Centrus Energy delivers first batch of uranium that\u2019s critical for advanced reactors Less than one percent of natural uranium is U-235, the uranium isotope capable of sustaining a nuclear chain reaction. Today\u2019s reactors use low-enriched uranium (LEU), which is almost 5 percent U-235. HALEU is enriched further to a concentration, or assay, of almost 20 percent U-235, which is still considered low-enriched compared<\/strong>with the 90-plus percent level that is required for weapons-grade uranium. The DOE projects that the United States will need more than 40 tonnes of HALEU<\/a> before the end of the decade. But advanced reactor makers are still years away from firing up their cores. For instance, TerraPower (backed by Bill Gates) announced last December that it was delaying its Natrium reactor demonstration<\/a> by two years because of a lack of HALEU fuel.
Centrus Energy\u2019s cascade of centrifuges produced its first batch of uranium fuel in November.
The 93 currently active nuclear-power reactors in the United States burn about 2,000 tonnes of uranium fuel each year. However, the type of uranium fuel those reactors use is not going to cut it for the advanced reactors<\/a> expected to go on line in the coming years, as part of the effort to meet the country\u2019s goal of 100 percent clean electricity<\/a> by 2035. The specialized fuel these advanced reactors will need is currently made on a commercial scale only in Russia<\/a>.
Not for long, though. Last week, Centrus Energy<\/a> in Bethesda, Md., jump-started the first commercial domestic nuclear fuel production<\/a> in the United States in 70 years by delivering the first load of high-assay, low-enriched uranium (HALEU) fuel made at its Piketon, Ohio, plant to the U.S. Department of Energy (DOE). The company is on track to produce 20 kilograms of HALEU by the end of the year, and then expects to produce 900 kg in 2024, says Jeffrey Cooper, director of engineering at Centrus.
This is a critical step toward large-scale deployment of advanced nuclear plants<\/a> in the United States. The DOE expects to invest about US $600 million<\/a> to mature next-generation reactors through its Advanced Reactor Demonstration Program<\/a>, and \u201cnine out of 10 of those reactors use HALEU fuels,\u201d Cooper says.
\u201cWe\u2019d like to avoid increasing our dependence on energy fuels from Russia. So it\u2019s critically important that we secure our supply of HALEU material, given the number of advanced reactors desiring to use it in the future for commercialization.\u201d \u2014Kathryn Huff, Department of Energy<\/strong><\/p>\n
\u201cThe higher concentration of U-235 allows for higher power densities in the cores of advanced reactor designs,\u201d Cooper says. That means more efficient reactors with smaller cores, longer core lives, and less fuel waste. The energy in just 3 tablespoons of HALEU can supply a lifetime\u2019s worth of power for the average U.S. consumer, according to Centrus.
Research reactors at U.S. national laboratories and universities today use a small amount of HALEU provided by the DOE. There are three different ways to make HALEU. Gaseous diffusion\u2014the \u201cold-school way we used to do it,\u201d according to Kathryn Huff<\/a>, the assistant secretary for nuclear energy<\/a> at the DOE, at federally owned enrichment facilities for the Manhattan Project and commercial nuclear sector for years\u2014fell from favor because it is extremely energy intensive.
Centrus and the Russian state-owned company Tenex, which are the only two outfits that can produce HALEU in the world, use a method called gaseous centrifusion. Centrus starts with nearly 5 percent enriched uranium in gas form and spins it at very high speeds in four-story-tall tubular centrifuges, where the centrifugal forces separate the isotopes based on weight. \u201cThe U-238 is flung to the wall, and U-235 stays preferentially in the interior,\u201d Cooper says. \u201cWe get two streams that come out\u2014the product stream, which is enriched in U-235, and what we call the tail stream, which has less material.\u201d
The gas is channeled through a cascade of centrifuges, where it gets progressively more enriched until reaching the target HALEU enrichment level of 19.75 percent. Centrus currently operates one cascade of 16 centrifuge machines.
Another promising enrichment technology, called laser enrichment, involves separating uranium isotopes based on the different energy levels at which their nuclei get excited. The technology is still in early stages of development, though, and Huff says that the DOE is closely watching Global Laser Enrichment<\/a> in Wilmington, N.C., as a company that\u2019s piloting the technology and that \u201ccould easily be a player in coming years.\u201d
Not all next-generation reactors will use HALEU, Huff points out. Small modular reactors<\/a> being developed by GE and Westinghouse<\/a>, for instance, use water as a coolant and uranium oxide as fuel, and are \u201cbasically shrunken versions of conventional reactors in the [United States]. They want to use standard LEU fuel,\u201d says Huff.
HALEU is needed instead for advanced reactors<\/a> with more creative coolants and fuels, which are trying to achieve very compact core sizes. These include Bellevue, Wash.\u2013based TerraPower\u2019s<\/a> sodium-cooled fast reactor, Rockville, M.D.\u2013based X-energy\u2019s<\/a> high-temperature gas reactor, and Alameda, Calif.\u2013based Kairos Power\u2019s<\/a> fluoride-salt-cooled high-temperature reactor. <\/p>\n
Centrus will have to build multiple cascades, each with 120 centrifuges, to make HALEU on a commercial scale. Right now, Centrus has an understanding in place<\/a> with TerraPower, but not a formal purchase agreement.
Uranium enrichment supplier Urenco<\/a>, which is co-owned by the British government, the Netherlands government, and German utilities, is also considering HALEU production<\/a> at its New Mexico\u2013based enrichment facilities, where it produces LEU today. Meanwhile, Lynchburg, Va.\u2013based BWXT, which in August announced that it will be producing 2 metric tons of HALEU<\/a> over the next five years for the National Nuclear Security Administration, is \u201cprepared to make more HALEU for the U.S. government in the future in support of the advanced-reactor market,\u201d says Sharon Smoot, president of BWXT\u2019s nuclear fuels business unit. \u201cLike any vendor, we look for market signals, and we\u2019re optimistic about what we see.\u201d
For now, the DOE intends to purchase about 25 tonnes of HALEU per year to kick-start the industry and give HALEU producers secure contracts from which they can expand production. \u201cWe\u2019d like to avoid increasing our dependence on energy fuels from Russia,\u201d Huff says. \u201cSo it\u2019s critically important that we secure our supply of HALEU material, given the number of advanced reactors desiring to use it in the future for commercialization.\u201d
Prachi Patel<\/a> is a freelance journalist based in Pittsburgh. She writes about energy, biotechnology, materials science, nanotechnology, and computing. <\/p>\n