Noble gas detection system reaches
maturity - Page 1

Matthias Auer of the CTBTO performs last checks prior to certification of the radionuclide noble gas system at RN75 in Charlottesville, Virginia, United States.

The set-up looks rather unimposing to the uninitiated eye: a container, a satellite dish, a generator. Yet this container in the midst of lush green scenery some kilometres to the southeast of Charlottesville, Virginia, United States, houses a highly sensitive apparatus. 

It’s a fine summer day in 2010, and a group of scientists and engineers put the finishing touches to an unusual installation.  The ordinary looking container is home to a monitoring station, part of a global network to watch over the planet.  Practically an artificial nose, it can sniff out the tiniest amounts of radioactive material in the air and provide evidence of a recently conducted nuclear explosion. 

Radionuclide station RN75 in Charlottesville is one of 80 stations worldwide that can detect radioactive particles in the air that may originate from a nuclear blast. The Charlottesville station has been  up and running for over eight years.  So, what’s new then?

The station is one of 40 that are being  equipped with additional detectors that can sniff radioactive gases in the air – another residue of a nuclear explosion.  With its certification on 19 August 2010, the Charlottesville station is the first radionuclide station with noble gas detection capabilities to be formally integrated into a global verification regime, designed under the Comprehensive Nuclear-Test-Ban Treaty (CTBT) to detect nuclear explosions anywhere on Earth.  The regime encompasses a worldwide network of over 300 monitoring stations, a data analysis centre and on-site inspections.

The SAUNA detection system was developed in Sweden.

Noble gases provide “smoking gun” evidence

A nuclear explosion ejects radioactive material – solid and gaseous – into the environment. These substances provide the ultimate evidence that a nuclear detonation has taken place.  Their detection depends on many factors, most of all on the setting in which the blast occurred.  A well-contained underground nuclear explosion will not release solid radioactive residues into the air.  But there is another way to detect such blasts – by finding their gaseous releases, radioactive noble gases, in particular xenon.

What are noble gases?  They are chemical elements that very rarely react with other elements to form larger compounds.  Their inertia is responsible for the “noble” label. Noble gas atoms are very small and pass easily through rock and sediment.  Once in the atmosphere, the gas is dispersed by the winds and can be caught by detection installations such as the one in Charlottesville, providing the “smoking gun” evidence of a nuclear explosion.