Safety and non-proliferation are two key premises –"important minimum requirements"- for global expansion of nuclear power and countries seeking nuclear use must adhere to these principles, Executive Director of the International Energy Agency (IEA) Nobuo Tanaka stressed during the International Conference on Access to Civil Nuclear Energy held in Paris. The meeting, initiated by France and co-organized by the International Atomic Energy Agency and OECD, aims to promote bilateral and multilateral cooperation between countries eager for nuclear access and willing to share nuclear experience.
But what about proliferation? Due to a new technology, the problem of proliferation will rather become worse than better. Two scientists are claiming that the ‘new’ uranium enrichment technology SILEX (separation of isotopes by laser excitation) is so proliferation prone that the dangers outweigh the so-called advantages: exponential improvements in efficiency.
In an article in Nature (March 4, 2010) the two -Francis Slakey (Upjohn lecturer in physics and public policy at Georgetown University, Washington DC) and Linda R. Cohen (professor of economics and law at the University of California, Irvine)- they warn that the world is heading towards the development of nuclear-enrichment technologies so cheap and small that they would be virtually undetectable by satellites. The say that those proliferation risks incurred from such technologies are “simply not worth the benefits”. Over the past 60 years, technologies that enrich uranium to make fuel for nuclear reactors have shown exponential improvements in efficiency. But those improvements also come with a heavy price: an increased risk of proliferation. It is far easier to covertly build a small, lower-energy enrichment facility than a large, energy-intensive one.
In their opinion, the newest laser enrichment technology — called separation of isotopes by laser excitation (SILEX) — offers more potential risks than benefits. The development and potential misappropriation of an enrichment facility too small and efficient to be detected could be a game-changer for nuclear proliferation.
Global Laser Enrichment, a subsidiary of GE Hitachi Nuclear Energy, has applied for a license from the US Nuclear Regulatory Commission (NRC) to operate a full-scale commercial SILEX plant in North Carolina. This is open for public petition until 15 March, and a final decision is expected to take at least another year. Numerous analysts, as well as the authors of a recent report from the American Physical Society ('Technical Steps to Support Nuclear Arsenal Downsizing'), have called for the NRC to examine proliferation risks as part of its licensing process. Such a barrier would discourage commercial research and development in this area, the authors suggest.
To assess the costs and benefits of a new technology, its efficiency must be measured. To make reactor fuel, the concentration of fissile uranium-235 must be increased compared with the uranium-238 in the sample. The efficiency of an isotope-separation technology can be measured in terms of the increase in the proportionate concentration of uranium-235 in the enriched stream — or ‘separative work units’ (SWU) — per megawatt-hour of electricity consumed by the plant (SWU MWh−1). The quantity of SWUs needed to produce a kilogram of reactor fuel depends on three factors: the percentage of uranium-235 required
in the final fuel, the percentage present in the natural uranium feedstock and the percentage acceptable in the depleted uranium tailings (waste). If uranium feed is cheap and SWUs expensive, fuel of a given enrichment level can be made in a cost effective way by using more uranium and living with a higher proportion of residual uranium-235 in the tailings. Alternatively, expensive uranium and cheap SWUs make it worthwhile to squeeze more of the uranium-235 out of the feedstock.
The initial enrichment method, developed in the 1940s and called the calutron, was a mass spectrometer that ionized the uranium and used magnetic fields to filter out the uranium- 235. This was displaced by the technique of gaseous diffusion, which forces uranium hexafluoride through semipermeable membranes.
In the 1960s, centrifuge enrichment was developed, which dramatically decreased the energy required. The technology’s efficiency has increased from roughly 0.5 SWU MWh−1 in 1945 to more than 5 SWU MWh−1 in the 1960s, and over 20 SWU MWh−1 today.
More than 20 countries have experimented with laser enrichment over the past two decades, including South Korea and Iran, without much success. SILEX was developed by the Australian company Silex Systems, and is now being commercialized exclusively by GE Hitachi. In 2006, Silex stated that it anticipated the technology to be anywhere from 1.6 to 16 times more efficient than first-generation centrifuges. The details are classified and the efficiency claims impossible to verify. But assuming a continuation of historical trends in enrichment efficiency it seems reasonable to assume a doubling of today’s best efficiency by 2020.
It is generally assumed that this improvement will lead to financial benefits for consumers. But such an effect would be small: about US$0.66 per household per month, as calculated in the Nature article. Doubling nuclear generation in the US by 2025 (a very ambitious growth scenario for the nuclear industry) could double the value of enrichment savings to US$1.32 per household a month. In addition, a change in the relative prices of enrichment services (lower) and natural uranium (higher) will increase the demand for SWUs in the production of fuel. If the price of the former halves and the price of the latter doubles, the authors of the Nature article calculate — based on a cost-optimization of formulae for enrichment processes from the Massachusetts Institute of Technology in Cambridge — that demand for SWUs will increase by 40% for the same level of electricity production from nuclear power.
