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Comprehensive Nuclear-Test-Ban Treaty

gamma detector

An International Monitoring System (IMS) is being constructed to monitor compliance with the Comprehensive Nuclear-Test-Ban Treaty

What is the Comprehensive Nuclear-Test-Ban Treaty?

A Comprehensive Nuclear-Test-Ban Treaty (CTBT) to ban all nuclear explosion tests was opened for signature in New York on 24 September 1996.  Australia signed the Treaty on the same day and ratified it on 9 July 1998. As of November 2010, 182 countries have signed and 153 have ratified. To see the latest country to sign or ratify and to find more information on the CTBT Organisation visit their website at http://www.ctbto.org.

How can nuclear tests be detected?

An International Monitoring System (IMS) is being constructed to monitor compliance with the Treaty. By analysing, integrating and comparing data from the IMS, the time, location and nature of a possible nuclear event can be determined. The network consists of 321 monitoring facilities and 16 radionuclide laboratories that monitor the earth for evidence of nuclear explosions in all environments. These monitoring facilities use a variety of methods to detect evidence of nuclear testing. Seismic, hydroacoustic and infrasound stations are employed to monitor the underground, underwater and atmosphere environments, respectively. The fourth technology detects radiation from atmospheric sampling.

Monitoring Technologies

Seismic (50 Primary & 120 Auxiliary)

Seismic monitors detect vibrations in the earth’s crust. The principal use of the seismic data in the verification system is to locate seismic events and to distinguish between an underground nuclear explosion and the numerous earthquakes that occur around the globe.

Hydroacoustic (11 stations)

Hydroacoustic monitoring detects acoustic waves produced by natural and artificial phenomena in the oceans. The data from the hydroacoustic stations are used in the verification system to distinguish between underwater explosions and other phenomena, such as sub-sea volcanoes and earthquakes, which also propagate acoustic energy into the oceans.

Infrasound (60 stations)

The infrasound network uses microbarometers (acoustic pressure sensors) to detect very low-frequency sound waves in the atmosphere produced by natural and artificial events.  The data collected is used to distinguish between atmospheric explosions and natural phenomena such as meteorites, explosive volcanoes, meteorological events and artificial phenomena such as re-entering space debris, rocket launches and supersonic aircraft.

Radionuclide (80 stations)

The 80 radionuclide stations can detect radioactive debris from atmospheric explosions or vented by underground or underwater nuclear explosions. The presence of specific radionuclides provides unambiguous evidence of a nuclear explosion. Forty of these stations will be capable of measuring for the presence of the relevant noble gases. See below for more on how these stations work.

Radionuclide Laboratories (16 stations)

The 16 Radionuclide Laboratories are used to verify samples that are suspected of containing radionuclide materials that may have been produced by a nuclear explosion.

What is ARPANSA's involvement with the Treaty?

ARPANSA is responsible for carrying out Australia's radionuclide monitoring obligations to the Comprehensive Nuclear-Test-Ban Treaty, and also responsible for the installation, implementation and operation of seven stations within Australia and its Territories.

What are the locations of the Australian monitoring stations?

Australia hosts all four technologies totalling 21 facilities within Australia and its territories.

Location State or Territory Type Treaty Code Coordinates
Lat Lon
Charters Towers Queensland Auxiliary Seismic Station AS004 -20.1 146.3
Fitzroy Crossing Western Australia Auxiliary Seismic Station AS005 -18.1 125.6
Narrogin Western Australia Auxiliary Seismic Station AS006 -32.9 117.2
Cape Leeuwin Western Australia Hydroacoustic Station HA01 -34.4 115.1
Davis Base Antarctica Infrasound Station IS03 -68.4 77.6
Narrogin Western Australia Infrasound Station IS04 -32.9 117.2
Hobart Tasmania Infrasound Station IS05 -42.1 147.2
Cocos Islands Western Australia Infrasound Station IS06 -12.3 97
Warramunga Northern Territory Infrasound Station IS07 -19.9 134.3
Warramunga Northern Territory Primary Seismic Station PS02 -19.9 134.3
Alice Springs Northern Territory Primary Seismic Station PS03 -23.7 133.9
Stephens Creek South Australia Primary Seismic Station PS04 -31.9 141.6
Mawson Antarctica Primary Seismic Station PS05 -67.6 62.9
ARPANSA, Melbourne Victoria Radionuclide Laboratory RL02 -37.5 144.6
Melbourne Victoria Radionuclide Station RN04 -37.5 144.6
Mawson, Antarctica Radionuclide Station RN05 -67.6 62.5
Townsville, QLD Queensland Radionuclide Station RN06 -19.2 146.8
Macquarie Island Tasmania Radionuclide Station RN07 -54 159
Cocos Islands Western Australia Radionuclide Station RN08 -12 97
Darwin Northern Territory Radionuclide Station RN09 -12.4 130.7
Perth Western Australia Radionuclide Station RN10 -31.9 116

A Typical Radionuclide Monitoring Station Process

Roof-top high volume air sampler
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The Radionuclide Monitoring process involves collecting particulate matter from the air onto a piece of filter material in a high volume air sampler for ~24 hours.
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Press used to compress the filter before analysis
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After this time the filter is taken from the air sampler, compressed into a disk.
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A gamma detector is used to measure radionuclides
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Finally, the filter sample is placed on a gamma detector for ~24 hours to be analysed.
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Decay chamber where natural radionuclides are allowed to decay
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The disk is then placed in a chamber to allow natural radionuclides to decay for ~24 hours.
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A computer monitors the workflow and collects data
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A computer monitors the workflow and collects data.
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Data is forwarded by satellite to the International Data Centre
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The data relating to the sampling conditions and radionuclides measured is then forwarded by satellite to the International Data Centre in Vienna where it is compiled and released to Countries participating in the Treaty.

 

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