Officials said the new system life cycle cost estimate includes money needed to research, construct and operate Yucca Mountain for 150 years.

The new cost estimate of $79.3 billion, when updated to 2007 dollars totals $96.2 billion -- a 38-percent increase from the last published estimate in 2001 of $57.5 billion.

Ward Sproat, director of the department's Office of Civilian Radioactive Waste Management, said the updated estimate takes into account a substantial increase in the amount of waste to be shipped and stored at the repository and more than $16 billion for inflation.

"This increased cost estimate is reasonable given inflation and the expected increase in the amount of spent nuclear fuel from existing reactors with license renewals," Sproat said. "We have marked significant project milestones this year and look forward to … nuclear waste currently sitting at 121 temporary locations around the country being safely stored at Yucca Mountain."