"RETHINKING" LOW-LEVEL RADIOACTIVE WASTE DISPOSAL

Approximately 15 years ago, the National Academy Press published “Rethinking High-Level Radioactive Waste Disposal”. The principles developed there could and should be equally applicable to low-level waste disposal. Since the present methods of low-level waste disposal are legally prescribed, this paper deals with what should be done when the present landfills fail. The objective would be to incur the lowest social costs-minimizing the public, worker, environmental and economic impact. Since our knowledge of the future is imperfect, we cannot know the state of the science nor of the public health in the future. Therefore, we cannot design the perfect covers or liners lasting 300 to 1000 years or more. We should design the simplest replacement of covers and liners or their equivalents. We should also take into account the state-of-the-art in monitoring devices as this will determine how much prevention and at what cost and how much remediation and at what cost should be anticipated. This assumes that thermodynamically stable forms are too expensive and exogenous events continue to occur. The state-ofthe-monitoring devices could include instruments such as chemical analysis on in-situ chips and nanotechnology allowing in-situ flow monitors that almost do not impinge on flow paths. In addition, the rise of human biomonitoring of environmental chemicals should be taken into account. After failure of the initial design, one needs to redo the risk analysis taking into account the reduction or increase in the source term, the changes in hydrogeological conditions, changes in the concentrations in the environmental media, new monitoring and remediation techniques, changes in expected ecological end states, changes in medical sciences, new laws and regulations and changes in social conditions and expectations at that time. It is strange that at this time, 20 years after the low level waste regulations, 10CFR61, were issued that there is no conceptual mathematical model that is peer reviewed and validated against data that takes all of the relevant processes, such as the performance of the covers and liners, into account. It is also extraordinary that present regulations, 40 CFR197, do not allow one to take into account changes in the human condition such as diet changes and the battle against cancer over these future time periods. New designs for arid regions would differ substantially from those for humid regions. These designs would take into account the principles developed in the “Rethinking” report and advice such as Occam’s Razor, simplify. The simplest and most easily replaced designs that would still meet regulatory requirements, whatever they would be, would be used. At present, the evapotranspiration design would be chosen. We can not now determine what would be the best design in the future. Because liner replacement would almost certainly be more hazardous than the consequences it is designed to prevent and the costs would not be commensurate with the benefits, berms and cutoff walls would be substituted instead, if needed. For humid regions, “impermeable” covers would be installed and berms and permeable reactive barriers added, if necessary. Scenarios taking into account changes in the hazards of the present system over time are being developed. The costs, benefits and risks for these new designs over time would be calculated. The costs, benefits and risks for these new designs would be compared with the legally mandated design at that time. The objective would be to protect real people from real risks over time rather than hypothetical people from hypothetical risks some time in the distant future.