Some Aspects of Ground-Water Solution Chemistry, Underground Nuclear Explosion Zones, Nevada Test Site 1
Silicate melts formed by contained underground nuclear explosions in silicate media scavenge most of the explosion-produced radionuclides and form bodies of radioactive glass at the base of collapse rubble chimneys. The glass may react with ground water, resulting in transfer of radioactivity to water, a possible means for radiocontamination of ground water at Nevada Test Site. Leaching experiments have investigated the transfer of radionuclides from glass to ground water.
Glass from the Rainier test in Tertiary tuff was broken and graded into size fractions which were sequentially equilibrated for two days and 56 days with water prepared to simulate the sodium bicarbonate ground water of the tuff. A small but constant amount (about 1 × 10−3 percent) of alpha and beta radioactivities of the glass was dissolved for particle fractions above 500 microns. Below 500 microns, dissolved radioactivities were higher and increased progressively with decrease in particle size. The first equilibration released more radioactivity than did the second equilibration. Dissolution characteristics are correlative with specific surface areas of the glass determined by the BET gas (argon, nitrogen) adsorption method.
Results indicate that ground water in silicate rock testing media may dissolve radioactive material from explosion glass to a degree that is of relevance to contamination of water supplies. Further work is required to understand fully the glass-water interactions and to develop means for quantitative estimation of in situ transfer of radioactivity from glass to water.