The SILEX process was developed in Australia by Silex Systems Limited, a publicly listed high technology innovation company founded in 1988, and was invented by Dr Michael Goldsworthy and Dr Horst Struve. The process builds on earlier work in laser enrichment that began in the 1970s, such as AVLIS (atomic vapor laser isotope separation) and MLIS (molecular laser isotope separation).
In November 1996 Silex Systems Limited signed a license and development agreement for the application of SILEX technology exclusively to uranium enrichment with the United States Enrichment Corporation (USEC) avoiding any problems for Australia under the Nuclear Non-Proliferation Treaty.
Silex Systems Limited concluded the second stage of testing in 2005 and began enacting its Test Loop Program. In 2007, an exclusive commercialization and licensing agreement was signed with General Electric Corporation. The Test Loop Program was transferred to GE's facility in Wilmington, North Carolina. Also in 2007, GE-Hitachi signed letters of intent for uranium enrichment services with Exelon and Entergy - the two largest nuclear power utilities in the USA.
In 2008, GE Hitachi Nuclear Energy (GEH) spun off Global Laser Enrichment (GLE) to commercialise the SILEX Technology and announced the first potential commercial uranium enrichment facility using the Silex process. The USA's Nuclear Regulatory Commission (NRC) approved a license amendment to operate the Test Loop. Also in 2008, Cameco Corporation, the world’s largest uranium producer, had joined GE and Hitachi as owners of their laser enrichment venture GLE.
In 2010, concerns were raised that the process poses a threat to global nuclear security; the process requires up to 75% less space and consumes considerably less energy than current enrichment technologies, it is reportedly almost undetectable from orbit potentially allowing rogue governments' activities to go undetected by the international community.
In August 2011 The New York Times reported that Global Laser Enrichment, a subsidiary of GE Hitachi Nuclear Energy, had applied to the Nuclear Regulatory Commission for a permit to build a commercial plant at Wilmington. Details of the process are secret.
On September 19, 2012, the Nuclear Regulatory Commission issued its initial decision concerning the application of GE-Hitachi Global Laser Enrichment LLC (GLE) for a license to possess and use source, byproduct and special nuclear material and to enrich natural uranium to a maximum of 8 percent 235U by a laser-based enrichment process at a facility that would be located near the City of Wilmington in New Hanover County, North Carolina. In its Initial Decision, the Board authorized the issuance of the license that was requested by GLE.
Details of the SILEX process 
According to Laser Focus World, the SILEX process exposes a cold stream of a mixture of uranium hexafluoride (UF6) molecules and a carrier gas to energy from a pulsed laser. The laser used is a CO2 laser operating at a wavelength of 10.8 μm (micrometres) and optically amplified to 16 μm, which is in the infrared spectrum. The amplification is achieved in a Raman conversion cell, a large vessel filled with high-pressure para-hydrogen.
The 16 μm wavelength laser preferentially excites the 235UF6, creating a difference in the isotope ratios in a product stream, which is enriched in 235U, and a tailings stream, which has an increased fraction of the more common 238U. The Sydney Morning Herald reports that "The lasers electrically charge the atoms, which become trapped in an electromagnetic field and drawn to a metal plate for collection."
According to John L. Lyman, the Silex Systems Ltd. (SSL) research facility in Australia uses a laser pulsed at a frequency of 50 Hz, a rate that results in great inefficiency. At 50 Hz, only 1% of the UF6 feedstock is processed. This results in a high fraction of feedstock entering the product stream and a low observed enrichment rates. Consequently, a working enrichment plant would have to substantially increase the laser duty cycle. In addition, the preparation time needed is prohibitively long for full-scale production. The SSL research facility requires ten hours of prep time for a one-hour enrichment test run, significantly restricting output.
Further details of the technology, such as how it differs from the older molecular laser isotope separation(MLIS) and atomic vapor laser isotope separation (AVLIS) processes are not known publicly. The technique can be used for the isotopic enrichment of chlorine, molybdenum and uranium, and similar technologies can be used with carbon and silicon.
Security classification of SILEX information 
SILEX is also distinctive in that it is currently the only privately held information that is classified by the U.S. government. In June 2001, the U.S. Department of Energy classified "certain privately generated information concerning an innovative isotope separation process for enriching uranium." Under the Atomic Energy Act, all information not specifically declassified is classified as Restricted Data, whether it is privately or publicly held. This is in marked distinction to the national security classification executive order, which states that classification can only be assigned to information "owned by, produced by or for, or is under the control of the United States Government." This is the only known case of the Atomic Energy Act being used in such a manner.
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