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Title: A conceptual performance assessment model of the dissolved actinide source term for the WIPP

Abstract

This paper presents a performance assessment model of dissolved actinide concentrations for the Waste Isolation Pilot Plant (WIPP). The model assesses the concentration of each actinide oxidation state and combines these concentrations with an oxidation state distribution. The chemical behavior of actinides in the same oxidation state is presumed to be very similar for almost all situations, but exceptions arising from experimental evidence are accommodated. The code BRAGFLO calculates the gas pressure, brine mass, gas volume, and mass of remaining Fe and cellulosics for each time step and computational cell. The total CO{sub 2} in the repository and dissolved Ca(OH){sub 2} is estimated. Lookup tables are constructed for pmH and f(CO{sub 2}) as a function of brine type and volume, moles of CO{sub 2}, and Ca(OH){sub 2}. Amounts of five soluble complexants are considered. A model based on the formulation of Harvie et al. produces tables of solubilities for each actinide oxidation state as a function of pmH, f(CO{sub 2}), brine composition, and complexant. Experimental data yield lookup tables of fractions of Th, U, Np, Pu, and Am in each oxidation state as a function of f(CO{sub 2}) and complexant. The tables are then used to provide a concentration ofmore » a particular actinide at particular values of pmH and f(CO{sub 2}). Under steady-state conditions, the oxidation state of each actinide that is most stable in the particular chemical environment controls the concentration of that actinide in solution. In the absence of steady-state conditions, the oxidation state distribution of interest is that of the dissolved actinide, and the oxidation states may be treated as if they were separate compounds.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE Office of Environmental Restoration and Waste Management, Washington, DC (United States)
OSTI Identifier:
474834
Report Number(s):
SAND-96-2654C; CONF-960911-7
ON: DE97004628; TRN: 97:010232
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Conference
Resource Relation:
Conference: Canadian Nuclear Society (CNS) international conference on deep geological disposal of radioactive waste, Winnipeg (Canada), 15-18 Sep 1996; Other Information: PBD: [1996]
Country of Publication:
United States
Language:
English
Subject:
05 NUCLEAR FUELS; WIPP; SOURCE TERMS; ACTINIDES; MATHEMATICAL MODELS; RADIOACTIVE WASTE DISPOSAL; VALENCE; COMPUTERIZED SIMULATION; B CODES; CARBON DIOXIDE; CALCIUM HYDROXIDES; SOLUBILITY; CONCENTRATION RATIO

Citation Formats

Weiner, R F, Stockman, C T, Wang, Y, and Novak, C F. A conceptual performance assessment model of the dissolved actinide source term for the WIPP. United States: N. p., 1996. Web.
Weiner, R F, Stockman, C T, Wang, Y, & Novak, C F. A conceptual performance assessment model of the dissolved actinide source term for the WIPP. United States.
Weiner, R F, Stockman, C T, Wang, Y, and Novak, C F. 1996. "A conceptual performance assessment model of the dissolved actinide source term for the WIPP". United States. https://www.osti.gov/servlets/purl/474834.
@article{osti_474834,
title = {A conceptual performance assessment model of the dissolved actinide source term for the WIPP},
author = {Weiner, R F and Stockman, C T and Wang, Y and Novak, C F},
abstractNote = {This paper presents a performance assessment model of dissolved actinide concentrations for the Waste Isolation Pilot Plant (WIPP). The model assesses the concentration of each actinide oxidation state and combines these concentrations with an oxidation state distribution. The chemical behavior of actinides in the same oxidation state is presumed to be very similar for almost all situations, but exceptions arising from experimental evidence are accommodated. The code BRAGFLO calculates the gas pressure, brine mass, gas volume, and mass of remaining Fe and cellulosics for each time step and computational cell. The total CO{sub 2} in the repository and dissolved Ca(OH){sub 2} is estimated. Lookup tables are constructed for pmH and f(CO{sub 2}) as a function of brine type and volume, moles of CO{sub 2}, and Ca(OH){sub 2}. Amounts of five soluble complexants are considered. A model based on the formulation of Harvie et al. produces tables of solubilities for each actinide oxidation state as a function of pmH, f(CO{sub 2}), brine composition, and complexant. Experimental data yield lookup tables of fractions of Th, U, Np, Pu, and Am in each oxidation state as a function of f(CO{sub 2}) and complexant. The tables are then used to provide a concentration of a particular actinide at particular values of pmH and f(CO{sub 2}). Under steady-state conditions, the oxidation state of each actinide that is most stable in the particular chemical environment controls the concentration of that actinide in solution. In the absence of steady-state conditions, the oxidation state distribution of interest is that of the dissolved actinide, and the oxidation states may be treated as if they were separate compounds.},
doi = {},
url = {https://www.osti.gov/biblio/474834}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Dec 31 00:00:00 EST 1996},
month = {Tue Dec 31 00:00:00 EST 1996}
}

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