Looks like an issue that neither has talked about much. This talks about a discussion that their advisors had.
Environmental Capital - WSJ.com : Climate Politics: For Once, No Hot Air
Douglas Holtz-Eakin, policy director for Sen. McCain, said nukes can’t be left out. ‘The Senate Majority leader is the problem—we have Yucca Mountain [storage facility], we have the technology. I can’t see why we don’t take advantage of that,” he said.
Jason Grumet, Sen. Obama’s energy adviser, appeared to leave the door cracked open—at first. “We have to overcome the problem, which is that renewable energy alone won’t do it,” he said. But, ticking off nuclear’s worries on his fingers—like safety, storage, and proliferation—he rushed to disavow “current nuclear” technology.