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The Nuclear Waste Problem
Deep burial is not the solution
Debate concerning the disposal of high-level radioactive wastes produced by nuclear power plants in Ontario and elsewhere continues. Two arguments are presented here which oppose the AECL plan of burying the wastes in a body of granite located somewhere in the Canadian Shield. The arguments are a) all parts of the Earth are inherently unstable, and changes resulting from this instability, some of which could affect a repository at depth, are entirely unpredictable, and b) directions of progress in physics in the next few centuries are also unpredictable, and it is conceivable, if not likely, that a ‘solution’ to the waste problem will be found, which will make the concept of burial obsolete.
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The frequent occurrence of earthquakes virtually everywhere, including the Canadian Shield, is a constant reminder of planetary instability. Although at present the Shield is not intersected by a major earthquake zone, some large-magnitude earthquakes have occurred in the past century, for example at Lake Temiskaming in 1935 (magnitude 6.2) and at Cornwall in 1944 ( magnitude 5.6). Smaller earthquakes, which can be detected only by seismographs, are extremely widespread and frequent. Examples of other earthquakes that have occurred well within the North American Plate are the New Madrid (Missouri) earthquakes of 1811-12 of magnitude greater than 8. Although minor progress has been made in earthquake prediction, it is certainly not possible at present to select a site anywhere in the Shield, and state that a major earthquake will not occur at that site in the near or distant future.
In addition, vertical and horizontal movements are in progress. For example, an uplift of nearly 200 meters has occurred in the Southern Canadian Shield during the past 10, 000 years, resulting from melting of the continental ice sheet. Ten thousand years ago, ‘Toronto’ was 100 metres under water.
Both earthquakes and non-uniform uplift produce fractures, and cause the opening
of exiting fractures. I have studied plutonic rock in the Canadian Shield for
49 years, and wish to emphasize that all rock bodies are fractured, and faults
are also very common.
Similar findings have been reported by AECL geologists, who have studied fractures
in great detail, and found them to extend to depths of 1200 metres. (Stone et
al. 1989).
The openings are immediately filled with water, and based on isotopic data,
some of this is surface water. The movement of water to and from the surface,
through fractures and faults, in plutonic and other rock, is not fully understood,
and over a period of a few centuries is unpredictable. Depending on a) the width
of fractures, b) the rate of flow of water through the fractures, and c) the
degree of decomposition of the containers, a significant mass of radioactive
waste could be transported to the Earth’s surface and the Biosphere. Of
special concern is Iodine 129, with a half-life of 16 million years. (Wiles
2002).
Although volcanism on a large scale has not occurred in northeastern North
America for several millions of years, it is noteworthy that numerous swarms
of dikes criss-cross
the entire Canadian Shield. A gabbro dike forms when a fracture extends to a
depth of 30 kilometres or more, opens, and is filled by molten rock identical
in composition to volcanic basalt, such as that found at Iceland. Cooling then
results in crystallization. For example, one of the dike swarms extends from
Georgian Bay to north of Montreal; the largest dike is 100 metres wide. Immediately
north of Ottawa, dike formation has resulted in a north-south extension of 1
km, increasing the distance between present-day Ottawa and Maniwaki by this
amount. In places these molten bodies have approached the Earth’s surface
closely, and may have poured out onto the surface. These events are also unpredictable.
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We know from experience that materials referred to as ‘waste’ can, as a result of technology and public awareness, become useful. With regard to high-level nuclear ‘wastes’ some procedure analogous to transmutation, or some entirely new procedure could, in the future, reduce the toxicity of the wastes, or make them useful. This was pointed out repeatedly by Gordon Edwards (1987) and others. Indeed when we compare the physics of only 120 years ago, we find that changes that occurred in this short period of time are both enormous and unforeseen. From this point of view, the wastes could be stored at or near the Earth’s surface, where they would be readily accessible, for whatever period of time is needed.
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In summary, the Waste Management and Disposal Concept, as outlined by AECL scientists and NWMO personnel, must be examined more carefully in relation to the instability and unpredictability of the Earth, including the Canadian Shield. Also, more serious consideration must be given to an alternative plan, based on confidence in science, in particular in the potential for progress in Physics. This makes necessary a delay of an unspecified period of time, while science progresses to the point where it becomes possible to solve the nuclear waste problem, without resorting to deep burial.
Sources:
Montgomery, Carla. 1995. Environmental Geology. Wm.C. Brown.
Wiles, D.R. 2002. The Chemistry of Nuclear Fuel Waste. Polytechnique Int. Press.
Shrader-Frechette, K.S. 1993. Burying Uncertainty. University of California
Press.
Stone, D. et al. 1989. Canadian Journal of Earth Sciences 26, 387-403.
Edwards, G. 1987. Canadian Coaltion for Nuclear Responsibility, No.7, p.15.
Ralph Kretz, PhD ( Geology)
Retired professor, University of Ottawa.
197 Augusta St.
Sandy Hill, Ottawa.
K1N 8C2
Jan. 2005.