Materials Interactions Relating to Long-Term Geologic Disposal of Nuclear Waste Glass

Abstract

In the geologic disposal of nuclear waste glass, the glass will eventually interact with groundwater in the repository system. Interactions can also occur between the glass and other waste package materials that are present. These include the steel canister that holds the glass, the metal overpack over the canister, backfill materials that may be used, and the repository host rock. This review paper systematizes the additional interactions that materials in the waste package will impose on the borosilicate glass waste form-groundwater interactions. The repository geologies reviewed are tuff, salt, basalt, and granite. The interactions emphasized are those appropriate to conditions expected after repository closure, e.g. oxic vs. anoxic conditions. Whenever possible, the effect of radiation from the waste form on the interactions is examined. The interactions are evaluated based on their effect on the release and speciation of various elements including radionuclides from the glass. It is noted when further tests of repository interactions are needed before long-term predictions can be made.

SRL in-situ tests in the United Kingdom: Part 2, Surface analyses of SRS waste glass buried for one and two years in limestone at Ballidon, UK

“…Among these samples are 'pineapple slices' of SRL 165/TDS, 131/35% TDS, ARM-l, and basalt glasses. These are the samples evaluated in the present study and are the same compositions used in other in-situ testing programs [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. In another study, the performance of these glass and waste glass systems in field tests involving different geologic media will be compared.…”

“…A multiphase experimental program to assess and understand waste glass behavior under a wide range of conditions has been in progress at the Savannah River Laboratory (SRL) for over a decade [3,4]. An important part of this experimental effort is to assess the effects of repository--re!evant conditions on performance of SRS waste glass, in both controlled laboratory tests, as well as in actual field experiments [5][6][7]. In laboratory tests, SRS waste glass, simulated and in many cases also fully radioactive, has been tested in environmen, _ of salt, basalt, shale, granite, clay and tuff.…”

Methods of calculating the post-closure performance of high-level waste repositories

“…Thus presently, an accurate description of the gas phase present in the vicinity of the tuff waste package can not be made. Bibler and Jantzen (1987) particularly mention a need for concern for HN03 production in moist air.…”

“…The effects of radiation, both gamma and alpha (after loss of containment), on the packing material and host rock should be inconsequential on basalt (see Bibler, 1985 andReed et al, 1985), but for salt, irradiation and heat could produce corrosive species that might effect canister corrosion and waste form leaching (see Pederson et al, 1984). The possibility of nitric acid formation in the moist air of the unsaturated tuff repository and subsequent enhancing effects on container corrosion also warrants attention (see Bibler and Jantzen, 1987;Reed and Van Konynenburg, 1988).…”