Single-Pass Leaching of Nuclear Melt Glass by Groundwater

Abstract

The work presented in this report was supported by the Department of Energy (DOE) through the Nevada Operations Office (NVOO) as part of the Radionuclide Migration Program at the Nevada Test Site (NTS). The purpose of this program is to inves tigate the potential for underground migration of radionuclides in groundwater from the sites of underground nuclear explosions. Borg et al. have comprehensively reviewed this subject and have included an annotated bibliography (1). Levy (2) discusses in detail the specific aspects of an underground nuclear explosion which are relevant to radionuclide contamination of the ground water.The technology required to study the NTS groundwater problem is very similar to that required for studying the geo logic disposal of high-level vitrified nuclear reactor wastes.The energy crisis of the 1970's has emphasized the need for nuclear power and consequently there is considerable interest in developing an environmentally-acceptable means for disposing of the resultant nuclear wastes. deMarsily et al. (3) have discuss ed the feasibility for geologic disposal of nuclear wastes and have concluded that ion exchange with the rock surrounding the repository is the most important barrier between the waste and the biosphere. The Study Group on Nuclear Fuel Cycles and Waste Management of the American Physical Society (4) concluded that the management of nuclear waste was well within existing techno logy and that economic and political questions provided the greatest problems for nuclear energy use. They also state that hydrogeologic transport is the most likely route for contamina tion of the biosphere by a waste repository.Information on the interaction of radionuclides with ground water in deeply-buried, high-level, long-term "waste repositories" is available at only a few locations. One is the OKLO natural reactor in Gabon which has for over 1.7 billion years retained some of the radionuclides also present in nuclear wastes (5). Another is the Nevada Test Site, where radionuclides were first deposited underground on September 19, 1967 during the 1.7 kt 0-8412-0498-5/79/47-100-093$05.50/0

Evaluation of the hydrologic source term from underground nuclear tests in Frenchman Flat at the Nevada Test Site: The Cambric test

“…matrix dissolution (most of the Na data greater than 10 −3 are for times earlier than 5 days). Therefore our predicted value of 10 −3.3 is in fair agreement with long-term glass dissolution rates based on Coles et al (1978). Failor et al (1983) did further flow-through tests on the Cambric glass under similar conditions, but included longer test durations.…”

“…There are two reports which provide the rate of release of elements from the Cambric melt glass in flow-through dissolution tests. Coles et al (1978) report release rate data at 25…”

“…Note that in both the Coles et al (1978) and Failor et al (1983) reports, the material tested was hand-picked glass grains, crushed and sieved to a 40-150 micron size fraction. Powder x-ray analysis showed that from 65-100% of the material was glassy, the rest being various proportions of silica and feldspar phases.…”

“…During the solution process, the U j and U im j are generally decomposed according to equations (19) and (20) such that the mass action phenomena in the aqueous speciation or surface complexation reactions can be explicitly incorporated. In this sense, the abundance of surface complexation sites on the minerals can be specified and used to control the overall partitioning of species between the aqueous and solid phases.…”

Hydrologic resources management program and underground test area operable unit fy 1997

“…An earlier study by Essington and Sharp (1968) studied the 2 day and 56 day equilibration of debris from the 1957 RAINIER with synthetic sodium bicarbonate groundwater to investigate the nature of radionuclide release and dependence of particle size. Coles et al (1978) reported initial 120 day results of a single pass leaching of a single nuclear explosive melt glass using bicarbonate groundwater from well 5B at the Nevada Test Site; Failor et al (1983) reports on the final results of the same experiment for a 420 day leaching trial for three melt glasses. Batch leaching experiments of nuclear explosive melt debris using bicarbonate water from NTS well J-13 and deionized water has been reported by Thompson (1990Thompson ( ,1991Thompson ( , and 1994.…”