Americium Transmutation Feasibility When Used as Burnable Absorbers - 12392
- United States Military Academy, West Point, New York 10996 (United States)
- University of South Carolina, Columbia, South Carolina 29208 (United States)
The use of plutonium in Mixed Oxide (MOX) fuel in traditional Pressurized Water Reactor (PWR) assemblies leads to greater americium production which is not addressed in MOX recycling. The transuranic nuclides (TRU) contribute the most to the radiotoxicity of nuclear waste and a reduction of the TRU stockpile would greatly reduce the overall radiotoxicity of what must be managed. Am-241 is a TRU of particular concern because it is the dominant contributor of total radiotoxicity for the first 1000 years in a repository. This research explored the feasibility of transmuting Am-241 by using varying amounts in MOX rods being used in place of burnable absorbers and evaluated with respect to the impact on incineration and transmutation of transuranics in MOX fuel as well as the impact on safety. This research concludes that the addition of americium to a non-uniform fuel assembly is a viable method of transmuting Am-241, holding down excess reactivity in the core while serving as a burnable poison, as well as reducing the radiotoxicity of high level waste that must be managed. The use of Am/MOX hybrid fuel assemblies to transmute americium was researched using multiple computer codes. Am-241 was shown in this study to be able to hold down excess reactivity at the beginning of cycle and shape the power distribution in the core with assemblies of varying americium content loaded in a pattern similar to the traditional use of assemblies with varying amounts of burnable absorbers. The feasibility, safety, and utility of using americium to create an Am/MOX hybrid non-uniform core were also evaluated. The core remained critical to a burnup of 22,000 MWD/MTM. The power coefficient of reactivity as well as the temperature and power defects were sufficiently negative to provide a prompt feedback mechanism in case of a transient and prevent a power excursion, thus ensuring inherent safety and protection of the core. As shown here as well as many other studies, this non-uniform assembly type successfully addresses the concerns of reduced control rod worth within advanced MOX assemblies because the Am/MOX hybrid fuel rods are on the periphery of the assembly. The radiotoxicity of the high level waste that must be managed from a single use of an Am/MOX hybrid batch is reduced for the first 1000 years in comparison to a regular UO{sub 2} batch. However, there is no heat-load advantage without multi-recycling the Am/MOX hybrid assemblies. As shown through numerous studies, the heterogeneous assembly model used as the basis for this research is capable of multiple recycles while still maintaining negative temperature and power coefficients of reactivity. Multi-recycling would provide an even greater reduction to the radiotoxicity of the high level waste as well as provide a heat-load advantage compared to a once through UO{sub 2} fuel cycle. (authors)
- Research Organization:
- WM Symposia, 1628 E. Southern Avenue, Suite 9-332, Tempe, AZ 85282 (United States)
- OSTI ID:
- 22293637
- Report Number(s):
- INIS-US-14-WM-12392; TRN: US14V1293115161
- Resource Relation:
- Conference: WM2012: Waste Management 2012 conference on improving the future in waste management, Phoenix, AZ (United States), 26 Feb - 1 Mar 2012; Other Information: Country of input: France; 12 refs.
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
AMERICIUM
AMERICIUM 241
BURNABLE POISONS
COMPUTER CODES
CONTROL ROD WORTHS
FUEL ASSEMBLIES
FUEL CYCLE
FUEL RODS
HIGH-LEVEL RADIOACTIVE WASTES
HYBRIDIZATION
MIXED OXIDE FUELS
PLUTONIUM
POWER COEFFICIENT
POWER DISTRIBUTION
PWR TYPE REACTORS
RECYCLING
SAFETY
TRANSMUTATION
URANIUM DIOXIDE