At IAH 2012, Dr. John A. Cherry, one of the world's foremost hydrogeologists, provided an excellent overview and critique of Canadian radioactive waste disposal. During his plenary on 20 September he examined the hydrogeologic history; current status; and made recommendations.
I looked forward to his talk, because in another life, I was involved with the Yucca Mountain site. I did not realize Cherry had been so involved with the nuclear waste issue, but was anxious to hear how a scientist of his stature addressed a most perplexing issue. I was not disappointed. I will do my best to summarize his talk.
He categorized Canada's nuclear power program as a successful one, with minimal groundwater impact. It is also an option in terms of minimizing GHGs. He noted that the CANDU (CANada Deuterium Uranium) reactor, a home-grown pressurized heavy water nuclear reactor, is well-known around the world. He also stated that Canada is the most nuclear-intensive country in the world.
But, like the US, Canada is searching for a final resting place for its high-level waste (HLW), now euphemistically called 'used fuel'. Their reactors are getting old and will require decommissioning. Permanent dry surface storage is not likely so as to not burden future generations.
Canada has fewer options for HLW disposal than does the USA. For example, thick unsaturated zones in arid regions are not available. The selected option is a Deep Geological Repository (DGR), 500-700m deep, in crystalline (granitic) or sedimentary rock that should retain its integrity for about one million years. The latter rock type is preferred by Cherry, although he described the granite 'rush to judgment' (my term, not his) as driving the Canadian approach until very recently.
Cherry first started in the nuclear waste disposal 'business' in the late 1960s while a professor at the University of Manitoba. He described his work at the Whiteshell site outside Winnipeg, where canisters were unexpectedly leaking and the site was becoming inundated in the spring. What to do?
So Cherry studied the groundwater flow system, which no one one had done. Turns out the clay beneath the site was fractured and the site was located in a groundwater discharge zone. In 1970 he recommended that the site be moved to a recharge zone. Bad move, you say? It will get into the groundwater system, but won't pond on the surface and contaminate the surficial environment. And, as was noted by Stephen Foster's 1975 paper, low-permeability media in which transport is diffusion-controlled are great places to store material that you do not want to move very far. That led Cherry to propose that low-K sedimentary rocks - unfractured shales, for example, would be better than granite and other plutonic rocks. The clay minerals in the shale would also provide an additional line of defense uncommon in granites: sorption of cationic radionuclides.
But the powers-that-were in the Canadian nuclear industry stuck by the granite option, even though there was no justification for it. Hydrogeologists/geoscientists were generally absent from the various commissions and committees examining waste options. The Nuclear Waste Management Organization (NWMO) did not have a hydrogeologist among its 29 members and the CNSC did not have a geoscientist on its 14-member board.
So, in Canada, after 35 years and $1B spent (by 2002), there was no record of how the granite DGR option was selected and no DGR.
In the USA, a 1978 report did not single out granite. A paper by J. Bredehoeft and T. Maini noted that crystalline rocks were often fractured. Cherry even noted that the Chinese had selected a remote site at the eastern edge of the Gobi Desert. But when their boreholes found fractures, they abandoned the site.
The Swedes, Finns, and Swiss, among others, had selected the granite option. But the Swedes and Finns now no longer claim that granite is a barrier although it is better than surface storage. They will use engineered granite repositories, using bentonite and copper canisters.
Cherry still supported the low-K, diffusion-controlled option, and noted that some Canadian nuclear power plants (e.g., Bruce) sit atop sedimentary rocks, so having a sedimentary low-K repository could mean little or no transportation for HLW.
The current status of the Canadian DGR quest:
1) in 2004, sedimentary rocks were added as an option; and
2) transparency and credible science are moving to the forefront.
1) How do you communicate the most credible science to the public; and
2) what scientific evidence is needed?
1) 'reword' the 1 million year promise;
2) have independent and transparent review;
3) have independent funding for research (e.g., NSERC); and
4) avoid misrepresenting science.
An excellent and comprehensive presentation in under an hour!
A final note - Cherry mentioned these publications as being useful:
Oreskes, Naomi, Kristin Shrader-Frechette and Kenneth Belitz, 1994. “Verification, validation, and confirmation of numerical models in the earth sciences,” Science 263: 641-646.
Oreskes, Naomi, 2004. “Science and public policy: What’s proof got to do with it?,” Environmental Science and Policy 7 (5): 369-383.
I also learned that Bill Alley, recently-retired Chief of Groundwater for the USGS, and his wife Rosemarie are about to publish, Too Hot To Touch: The Problem of High-Level Nuclear Waste.
Things are heating up!
"It's where voter registration is lowest." - John Cherry, (semi-facetiously) suggesting a rationale for selection of granite for HLW disposal.