Isotope producers in atmospheric monitoring initiative

The detector system was installed in October at ANSTO's medical isotope production facility at Lucas Heights, ANSTO and PNNL announced yesterday. A similar monitoring system has already been installed in a monitor stack at the Institute for Radioelements (IRE) at Fleurus in Belgium. Both ANSTO and IRE produce molybdenum-99 by irradiating uranium in a reactor, releasing gaseous fission products including xenon isotopes in the process.

The gases present no danger to the public, but have features that look similar to those produced by a nuclear explosion. The Comprehensive Nuclear Test Ban Treaty Organisation (CTBTO) Preparatory Commission - which operates an international monitoring system to look for signs of nuclear explosions, including atmospheric monitoring - has said radioxenon is "like the DNA of a nuclear explosion".

PNNL is working with the US Departments of State and Defense and the National Nuclear Security Administration to install a network of detectors through the STAX (Source Term Analysis of Xenon) project. Data from the monitors will be confidentially transmitted to a central database for compilation, analysis, and screening, and will be used in a model to predict xenon levels in the atmosphere. In the event of a suspected nuclear explosion, information collected from monitors such as those installed at Lucas Heights and Fleurus will help to ensure emissions from medical isotope production are not misinterpreted.

"These first-of-their kind sensor systems, one in each hemisphere, will help with international measurements for detecting underground nuclear explosions," said Judah Friese, PNNL principal investigator, said. "While these are the first companies to install these systems, more installations are planned at locations around the globe to increase confidence in international nuclear explosion monitoring … It's important to understand the levels and timing of xenon released by medical isotope facilities the world over, which is significant but relatively uncharted until now."

Emmy Hoffmann, ANSTO manager of environmental monitoring, said the opportunity to support the development or enhancement of nuclear forensic capabilities enhanced regional nuclear security as well as the cohesive global nuclear footprint.

"ANSTO has considerable nuclear policy and technology expertise, and we are delighted to join our international counterparts in the STAX project and contribute on a global scale," she said.

ANSTO's OPAL (Open Pool Australian Light-water) reactor was commissioned in 2006 and has the capacity to produce half the world's supply of molybenum-99. Molybdenum-99 is used to generate technetium-99m, which is the world's most widely used radionuclide for medical imaging. Both isotopes have very short half-lives, so a constant, stable supply is needed.

The Vienna-based CTBTO Preparatory Commission was founded in 1996 and is responsible for promoting the CTBT and the developing the verification regime so that it is operational when the treaty, which bans nuclear explosions "by everyone, everywhere", enters into force. The treaty has been signed by 184 countries of which 167 have also ratified it, including France, Russia and the UK, but cannot enter force until it has also been signed and ratified by specific nuclear technology holder countries, including China, Egypt, India, Iran, Israel, North Korea, Pakistan and the USA. India, North Korea and Pakistan have yet to sign it.