Critique of the National Academy of Sciences Study of the Isolation System for Geologic Disposal of Radioactive Waste

Abstract

The 1983 report of the Waste Isolation Systems Panel of the National Academy of Sciences (referred to as NAS-83) introduces a solubility limited dissolution (SLD) theory to estimate release rates from high-level radioactive waste packages. It is pointed out that this theory, as presented, should apply equally well to each grain of average rock, but that when applied to that problem, it overpredicts the observed dissolution rate of SiO/sub 2/ by seven orders of magnitude. The SLD theory also predicts that cesium and other trace elements are leached out of rock grains orders of magnitude more rapidly than the SiO/sub 2/; it is shown that this is clearly contrary to the experimentally observed situation. Other shortcomings of the NAS-83 treatment are pointed out. Modifications to the theory that avoid these large discrepancies are suggested; when applied to the waste problem, they pose some very important questions that should be answered before proceeding with waste management problems. For example, they suggest that reprocessing may reduce the hazards from waste by a factor of 10 million, and that synroc may be millions of times more secure against leaching than waste glass.