Huge Energy Measure OKd by Conferees : Congress: Opposition from environmentalists and outraged Nevada senators could still prevent final approval.

After a marathon session, House and Senate negotiators reached an agreement early Thursday on legislation to establish a new national energy strategy that its supporters say would reduce oil consumption and change the way electricity is generated in the United States.

Nearly two years in the making, the massive, 1,300-page bill is designed to effect major changes in the way domestic energy is produced and consumed by expanding the use of nuclear power, increasing conservation through new efficiency standards for most electrical products and encouraging the development of both renewable and alternative fuels.

Supporters of the bill--which, although a patchwork of hard-fought compromises, is still the most comprehensive energy legislation to come out of Congress in 15 years--said that the combined effect of its many technical provisions should eventually reduce domestic consumption of oil by between 5 million and 7 million barrels a day.

“This bill is historic,” declared one of its chief authors, Senate Energy Committee Chairman J. Bennett Johnston (D-La.). “It provides for a revolution in the way we generate electricity . . . a revolution in alternative fuels . . . and the most extensive energy efficiency and conservation provisions ever enacted.”

But the mammoth energy bill--sometimes compared to a giant supertanker navigated through treacherous shoals--faces at least one more legislative squall before it can be brought to the floor for final passage by the House and the Senate in the closing days of the legislative year.

The latest controversy concerns a technical provision, added by the House-Senate conference committee, that opponents fear would make it easier for the Department of Energy to build a high-level nuclear waste dump at Yucca Mountain in Nevada, about 100 miles northwest of Las Vegas.

Denouncing that and other 11th-hour compromises as “giveaways” to the nuclear power industry, environmentalists turned against the bill and joined with Nevada’s two angry senators in an effort to defeat the measure if what they called the “screw Nevada” provision is not removed.

“The good things in the bill just don’t outweigh the gifts to the nuclear industry, and we are going to have to oppose the bill,” said Melanie Griffin, energy program director for the Sierra Club, which had supported earlier versions of the bill.

A spokesman for Sen. Richard H. Bryan (D-Nev.) said that he and Sen. Harry Reid (D-Nev.) will try to filibuster the bill when it comes to the Senate floor and might even seek to disrupt the passage of other legislation unless the Yucca Mountain provision is changed.

“It’s unfortunate, but the only way we see of working something out on this bill is by grinding everything to a halt,” the spokesman said.

While Bryan does not have enough support to sustain a filibuster, forcing a procedural vote to end one could delay final passage of the bill at a time when Congress is rushing to complete its work before adjourning on Monday or Tuesday.

The provision Bryan wants removed would allow the Environmental Protection Agency to draw up a special set of disposal regulations governing radioactive emissions from the high-level waste that the Energy Department wants to deposit at Yucca Mountain. The regulations in turn would be based on guidelines to be formulated by the National Academy of Sciences.

That plan, opponents fear, is meant to make it easier for the department to use the Yucca site, because the new regulations are expected to be more lenient than the EPA might otherwise draft.

Although the nuclear waste dispute is the only one still threatening final passage of the bill, several other last-minute changes made by the negotiators also have triggered controversy.

One of them, a compromise on alternative fuels, pushed back the deadlines set in a tougher Senate bill for privately owned fleet vehicles to phase in the use of non-gasoline fuels. Under the compromise, private fleets of more than 50 cars or buses will have to begin purchasing alternatively fueled vehicles in 1999 and will have until the year 2006 to meet a requirement that 70% of the new vehicles they purchase be alternatively fueled. In the Senate’s original bill, the phase-in would have occurred between 1998 and the year 2000.