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Global Laser Enrichment (GLE), a business venture of Silex (51%) and Cameco (49%), has been developing a next-generation, laser-based technology for potential commercial application in enriching uranium, with an option for Cameco to attain a majority interest of up to 75% ownership. Laser uranium enrichment technology provides highly selective excitation of U-235 in UF₆ and is expected to be more flexible and cost-effective than other technologies. For more information see Laser processes section below.


Laser processes

mce-anchorLaser enrichment processes have been the focus of interest for some time. They are a possible third-generation technology promising lower energy inputs, lower capital costs and lower tails assays, hence significant economic advantages. One of these processes is almost ready for commercial use. Laser processes are in two categories: atomic and molecular.
Development of the Atomic Vapour Laser Isotope Separation (AVLIS, and the French SILVA) began in the 1970s. In 1985 the US Government backed it as the new technology to replace its gaseous diffusion plants as they reached the end of their economic lives early in the 21st century. However, after some US$ 2 billion in R&D, it was abandoned in USA in favour of SILEX, a molecular process. French work on SILVA ceased following a 4-year program to 2003 to prove the scientific and technical feasibility of the process. Some 200kg of 2.5% enriched uranium was produced in this.
Atomic vapour processes work on the principle of photo-ionisation, whereby a powerful laser is used to ionize particular atoms present in a vapour of uranium metal. (An electron can be ejected from an atom by light of a certain frequency. The laser techniques for uranium use frequencies which are tuned to ionize a U-235 atom but not a U-238 atom.) The positively-charged U-235 ions are then attracted to a negatively-charged plate and collected. Atomic laser techniques may also separate plutonium isotopes.
Most molecular processes which have been researched work on a principle of photo-dissociation of UF₆ to solid UF₅⁺, using tuned laser radiation as above to break the molecular bond holding one of the six fluorine atoms to a U-235 atom. This then enables the ionized UF₅ to be separated from the unaffected UF₆ molecules containing U-238 atoms, hence achieving a separation of isotopes.* Any process using UF₆ fits more readily within the conventional fuel cycle than the atomic process.
* A similar principle can be used in enriching atomic lithium, with magnetic separation of the ionized atoms, leaving pure Li-7.
mce-anchorThe main molecular laser process to enrich uranium is SILEX, which utilises UF₆ and is now known as Global Laser Enrichment (GLE). In 2006 GE Energy entered a partnership with Australia's Silex Systems to develop the third-generation SILEX process. It provided for GE (now GE Hitachi) to construct in the USA an engineering-scale test loop, then a pilot plant or lead cascade, before moving to a full commercial plant. GLE will now decide in the light of commercial considerations on whether to proceed with a full-scale enrichment facility at Wilmington. The project is licensed to enrich up to 8% U-235; enrichment to almost 20% U-235 is envisaged but not yet licensed.
As well as $20 million upfront and subsequent payments, the licence agreement with GE was to yield 7-12% perpetual royalties, the precise amount depending on the cost of deploying the commercial technology as well as several progress payments. In-mid 2008 Cameco bought into the GLE project, paying $124 million for a 24% share, alongside GE (51%) and Hitachi (25%). (Earlier, in 1996 USEC had secured the rights to evaluate and develop SILEX for uranium but bailed out of the project in 2003.) In April 2016 GE and Hitachi notified their intention to exit GLE, and during subsequent negotiations Silex funded 76% of GLE’s R&D at Wilmington, North Carolina. In February 2019 Silex Systems and Cameco agreed to buy out the GEH 76% share in GLE for US$ 20 million on a deferred payment basis, so that Cameco held 49% of GLE and Silex 51%. Cameco had an option to purchase an additional 26% of GLE. The agreement called for Silex and Cameco to pay $300,000 per month to complete construction of the prototype enrichment facility which had been partially built by GEH. Final US government approvals for the buyout were granted in January 2021. Silex said that “the Paducah commercial opportunity represents an ideal path to market for our disruptive SILEX laser enrichment technology.”
Earlier in August 2013 GLE submitted a proposal to the DOE to establish a “$1 billion” laser enrichment plant at Paducah, Kentucky to enrich high-assay tails (above 0.34% U-235) owned by the DOE to natural uranium level (0.7% U-235). There is about 115,000 tonnes of these at Paducah and Portsmouth (among a total of 550,000 t tails). Negotiations with the DOE continued into 2016, and in November an agreement was signed with the DOE for it to supply about 300,000 tonnes of high-assay tails, justifying construction by GLE of the Paducah Laser Enrichment Facility (PLEF). PLEF would become a commercial uranium enrichment production facility under a US NRC licence, producing about 100,000 tonnes of natural-grade uranium over 40 years or more. The DOE would dispose of the reduced-assay balance. The estimated plant size is 0.5 to 1.0 million SWU/yr, since purchases of DU may not exceed 2000 t/yr natural uranium equivalent.
Earlier in mid-2009 GEH submitted the last part of its licence application for this GLE plant at Wilmington, and following review of provisions for the physical protection of special nuclear material and classified matter, material control and accounting, plus further review by the NRC Atomic Safety and Licensing Board, a full licence to construct and operate a plant of up to 6 million SWU/yr was issued in September 2012.
Meanwhile, GLE is completing the test loop programme, the initial phase of which was successful in meeting performance criteria, and engineering design for a commercial facility commenced. GLE is operating the test loop at Global Nuclear Fuel's Wilmington, North Carolina fuel fabrication facility (GNF is a GE-led joint venture with Toshiba, and Hitachi). In October 2021 the first full-scale laser system module successfully completed initial testing at Silex’s Lucas Heights facility in Sydney.
GLE is planning to complete the commercial pilot demonstration project by the mid-2020s, after which a feasibility assessment will be conducted for the proposed Paducah Laser Enrichment Facility (PLEF), which GLE hopes to deploy for the production of natural grade uranium by 2030.
Applications to silicon and zirconium stable isotopes are also being developed by Silex Systems near Sydney.
CRISLA is another molecular laser isotope separation process which is the early stages of development. In this a gas is irradiated with a laser at a particular wavelength that would excite only the U-235 isotope. The entire gas is subjected to low temperatures sufficient to cause condensation on a cold surface or coagulation in the un-ionized gas. The excited molecules in the gas are not as likely to condense as the unexcited molecules. Hence in cold-wall condensation, gas drawn out of the system is enriched in the U-235 isotope that was laser-excited. NeuTrek, the development company, is aiming to build a pilot plant in USA.