Nuclear power is the source of 19 percent of the electricity generated in the United States and 15 percent in Canada, making up a significant percentage of each country’s share of energy derived from non-fossil-fuel sources. Producing this electricity generates waste in the form of highly radioactive spent fuel and other nuclear waste that, while less radioactive, still requires isolation from the biosphere.The challenges of finding a site for permanent disposal of spent fuel are well known. But disposing of waste that is less radioactive can be difficult as well, as Ontario Power Generation, or OPG, is finding out with its plans for a deep geologic repository less than a mile from Lake Huron. The repository, if licensed, could open by 2018. It would be the first permanent disposal facility for radioactive waste to operate in the Great Lakes basin.