The Reporter's Handbook on Nuclear Materials, Energy & Waste Management

Section 2: Sustainability: Will There Be Enough Uranium and Nuclear Fuel and at What Cost?

| 53 Section 2 Nuclear Energy and Other Civilian Uses Sustainability:WillThere Be Enough Uranium and Nuclear Fuel and atWhat Cost? Written by Michael R. Greenberg, based in part on an interview with William Szymanski, with comments by Seth Blumsack Background The nuclear fuel cycle for energy production begins with exploration for uranium . It ends with transport of fuel, installation, use of the fuel at a nuclear power plant, and removal of the spent fuel to an on-site storage facility. In between are stages that are the focus of this brief and are often overlooked: (1) mining, (2) milling, conversion, and enrichment, and (3) fuel fabrication. (See “Closing the Civilian Nuclear Fuel Cycle,” “Nuclear Power Plant Safety Systems,” “Decommissioning Nuclear Facilities,” “Transportation of Nuclear Waste,” and “Nuclear Waste Policy.”) With regard to terms used in this brief, uranium refers to mined uranium ore or enriched commercial or weapons grade uranium; nuclear fuel refers to commercial-grade enriched uranium that has been processed into fuel pellets and rods for use in commercial nuclear reactors. Another distinction is between fuel fabricating companies and plant operators. Fabricating companies purchase enriched uranium for processing into fuel pellets and rods, that is, nuclear fuel. Operators purchase processed nuclear fuel, not uranium. Companies such as Areva and Westinghouse fabricate fuel and manufacture and service nuclear power plants. But they do not sell to wholesalers and final electricity customers. 54 | The Reporter’s Handbook: Briefs Mining Uranium occurs naturally, consisting primarily of two isotopes, uranium 235 (U-235) and uranium 238 (U-238). (See “Radionuclides.”) Both have 92 protons in their nuclei, but U-235 has 143 neutrons compared with 146 for the heavier U-238. U-235 is the most easily fissionable isotope of uranium and is only about 0.7% of natural uranium; U-238 is 99.3%. There are three major kinds of uranium mining activities. Underground mines are locations where a shaft or tunnel is dug into the rock and workers extract the uranium- laden ore. In open pit mining, the second approach, the overburden (top layer of soil, rock, or other material) is removed and equipment is used to shovel up the rock containing the ore. Both underground and open pit mines use conventional mining methods to first extract ore from rock through drilling and blasting. In situ leaching (ISL) is the third method of extracting uranium from ore for commercial power plants. That method injects chemicals into the ground that oxidize the ore so that uranium can be leached out and placed into solution to be pumped to the surface for processing into uranium concentrate in a processing plant. Because no excavation of rock takes place, ISL operations, when compared with conventional mining and milling, generate significantly less residual waste and cause much less disruption to the landscape. However, ISL is limited to ore contained in porous geological formations through which large volumes of solution can pass. Milling, Conversion, and Enrichment Nuclear power plants require uranium fuel containing 3–5% U-235, referred to as “low-enriched uranium” (LEU), hence naturally occurring uranium must be processed and the U-235 portion enriched relative to U-238. The ore from the mine is transported to a mill where it is broken down mechanically and chemically to separate a marketable uranium concentrate product, also called “yellow cake” or uranium oxide (U3O8), from unmarketable minerals. Uranium concentrate in oxide form must be chemically treated to convert it to uranium hexafluoride (UF6), a feedstock for uranium enrichment. The enrichment process uses gaseous diffusion or gas centrifuge to prepare the material for conversion to fuel. The details of enrichment processes are considered proprietary by the commercial fuel producers. (See “Managing the Nuclear Weapons Legacy.”) Fuel Fabrication From an enrichment plant, the LEU in the form of UF6 is reconverted back to an oxide and made into pellets at a fuel fabrication facility. The fabricator inserts the pellets into fuel rods that are bundled into fuel assemblies for Sustainability | 55 loading into the core of a nuclear reactor. Each stage of the fuel cycle process requires separate business agreements, though some contractors are involved in multiple stages of the fuel cycle. Plant operators must plan ahead for the 12-to-24-month cycle when 20 to 40% of the fuel will need to be replaced. In short, there is nothing simple about the scientific or organizational capacities required to refuel nuclear power plants. Overall, for...