If a nuclear explosion were to happen tomorrow somewhere in the world – even deep underground – a small amount of gas called radioxenon would likely be released. This radioactive form of the element xenon is a key way scientific sleuths around the world – including those at the Department of Energy (DOE) – confirm nuclear tests.

PNNL technician Jennifer Mendez attaches a gas cylinder to one of the systems used to measure samples collected at International Monitoring System stations.
PNNL technician Jennifer Mendez attaches a gas cylinder to one of the systems used to measure samples collected at International Monitoring System stations.

To help these sleuths find these radioactive needles-in-a-haystack, the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO PrepCom), based in Vienna, Austria, operates the International Monitoring System (IMS), a highly sensitive global network of sensors that can detect radioxenon and provide the clues that a suspicious event was nuclear and needs further investigation.

The quality of analysis performed by the IMS is critical to getting the readings right. Instead of a nuclear test, suspect readings could come from a facility making medical isotopes, for example. DOE and NNSA experts play a significant part in maintaining and improving that system.

PNNL and INL provide outstanding support for the international nuclear explosion monitoring and verification effort.

Kasia Mendelsohn
NNSA’s Acting Deputy Administrator for the Office of Defense Nuclear Nonproliferation

One way the CTBTO PrepCom assures the quality of its work is through regular proficiency tests of the equipment and analysis. Two DOE sites play critical roles in these tests – Pacific Northwest National Laboratory (PNNL) and Idaho National Laboratory (INL). PNNL accepts gas and air filter samples of high interest from IMS stations for detailed analysis. Meanwhile, INL provides the CTBTO PrepCom with precise quantities of radioxenon gas that help calibrate instruments used in the proficiency tests, ensuring that IMS laboratories can maintain their high level of accuracy and preparedness.

PNNL and INL are operated by DOE but are truly U.S. Government resources – their nuclear explosion monitoring work is supported by NNSA, the Department of Defense, and the Department of State. NNSA also supports INL’s ability to improve the quality and utility of the radioxenon used in the tests. PNNL has a range of projects dedicated to improving detection and analysis of radioxenon and its role in nuclear explosion monitoring.

“PNNL and INL provide outstanding support for the international nuclear explosion monitoring and verification effort,” said Kasia Mendelsohn, NNSA’s Acting Deputy Administrator for the Office of Defense Nuclear Nonproliferation. “NNSA experts continue to innovate and share their knowledge with CTBTO PrepCom and international partners to reinforce the U.S. commitment to a world without nuclear explosive testing.”