Gasoline prices in the future will not be controlled and the government will not allocate supplies except in case of a "severe, critical shortage," Energy Secretary James Edwards said yesterday.

In an interview, the former South Carolina governor all but ruled out any interference with the market during most supply interruptions and turned thumbs down on rationing as a way to allocate fuel. "It was a horrible situation" in World War II, he recalled. "The black market goes rampant. I hope that would be the last thing we'd ever come to."

Instead, Edwards said DOE is rewriting oil-shortage contingency plans inherited from the Carter administration in ways to maximize reliance on the market.

The lack of a free market during past fuel shortages was one reason for long gasoline lines, he argued. In a future cutoff, he said, "I would let the market run free. . . . Private sector forces . . . can allocate better than any of us here in Washington can do." But in "severe, critical shortages, then the government would have to take over and allocate," he said. "In a warlike situation, to the armed services, for example."

Edwards also reaffirmed the Republican administration's commitment to foster the reprocessing of spent nuclear fuel on a commercial basis. "President Reagan is in favor of reprocessing," he said. "He has made that decision."

And he said he has made no decision on the complex question of whether to speed dereguation of natural gas beyond what is already called for by law. Responding to reports that David Stockman, director of the Office of Management and Budget, says such a decision has been made, Edwards declared: "It may have been made; it hasn't been made here."

The secretary also defended the latest administration budget proposals, including the major cuts in spending for solar and fossil-fuel research and commercialization, on the grounds the department will still be spending just as much on them as on nuclear energy.

The free-market allocation approach appears to follow recommendations from the National Petroleum Council's Energy Preparedness Committee, which was to vote yesterday on such a plan. However, smaller oil companies without their own crude oil sources complained that a failure to allocate crude oil among refiners when there are shortages could put them out of business. The NPC report "might be the plan we would take and start working from," Edwards said. "Some things I like about it and others I would change."

The secretary confirmed that he had gone through "a rather extensive discussion" with the Office of Management and Budget on the size of DOE funding for nuclear energy programs, but he said he lost on only one item: a proposal to fund $35 million in research at the unused nuclear reprocessing plant at Barnwell, S.C. "We have time to do that later on," he said.

Reports that he wants DOE to buy the $362 million plant had misinterpreted his use of the word "acquire," Edwards said. "Some of the utility people are saying, 'Let's get together and buy Barnwell and give it to the government,'" he said. Edwards added that the idea is still in the talking stage, a remark confirmed by industry spokesmen.

Tom Kuhn, vice president of the American Nuclear Energy Council, said the idea is "very much in the gestation phase" and that most major questions of financing and organization had not even been discussed. Other industry sources said the proposal, wholly Edwards' idea, would take years of negotiations among participating firms, the government and state public utility regulators for what is widely considered an obsolete plant. The current budget fails even to include the annual $11 million that Congress had routinely appropriated to keep the place running.

Some groups, such as the Consumer Energy Federation of America, have attacked the DOE budget as strongly pro-nuclear, and have called for similar cuts in programs dealing with different types of energy sources rather than having the cuts concentrated outside the nuclear area.

Edwards, who stressed he doesn't "want to be labeled a 'nuclear' person," said DOE funding for nuclear development programs other than fusion energy is comparable to funding for solar energy development and conservation when current tax credits are counted.