※This measurement was finished on March 21, 2012. Will please see page of radiation monitoring post (the west for Hodogaya Ward France) (surface of the earth 1m) in future.
By method that followed "environmental γ (gamma) line assay with consecutive monitors", we continue atmospheric γ (gamma) dose of radioactivity in the roof (from the ground 23m) of environmental science research institute of 1, Takigashira, Isogo-ku and measure manual of Ministry of Education, Culture, Sports, Science and Technology from 1983 and, in Motoichi, announce the data as radiation monitoring post on homepage.
→ Please click this.
As we measure radiation dose in 50cm in height and 1m in addition to this radiation monitoring post from the surface of the earth in city three spots (Tsuzuki Ward government office, southern part greenery office, environmental science research institute) from June 13, 2011, we will tell about the data here.
(1) Tsuzuki Ward government office (Chigasakichuo, Tsuzuki-ku, Yokohama-shi)
(2) Southern greenery office (3, Kounandai, Kounan-ku, Yokohama-shi)
(3) Environmental science research institute (1, Takigashira, Isogo-ku, Yokohama-shi)
We assume the weekly measurement from September 11, 2011. In addition, we change model about measuring instrument.
[result of a measurement from September 11, 2011]
※We publish result of a measurement after the next day of the measurement.
[result of a measurement from June 13, 2011 to September 10]
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(1) Measuring instrument
In this investigation, we measure with facility measuring instrument which there is of carrying around in small size said to be the next survey meter. In addition, we change model of measuring instrument from September 11, 2011.
Model name Measuring instrument from September 11, 2011
TCS-172B (product made in Hitachi Aloka Medical Corporation)
Measuring instruments from June 13, 2011 to September 10
TCS-161A (product made in Hitachi Aloka Medical Corporation)
Detector NaI(Tl) scintillation detector (φ 25.4mm *25.4mm)
Measurement lines class γ (gamma) line
Measurement unit Microsievert every hour [μSv/h]
Dose rate measurement range 0.01-30μSv/h [μSv/h]
(2) Method for measurement
We carry out by method that followed "emergency environmental radiation monitoring guideline" by the Nuclear Safety Commission. We perform the measurement at three points of fixed points per one spot.
Measurement height measures 4 directions at altitude of 50cm and 1m each from the surface of the earth and publishes the mean.
(3) The measurement period and the number of measurement
We measured every day from June 13, 2011 to September 10, but are doing with the weekly measurement from September 11 to the end of December as there was not big change to the measurements for 3 months.
Unevenness comes out to measurements even if we measured the same radiation by the measurement of radiation dose with survey meter. In addition, measurements of radiation change by wind or the rain even if they receive influence with geological feature of measurement point or neighboring buildings and measure at the same place.
[Gy/h] is credit indicating quantity of energy which radiation has in gray every hour. [Sv/h] is credit to express size of influence that radiation gives in the human body in sievert every hour.
[conversion table] When we assume 1 Gy = 1Sv
|1||Gy/h||Gray every hour||=||1||Sv/h||Sievert every hour|
|1,000||mGy/h||Millimeters gray every hour||=||1,000||mSv/h||Millisievert every hour|
|1.000,000||μGy/h||Microgray every hour||=||1 million||μSv/h||Microsievert every hour|
|1 billion||nGy/h||Nanogray every hour||=||1 billion||nSv/h||Nanosievert every hour|
Environmental Planning Bureau Environment Administration Division telephone 045-671-2499 (weekdays from 8:30 to 17:15)