By MATTHEW L. WALD WASHINGTON, June 18 — To provide more electricity and less carbon emission, the Bush administration has revived talk of nuclear power, with top officials discussing the possibility of hundreds of new reactors. But it has been nearly 30 years since the last plant was ordered in the United States, and whatever policy makers say, ending that drought will largely depend on three numbers, industry experts argue: $5 natural gas; $1,000 capital expenses; and storing 77,000 tons of radioactive waste. And there is substantial doubt that those numbers are realistic. The last item, waste storage, is getting new attention as the Energy Department tries to determine whether Yucca Mountain, about 90 miles from Las Vegas, is suitable for a long-term repository. And the change of power in the Senate brings a fierce Yucca opponent, Harry Reid, Democrat of Nevada, to the position of deputy majority leader. But whether Yucca can be built and accept 77,000 tons of waste — the amount it is supposed to accept in coming years — is not the only prerequisite for the industry to start again. "Yucca is a necessary, but insufficient, condition," said David Morris, a Minneapolis electricity expert who does not favor nuclear power. He and others, including people who want new reactors, say the industry needs a licensing system that will not subject reactors to the last-minute problems that increased costs on the current batch. But most of all, they say, the industry needs plants that are far cheaper to build than even the current optimistic estimates suggest. A permanent increase in the price of natural gas would also be nice, along with a consensus that the other competing fuel, coal, is too dangerous for the global climate. For the nuclear industry, the problem most under its control is the reactor's price. The people who want to sell reactors do not yet have an acceptable new design on the market but say they can develop one to compete with natural gas. The Nuclear Energy Institute, a trade association, says that reactors would have to sell for no more than $1,000 for each kilowatt of generating capacity — an industry measure. (A kilowatt is the amount required to keep 10 bulbs of 100 watts each lighted; a kilowatt-hour, the typical unit on a homeowner's bill, would keep those bulbs lighted an hour.) That $1,000 is substantially more expensive than natural gas plants, which make up about 90 percent of the power plants built the last five years and sell for $500 or $600 for a kilowatt of capacity. But reactors are less costly to run because uranium is cheap, while a million B.T.U.'s of gas — enough to generate about 170 kilowatt-hours in the most efficient plant — will sell for $4 to $5 over the next few years, the nuclear industry says. In briefings for Wall Street analysts, the Nuclear Energy Institute has said that reactors at $1,000 a kilowatt produce electricity more cheaply than do gas plants when gas hits $5 for a million B.T.U.'s; Westinghouse Electric, which hopes to sell new reactors, says the figure is $4. Not counting some recent sharp spikes in California, gas has been in the $4 range lately, double what it was two years ago, and has sometimes surpassed $5. But some people doubt whether gas will stay that high for long. Among them is William T. McCormick Jr., chairman and chief executive of CMS Energy, which operates the Palisades nuclear plant in Michigan and runs a system of natural gas pipeline and distribution companies. It owns the largest terminal in North America for unloading ships carrying liquefied natural gas from abroad, in Lake Charles, La., which it is doubling in size, and is also trying to build terminals in Mexico. If the price stays at $5, "on a long- term basis, you can find an awful lot of gas," Mr. McCormick said in an interview. And if drillers find a lot of gas in North America, he added, the price will come back down. And he said imported liquefied natural gas could be found for little over $3 for a million B.T.U.'s. Indonesia, Australia and countries in the Persian Gulf region and on the west coast of Africa will all drill, liquefy and export for that price, he said, and their supplies are vast. And is it possible to build a reactor for $1,000 a kilowatt? Some of the 103 now in service cost more than triple that amount — even more in today's dollars. But proponents are counting on more efficient building techniques and lower interest costs. Westinghouse Electric spent much of the 1990's designing a reactor that would be easier to build and operate. It wanted fewer moving parts and more parts that could be assembled at a factory instead of in the field, cutting construction costs and reducing quality questions. The plant, called the AP-600 — for advanced passive, 600 megawatts — would have cost $1,400 to $1,500 a kilowatt, the company said, but the real number is uncertain because none were ordered. Similarly, General Electric designed the Advanced Boiling Water Reactor, which it said would sell for $1,400 to $1,600, "depending on the host country," but nobody in the United States ordered one either. Now Westinghouse is redesigning the AP-600 as a 1,000-megawatt plant. That increase in capacity, it says, will raise capital costs only 10 percent, bringing the capital cost per kilowatt down to $1,000. But that cost, Westinghouse says, can be brought that low only after builders get practice putting up plants efficiently. "We're quite comfortable in competing with both gas and coal," said Charles W. Pryor, chief executive of Westinghouse Electric — now a subsidiary of BNFL, the former British Nuclear Fuels. The plants would largely be built in factories to cut costs and quality problems, Mr. Pryor said, and legal questions would be settled before construction started. In fact, the Nuclear Regulatory Commission has already revised its licensing process, although no one has tested it. There is some belief that not all the energy eggs should go in the natural gas basket. The Georgia Public Service Commission, for example, regularly requires utility companies to ask for bids from outside companies to provide new plants. This year the commission demanded that Georgia Power, the biggest utility in the state, mention nuclear and coal in its requests for proposals. One idea, said Daniel R. Cearfoss, a staff engineer for the commission, is fuel diversity. The commission would like to know how much extra it would cost to hedge the state's energy bets by building plants that would use uranium or coal. But Mr. Cearfoss said that he doubted anyone would propose a nuclear plant, and that even if someone did, the bid would be hard to evaluate because there was no modern track record for construction costs. Georgia, however, is often cited as a possible ice-breaker for nuclear power; its twin-unit Vogle plant has space for four reactors, and the betting among experts is that if another reactor is ordered, it will go next to an existing one. The Southern Company owns Georgia Power, along with Alabama Power, Mississippi Power and Gulf Power, and operates six reactors. Laura Gillig, a spokeswoman for Southern, said that even though nuclear power "is going through some sort of renaissance, it still needs that public support." "And," she added, "it does need to be competitive." Copyright 2001 The New York Times Company