When North Korea tested its sixth nuclear weapon in September 2017, instruments all over the world and in orbit lit up, gathering vast streams of data that scientists used to characterize the blast. Was it nuclear? How big was it? What materials were used? What kind of device blew up? And how did we know?
An entire branch of multidisciplinary science – the science of nuclear nonproliferation – is devoted to answering those questions. Timely, accurate, science-based answers are indispensable to evaluating nuclear threats to national and global security and giving policy makers the information they need to formulate appropriately measured responses.
Easy to describe, but complex to carry out, nonproliferation science tracks peaceful nuclear activity and weapons programs and develops tools and methods to counter the spread of nuclear weapons, materials and technologies. This nonproliferation work includes nuclear safeguards, which verify nuclear materials are secure and kept from a weapons program, and proliferation detection, which involves continuously scanning the atmosphere and tracking earth-shaking events to determine if a weapons test has occurred.
Few organizations on the planet have the breadth and depth of scientific expertise across a range of disciplines – from nuclear physics to seismology – to detect a nuclear detonation, characterize it and distinguish it from natural events such as earthquakes and space weather. Figuring out whether a nation is pursuing a nuclear weapons program requires recognizing that program, spotting the materials it requires, identifying the processing involved, and so forth. In other words, it takes a nuclear weapons lab to find a nuclear weapons lab.
Decades ago, after developing the first atomic bomb, Los Alamos National Laboratory developed and implemented scrupulous material control and accounting for its own nuclear material. That research led to inventing a wide range of satellite-borne and Earth-based instruments; many of the latter are used by the International Atomic Energy Agency to monitor nuclear activity. Instruments in space detect X-rays, gamma rays, and neutrons – all signatures of a nuclear explosion – anywhere on the globe, including hyper-secretive North Korea. Scientists tease out those signatures from the data “noise.”
We do this work in concert with the other National Nuclear Security Administration laboratories, Sandia and Lawrence Livermore, which have their own areas of expertise related to nonproliferation. For instance, using a ground-based global network of sensors designed by Los Alamos and developed by Sandia, scientists can distinguish the unique seismic signature of an underground nuclear test from the similar tremors caused by an earthquake or a mining operation. Those distinctions are crucial – no one wants to start a war over a misinterpreted mineshaft collapse in Asia.
Detecting a detonation is crucial – but what about detecting a weapons program before a test? The best pre-emptive strategy would be to understand, detect and block the pathways to nuclear weapons development before it’s too late. Los Alamos is leading the science to achieve that goal through continuous theoretical exploration, supercomputer modeling and actual experiment.
The global watch provided by these nuclear nonproliferation strategies, which support the 180 nations agreeing not to pursue nuclear weapons under the Nuclear Nonproliferation Treaty, has succeeded in stemming, but not eliminating, the spread of nuclear weapons. It’s not easy. The North Korea tests remind us all to maintain our focus on the cutting-edge science underpinning the treaty’s success. If other rogue nations grow emboldened to test nuclear weapons despite international pressure, teams of dedicated physicists, seismologists, space-weather scientists, geologists and a wide range of other researchers will continue to answer the call for fact-based analysis that only nonproliferation science can deliver.
Nancy Jo Nicholas is the Principal Associate Director of Global Security at Los Alamos National Laboratory, where she oversees the science of nuclear nonproliferation.
