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Measurement of radiation and radioactivity in Tokyo Port

Jun.23,2016 17:00 update

 As a countermeasure against harmful rumors related to the accident at TEPCO's Fukushima Daiichi Nuclear Power Plant, we have decided to monitor the radiation in the atmosphere at each container wharf in Tokyo Port and radioactivity in the seawater in the Port and radiation dose on the surface of containers through cooperation with Tokyo Port Terminal Corporation. The measurement result shall be disclosed on this website. 

・April 14, 2011 ~ May 8, 2011

atmosphere (every Monday and Thursday), seawater(from Monday to Friday)

・May 9, 2011 ~ March 31, 2013

atmosphere, seawater, container surface(from Monday to Friday)

・April 1, 2013 ~March 31, 2014

atmosphere, seawater, container surface(every Monday and Thursday)

・April 1, 2014 ~

atmosphere, seawater, container surface(every Thursday (or Friday sometimes))

* business days only

 Map of monitoring site

Map of monitoring site

・The measurement for radiation in the atmosphere and at container surfaces are conducted with support of Nippon Kaiji Kentei Kyokai, and for radioactivity in the seawater, Tokyo Metropolitan University.
・Amount of radiation in the air is measured with scintillation style survey meter 1.5 meter above ground level (1.0 meter above ground level by May 5, 2011).

Measurement result

【Reference】
Sievert(Sv), a unit for amount of radiation, roughly indicates the degree of effect when human body is affected by radioactivity. The annual radiation exposure level from the natural world, such as from outer space, air, soil, and food, is about 2,000-5,000μSv.(Excerpted from Tokyo Metropolitan Institute of Public Health data
This is about 0.23-0.57μSv/h when converted into hourly exposure.

Becquerel(Bq), a unit for radiation, shows the strength of radiation emitted from radioactive substances. The Nuclear Safety Commission indicates the index value regarding intake restriction of radioactive substances within tap water in "Antidisaster Measures for Nuclear Facilities"*. The index value is 300Bq/kg for radioactive iodine(1311), and 200Bq/kg for radioactive cesium (Cs).
*Source:"Antidisaster Measures for Nuclear Facilities", Nuclear Safety Commission Homepage (June 1980, Last revised 2010)(Excepted from Tokyo Metropolitan Institute of Public Health data)
Excerpted from Tokyo Metropolitan Institute of Public Health data)

1. Radiation in the atmosphere

*Measurement is conducted in the morning in front of central gates in each container piers, and the average of the indicated two extreme values is recorded.

(Unit:μSv/h)

Area OiAomiShinagawaCentral Breakwater Reclaimed Land Remarks
Jun.23(Thu) 0.05 0.04 0.04 0.04
Jun.16(Thu) 0.05 0.05 0.06 0.05
Jun.9(Thu) 0.05 0.05 0.06 0.05
Jun.2(Thu) 0.05 0.05 0.04 0.05
May.26(Thu) 0.05 0.05 0.05 0.05
May.19(Thu) 0.04 0.04 0.04 0.04
May.12(Thu) 0.05 0.05 0.05 0.05
Apr.28(Thu) 0.05 0.05 0.05 0.05
Apr.21(Thu) 0.05 0.05 0.05 0.05
Apr.14(Thu) 0.05 0.05 0.04 0.05

Published data in 2014

Published data in 2013

Published data in 2012

Published data in 2011

2. Radioactivity in the seawater (surface)

*Seawater to measure is obtained at the point between Oi Container Wharf and Aomi Container Wharf in the morning.
*"ND" means that the data were blow thedetection limit (not detected).

(Unit:Bq/L)

Type Iodine-131Caesium-134 Caesium-137Remarks
Jun.23(Thu) ND ND ND
Jun.16(Thu) ND ND ND
Jun.9(Thu) ND ND ND
Jun.2(Thu) ND ND ND
May.26(Thu) ND ND ND
May.19(Thu) ND ND ND
May.12(Thu) ND ND ND
Apr.28(Thu) ND ND ND
Apr.21(Thu) ND ND ND
Apr.14(Thu) ND ND ND

Published data in 2014

Published data in 2013

Published data in 2012

Published data in 2011

3.Radiation at container surfaces

*Measure radiation dose on the surface of each sample container at the gate of pier head, and disclose number of samples, maximum volume, minimum volume, average volume by pier.
*Baseline of decontamination is 3 times higher than the amount in the atmosphere. Baseline of warning (alert) is higher than 5 μSv/h.

(Unit: pcs,μSv/h)

Area Oi Aomi Shinagawa Central Breakwater Reclaimed Land
Jun.23(Thu) samples 24 14 6 6
maximum 0.05 0.06 0.04 0.04
minimum 0.01 0.01 0.02 0.02
average 0.03 0.03 0.03 0.03
decontaminated 0 0 0 0
Jun.16(Thu) samples 22 17 6 6
maximum 0.05 0.03 0.04 0.04
minimum 0.01 0.01 0.01 0.02
average 0.03 0.02 0.03 0.03
decontaminated 0 0 0 0
Jun.9(Thu) samples 25 15 4 7
maximum 0.05 0.04 0.03 0.04
minimum 0.01 0.01 0.01 0.02
average 0.03 0.02 0.02 0.03
decontaminated 0 0 0 0
Jun.2(Thu) samples 26 19 8 6
maximum 0.05 0.04 0.04 0.04
minimum 0.01 0.01 0.02 0.02
average 0.03 0.02 0.03 0.03
decontaminated 0 0 0 0
May.26(Thu) samples 25 15 5 4
maximum 0.05 0.04 0.03 0.03
minimum 0.02 0.01 0.01 0.02
average 0.03 0.02 0.02 0.03
decontaminated 0 0 0 0
May.19(Thu) samples 25 14 4 7
maximum 0.06 0.04 0.04 0.04
minimum 0.01 0.01 0.02 0.02
average 0.03 0.02 0.03 0.03
decontaminated 0 0 0 0
May.12(Thu) samples 25 10 5 5
maximum 0.06 0.05 0.04 0.04
minimum 0.02 0.02 0.03 0.02
average 0.03 0.03 0.04 0.03
decontaminated 0 0 0 0
Apr.28(Thu) samples 23 17 5 6
maximum 0.04 0.04 0.03 0.04
minimum 0.01 0.01 0.01 0.02
average 0.03 0.02 0.02 0.03
decontaminated 0 0 0 0
Apr.21(Thu) samples 27 13 5 6
maximum 0.05 0.04 0.05 0.04
minimum 0.02 0.01 0.02 0.02
average 0.03 0.03 0.03 0.03
decontaminated 0 0 0 0
Apr.14(Thu) samples 23 19 5 7
maximum 0.04 0.04 0.04 0.04
minimum 0.01 0.01 0.02 0.02
average 0.03 0.03 0.03 0.03
decontaminated 0 0 0 0

Published data in 2014

Published data in 2013

Published data in 2012

Published data in 2011

For inquiries about our business,
please contact us through the following:

Bureau of Port and Harbor,Tokyo Metropolitan Government

EMail:kouwan_kouhou@section.metro.tokyo.jp

8-1 Nishishinjuku 2-chome Shinjuku-ku Tokyo 163-8001, Japan