WASHINGTON — Federal regulators took a first step Monday toward allowing a radioactive waste dump in Nevada, agreeing to formally review the government's license application for the dump.

It will still take the Nuclear Regulatory Commission up to four years to consider the Energy Department's 8,600-page application and decide whether to grant the federal government permission to build the 77,000-ton dump.

Still the NRC's determination that the license application was complete enough to be "docketed" for review was a step forward for the Energy Department, which submitted the application in June after years of delay.

The commissioners' decision came over objections from the state of Nevada, which does not want to host the nation's first nuclear waste dump, which would be carved into a volcanic ridge called Yucca Mountain 90 miles northwest of Las Vegas.

Nevada's attorneys had already unsuccessfully petitioned the NRC to reject the license application. Nevada lawmakers, led by Senate Majority Leader Harry Reid, D-Nev., vowed to continue their opposition.

"While we were hopeful the Nuclear Regulatory Commission would reject Yucca Mountain's license application, the latest development was a formality we expected," Reid said. "I am confident the commissioners will see the same bad information and evidence of mismanagement Nevadans already have and will reject the Energy Department's plan."

Nearly $14 billion has already been spent on the repository and the total cost is now pegged at $96.2 billion. The opening date has been pushed back repeatedly and the best-case scenario is now 2020, presuming Congress grants adequate funding, something Reid's opposition has prevented in recent years.