When the nuclear industry looks at the Bush administration's initiatives to promote a new generation of nuclear power plants, it sees a giant dollar sign. Critics see a giant mushroom cloud. For investors and taxpayers, who will have to pony up the cash, the sign may be a giant question mark.

No one has placed an order for a nuclear plant since 1973, but a House-Senate conference committee is weighing an energy bill that includes a clutch of proposals to revive the moribund industry. No matter what bill comes out, however, financial experts and the companies that would order such plants predict that regulatory hurdles and economic risks mean the launch of new plants is at least a decade away -- if ever.

"Moody's would go bananas if we announced we were going to build a nuclear plant," said Thomas E. Capps, chief executive officer of the energy company Dominion Resources Inc., referring to the reaction of credit-rating institutions.

Virginia-based Dominion, which serves nine states and operates four nuclear plants, is among the handful of companies considered most likely to want to build a plant. Capps said the nation should invest more in such plants, but he held out little hope that that would happen without greater incentives than those being discussed on Capitol Hill.

The Department of Energy splits with industry the cost of selecting sites for new plants. Various proposals in the energy bill would have taxpayers share the cost of licensing the first generation of new plants, offer loan guarantees and set caps on industry liability in an accident. A proposal by the White House would protect investors against regulatory holdups by defraying the cost of certain types of delays. Some legislators would give the industry protection against fluctuations in the price of electricity.

Advocates in Congress say such measures are justified because nuclear energy can help reduce the country's dependence on foreign oil, because nuclear energy seems ever more viable as oil prices soar, and because nuclear power does not produce greenhouse gases that are linked to global warming.

Capps said the proposed incentives do not go far enough.

"A new 1,400-megawatt nuclear power plant is going to cost about $2.6 billion," he said. "It is going to take 61/2 years to build. While you are building, you have to issue equity, you have to service that equity. You have to issue bonds; you have to service the bonds with interest. You don't have any money coming in. You have an average of $1.3 billion out for 61/2 years that is not earning anything."

"We are not going to build one under those financial conditions," he said.

Capps said his main concern is that anti-nuclear activists would tie up the approval of new plants through court challenges, and that such delays would cause unacceptable financial risks. If the nation thinks nuclear power is important enough, he said, Congress ought to eliminate the possibility of lawsuits and decree that the federal Nuclear Regulatory Commission (NRC) will be the final arbiter of concerns raised by the public.

Critics of the new initiatives say the federal government has a long history of subsidizing the nuclear industry, and warn that the proposals would hurt taxpayers -- and undermine public safety.

"If you throw enough money to build four, five power plants at industry, four, five plants may get built, but no one should confuse that with an economically healthy revival of nuclear power," said former NRC commissioner Peter Bradford, an energy policy consultant at Bradford Brook Associates in Vermont.

Anna Aurilio, legislative director at U.S. PIRG (Public Interest Research Group), an anti-nuclear environmental and consumer group, said improving energy efficiency would be seven times as cost-effective as building new nuclear plants. Although nuclear power plants do not emit greenhouse gases, radioactive waste remains dangerous for long periods -- making nuclear energy an unattractive approach to deal with global warming, she said.

Both supporters and critics of the nuclear industry noted that continuing delays over the opening the government's long-term nuclear waste storage plant at Yucca Mountain in Nevada add to the problem. One industry group has sought to build a temporary storage site on the land of the Skull Valley Goshute tribe in Utah, but this proposal has been bitterly opposed, including by states through which the waste would have to pass.

Arjun Makhijani, president of the Institute for Energy and Environmental Research, a nonprofit advocacy group, said it would be dangerous for the government to promise compensation for regulatory delays.

"It puts a lot of pressure on the NRC to hand out licenses, because it will be under pressure financially," he said of the Bush risk-insurance proposal. "Any form of risk insurance to compensate the industry for delays in the licensing process would be very detrimental to safety."

Bradford said market forces, not government incentives, ought to decide which energy sources the nation develops.

"I can tell you with some confidence that it is not sensible," he said. "Picking technological winners is the kind of foolishness that Republicans regularly accuse Democrats of in other areas."

But Wall Street and the nuclear industry say the high capital costs of nuclear power plants, their security needs and the nation's long-term energy needs make it essential that the federal government actively support new plants.

Marvin Fertel, chief nuclear officer at the Nuclear Energy Institute, an industry group, said the average age of the nation's 103 nuclear plants is 22 to 23 years. The oldest plants were built in the 1950s, and it is time to bring a new generation of plants online, he added.

New techniques in design and construction make it possible to standardize plants and make them safer, he said. Although taxpayer support will be crucial for the first few plants, private money would build subsequent plants because investors would see that the regulatory and political climate was receptive, he said.

Caren Byrd, executive director in the global power and utilities group at Morgan Stanley, agreed that for the first time in a long time, Wall Street believes new nuclear plants could be part of the nation's long-term future.

"But without something that indicates a federal policy, it will be difficult," she said. She recalled the fate of the Shoreham nuclear plant in New York, which was shut down after construction in 1985 because of public opposition. Dozens of plants were canceled in the 1980s, and others were plagued with cost overruns as a result of delays. "Tens of billions went down the drain that time," Byrd said.

"We can't take that risk, and the investment community has long memories," she said.

Nuclear Regulatory Commission Chairman Nils J. Diaz said regulations adopted in 1992 ensure that companies that get a license to build a plant will receive an operating license. Companies will have to show the plant was built according to specifications, but new rules ensure that operators will not have to wait for an operating license after sinking billions into construction, he said.

Diaz said some companies were thinking about applying for licenses by the end of 2007 or early 2008. The commission would take as long as three years to approve such applications, Diaz said. Given that construction would take several years, the earliest that new plants could become operational would be around 2015.

Marilyn Kray, president of NuStart Energy Development, a consortium of nine utilities that is considering filing applications for two nuclear plant licenses, acknowledged that much could change in a decade. The companies she represents are optimistic about nuclear power plants, she said, but would ultimately decide which energy sources to explore depending on changes in the economic, financial and political climate.

"There is guarded optimism at this point," she said. "From a power company perspective, you say I am open as long as it is good for the shareholders."

Delays in the opening of the long-term nuclear waste storage facility at Yucca Mountain, Nev., add to the uncertainty of building new nuclear plants.