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Title: Some characteristics of potential backfill materials

Abstract

A backfill material is one of the multiple barriers that may be involved in the disposal of nuclear waste. Such backfill should be a desiccant with the hydrous product having acceptable stability; it should sorb any released radioisotopes, and it should reseal any breached site. The backfill must also have acceptable thermal conductivity. This report presents data on the rate of hydration and the nature of the product of reaction of some candidate backfill materials with water and with brine. Thermal conductivity data is reported for both the reactants and the products. Granular MgO at 150/sup 0/C completely hydrates in less than 10 hours. At 60/sup 0/C and 20/sup 0/C, such extensive hydration requires about 100 and 1000 hours, respectively. The product of the reaction is stable to more than 300/sup 0/C. A doped discalcium silicate was less reactive and the product contains less water of crystallization than the MgO. The reaction product of dicalcium silicate is cementous, but it has low thermal stability. Bentonite readily reacts with water and expands. The reaction product has the properties of vermiculite, which indicates that magnesium ions have diffused into the bentonite structure and are not simply adsorbed on the surface. If bentonitemore » is emplaced in a saline environment, the properties of vermiculite, the reaction product, should also be considered. The thermal conductivity of MgO, discalcium silicate, and bentonite is primarily dependent on the porosity of the sample. A slight increase in thermal conductivity was found with increased temperature, in contrast to most rocks. If the conductive data for the different materials is equated to the same porosity, MgO has the superior thermal conductivity compared to bentonite or discalcium silicate.« less

Authors:
Publication Date:
Research Org.:
Lehigh Univ., Bethlehem, PA (USA)
OSTI Identifier:
6105653
Report Number(s):
ONWI-449
ON: DE83014668
DOE Contract Number:  
AC06-76RL01830; AC02-83CH10140
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; 36 MATERIALS SCIENCE; BACKFILLING; MATERIALS TESTING; BENTONITE; HYDRATION; THERMAL CONDUCTIVITY; CALCIUM SILICATES; MAGNESIUM OXIDES; RADIOACTIVE WASTE DISPOSAL; DOPED MATERIALS; POROSITY; SORPTIVE PROPERTIES; VERMICULITE; ALKALINE EARTH METAL COMPOUNDS; ALUMINIUM COMPOUNDS; ALUMINIUM SILICATES; CALCIUM COMPOUNDS; CHALCOGENIDES; CLAYS; INORGANIC ION EXCHANGERS; ION EXCHANGE MATERIALS; IRON COMPOUNDS; IRON SILICATES; MAGNESIUM COMPOUNDS; MAGNESIUM SILICATES; MANAGEMENT; MATERIALS; MICA; MINERALS; OXIDES; OXYGEN COMPOUNDS; PHYSICAL PROPERTIES; SILICATE MINERALS; SILICATES; SILICON COMPOUNDS; SOLVATION; SURFACE PROPERTIES; TESTING; THERMODYNAMIC PROPERTIES; TRANSITION ELEMENT COMPOUNDS; WASTE DISPOSAL; WASTE MANAGEMENT; 052002* - Nuclear Fuels- Waste Disposal & Storage; 360603 - Materials- Properties

Citation Formats

Simpson, D R. Some characteristics of potential backfill materials. United States: N. p., 1983. Web. doi:10.2172/6105653.
Simpson, D R. Some characteristics of potential backfill materials. United States. https://doi.org/10.2172/6105653
Simpson, D R. 1983. "Some characteristics of potential backfill materials". United States. https://doi.org/10.2172/6105653. https://www.osti.gov/servlets/purl/6105653.
@article{osti_6105653,
title = {Some characteristics of potential backfill materials},
author = {Simpson, D R},
abstractNote = {A backfill material is one of the multiple barriers that may be involved in the disposal of nuclear waste. Such backfill should be a desiccant with the hydrous product having acceptable stability; it should sorb any released radioisotopes, and it should reseal any breached site. The backfill must also have acceptable thermal conductivity. This report presents data on the rate of hydration and the nature of the product of reaction of some candidate backfill materials with water and with brine. Thermal conductivity data is reported for both the reactants and the products. Granular MgO at 150/sup 0/C completely hydrates in less than 10 hours. At 60/sup 0/C and 20/sup 0/C, such extensive hydration requires about 100 and 1000 hours, respectively. The product of the reaction is stable to more than 300/sup 0/C. A doped discalcium silicate was less reactive and the product contains less water of crystallization than the MgO. The reaction product of dicalcium silicate is cementous, but it has low thermal stability. Bentonite readily reacts with water and expands. The reaction product has the properties of vermiculite, which indicates that magnesium ions have diffused into the bentonite structure and are not simply adsorbed on the surface. If bentonite is emplaced in a saline environment, the properties of vermiculite, the reaction product, should also be considered. The thermal conductivity of MgO, discalcium silicate, and bentonite is primarily dependent on the porosity of the sample. A slight increase in thermal conductivity was found with increased temperature, in contrast to most rocks. If the conductive data for the different materials is equated to the same porosity, MgO has the superior thermal conductivity compared to bentonite or discalcium silicate.},
doi = {10.2172/6105653},
url = {https://www.osti.gov/biblio/6105653}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun May 01 00:00:00 EDT 1983},
month = {Sun May 01 00:00:00 EDT 1983}
}