更新日：平成23年6月21日

Readings of environmental radioactivity in Shizuoka Prefecture following the emergency situation at Tokyo Electric Power Fukushima Dai-ichi Nuclear Power Plant (Links to information in Portuguese, Chinese and Korean.)

平成23年6月21日 午後5時00分

Readings of radioactivity in the air and water are at levels that do not have a negative health impact. Please go about business as usual.

Information in Portuguese, Chinese and Korean. Please click here: Portuguese（PDF：106KB）, Chinese（PDF：183KB） and Korean（PDF：177KB）.

June 21, 2011 (5 p.m.)

On the request of the Ministry of Education, Culture, Sports, Science and Technology, Shizuoka Prefecture is conducting measurements of environmental radiation.

Radioactivity measurements of drinking water and fallout (radioactive dust) began on March 18.

Additionally, Shizuoka Prefecture independently established transportable monitoring posts to measure environmental radioactivity levels in the cities of Shimoda, Numazu, and Iwata beginning March 23.

The radioactivity measurement of six places of tap water in Shizuoka that was measured every day from March 24 was changed to a weekly measurement to be held every Tuesday from May 1. However, daily measurement will be resumed in the case of an emergency.

 

Measured results of environmental radiation (air dose rate) are compiled every day at 9 a.m. and 5 p.m. and released soon thereafter. Breakdowns of radioactive nuclides in both drinking water and fallout are compiled every day at 5 p.m.

The measured results (vakues minus cosmic radiation) are as follows.

Units for environmental radiation are in nGy/h (nanogray per hour) unless otherwise noted.

                1nGy/h (nanogray per hour) ≒ 1nSv/h (nanosievert per hour)

                1nSv/h (nanosievert per hour) = 0.001μSv/h (microsievert per hour) = 0.000001mSv/h (millisievert)

There are no adverse health effects at current levels.

 

<Measured results from 9 a.m. June 21, 2011 to 5 p.m. June 21, 2011>

1. Measured results from 9 a.m. June 21, 2011 to 5 p.m. June 21, 2011 of environmental radiation (as of  5 p.m. June 21, 2011)

[Units: nGy/h (nanogray per hour)] *Times below are written in 24-hour notation*

     Shizuoka: minimum value 39.3 (9:00-11:00), maximum value 41.2 (13:00-14:00,15:00-16:00), average value 40.4

     Shimoda: minimum value 46.5 (15:00-16:00), maximum value 48.3  (9:00-10:00), average value 47.1

     Numazu: minimum value 41.3 (9:00-10:00,11:00-13:00), maximum value 42.0 (14:00-15:00), average value 41.6

     Iwata: minimum value 44.7 (11:00-12:00,15:00-16:00), maximum value 45.5 (9:00-10:00), average value 45.0

Times in ( ) represent the time the value was recorded.

Shizuoka City’s usual band of fluctuation: 28.1-76.5 nGy/h

National survey of environmental radioactivity level standards by the Ministry of Education, Culture, Sports, Science and Technology from 2007-2009—minimum value: 13.3nGy/h, maximum value: 153nGy/h

 

2. Measured results from 9 a.m. June 20, 2011 to 9 a.m. June 21, 2011 of collected fallout (radioactive dust) (as of 5 p.m. June 21, 2011).

[Units: Bq/m2 (becquerel per square meter)] ND=not detectable

 Iodine-131: ND, Cesium-137: ND, Cesium-134: ND  (Measurement location: Ikeshinden, Omaezaki)

 Measurements on March 22 detected an infinitesimal amount of radioactive material thought to have originated from Fukushima Dai-ichi Nuclear Power Plant. Analysis of the increase in air dose rate from the radioactive material, including radioactive materials following the initial crisis until today, has resulted in a total of approximately 0.000003mSv/h (approx.0.003μSv/h). Should this situation continue for one year, the exposure dose from radioactive material would be approximately 0.026mSv (millisievert) (approx. 26μSv (microsievert)), approximately 1/35 of the 1mSv annual exposure dose limit.

Including infants, these levels do not have a negative influence on one’s health.

 

3. Measured results from June 21, 2011 of drinking water (as of 5 p.m. June 21, 2011)

 [Units: Bq/kg (becquerel per kilogram)] ND=not detectable

   Kita Ando, Shizuoka—Iodine-131:ND, Cesium-137:ND

   Nakajima, Mishima—Iodine-131:ND, Cesium-137:ND (as of 5 p.m. June  21, 2011)

   Ōka, Shimada—Iodine-131:ND, Cesium-137:ND (as of 5 p.m. June  21, 2011)

   Teradani, Iwata—Iodine-131:ND, Cesium-137:ND (as of 5 p.m. June  21, 2011)

   Usami, Ito—Iodine-131:ND, Cesium-137:ND (as of 5 p.m. June  21, 2011)

   Inatori, Higashi Izu-cho—Iodine-131:ND, Cesium-137:ND (as of 5 p.m. June  21, 2011)

   Kouchi, Shimoda—Iodine-131:ND, Cesium-137:ND )(as of 5 p.m. June  21, 2011)

Only measurements from March 22 detected infinitesimal amounts of Iodine-131 (0.14Bq/kg) thought to have resulted from Fukushima Dai-ichi Nuclear Power Plant. From this, the exposure dose would be approximately 0.0000055mSv (millisievert) (approx. 0.0055μSv (microsievert)), approximately 1/180,000 of the 1mSv annual exposure dose limit.

After May 1, water measurements will be carried out only once a week on Tuesday (excluding  Kita Ando). However, in the case of an emergency, measurements will be carried out daily in all locations.

Including infants, these levels do not have a negative influence on one’s health.

 

4. Measured results from 10 a.m. March 1, 2011to 10 a.m. June 1, 2011 of collected fallout (radioactive dust) (as of 5 p.m. June 17, 2011).

[Units: Bq/m2 (becquerel per square meter)] ND=not detectable

4.1 Measured results from 10 a.m. March 1, 2011 to 10 a.m. April 1, 2011 of collected fallout (as of 5 p.m. April 27, 2011).

Iodine-131: 1,100, Cesium-137: 540, Cesium-136: 36, Cesium-134: 550 (Measurement location: Kita Ando, Shizuoka) 

4.2 Measured results from 10 a.m. April 1, 2011 to 10 a.m. May 2, 2011 of collected fallout (as of 5 p.m. May 19, 2011).

Iodine-131: 17, Cesium-137: 86, Cesium-136: 1.1, Cesium-134: 87 (Measurement location: Kita Ando, Shizuoka) 

4.3 Measured results from 10 a.m. May 2, 2011 to 10 a.m. June 1, 2011 of collected fallout (as of 5 p.m. June 17, 2011).

Iodine-131: 0.47, Cesium-137: 12, Cesium-136: ND, Cesium-134: 11 (Measurement location: Kita Ando, Shizuoka) 

 

The measurements detected a trace amount of radioactive material thought to have originated from Fukushima Dai-ichi Nuclear Power Plant. Analysis of the increase in air dose rate from the radioactive material has resulted in a total of approximately 0.0000075mSv/h (approx.0.0075μSv/h). Should this situation continue for one year, the exposure dose from radioactive material would be approximately 0.067mSv (millisievert) (approx. 67μSv (microsievert)), approximately 1/15 of the 1mSv annual exposure dose limit.

Including infants, these levels do not have a negative influence on one’s health.

 

Shizuoka Prefecture’s Environmental Radiation Monitoring Center is monitoring environmental radioactivity around Hamaoka Nuclear Power Plant 24 hours a day.

Including infants, these levels do not have a negative influence on one’s health.