EARLY GUIDANCE FOR ASSIGNING DISTRIBUTION PARAMETERS TO GEOCHEMICAL INPUT TERMS TO STOCHASTIC TRANSPORT MODELS

Kaplan, D ; Margaret Millings, M

Savannah River Site (S.C.)

关键词: Radioactive Waste Disposal;    Stochastic Processes;    Radionuclide Migration;    Mathematical Models;    Solubility;   

DOI  :  10.2172/891661
RP-ID  :  WSRC-STI-2006-00019
RP-ID  :  DE-AC09-96SR18500
RP-ID  :  891661

美国|英语

来源: UNT Digital Library

【 摘 要 】

Stochastic modeling is being used in the Performance Assessment program to provide a probabilistic estimate of the range of risk that buried waste may pose. The objective of this task was to provide early guidance for stochastic modelers for the selection of the range and distribution (e.g., normal, log-normal) of distribution coefficients (K{sub d}) and solubility values (K{sub sp}) to be used in modeling subsurface radionuclide transport in E- and Z-Area on the Savannah River Site (SRS). Due to the project's schedule, some modeling had to be started prior to collecting the necessary field and laboratory data needed to fully populate these models. For the interim, the project will rely on literature values and some statistical analyses of literature data as inputs. Based on statistical analyses of some literature sorption tests, the following early guidance was provided: (1) Set the range to an order of magnitude for radionuclides with K{sub d} values >1000 mL/g and to a factor of two for K{sub d} values of <1000 mL/g. This decision is based on the literature. (2) Set the range to an order of magnitude for radionuclides with K{sub sp} values <10{sup -6} M and to a factor of two for K{sub d} values of >10{sup -6} M. This decision is based on the literature. (3) The distribution of K{sub d} values with a mean >1000 mL/g will be log-normally distributed. Those with a K{sub d} value <1000 mL/g will be assigned a normal distribution. This is based on statistical analysis of non-site-specific data. Results from on-going site-specific field/laboratory research involving E-Area sediments will supersede this guidance; these results are expected in 2007.