Partnership to ensure continued nuclear explosion monitoring

Medical isotopes are used daily around the world to

visualize and diagnose cancer, heart disease and other serious

ailments. However, their production can emit gasses that, while posing no

danger to the public, have features that look similar to those produced by a

nuclear explosion.

The Department of Energy’s Pacific Northwest National

Laboratory in Richland is working with production facilities around the

world to install monitors that will help understand more about the levels and

timing of these emissions. 

Using that information, governments and agencies watching

for signatures of nuclear explosions can more easily assess their readings and

ensure that emissions from medical isotope production are not misinterpreted.

PNNL worked with the Australian Nuclear Science and

Technology Organisation to install a detector system at ANSTO’s medical isotope

production facility in Lucas Heights, Australia, in the fall.

Previously, the Institute for Radioelements in Fleurus,

Belgium, installed a monitor in its effluent stack. 

Both IRE and ANSTO produce the medical isotope

Molybdenum99, or Moly-99, by irradiating uranium in a reactor. Gaseous

fission products, like the isotopes of xenon, are released in the process,

increasing worldwide background levels of this gas.

 “These first-of-their kind sensor systems, one in each

hemisphere, will help with international measurements for detecting underground

nuclear explosions,” said Judah Friese, principal investigator at PNNL, in a

news release. “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.” 

The Preparatory Commission for the Comprehensive

Nuclear-Test-Ban Treaty Organization notes that

four radioxenon isotopes are possible indicators of a

nuclear explosion and may provide forensic evidence for analysts. CTBTO

PrepCom analysts track airborne radioxenon through the International

Monitoring System.  

PNNL scientists are experts in developing methods

of detecting extremely low levels of radioactive isotopes. While the

monitors being installed in the stacks are off-the-shelf devices, they’ve been

slightly modified to PNNL specifications.

“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,” Friese said. “Stack release data will

support the job of analysts monitoring the globe for nuclear explosions.”

PNNL is working with the U.S. Departments of State and

Defense and the National Nuclear Security Administration to install additional

detectors via a project called STAX, or Source Term Analysis of

Xenon.  

There are currently no companies in the United States that

produce Moly-99 through the fission of uranium, PNNL said. However, about

40,000 Americans receive doses of Technetium-99m each day, typically to

diagnose cancer, heart disease and other serious health conditions. 

The network of stack monitors will confidentially transmit

data to a central database for compilation, analysis, and screening, PNNL said.

Eventually, the data created by these stack monitors will be used in a model

that predicts xenon levels in the atmosphere.  In the event of a

suspected nuclear explosion, this knowledge can quickly rule out unrelated

sources of xenon.