Page 3 - Radionuclide data processing and analysis

Automatic radionuclide event screening cont.

The radionuclide screening process focuses on the concentrations of observed relevant radionuclides. Relevant radionuclides are radionuclides that are specific to nuclear explosions, comprising those from the nuclear fission itself, plus those resulting from, for example, interaction of neutrons emitted during the explosion with the surrounding material.

The relative quantities of different isotopes detected in a sample analysis can provide information about the time of an explosion and possibly about the environment in which the explosion took place, i.e. underwater, in the air or underground.

The findings of the screening process are presented in the Standard Screened Radionuclide Event Bulletin (SSREB). This report, along with raw data and the other bulletins, are made available to the Member States.  It is their prerogative to make the final judgement on the findings.

Samples containing category 5 radionuclides demand immediate attention as they may contain multiple specific radionuclides generated by a nuclear explosion. They are sent to two of 16 laboratories for further analysis.

Radionuclide noble gases

Half of the 80 radionuclide particulate stations are expected to be equipped with noble gas monitoring technology. The systems currently under experimental testing can measure certain isotopes of the noble gas xenon. These isotopes are highly volatile and likely to be released even from underground explosions, whereby radionuclides particles are contained.

Some monitoring stations with noble gas technology employ the same detection method as that used by radionuclide particulate stations and send gamma ray spectra of daily measured samples. Other stations use a different method of measuring the radionuclide noble gases contained in a sample by looking at the combined beta and gamma radiation.

The 40 radionuclide particulate stations equipped with noble gas monitoring technology use several different detection methods to measure radionuclide noble gases.

Event categorization of noble gas samples is a highly demanding task, since some civilian sources may produce radioactive xenon in concentrations close to nuclear weapons test specifics.  Work is continuing to advance the event categorization of noble gas findings.

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Timelines of data processing and analysis