On March 21st, 2011, a sampling survey, conducted as a part of monitoring
of surrounding environment, detected radioactive materials in the seawater
around the water discharge port (south) 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 22nd, 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 26th).
We have also informed NISA of the results of seawater sampling surveys
which have been implemented since April 2nd at three different points
within 15 km area of Fukushima Daiichi Nuclear Power Station. (Since April
5th, sampling has been implemented at six different points, and since
April 6th, it has been conducted twice a day at six different points.)
The data of detected three nuclides (Iodine-131, Cesium-134 and Cesium-137)
will be reported as fixed data. Other nuclide figures are to be
re-evaluated based on the improved measures for recurrence prevention
which have been prepared in accordance to a warning from NISA on April
On April 17th, 2011, we conducted sampling surveys to evaluate the spread
of radioactive materials which were detected at Fukushima Daiichi Nuclear
Power Station. Since the radioactive materials were detected as shown in
the exhibit, we informed NISA and the government of Fukushima Prefecture
of the results.
In accordance with the direction from NISA on April 15th, 2011, four
points at 3 km off the coast and two points at 8 km off the coast have
been added to sampling since April 17th, 2011.
Sampling surveys on two points at 3 km off the coast, one point at 8 km
off the coast, and five points at 15 km off the coast are canceled due to
the bad weather.
Concerning the nuclides of Plutonium-238, Plutonium-239, and Plutonium-240
in the seawater, sampling and analyses ware conducted on April 5th and 6th,
and no above nuclides have been detected from the analyzed samples.
We will continuously conduct the same sampling surveys.
attachment1:Results of Nuclide Analysis of Seawater(PDF 15.5KB)
attachment2:Fukushima Daiichi Nuclear Power Station:
Plutonium Analysis result in the seawater(PDF 41.2KB)
attachment3:Radioactivity Density of Seawater(PDF 49.5KB)