Laser monitoring of UF6 cylinders developed

During the recent IAEA Safeguards Symposium in Vienna, attention focused not only on ways to safeguard new GEN IV reactors, but also on how to implement new safeguards approaches for existing facilities. One such approach, in testing by the Joint Research Centre (JRC) of the European Commission since March 2009, involves a laser-based monitoring technique to track uranium hexafluoride (UF6) cylinders while in motion. According to the JRC’s presentation to the Safeguards Symposium, the system is now able to recognise all types of cylinders—which holds a great deal of promise for future verification activities.

UF6 can be used in enrichment operations. Although it is processed in civil enrichment plants to produce low-enriched uranium, it can also be used to produce high-enriched uranium for nuclear explosives. From a non-proliferation perspective, it is therefore important to ensure that declarations concerning the flow of cylinders used to store, transport and process UF6 are correct.

Different identification techniques for UF6 cylinders were evaluated between 2005 and 2007, including stand-alone surveillance, identification tags, passive radio frequency and reflective particle tags. But the operators were either reluctant to use these techniques, or they proved to be insufficiently effective. Laser based technology—which permits the cylinder surface to be scanned—was then examined, and two techniques suggested. The British company Ingenia Technology Limited worked on a laser surface authentication system (LSA) that was ultimately not selected by the IAEA. As Stéphanie Poirier from the IAEA Department of Safeguards explained in 2007, this was because ‘the proximity of the laser to the cylinder being scanned was too close for UF6 cylinders’ and ‘too much constraint [was put] on the field system and the operator’.

A different technique, one which uses 3-D laser surface mapping was instead chosen for the Agency’s Laser Item Identification System (L2IS). Developed by the JRC, it captures the cylinder’s side surface, which becomes a ‘fingerprint’. The verification process comprises two steps: the first is an ‘attended initial scan’ during which cylinders are made available so that their ‘surface identity’ can be established and stored in a laptop. The second step is an ‘unattended scan’ which records the surface identity of all cylinders entering and exiting the enrichment process area. At this stage, the L2IS is coupled with the IAEA standard surveillance system. Ms Poirier concluded in 2007 that ‘the L2IS system appears to be reliable and consistent with the needs specified by the IAEA’; it also contributes to the objective of optimizing safeguards activities by decreasing the inspection implementation workload.

Sonia Drobysz, Paris