Armageddon’s Fingerprints
Around the world a network of detectives searches for evidence of illicit nuclear activity. Is it enough to keep us safe from a nuclear catastrophe?
by Mark Wolverton | January 18, 2019
Read the full article at the Science History Institute.
Excerpt:
When routine inspections aren’t enough—as was the case with Iran before it signed in 2015 what’s known as the Iran nuclear deal (more formally, the Joint Comprehensive Plan of Action)—other measures beyond U.N. sanctions and diplomatic protests are possible. At this point inspectors become detectives or forensic specialists scrutinizing a crime scene for clues. That calls for measures beyond the usual record checking, container counting, radiation scanning, and facility tours.
“One of the best ways of hiding something is you take all the stuff out of the room and then you repaint the room,” says R. Scott Kemp, director of the Laboratory for Nuclear Security and Policy at MIT, describing a neat disappearing trick. “And if there were any uranium particles, for example, that were just absorbed onto the surface of the walls, they get coated with paint. And then if you come in with a swipe and you try to pick them up, you won’t get them, because they’re encapsulated in the paint.” Inspectors have responded with lasers, specifically laser-induced breakdown spectroscopy, where, says Kemp, “you take a laser, you hold it up to the paint, you blast it, it vaporizes the paint and anything else in it, and then it looks for characteristic emission lines associated with uranium and plutonium in that vapor.”
Coupled with other measures, including satellites that search for infrared signatures from power plants and good old-fashioned intelligence analysis, such techniques will sooner or later ferret out any ongoing violation. More difficult, however, is trying to determine past activities. A state might not be presently enriching uranium for bomb fuel or doing anything else untoward, but what if it had made and stored weapons-grade materials before the arrival of nosy IAEA inspectors? “There are not as yet ways of really reconstructing historical operation of declared sites,” Kemp says. “If we go into a place and they say, ‘Oh yeah, we hadn’t told you about this, here’s our enrichment plant, of course there was uranium, here it is.’ There really isn’t any available technique for determining, ‘Well, how much uranium did you produce and what’s the history of the operation?’ ”
What do you do when the nuclear “smoking gun” has long ago stopped smoking? Kemp and his MIT colleague, nuclear scientist Michael Short, are among a small group of researchers working to answer that question. While looking for a way to better quantify radiation damage in materials, Short encountered a long-forgotten idea from Manhattan Project scientist Eugene Wigner, who proposed that atoms and molecules in a material can be dislocated from their usual positions by ionizing radiation, such as X-rays and gamma rays, and that some of this energy can be stored by the atoms. Short reasoned if such stored energy, or “Wigner energy,” could be released under heat, it would produce a “fingerprint” of the defects and the specific events that caused them.
Short immediately recognized this capability would be useful in civilian nuclear applications, such as in assessing the condition of reactor vessels during periodic inspections. But he and Kemp realized it might have an even more important role. “Scott and I think we can take, say, the centrifuges in Iran, measure the stored energy, . . . figure out how many bombs they’ve made, and see if they’re lying [when they claim to have made a greater or lesser number of bombs].” Kemp says the technique could determine both the type and amount of radiation to which something has been exposed; in other words, you can “lift these fingerprints of history from a pipe, a plastic gasket, or even the assembly table.” That would allow them to reconstruct the past operation of an enrichment plant or other nuclear facility, thus providing data that could be checked against a state’s officially declared records.
The work is still in its early stages but has already yielded promising results. The technique can show whether a material, such as stainless steel or Teflon, has been irradiated, but the crucial issue is to be able to detect precise levels of radiation over a very short time. So far, Short says, “We can detect the equivalent of about 5 or 10 years of enrichment, which is not good enough yet.” But once the process can detect recent illegal enrichment, say, 6 months ago, it will provide foolproof means for catching treaty violations. Short adds, “The preliminary results we’ve been getting are making me excited enough to think there’s something there. We’ve just got to test more samples in more controlled conditions.”