Skip to main content

Recent Developments in Laser – Isotope Separation (SILEX) for Uranium Enrichment: Program Update and Nonproliferation Aspects

Tuesday, July 17, 2012
12:00-1:30 PM
Rayburn House Office Building
Room B-369


  • Ms. Ruth Ravitz Smith, Senior Vice-President of Global Government Affairs and Policy at GE Hitachi Nuclear Energy
  • Dr. James Acton, Senior Associate in the Nuclear Policy Program at the Carnegie Endowment for International Peace
  • Prof. Francis Slakey, Upjohn Lecturer on Physics and Public Policy at Georgetown University and Associate Director of Public Affairs for the American Physical Society (APS)


  • Dr. Norman Neureiter, Senior Advisor to the Center for Science Diplomacy and Acting Director of the Center for Science, Technology and Security Policy at the American Association for the Advancement of Science

On July 17, the Center for Science, Technology and Security policy at the American Association for the Advancement of Science held a panel discussion on the current state of Laser Isotope Separation (LIS) technology, particularly the SILEX (Separation of Isotopes by Laser Excitation) process, and the nonproliferation implications thereof.

Ms. Smith spoke about the history and current status of the SILEX process, pointing out that she was neither a nonproliferation nor technical expert. SILEX, originally developed in Australia, is both proprietary and classified in both countries, in accordance with a bilateral agreement between Australia and the United States. GE-Hitachi’s Global Laser Enrichment group (GLE) has applied to the Nuclear Regulatory Commission (NRC) for a license to construct a commercial-scale facility in Wilmington, N.C., although GLE has not made a final decision with regard to commercialization. The NRC’s Atomic Safety Licensing Board held a closed hearing on the subject last week, with a final decision expected later this year.

Smith emphasized GLE’s commitment to keeping the SILEX process secret, both for commercial and nonproliferation reasons. All workers at the facility must have Q-level clearance and be U.S. citizens, and information is compartmentalized on a need-to-know basis. GE is the majority shareholder in GLE, and the only one with access to the SILEX technology. The commercial facility in Wilmington would take up 600,000 square feet (or roughly the size of three Wal-Mart stores), and would enrich to a maximum of 8%. Controls were built into the process to inhibit enrichment to higher levels.

She pointed to a 2010 review that GLE had commissioned on SILEX’s proliferation impact, the details of which have been withheld for proprietary reasons. It concluded that SILEX posed no greater proliferation risk than gas centrifuge technology and was beyond the capability of most states to implement; that deployment of SILEX facilities would be detectable; and that nonproliferation efforts were well served by the domestic development and deployment of the technology.

Dr. Slakey compared the miniaturization of nuclear fuel cycle facilities to that of data storage media, suggesting that ever-smaller facilities raise the possibility of covert proliferation. He pointed to three new technologies showing this trend, at varying levels of development:

  • A Harvard grad student working with ultra-cold atom traps stumbled on a technique that could reveal a method for “practically undetectable uranium enrichment” if he published his research (which was still in the very early stages). He voluntarily shut down his research.
  • A Texas professor has a patent pending on a laser excitation technique for medical isotopes which could be used for uranium enrichment.
  • The commercial-scale SILEX facility that GE is in the process of obtaining a license to construct.

He quoted a multi-agency U.S. proliferation assessment of SILEX in 1999, which pointed out that laser enrichment has always been a concern for reasons of concealment and that SILEX would renew interest in the technology by both benign actors and proliferators, but that the technical challenges of the process and the classification regime could contain the technology. Slakey expressed skepticism of this last point, pointing out that U.S. nuclear secrets have leaked frequently in the past.

In this vein, he suggested that the NRC could be helpful in restraining proliferation. He argued that the NRC is in an advantageous position, as it reviews licenses for new fuel cycle facilities right at the threshold of commercial viability – the point at which they become attractive to proliferators. Conducting such assessments would sensitize the industry to proliferation concerns, making them design in anti-proliferation measures into the facilities. He pointed to a pending APS petition to the NRC to conduct proliferation assessments of enrichment and reprocessing facilities, which has received broad support. These assessments would consider whether the technology in question could be altered easily to allow diversion of nuclear material, whether facilities could constructed and operated without being detected, and whether there were traceable components and technology that could reveal such a facility’s existence1. A final NRC decision on the petition is expected in October. Carrying out such a review for the Wilmington SILEX facility could be a model for future fuel cycle developments – which, as he pointed out, could pose even greater proliferation risks.

In order to put the economics of the question into perspective, Dr. Slakey pointed to a 2010 article in Nature (available to subscribers only) which suggested that, even under the most optimistic assumptions, the SILEX process could save the average American household less than two dollars annually2.

Dr. Acton stated up front that he was a strong supporter of nuclear power, in order to combat climate change. He argued that holistic cost-benefit analyses – weighing both economic and proliferation consequences – were needed for new nuclear technologies, but had never been done adequately. The GE internal report, while a positive step, was only 7 pages long – including 3 pages of author biographies – in comparison to the Bush Administration’s 116 page proliferation assessment of its Global Nuclear Energy Program (GNEP)3 plan. He also took issue with the report’s apparent assumption that a proliferator would use a large commercial scale facility, as opposed to a much smaller one that could produce a few bombs worth of material annually.

Such proliferation assessments, he argued, must take into account both the probability and consequences of the spread of the technology in question. The former depends on both the probability of information leaks and the effect that demonstrating commercial viability of a technology might have in focusing proliferator efforts to develop it indigenously. The latter depends on three different criteria (in descending order of importance): the ease with which the technology could produce highly enriched uranium (HEU) which can be used for nuclear weapons4, the detectability of facilities using the technology, and how easy it would be for the IAEA to safeguard such facilities.

Dr. Acton was clear in pointing out that such holistic assessments would be more involved than assessments based on the factors identified by Dr. Slakey above. Ideally, these would be conducted by the State Department, with substantial input from the National Nuclear Security Administration. He nonetheless supported Dr. Slakey’s petition, as he viewed even limited assessments carried out by a non-ideal organization to be preferable to no assessments. Should the petition be rejected by the NRC, he encouraged congressional action to mandate the executive branch to perform the assessments.

If such a review showed that SILEX (or any fuel cycle technology) would adversely affect proliferation, Dr. Acton did not believe that U.S. work on it should necessarily be abandoned. That step should also take into account how much a U.S. decision not to commercialize would affect other states’ efforts to develop technology, the legal status of SILEX intellectual property if GE did not pursue the technology, and whether Australia might look to other partners to develop SILEX.

1 Dr. Slakey would certainly welcome more in-depth assessments, such as those outlined by Dr. Acton below, but the APS petition focused on more modest goals for practical reasons.
2 A description of the Nature article’s methodology and conclusions is given in this APS document (no subscription necessary).
3 Dr. Acton considered the GNEP proliferation assessment to be insufficient, but nonetheless more in-depth than GE’s SILEX assessment (he was one of a few subject matter experts GE allowed to review excerpts from the document).
4 He pointed out that, for various technical reasons, SILEX might possess a comparative advantage or comparative disadvantage in HEU production compared to centrifuge technology. Resolving this issue would be an important part of the proliferation assessment.