On March 21, 2011, we conducted sampling, as a part of monitoring of
 surrounding environments, and detected radioactive materials in the
 seawater around the water discharge canal (of the south side) of
 Fukushima Daiichi Nuclear Power Station, which was damaged by the
 Tohoku - Pacific Ocean Earthquake. Therefore, we informed Nuclear
 and Industrial Safety Agency (NISA) and the government of Fukushima
 Prefecture of the results.
 Since March 22, we have conducted seawater sampling surveys at four
 points off the shore of Fukushima Daiichi Nuclear Power Station
 (twice a day at two points out of such four points since March 26).

 Since April 17, we have also conducted sampling surveys at four
 points (2 points have been added since April 26, another 3 points
 since April 30, and another 1 point since May 5, 10 points in total)
 of 3 km off the shore of Fukushima Daiichi Nuclear Power Station,
 two points of 8 km off the shore of the Power Station and 6 points
 of 15 km off the shore of the Power Station and informed them of
 evaluation results.
 Also, we added another 4 points off the shore since May 27 and 3
 points off the shore since June 2.

 The data of three detected nuclides (Iodine-131, Cesium-134 and
 Cesium-137) will be reported as fixed data. Other nuclide figures
 are to be re-evaluated. (Previously announced)

 On June 4, 2011, we conducted sampling to evaluate the spread of
 radioactive materials to the ocean which were detected at Fukushima
 Daiichi Nuclear Power Station. Since the radioactive materials were
 detected as shown in the attachment, today, we informed NISA and the
 government of Fukushima Prefecture of the results.

 Due to severe weather condition, sampling at 3 points off shore,
 which had been planned yesterday has been cancelled.

 We will continuously conduct the similar sampling. 

attachment1: Results of Nuclide Analysis of Seawater(PDF 57.5KB) 
attachment2: Radioactivity Density of Seawater(PDF 56.6KB)