The construction, heat signature and power usage of large nuclear enrichment plants can usually be detected, but smaller centrifuge plants can be kept secret for years, as the recent revelation of a facility being built in Qom, Iran, shows. If laser enrichment is as efficient as has been suggested, then it could occupy a space substantially smaller than a warehouse (75% smaller than centrifuge technologies) and draw no more electricity than a dozen typical houses. This could put such plants well below the detection threshold of existing surveillance technology — even when used to enrich uranium on a large scale.
Hidden costs of nuclear power
As a contrast to the savings anticipated from laser enrichment, calculated in the article, consider the public costs associated with containing such technologies. According to the Congressional Research Service, the US government spent roughly US$990 million in 2008 on nonproliferation programs. In particular, this included more than US$200 million to research and develop technology to detect covert enrichment facilities. Others estimate that US$5 billion — 10% of the US government’s annual budget for nuclear-security activities — can be credited to non-proliferation activities.
Over the past decade, the United States has spent money on non-proliferation activities at a total cost of more than US$50 per household a month.
An increase in the number of countries with access to perhaps-undetectable laser enrichment technologies would only increase these costs. As a first step in containing the risks of laser enrichment, Congress should require that an evaluation of proliferation risks be part of the NRC licensing process. Such an evaluation would be a natural extension of the NRC’s mandate to ensure that technology is not used “in a manner that is hostile to the interests of the United States”. The NRC already has a process for evaluating confidential information, so this need not be difficult to enact.
An argument has been made that by developing laser enrichment technology in the United States, US entities can ensure that the technology is adequately safeguarded against proliferation. History does not instill confidence in this approach. Previous enrichment technologies — the calutron, gas centrifuge and advanced centrifuge — have all created proliferation risks over the past 50 years despite efforts to withhold the information.
A second argument offered in favour of developing such technologies is that if the United States doesn’t do so, some other country will, in which case the costs of protecting against proliferation will be even higher. There are two responses to this: first, if the United States ceases development and takes no further action, the technology will certainly be delayed. Second, to limit the availability of the technology, the United States need now only negotiate with the handful of technologically advanced countries capable of laser enrichment innovation. It would be best if all nations took a stance of repressing new technologies for more efficient uranium enrichment. But it is clear that the risk of proliferation will only decrease when nuclear power is phased-out.
Sources: ‘Secrets, lies and uranium enrichment: The classified Silex project at Lucas Heights’, Greenpeace, 2004 / ‘Stop laser uranium enrichment’, Francis Slakey and Linda R.Cohen in: Nature, 4 March 2010 / http://www.wise-uranium.org/eproj.html#SILEX / Xinhua News Agency, 8 March 2010
Laser enrichment plants can be used to produce highly enriched uranium in just a few stages, as opposed to the thousands of stages required using centrifuges. A 1977 report by the US Office of Technology Assessment (OTA) highlighted this as one of the major proliferation problems posed by laser enrichment The report also expressed the concern that the sale of laser enrichment technology by commercial entities, could hasten the proliferation of the technology.
The sensitive nature of the SILEX technology was formally recognised in 1996, after SILEX Systems signed an agreement with the United States Enrichment Corporation (USEC). The US Department of Energy (DOE) then classified the SILEX process as “Restricted Data”, RD – a classification that usually relates to the design of nuclear weapons, or the use or acquisition of nuclear material suitable for their construction.
This was the first time in history that privately held technology was given this classification.
On April 30, 2003, USEC Inc. announced that it is ending its funding for research and development of the SILEX laser-based uranium enrichment process. USEC has been funding R&D on the SILEX process since 1996, when the Company signed an agreement with Silex Systems Limited in Australia. USEC will now focus all of its advanced technology resources on the demonstration and deployment of USEC’s American Centrifuge uranium enrichment technology. On May 22, 2006 GE Energy’s nuclear business has signed an exclusive agreement with Silex Systems Limited, an Australia-based technology innovator, to license the technology and develop the company's next generation low enriched uranium manufacturing process in the United States. The transaction is subject to, among other things, governmental approvals and regulatory controls on the design, construction and operation of the process. On October 4, 2006, Silex announced that GE Energy's nuclear business and Silex Systems Limited received the U.S. government authorizations required to proceed with an agreement granting GE exclusive rights to develop and commercialize Silex’s laser-based uranium enrichment technology.