Prerequisites For Radioactive Waste Management
Hannes Alfvén, Nobel laureate in physics, described the as yet unresolved dilemma of permanent radioactive waste disposal:
“The problem is how to keep radioactive waste in storage until it decays after hundreds of thousands of years. The deposit must be absolutely reliable as the quantities of poison are tremendous. It is very difficult to satisfy these requirements for the simple reason that we have had no practical experience with such a long term project. Moreover permanently guarded storage requires a society with unprecedented stability.”
Thus, Alfvén identified two fundamental prerequisites for effective management of high-level radioactive waste: (1) stable geological formations, and (2) stable human institutions over hundreds of thousands of years. However, no known human civilization has ever endured for so long. Moreover, no geologic formation of adequate size for a permanent radioactive waste repository has yet been discovered that has been stable for so long a period.
Because some radioactive species have half-lives longer than one million years, even very low container leakage and radionuclide migration rates must be taken into account. Moreover, it may require more than one half-life until some nuclear waste loses enough radioactivity so that it is no longer lethal to humans. Waste containers have a modeled lifetime of 12,000 to over 100,000 years and it is assumed they will fail in about two million years. A 1983 review of the Swedish radioactive waste disposal program by the National Academy of Sciences found that country’s estimate of about one million years being necessary for waste isolation “fully justified.”
The Nuclear Waste Policy Act did not require anything approaching this standard for permanent deep-geologic disposal of high-level radioactive waste in the United States. U.S. Department of Energy guidelines for selecting locations for permanent deep-geologic high-level radioactive waste repositories required containment of waste within waste packages for only 300 years. A site would be disqualified from further consideration only if groundwater travel time from the “disturbed zone” of the underground facility to the “accessible environment” (atmosphere, land surface, surface water, oceans or lithosphere extending no more than 10 kilometers from the underground facility) was expected to be less than 1,000 years along any pathway of radionuclide travel. Sites with groundwater travel time greater than 1,000 years from the original location to the human environment were considered potentially acceptable, even if the waste would be highly radioactive for 200,000 years or more.
Moreover, the term “disturbed zone” was defined in the regulations to exclude shafts drilled into geologic structures from the surface, so the standard applied to natural geologic pathways was more stringent than the standard applied to artificial pathways of radionuclide travel created during construction of the facility.
Read more about this topic: Nuclear Waste Policy Act
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