Hanford groundwater modeling: a numerical comparison of Bayesian and Fisher parameter estimation techniques
This report is concerned with the performance of two promising techniques for estimating the parameters of groundwater models developed and applied by Rockwell Hanford Operations at the US Department of Energy Hanford site. The report begins with a fairly general formulation of the parameter estimation problem which helps to explain the capabilities and differences of the two estimation techniques (weighted least-squares and maximum likelihood). Particular emphasis is placed on the role of model input errors due to initial condition, boundary condition and source term uncertainties. It is shown that the weighted least-squares estimation algorithm (a Fisher estimator) essentially ignores input errors while the maximum likelihood estimation algorithm (a Bayesian estimator) accounts for these errors in a systematic way. Performance differences between these estimators are negligible when input errors are minor. When input errors are large, however, the maximum likelihood estimator appears to give significantly better estimates. This is illustrated with a numerical example based on an application of the RHAFE groundwater flow model to a hypothetical twelve element, three dimensional aquifer. Recommendations indicating the most promising directions for future research and application are provided at the end of the report.
- Research Organization:
- Resource Management Associates, Lafayette, CA (USA)
- DOE Contract Number:
- AC06-77RL01030
- OSTI ID:
- 6636751
- Report Number(s):
- RHO-C-24; TRN: 81-005035
- Country of Publication:
- United States
- Language:
- English
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12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
AQUIFERS
FLOW MODELS
MATHEMATICAL MODELS
GROUND WATER
COMPARATIVE EVALUATIONS
HAPO
LEAST SQUARE FIT
MAXIMUM-LIKELIHOOD FIT
RADIOACTIVE WASTE DISPOSAL
UNDERGROUND DISPOSAL
HYDROGEN COMPOUNDS
MANAGEMENT
NATIONAL ORGANIZATIONS
NUMERICAL SOLUTION
OXYGEN COMPOUNDS
US AEC
US DOE
US ERDA
US ORGANIZATIONS
WASTE DISPOSAL
WASTE MANAGEMENT
WATER
580100* - Geology & Hydrology- (-1989)
052002 - Nuclear Fuels- Waste Disposal & Storage
053000 - Nuclear Fuels- Environmental Aspects