The nuclear industry has started a new lobbying effort, hiring three former senators — Evan Bayh, an Indiana Democrat; Judd Gregg, a New Hampshire Republican; and Spencer Abraham, a Michigan Republican and a former energy secretary — and William M. Daley, a former chief of staff to Mr. Obama. The group, called Nuclear Matters, has begun an advertising campaign in major newspapers. So far, the group does not appear to have a strategy beyond raising awareness, or, as Mr. Bayh said in an interview, “starting a national conversation.”

An antinuclear group based in Washington, the Nuclear Information and Resource Service, referred to both Nuclear Matters and the Center for Climate and Energy Solutions as “de facto nuclear industry front groups” and said the groups were trying to create a false impression that environmentalists were warming to nuclear power.

Many reactors now fall into the category of “merchant generators,” which means their only income is whatever they can get by selling their electricity in markets depressed by the recession and cheap gas. So there are no clear options for preserving old reactors without a carbon tax or similar incentive for zero-carbon generation. But the paper’s co-author, Douglas Vine, said one option could be rules the E.P.A. is planning to issue that would force existing coal-fired plants to cut their carbon dioxide output.

Mr. Vine said that with some new form of carbon trading, coal-fired power plants obliged to cut their output might comply by paying for new nuclear production, or continued production from a nuclear reactor that would otherwise have had to close. Those coal plants could take credit for zero-carbon electricity to blend in with their own high-carbon production. But the idea faces regulatory obstacles, he said, among them ensuring that any nuclear production that the coal plants might subsidize was not going to happen without such a deal.

Mr. Vine said that closing reactors was a step back for climate stabilization. “Part of its problem is that it’s not new. It’s taken for granted. It’s just assumed it’s going to be there, providing this reliable, zero-carbon energy source,” he said. That proved not to be the case when the power company Dominion said it was closing the Kewaunee reactor in Wisconsin, which was running well and had no political opposition but was losing money. “One day we woke up and saw Kewaunee was closing,” he said.