House and Senate conferees named Yucca Mountain, Nev., the site of the nation's first and only high-level nuclear-waste dump yesterday, scrapping a complex selection process established by Congress in 1982 in favor of a quick decision on a politically charged question.

The conferees agreed, as part of the $30.2 billion deficit-reduction bill, to drop consideration of dump sites in Texas and Washington state and begin studies at the Nevada site, about 85 miles northwest of Las Vegas. The legislation also would eliminate a requirement that the Energy Department identify a second nuclear dump site in an eastern state.

The legislation, which now goes to the Senate and House for approval, essentially tosses out a delicate compromise crafted five years ago to assure that science, rather than politics, would dictate placement of the nation's first nuclear dump.

The multibillion-dollar facility eventually will hold thousands of tons of radioactive military waste and spent fuel rods from nuclear power plants. The site must be in an area geologically stable enough to prevent environmental contamination for at least 10,000 years.

The program has been in turmoil since May 1986, when the Energy Department narrowed the list of candidates to three and announced it was suspending a search for a similar site in the East. An eastern disposal site was required in the 1982 law, largely to allay westerners' fears that they would be asked to shoulder the nation's entire nuclear-waste burden.

Backers of the legislation, drafted by Senate Energy Committee Chairman J. Bennett Johnston (D-La.), contend that choosing Yucca Mountain now will save the government nearly $4 billion in geological tests and exploratory drilling.

Opponents, including Sen. Alan K. Simpson (R-Wyo.), argued unsuccessfully that short-cutting the process might prove even more costly by undermining public confidence and delaying nuclear-waste disposal. "If Nevada isn't it, we're all in deep trouble," Simpson said yesterday.

The legislation was criticized by environmental groups, who contend that the nuclear-waste situation does not warrant a hasty choice for a dump site.

"It's a lousy way to pick the nation's first waste repository," said Brooks Yeager, a lobbyist for the Sierra Club. "There was just overwhelming political momentum not to have to deal with this again. Nevada is the victim of a high-stakes game of musical chairs."

Other critics warned that the Nevada selection may not prove the ultimate solution. "A lot of people think they're off the hook now," said Rep. Ron Wyden (D-Ore.). "But if Nevada proves unsuitable, people will say, 'Well, there's still that place in the Pacific Northwest.' "

The legislation would shelve, at least temporarily, DOE's efforts to build a temporary nuclear-waste storage facility in Tennessee. DOE officials proposed the facility as an "interim" storage site for spent fuel rods, for which it has agreed to assume responsibility in 1998. By most estimates, a permanent repository will not be in operation by then.

The proposal was bitterly opposed by Tennesseans and environmental groups, who contended the facility would almost certainly become permanent.

Meanwhile, the House voted, 399 to 16, to reauthorize the Endangered Species Act for five years, strengthen its provisions and increase spending to save endangered species to $56 million in 1988. The spending would rise to $66 million in 1992. The government now spends $39 million to help prevent extinction of 827 endangered and 142 threatened animals listed by the Interior Department's Fish and Wildlife Service.

The measure, which is similar to one passed by the Senate Environment Committee, now goes to the Senate for consideration.