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Title: Geochemistry Model Abstraction and Sensitivity Studies for the 21 PWR CSNF Waste Package

Abstract

The CSNF geochemistry model abstraction, as directed by the TWP (BSC 2002b), was developed to provide regression analysis of EQ6 cases to obtain abstracted values of pH (and in some cases HCO{sub 3}{sup -} concentration) for use in the Configuration Generator Model. The pH of the system is the controlling factor over U mineralization, CSNF degradation rate, and HCO{sub 3}{sup -} concentration in solution. The abstraction encompasses a large variety of combinations for the degradation rates of materials. The ''base case'' used EQ6 simulations looking at differing steel/alloy corrosion rates, drip rates, and percent fuel exposure. Other values such as the pH/HCO{sub 3}{sup -} dependent fuel corrosion rate and the corrosion rate of A516 were kept constant. Relationships were developed for pH as a function of these differing rates to be used in the calculation of total C and subsequently, the fuel rate. An additional refinement to the abstraction was the addition of abstracted pH values for cases where there was limited O{sub 2} for waste package corrosion and a flushing fluid other than J-13, which has been used in all EQ6 calculation up to this point. These abstractions also used EQ6 simulations with varying combinations of corrosion rates ofmore » materials to abstract the pH (and HCO{sub 3}{sup -} in the case of the limiting O{sub 2} cases) as a function of WP materials corrosion rates. The goodness of fit for most of the abstracted values was above an R{sup 2} of 0.9. Those below this value occurred during the time at the very beginning of WP corrosion when large variations in the system pH are observed. However, the significance of F-statistic for all the abstractions showed that the variable relationships are significant. For the abstraction, an analysis of the minerals that may form the ''sludge'' in the waste package was also presented. This analysis indicates that a number a different iron and aluminum minerals may form in the waste package other than those described in the EQ6 output files which are based on the use of a thermodynamic database.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
YMP (Yucca Mountain Project, Las Vegas, Nevada)
Sponsoring Org.:
USDOE
OSTI Identifier:
859050
Report Number(s):
MDL-DSU-MD-000001 REV 00
MOL.20021107.0154 DC#33292; TRN: US0600429
DOE Contract Number:  
NA
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; 36 MATERIALS SCIENCE; ALUMINIUM; CORROSION; GEOCHEMISTRY; IRON; MINERALIZATION; PH VALUE; REGRESSION ANALYSIS; SENSITIVITY; THERMODYNAMICS; WASTE FORMS; SPENT FUELS; RADIOACTIVE WASTE DISPOSAL

Citation Formats

P. Bernot, S. LeStrange, E. Thomas, K. Zarrabi, and S. Arthur. Geochemistry Model Abstraction and Sensitivity Studies for the 21 PWR CSNF Waste Package. United States: N. p., 2002. Web. doi:10.2172/859050.
P. Bernot, S. LeStrange, E. Thomas, K. Zarrabi, & S. Arthur. Geochemistry Model Abstraction and Sensitivity Studies for the 21 PWR CSNF Waste Package. United States. doi:10.2172/859050.
P. Bernot, S. LeStrange, E. Thomas, K. Zarrabi, and S. Arthur. Tue . "Geochemistry Model Abstraction and Sensitivity Studies for the 21 PWR CSNF Waste Package". United States. doi:10.2172/859050. https://www.osti.gov/servlets/purl/859050.
@article{osti_859050,
title = {Geochemistry Model Abstraction and Sensitivity Studies for the 21 PWR CSNF Waste Package},
author = {P. Bernot and S. LeStrange and E. Thomas and K. Zarrabi and S. Arthur},
abstractNote = {The CSNF geochemistry model abstraction, as directed by the TWP (BSC 2002b), was developed to provide regression analysis of EQ6 cases to obtain abstracted values of pH (and in some cases HCO{sub 3}{sup -} concentration) for use in the Configuration Generator Model. The pH of the system is the controlling factor over U mineralization, CSNF degradation rate, and HCO{sub 3}{sup -} concentration in solution. The abstraction encompasses a large variety of combinations for the degradation rates of materials. The ''base case'' used EQ6 simulations looking at differing steel/alloy corrosion rates, drip rates, and percent fuel exposure. Other values such as the pH/HCO{sub 3}{sup -} dependent fuel corrosion rate and the corrosion rate of A516 were kept constant. Relationships were developed for pH as a function of these differing rates to be used in the calculation of total C and subsequently, the fuel rate. An additional refinement to the abstraction was the addition of abstracted pH values for cases where there was limited O{sub 2} for waste package corrosion and a flushing fluid other than J-13, which has been used in all EQ6 calculation up to this point. These abstractions also used EQ6 simulations with varying combinations of corrosion rates of materials to abstract the pH (and HCO{sub 3}{sup -} in the case of the limiting O{sub 2} cases) as a function of WP materials corrosion rates. The goodness of fit for most of the abstracted values was above an R{sup 2} of 0.9. Those below this value occurred during the time at the very beginning of WP corrosion when large variations in the system pH are observed. However, the significance of F-statistic for all the abstractions showed that the variable relationships are significant. For the abstraction, an analysis of the minerals that may form the ''sludge'' in the waste package was also presented. This analysis indicates that a number a different iron and aluminum minerals may form in the waste package other than those described in the EQ6 output files which are based on the use of a thermodynamic database.},
doi = {10.2172/859050},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2002},
month = {10}
}