For decades, laser uranium enrichment occupied an awkward position in the nuclear industry: technically compelling, extensively researched, and repeatedly unable to displace the gas centrifuge.
The renewed interest in nuclear power, combined with concerns over Western enrichment capacity and the emerging demand for higher assay fuels, has reopened the question of whether laser isotope separation can become more than an advanced research program.
Unlike conventional enrichment technologies, laser processes do not primarily exploit the very small mass difference between uranium 235 and uranium 238. Instead, they take advance of the subtle differences in how the two isotopes interact with light. If a laser is tuned at a specific wavelenght, U-235 can be selectively excited while U-238 is affected far less. The engineering challenge is then to transform that selective excitation into a physical separation process and over decades engineered tried different strategies.
Atomic Vapor Laser Isotope Separation, or AVLIS, is a good historical example. In AVLIS, metallic uranium is heated to roughly 2000 to 3000°C to produce an atomic vapor. Tuned lasers selectively ionize U-235 atoms, which can then be separated electrostatically from neutral U-238. The US invested around $1.7-2 billion in AVLIS development over several decades sicne the 70s and pilot systems achieved to processed thousands of kilograms of uranium. Yet USEC terminated the program in 1999, declaring that the expected profitability did not justify the additional capital expenditure necessary to commercialize the process.
The most advanced contemporary program is SILEX, being commercialized by Global Laser Enrichment, or GLE. Silex Systems owns 51% of GLE, while Cameco owns 49% and has an option that could increase its ownership to 75%. Silex also retains a royalty of at least 7% on revenue generated using the technology.
The important development is technological maturity: following a six month demonstration campaign, the SILEX process was assessed at Technology Readiness Level 6 and GLE reported integrated operation under relevant conditions and production at the scale of hundreds of kilograms of enriched uranium product with base at the Paducah Laser Enrichment Facility in Kentucky. What´s also interesting in this specific facility is that Silex could process depleted uranium hexafluoride remaining from the former Paducah gaseous diffusion plant, since this gaseous diffusion was relatively inefficient and the material still contains meaningful quantities of U-235.
According to GLE, the target capacity would be up to 6 million SWU/year, although initial production would be closer to 2 million SWU/year. The company says approximately $600 million of private capital has already been invested.
And SILEX is no the only one. LIS Technologies is developing CRISLA, another molecular laser enrichment approach. The company declared that its process could produce LEU in a single stage and HALEU in two stages. Its technology has independently reached TRL 4, and the company reports that 60% of their tecnology reached TRL 5. Hexium, on the other side, is developing AVLIS technology initially for lithium isotope separation and is collaborating with Oklo, TerraPower and Lawrence Livermore National Laboratory on the potential application of AVLIS to HALEU production.
This post is based on the Raw Science analysis “The third generation of uranium enrichment: Laser isotope separation” which focuses on AVLIS, MLIS, SILEX and CRISLA technologies, their maturity and the emerging company landscape.