Laboratory analysis of water retention in unsaturated zone materials at high temperature

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Authors:Constantz, Jim
Author Affiliations:Primary:
U. S. Geol. Surv., Water Resour. Div., Menlo Park, CA, United States
Volume Title:Role of the unsaturated zone in radioactive and hazardous waste disposal
Volume Authors:Mercer, James W., editor; Rao, P. S. C.; Marine, I. Wendell
Source:p.147-164; Role of the unsaturated zone in radioactive and hazardous waste disposal, Philadelphia, PA, May 31-June 4, 1982, edited by James W. Mercer, P. S. C. Rao and I. Wendell Marine. Publisher: Ann Arbor Sci. Publ., Ann Arbor, MI, United States. ISBN: 0-250-40620-9
Publication Date:1983
Note:In English. 12 refs.; illus. incl. 4 tables
Summary:The disposal of high-level radioactive wastes in the unsaturated zone may cause large temperature gradients in the immediate vicinity of the disposal site. Predicting the fate of high temperature wastes necessitates an adequate understanding of heat and mass transfer through the surrounding material. A quantification of the influence of temperature upon water retention characteristics in unsaturated materials is essential for prediction of heat and mass transfer. Previous investigations indicate that the influence of temperature upon water holding characteristics is significant and that additional work is necessary for a more complete understanding of the magnitude of the effect. The purpose of this study is to extend the temperature range investigated and to extend the experimental conditions to incorporate both draining and wetting processes. In the present investigation, the water retention is measured up to 95 C, using a new experimental technique. This technique provides a means of examining the usefulness of applying simple capillary retention theory to pore water retention above 50 C. Three results of these experiments on Tipperary Sand are notable in connection with high temperature water retention characteristics: (1) apparent compaction of the sand samples may have been caused by the high temperature conditions. This suggests that predictions of the physical behavior of unsaturated zone materials in the immediate vicinity of high temperature wastes should consider the effect of compaction of the material in response to thermal loading; (2) the results show that measurably less water is held at high temperature below about 50% saturation than is predicted by a simple capillary retention model; and (3) results indicate that the influence of temperature or gas bubble formation within the pore water system may measurably decrease the water holding capacity of sand at high temperature above 50% saturation. Therefore, failure of the LaPlace equation to predict the effect of temperature above 50 C on water retention may be explained by the inadequacies of a simple surface tension-temperature correction to properly describe capillary retention forces existing at lower values of the pore water matric potential (psi), and the inability of the correction to handle bubble formation at the highest values of psi. (See also W87-06947) (Lantz-PTT)
Subjects:Compaction; Engineering geology; Experimental studies; High temperature; Laboratory studies; Radioactive waste; Saturation; Soils; Surveys; Temperature; Unsaturated zone; Waste disposal; Water regimes; Churchill County Nevada; Nevada; United States; Materials, properties; Tipperary Sand; Water retention
Record ID:1984003223
Copyright Information:GeoRef, Copyright 2018 American Geosciences Institute. Reference includes data from USGS product, Selected Water Resources Abstracts, Reston, VA, United States
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