, 
water intake canal, auxiliaries, Units 5 and 6. In order to evaluate the 
impact to surrounding environment by that cleaning work, we increased 
sampling points. We are notifying the analysis result of the above at the 
same time.

We reported the above results to NISA as well as to the government of 
Fukushima Prefecture today.
We will continuously conduct the same sampling surveys.

*Pit: vertical shaft made of concrete 

 
Appendix1: Nuclide Analysis Results of Radioactive Materials in Seawater 
           Fukushima Daiichi Nuclear Power Station; the shallow draft quay, 
           Unit 1-4 screen, and the water intake canal of Units 1-4 
                                                              (PDF 13.8KB)  
Appendix2: Nuclide Analysis Results of Radioactive Materials in Seawater 
           at the seawater intake of Units 5 and 6, Fukushima Daiichi 
           Nuclear Power Station (PDF 10.8KB)  
Appendix3: Radioactivity Density of Seawater (PDF 45.1KB)