September 16, 2011 | 1
I confess, I don’t normally keep an eye out for the latest publications in the Journal of Environmental Radioactivity, but one recent paper on radioxenon measurements is of particular interest.
This paper, as it turns out, is by one of the leading researchers in radioxenon testing, who happens to be a former professor and advisor of mine at The University of Texas at Austin. Dr. Steven Biegalski is an Associate Professor of Nuclear Engineering at UT Austin, and recently published the first measurement results of radiation from the Fukushima plant disaster using atmospheric radioxenon measurements.
Radioxenon testing involves taking air samples and looking for xenon-133, an isotope of the noble gas that is formed as a byproduct of nuclear reactions and acts as a tracer. When uranium-235 is bombarded with spare neutrons in a reactor, the uranium atom is split into smaller components. Scientists can look for these tracer elements much like a forensic crime scene investigator would look for bullet fragments or other clues at a crime scene.
Abnormally high concentrations of radioactive “stuff” indicate that a nuclear event of some sorts occurred somewhere at some time. Typically, the “stuff” scientists look for is xenon-133.
Shortly after the Fukushima disaster, Dr. Biegalksi and his colleagues at Pacific Northwest National Laboratory (PNNL) started noticing elevated concentrations of xenon-133 in the atmosphere – over 4,300 miles from the Fukushima disaster site.
While official news out of Japan was hard to come by in days following the disaster (and to some extent, today still), radioxenon measurements were providing insight into the severity of the disaster. From an interview with UT Austin:
“As the measurements came in sooner and at higher concentrations than we initially expected, we quickly came to the conclusion that there were some major core melts at those facilities,” Biegalski said. “I remember being in the lab thinking, ‘Wow, if this is all true we have a far more bigger accident than what we’re hearing right now.’”
Radioxenon testing has its origins in nuclear warfare. During the Cold War, tanker planes (as part of the Constant Phoenix program) were outfitted with radiation testing equipment to warn of nuclear attacks, and have been used more recently to keep an eye out for nuclear tests around the world, which are banned by the Comprehensive Test Ban Treaty.
In 2006 and again in 2009, the lone remaining Constant Phoenix tanker plane collected measurements following North Korea’s underground nuclear tests, confirming the seismic data recorded by pretty much everyone within 100 miles of the explosion.
While a lot of focus is put on nuclear reactor technology, the other side of nuclear science and engineering, the non-proliferation technologies like radioxenon testing, are equally important and as relevant as ever. However, with shrinking budgets for the U.S Department of Energy, which oversees national laboratories like PNNL, one wonders if we will expose a radioxenon “gap“.