We periodically measure radioactivity of the air and seawater near the 
power station, environment samples such as the soil and pine needles as 
analyses of environment samples*1. We have detected slight amounts of 
radioactive materials such as cesium and iodine emitted into the air by 
the accident at Fukushima Daiichi Nuclear Power Station, however, they are 
below the level to give significant effects on the surroundings.
                        (Previously announced on April 13, May 13, and 26)

Until today, as periodic sampling, we measured the filters which captured 
dust in air during May at 3 monitoring posts located around the power 
station by using dust radiation monitor. As a result, same as previous 
month, small amount of radioactive materials (cesium 134, 137, and niobium 
95) were detected from 3 filters, which were slightly above detection 
limits.
              (Please refer to the attachment for the measurement results)

Since we haven't found any abnormality in the operation status, exhaust 
stack monitors, or measurement results of reactor water sampling, we 
assume these radioactive materials was emitted into the air by the 
accident at Fukushima Daiichi Nuclear Power Station and captured.

The measured amount of radioactive cesium 134 from the dust in air during 
May is approximately 1/80,000 of the density limit in the air 2 x 10-5
Bq/cm3 (announcement density*2), the measured amount of radioactive cesium 
137 is approximately 1/ 100,000 of the density limit in the air 3 x 10-5
Bq/cm3 (announcement density), the measured amount of radioactive niobium 
95 is approximately 1/8,000,000 of the density limit in the air 7 x 10-5
Bq/cm3 (announcement density), considerably low.
The radiation dose received from the total radioactive materials from the 
dust in air during May is approximately 2 x 10-5 mSv/year, this is 
approximately 1/120,000 of radiation dose received from nature in a year 
(2.4 mSv), and is considerably lower than radiation dose received from 
X-ray at the chest (0.05 mSv, one time).

The current measurement value of monitoring posts which are installed 
around the site boundary and measure air dose rate, and dust radiation 
monitors*3 which are installed near monitoring posts are within the limit 
of normal value, there is no impact to the environment of the site 
periphery.

We will continue to measure radioactivity of the environment sample 
periodically.

                                                                       END

Attachment 1:Periodic measurement results of radioactive materials at
             Kashiwazaki Kariwa Nuclear Power Station(PDF 10.5KB)
Attachment 2:Detection points of few radioactive materials on the periodic
             measurement at Kashiwazaki Kariwa Nuclear Power Station
             (PDF 34.0KB)

*1: Analyses of the environment samples
We periodically conduct surveys on radioactive materials contained such 
as in seawater near the power station, the soil, pine needles, and milk 
in accordance with the "Agreement regarding ensuring security of the area 
surrounding the nuclear power station" (known as "Security Agreement").

*2: Announcement density
"Announcement for definition of radiation dose equivalent limit based on 
the provision by the rule for installation and operation of actual use 
reactor for generation" (It is defined that, in case certain density of 
air is breathed continuously for 1 year, the radiation dose equal to 1 mSv 
which is the radiation dose limit of general public for 1 year.)

*3: Dust radiation monitor
A measurement equipment installed around site boundary, which captures 
dust in the air continuously every 6 hours and measures radioactivity 
inside. Used filters are also collected for periodical detail measurement.
Dust radiation monitors are installed near 3 of 9 monitoring posts which 
are installed around site boundary.