An Overview ofthe Nuclear Fuel Cycleand Radioactive MaterialsIndustry Chuck Cain U.S. Nuclear Regulatory Commission, Region IV Arlington, Texas
Implementing Legislation • Atomic Energy Act of 1954 • established the Atomic Energy Commission (AEC) • Energy Reorganization Act of 1974 • separated the peaceful uses regulatory function from the weapons function • established the NRC • weapons function eventually included in Department of Energy (DOE)
Energy Policy Act of 2005 • Authorizes NRC to regulate naturally occurring material and accelerator-produced material
Agreement States • These are States that have agreements with NRC to regulate radioactive materials within their borders (except reactors) • All States in NRC Region IV are Agreement States except Montana, Wyoming, South Dakota, Idaho, Alaska, and Hawaii
Since 9/11… • …particular attention is paid to security and not only safety (user qualification and equipment)
Uranium Mining and Milling • Mining by conventional methods or by In-situ leaching • Ore is < 1% uranium • Mill extracts uranium from ore; rest is tailings • Mill product is uranium oxide (known as yellowcake) and is shipped in 55-gallon drums
The Sweetwater Mine & Mill (Wyoming)
Atlas Minerals on Colorado River near Moab, UT
Yellowcake Product Yellowcake is packaged into 55-gallon drums and prepared for shipment.
Facts About Yellowcake • Can be held in hands without harm. • A drum of yellowcake weighs about 1,000 pounds. • Natural uranium contains mostly uranium-238 (99.3%). • We want the U-235 which is only 0.7% of natural uranium.
Enriched Uranium • The next challenge is to enrich the uranium (increase the proportion of U-235) • Enrichment plants usually work by gaseous diffusion; therefore, the uranium must be converted to a gas.
Conversion Plants Produce UF6 • Yellowcake can be converted to uranium hexafluoride which has a triple point of 147° F • Honeywell, Metropolis, IL • Sequoyah Fuels, Gore, OK (closed)
Enrichment Plants • Since an atom of U-238 is larger than an atom of U-235, the atoms can be filtered at a gaseous diffusion enrichment plant. • Uranium must be enriched to ~10% to make nuclear fuel for a reactor.
Depleted Uranium • Depleted uranium is a waste product of the enrichment process. • Depleted uranium is “depleted” in U-235 (less than 0.7% U-235). • DU can be used for purposes where a heavy mass is needed, such as military projectiles.
New Technologies • Gas centrifuge • Louisiana Energy Services • Areva • Laser separation
Fuel Fabrication • The enriched UF6 is converted to a powdered chemical form and made into fuel pellets.
Spent Fuel • Eventually fuel elements become “poisoned” during the fission process and need to be replaced. • This is considered “high-level” waste. • There is still much good U-235 left in spent nuclear fuel. • The “poisons” (byproduct material) produced during the fission process are high-energy gamma emitters.
Spent fuel stored in a fuel pool
What’s next for spent fuel? • Several options • store at reactor site in pool • store at site in Independent Spent Fuel Storage Installation (ISFSI) • burial at geological repository • reprocess (recycle) to separate the remaining good uranium from the waste
Rancho Seco ISFSI
Also, Low-Level Waste • Contaminated or potentially contaminated items such as protective clothing, building materials, tools, etc. • Burial at licensed disposal site such as EnergySolutions (UT or SC), U.S. Ecology (WA)
Quantity of Radioactive Material • Unit of measurement - curies or becquerels
Half-Life • Time it takes for half of a radioactive material to decay • Cobalt-60, 5 years • Uranium, millions of years • Some materials decay with a half-life in minutes or seconds, such as those for medical use.
Dose to Radiation • Units of rems or sieverts • Radiation worker limit is 5 rems • Limit for a member of the public is 100 millirems
Kinds of Licenses • Specific • General (e.g., tritium exit signs) • Exempt (e.g., smoke alarms)