Environmental Engineering Reference
In-Depth Information
Thus, Alfvén identified two fundamental prerequisites for effective management of high-level
radioactive waste: (1) stable geological formations, and (2) stable human institutions over hun-
dreds 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 (Vandenbosch
and Vandenbosch 2007, 10). 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 an
expected lifetime of 12,000 to over 100,000 years, depending on the design (USDOE 2002), 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 1 million years being necessary for waste isolation “fully justified” (Yates 1989, 33).
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. Department of Energy
guidelines for selecting locations for permanent deep geologic high-level radioactive waste reposi-
tories required containment within waste packages for only 300 years (USDOE 1984, 47767; 10
Code of Federal Regulations 960.2). A site would be disqualified from further consideration only
if groundwater travel time from the “disturbed zone” of the underground facility to the “acces-
sible environment” (atmosphere, land surface, surface water, oceans, or lithosphere extending no
more than ten kilometers from the underground facility) was expected to be less than 1,000 years
along any pathway of radionuclide travel (USDOE 1984, 47760; 10 Code of Federal Regulations
960.4-2-1[d]). Sites with groundwater travel time greater than 1,000 years from the original loca-
tion 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 (USDOE 1984),
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.
Nuclear waste repositories will be closed and sealed when their maximum capacity is reached.
Current repository closure plans require backfilling of waste disposal rooms, tunnels, and shafts
with rubble from initial excavation and sealing openings at the surface, but do not require com-
plete or perpetual isolation of radioactive waste from the human environment. DOE guidelines
contain no requirements for permanent off-site or on-site monitoring after closure. This may seem
imprudent considering repositories will contain millions of dollars' worth of spent reactor fuel
that might be recovered by legal or illicit means, reprocessed, and used again either in reactors
generating electricity, in weapons applications, or possibly in terrorist activities.
Previous experiences sealing mine tunnels and shafts have not been particularly successful,
especially where there is any hydraulic pressure from groundwater infiltration into disturbed
underground geologic structures. Historical attempts to seal smaller boreholes created during
exploration for oil, gas, and water are notorious for their high failure rates, often in less than fifty
years (D'Appolonia Consulting Engineers 1979).
In many European countries (e.g., Britain, Finland, the Netherlands, Sweden, and Swit-
zerland), the risk or dose limit for a member of the public exposed to radiation from a future
high-level nuclear waste facility is considerably more stringent than that suggested by the Inter-
national Commission on Radiation Protection or proposed in the United States. European limits
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