The Washington Post and other sources are reporting the announcement by Iranian President Mahmoud Ahmadinejad that Iran has a program of Laser Enrichment of Uranium It is believed that the laser enrichment is still at experimental quantities and that the main enrichment is still centrifuges.
Laser enrichment has been covered here before. GE is building a facility for uranium enrichement using lasers which should be in operation in 2012 or 2013.
General Electric has licenced and is commercializing a laser uranium enrichment process. The Silex laser uranium enrichment process has been indicated to be an order of magnitude more efficient than existing production techniques but again, the exact figure is classified.
Australian scientists Michael Goldsworth and Horst Struve developed the process, and from 1996 to 2002 received support from the United States Enrichment Corp. (Bethesda, MD); the two scientists have since formed a public corporation, Silex Systems (Lucas Heights, NSW, Australia). Last year they licensed the Silex process to General Electric. The process is based on selective excitation of uranium hexafluoride (UF6) molecules that contain U-235 by laser light at a narrow spectral line near 16 µm, but few details have been released (see figure). The Los Alamos National Laboratory (Los Alamos, NM) initially explored the concept three decades ago, but the U.S. Department of Energy later abandoned it in favor of atomic-vapor laser isotope enrichment.
The CO2 lasers can generate 1 J pulses, but only at a limited repetition rate, and only a fraction of the pulse is in the pump band. Unspecified “additional nonlinear optical tricks” are needed to convert the CO2 pump light to the correct wavelength to pump the Raman cell. The lasers are 1% efficient and the Raman conversion 25% efficient, so the overall efficiency is 0.25%.
With many details classified or proprietary, it is hard to quantify the processing. Lyman wrote that if a laser could illuminate a one-liter volume at an ideal repetition rate, it would take about 100 hours to produce one kilogram of U-235-assuming complete separation of the U-235 and U-238 isotopes. However, most processes require multiple stages of separation, and according to Lyman’s comments, a 5000 Hz laser would be needed to process all the feed stream (a mixture of UF6 and an unidentified diluting gas).
The new solid state lasers could be more efficient for the desired frequency and wavelengths.
The specific energy consumption is 2300-3000 kWh/SWU for Gaseous Diffusion, versus 100-300 kWh/SWU for gas centrifuge. The number of stages required to produce LEU is about 30 times larger in the diffusion plant than in the centrifuge plant.
A kilogram of LEU requires roughly 11 kilograms U as feedstock for the enrichment process and about 7 separative work units (SWUs) of enrichment services. To produce one kilogram of uranium enriched to 3.5% U-235 requires 4.3 SWU if the plant is operated at a tails assay 0.30%, or 4.8 SWU if the tails assay is 0.25% (thereby requiring only 7.0 kg instead of 7.8 kg of natural U feed).
Areva’s recently announced Idaho enrichment plant, estimated to cost $2 billion, is expected to supply 3 million SWU or half the capacity of the GE plant at full production. The full-scale GE plant, expected to supply 3.5-6.0 million SWU, will require additional investor commitments. The GE laser enrichment plant would start at 1 million SWU/year and then get expanded Close to one million kilograms/year of enriched uranium using 7 SWU per kg.
Silex is also examining Oxygen-18 (PET medical imaging) and Carbon-13 (medical diagnostic) laser separation.
Laser enrichment at Idaho Samizdat
Worldwide Uranium demand and Nuclear Reactor fuel requirements translate into a requirement for uranium enrichment separative work services in the range 35–38 million SWU/year over the next 10 years.
About 120,000 kg SWU are required to enrich the annual fuel loading for a typical large (1,000 MWe) nuclear reactor.
Uranium: 8.9 kg U3O8 x $53 472 Conversion: 7.5 kg U x $12 90 Enrichment: 7.3 SWU x $135 985 [Silex could reduce this by 3-10 times] Fuel fabrication: per kg 240 Total, approx: US$ 1787
The capacity of all these potential centrifuge and laser projects totals almost 90 million SWU per year, sufficient to meet the needs of WNA’s Upper Scenario for the year 2024, and well in excess of requirements before that year and for the other two scenarios.
Enrichment requirements for the world’s growing fleet of nuclear power plants are expected to expand significantly. Current enrichment capacity on a world-wide basis is just sufficient to meet requirements, but the potential pace of enrichment capacity expansion is expected to out-strip the growth in requirements. Thus, it is not likely that all this expansion potential will come to fruition. The continuation of enrichment trade restrictions in the USA and European Union (EU) will have a major bearing on which projects go forward. Perhaps the biggest uncertainties are the status of USEC’s American Centrifuge Project (ACP) and the feasibility of GE Hitachi-Global Laser Enrichment LLC’s (GLE) laser-based SILEX process.
The potential outlook for primary production, shown in Figure above, points toward a large increase in capacity. Russia’s Rosatom plans to increase capacity, between expansion at its existing four facilities and the International Uranium Enrichment Center, by almost 50 percent – up to an eventual level of about 38 million SWU per year. CNNC in China is increasing its capacity of Russian-supplied centrifuges by 50 percent.
Los Alamos estimate –
The annual operating cost for a laser isotope separation facility is estimated to be about 100 million dollars, in contrast to about 500 million for a gaseous diffusion plant and 100 to 200 million for a gas centrifuge plant. Our estimates of capital and operating costs for a laser isotope separation facility indicate a cost per SWU of about $30.
Depleted Uranium left over from previous enrichment has one third of the uranium percentage as natural uranium. There is about 1.5 million tons of depleted uranium with 0.3 percent U-235 About 100,000 tons of 5% enriched uranium fuel could be produced from the depleted uranium.
Laser processes promise lower energy inputs, lower capital costs and lower tails assays, hence significant economic advantages. Several laser processes have been investigated or are under development.
None of the laser processes below are yet ready for commercial use, though SILEX is well advanced and expected to begin commercial production in 2012
Atomic vapor laser isotope separation (AVLIS)
Atomic vapor laser isotope separation employs specially tuned lasers to separate isotopes of uranium using selective ionization of hyperfine transitions. The technique uses lasers which are tuned to frequencies that ionize a 235U atom and no others. The positively-charged 235U ions are then attracted to a negatively-charged plate and collected.
Molecular laser isotope separation (MLIS)
Molecular laser isotope separation uses an infrared laser directed at UF6, exciting molecules that contain a 235U atom. A second laser frees a fluorine atom, leaving uranium pentafluoride which then precipitates out of the gas.
Separation of Isotopes by Laser Excitation (SILEX)
Separation of isotopes by laser excitation is an Australian development that also uses UF6. After a protracted development process involving U.S. enrichment company USEC acquiring and then relinquishing commercialization rights to the technology, GE Hitachi Nuclear Energy (GEH) signed a commercialization agreement with Silex Systems in 2006. GEH has since begun construction of a demonstration test loop and announced plans to build an initial commercial facility. Details of the process are restricted by intergovernmental agreements between USA and Australia and the commercial entities. SILEX has been indicated to be an order of magnitude more efficient than existing production techniques but again, the exact figure is classified
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