Analysis of congruent matrix release, precipitation, and time-distributed containment failure on spent fuel performance
The Analytical Repository Source-Term (AREST) code has been developed for source-term evaluation of spent fuel as a final waste form in geologic repositories. AREST contains a set of analytical equations for the time-dependent diffusional mass transport of both solubility-limited and inventory-limited radionuclides from a spent fuel in a failed container surrounded by a shell of packing or other porous material imbedded in a porous host rock. Three factors that affect release performance are congruent dissolution of the UO/sub 2/ matrix: chemical instability of the UO/sub 2/ matrix, with precipitation of a more stable uranium phase within the waste package: and the attenuation of release rate by distribution of containment failures with time. For congruent matrix dissolution, the release rates of included nuclides are proportional to the product of solubility-limited release of uranium and the fractional abundance of the nuclide. For certain conditions, congruent release rates are calculated to be up to 10 orders of magnitude lower than release rates assuming individual solubility-limits. Precipitation of a more stable, lower solubility uranium phase within the waste package is shown to increase release rates from the UO/sub 2/ matrix compared to the non-precipitation case, in agreement with previous calculations. During the first 300 to 1000 years after repository closure, the distribution of containment failures with time will act to attenuate the peak average release rates of soluble, long-lived nuclides, such as iodine-129, to values smaller than release rates below regulatory limits. 27 refs., 5 figs.
- Research Organization:
- Pacific Northwest Lab., Richland, WA (USA)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 5195460
- Report Number(s):
- PNL-SA-15403; CONF-871124-95; ON: DE88008177
- Resource Relation:
- Conference: Fall meeting of the Materials Research Society, Boston, MA, USA, 30 Nov 1987
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
FLOW RATE
MATHEMATICAL MODELS
GROUND WATER
HIGH-LEVEL RADIOACTIVE WASTES
UNDERGROUND DISPOSAL
A CODES
CONTAINERS
EVALUATION
FAILURES
MASS TRANSFER
RADIOACTIVE WASTE MANAGEMENT
SPENT FUELS
WASTE FORMS
COMPUTER CODES
ENERGY SOURCES
FUELS
HYDROGEN COMPOUNDS
MANAGEMENT
MATERIALS
NUCLEAR FUELS
OXYGEN COMPOUNDS
RADIOACTIVE MATERIALS
RADIOACTIVE WASTES
REACTOR MATERIALS
WASTE DISPOSAL
WASTE MANAGEMENT
WASTES
WATER
052002* - Nuclear Fuels- Waste Disposal & Storage
053000 - Nuclear Fuels- Environmental Aspects