A new laboratory for analysis of nuclear micro-particles, inaugurated last Friday at the European Commission’s Joint Research Centre (JRC) in Karlsruhe, Germany, will boost international nuclear safeguards and non-proliferation activities.
A state-of-the-art Large Geometry Secondary Ion Mass Spectrometer (LG-SIMS) instrument is the latest addition to the worldwide network of laboratories for detection and analysis of nuclear material in samples taken by the International Atomic Energy Organization (IAEA). The €3.5-million (US$4.4-million) high-precision kit, housed in a specially built zero-vibration lab in the JRC’s Institute for Transuranium Elements (ITU), is designed to improve by an order of magnitude the analytical capability of standard SIMS facilities.
The apparatus can be operated both as an ion microscope that scans for uranium particles in dust samples taken from inside nuclear installations, and as a powerful mass spectrometer for high-resolution isotopic measurements. The detection of uranium particles is facilitated by newly developed software that can efficiently track down and analyse uranium particles in swipe samples typically containing several tens of millions of other particles.
The ratio of uranium’s two naturally occurring isotopes, uranium-238 and uranium-235, serves as a measure of the enrichment of uranium produced at a nuclear installation. Unlike smaller machines, large geometry SIMS can also trace the minor uranium isotopes 234 and 236, which could yield information about the enrichment technique as well as the uranium’s point of origin and last legal owner. Uranium-236, for example, only occurs in reprocessed material. The full isotopic fingerprint of a uranium sample thus helps nuclear authorities to determine any undeclared and potentially weapon-related activities at nuclear installations around the world.
What’s more, large-geometry SIMS produces analytical results within less than 24 hours. In alternative ‘fission-track’ techniques, such as those used in US labs, samples must be first radiated with neutrons before the fission products of the uranium they may contain can be determined. The whole process can take several weeks.
“Searching for undeclared uranium is like looking for a needle in a haystack,” says Ollie Heinonen, a senior fellow at the Belfer Center for Scientific and International Affairs in Cambridge, Massachusetts. “Large geometry SIMS will be a very important additional component in the IAEA’s continuously developing verification regime.”
Uranium-enrichment facilities and nuclear-reprocessing facilities, where plutonium is extracted from the waste of nuclear power plants, are of particular interest to international safeguard authorities. If the result of an analysis hints at undeclared nuclear activities — as has been the case in the past in North Korea and Syria — the IAEA will usually request a special inspection of the sites in question. If the request goes unheeded, as with North Korea in 1992, the agency will refer the case to the Security Council of the United Nations. The international nuclear safeguards system was further strengthened in 2003 after the discovery of unreported uranium enrichment activities in Iran.
Samples taken by IAEA inspectors are sent to at least two labs for independent analysis. And to exclude the possibility of political bias, all samples arrive at labs in encoded form.
At the JRC in Karlsruhe, around 100 samples a year can be handled in the future.
“We are well aware of the responsibility of our work,” says Klaus Lützenkirchen, head of nuclear safeguards and forensics at the ITU. “Clearly, any mistake we might make has the potential of causing a severe diplomatic imbroglio.”
Photo: The new Large Geometry-Secondary Ion Mass Spectrometry (LG-SIMS) instrument © EU, 2012