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Title: Interpretation of leaching data for cementitious waste forms using analytical solutions based on mass transport theory and empiricism

Abstract

The analysis of leaching data using analytical solutions based on mass transport theory and empiricism is presented. The waste forms leached to generate the data used in this analysis were prepared with a simulated radioactive waste slurry with traces of potassium ion, manganese ions, carbonate ions, phosphate ions, and sulfate ions solidified with several blends of cementitious materials. Diffusion coefficients were estimated from the results of ANS - 16.1 tests. Data of fraction leached versus time is presented and discussed.

Authors:
; ; ;  [1]
  1. (Oak Ridge National Lab., TN (USA))
Publication Date:
OSTI Identifier:
7245021
Report Number(s):
CONF-8904178-
Journal ID: ISSN 0093-3066; CODEN: ACEPC; TRN: 90-010306
Resource Type:
Conference
Resource Relation:
Journal Name: American Chemical Society, Division of Environmental Chemistry, Preprints; (USA); Journal Volume: 29:1; Conference: Symposium on leaching tests, Dallas, TX (USA), 9-14 Apr 1989
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; LEACHING; ANALYTICAL SOLUTION; CALCULATION METHODS; CEMENTS; COMPUTER CODES; DATA ANALYSIS; HAZARDOUS MATERIALS; RADIOACTIVE WASTES; BUILDING MATERIALS; DISSOLUTION; MATERIALS; RADIOACTIVE MATERIALS; SEPARATION PROCESSES; WASTES; 540210* - Environment, Terrestrial- Basic Studies- (1990-); 052002 - Nuclear Fuels- Waste Disposal & Storage; 540310 - Environment, Aquatic- Basic Studies- (1990-)

Citation Formats

Spence, R.D., Godbee, H.W., Tallent, O.K., and Nestor, C.W. Jr. Interpretation of leaching data for cementitious waste forms using analytical solutions based on mass transport theory and empiricism. United States: N. p., 1989. Web.
Spence, R.D., Godbee, H.W., Tallent, O.K., & Nestor, C.W. Jr. Interpretation of leaching data for cementitious waste forms using analytical solutions based on mass transport theory and empiricism. United States.
Spence, R.D., Godbee, H.W., Tallent, O.K., and Nestor, C.W. Jr. 1989. "Interpretation of leaching data for cementitious waste forms using analytical solutions based on mass transport theory and empiricism". United States. doi:.
@article{osti_7245021,
title = {Interpretation of leaching data for cementitious waste forms using analytical solutions based on mass transport theory and empiricism},
author = {Spence, R.D. and Godbee, H.W. and Tallent, O.K. and Nestor, C.W. Jr.},
abstractNote = {The analysis of leaching data using analytical solutions based on mass transport theory and empiricism is presented. The waste forms leached to generate the data used in this analysis were prepared with a simulated radioactive waste slurry with traces of potassium ion, manganese ions, carbonate ions, phosphate ions, and sulfate ions solidified with several blends of cementitious materials. Diffusion coefficients were estimated from the results of ANS - 16.1 tests. Data of fraction leached versus time is presented and discussed.},
doi = {},
journal = {American Chemical Society, Division of Environmental Chemistry, Preprints; (USA)},
number = ,
volume = 29:1,
place = {United States},
year = 1989,
month = 1
}

Conference:
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  • Despite the demonstrated importance of diffusion control in leaching, other mechanisms have been observed to play a role and leaching from porous solid bodies is not simple diffusion. Only simple diffusion theory has been developed well enough for extrapolation, as yet. The well developed diffusion theory, used in data analysis by ANSI/ANS-16.1 and the NEWBOX program, can help in trying to extrapolate and predict the performance of solidified waste forms over decades and centuries, but the limitations and increased uncertainty must be understood in so doing. Treating leaching as a semi-infinite medium problem, as done in the Cote model, resultsmore » in simpler equations, but limits, application to early leaching behavior when less than 20% of a given component has been leached. 18 refs., 2 tabs.« less
  • Despite the demonstrated importance of diffusion control in leaching, other mechanisms have been observed to play a role and leaching from porous solid bodies is not simple diffusion. Only simple diffusion theory has been developed well enough for extrapolation, as yet. The well developed diffusion theory, used in data analysis by ANSI/ANS-16.1 and the NEWBOX program, can help in trying to extrapolate and predict the performance of solidified waste forms over decades and centuries, but the limitations and increased uncertainty must be understood in so doing. Treating leaching as a semi-infinite medium problem, as done in the Cote model, resultsmore » in simpler equations, but limits, application to early leaching behavior when less than 20% of a given component has been leached. 18 refs., 2 tabs.« less
  • The results from leaching tests on two different sets of solid waste forms are analyzed using NEWBOX (a computer program for parameter estimation in diffusion problems). The solid waste forms were made by incorporating the sludge from a biodenitrification process in cementitious admixtures. The solids (one set with calcium silicate and the other with sodium silicate additive) were leached using tests based on the MCC-1 and ANSI/ANS-16.1-1986 test protocols. A slightly modified MCC-1 (1-, 3-, 7-, 14-, and 28-day) procedure and the abbreviated (5-day) ANS-16.1 procedure were used with demineralized water as leachant and waste forms that were cylindrical (diametermore » of 2.5 cm and length of 4.5 cm).« less
  • Predicting the long-term performance of low-level nuclear wastes that have been solidified in cementitous materials is the subject of this report. The authors approach has included use of several types of leach tests to help elucidate release mechanisms. Test ANS16.1 has been modified by using actual groundwater as opposed to distilled water as the leachant. In addition static leach tests, once-through flow leach test and combined leach/adsorption tests where the waste form is surrounded by sediment to simulate shallow land burial have been performed. Geochemical modeling of leachates from the various tests suggest that many major constituents in cement andmore » grout waste forms and some trace metal contaminants may be solubility controlled. Using hypothetical hydrologic scenarios representative of arid Western United States disposal sites, the difference in mass flux for selected constituents are discussed assuming diffusion control in one case and solubility in a second case.« less
  • This work investigates the physical property changes of cement-based waste forms before and after leaching in acetic acid solutions. Specimens were prepared in the laboratory with a Type I Portland cement and synthetic metal sludges. The physical properties (water content, densities, and porosity) of the waste forms were examined before and after leaching. The study showed that a leached layer developed on the surface of every leached specimen. The physical properties of the leached layer, which were highly porous and lighter weight in nature, were distinctly different from those of the original material.