MONTPELIER - Don't count on Yucca Mountain or any other national solution for the long-term storage of spent nuclear fuel, a consulting group told lawmakers Thursday.

A sign warns of radiation on the Hanford nuclear reservation Thursday, April 3, 2008 near Richland, Wash. Each year, the federal government spends roughly $2 billion to work toward cleaning up the nation's most contaminated nuclear site.(AP Photo/Ted S. Warren) As the Vermont Legislature considers Vermont Yankee's proposal to continue operating past its 2012 expiration date, lawmakers should assume that all the radioactive spent fuel left will be stored on-site in Vernon, nuclear consultants said.

Bruce Lacy, the founder of Iowa's Lacy Consulting Group, told members of several House and Senate committees that dry cask storage of this waste material at nuclear power plants has become the default United States policy.

"We are storing it here in Vermont right now, but it is not going out of state unless there is a national movement," Lacy said. "We need a positive will of Congress."

Yucca Mountain, a ridgeline adjacent to nuclear weapons test sites in Nevada, was selected by the U.S. Department of Energy in 1987 as the storage facility for spent nuclear waste and other radioactive materials from nuclear power plants across the country.

But that site has sat unused since then, tied up with political disputes and doubts by the U.S. Congress. The Department of Energy filed a formal application to use the site late last year with the Nuclear Regulatory Commission, but even that process seems fraught with problems, including funding.

Here in Vermont, lawmakers are considering a request by the owners of Vermont Yankee to extend the Vernon plant's operating license for another 20 years beyond its 2012 end date. Storage of the nuclear waste - the byproduct of creating nuclear power - is one of the chief concerns lawmakers are struggling with.

Vermont Yankee now stores its nuclear waste in its spent fuel pool within the reactor and in underground, dry cask storage units - essentially steel and concrete storage units intended to keep the waste stored safely as it degrades naturally. Entergy Vermont Nuclear, the company that owns the plant, won legislative approval for those storage units in 2005.

Lacy said Vermont Yankee has 1,911 bundles of the waste stored in its spent fuel pool and another 340 bundles stored in dry cask units at the facility, which is located south of Brattleboro along the Connecticut River in the small town of Vernon.

The facility has enough storage room - thanks to the additional space allowed by the dry cask units - to continue storing its waste until 2032, which is when it would cease operating if its application to continue past 2012 is approved.

Rep. Sarah Edwards, P-Brattleboro, is a longtime critic of Vermont Yankee and a member of the House Natural Resources and Energy Committee. She said she worried about the long-term storage of the waste at the Vernon facility, especially if there is a natural disaster there, such as flooding.

She was surprised Thursday to learn that federal regulators did not consider the possible implications of global warming in their flooding predictions for the facility.

"Their belief is that the water levels are relatively stable," Lacy told lawmakers.

Whenever Vermont Yankee is decommissioned - whether that is in 2012 or 2031 - the state should assume that the nuclear waste continue to be stored at the facility because there is no other viable national option, Lacy told lawmakers.

"This could be stored on site for a long time," he said.

Another type of waste produced at Vermont Yankee also needs to find a long-term home. So-called low-level radioactive waste - anything from contaminated clothes and equipment to materials directly exposed to neutrons in the plant's reactor - can only be stored in sites approved by the NRC, Lacy explained.

Radioactive waste dumps in South Carolina and Washington have often taken most of these classes of waste for the nuclear industry, but those sites will soon stop taking shipments from states not in their compact.

However, a new site is being constructed in Texas, which Vermont does have a contract with to store these materials, Lacy said. But the availability and cost of disposal is a wildcard in the debate over the future of Vermont Yankee.

"You cannot decommission a power plant without a contract for a disposal site," he said.

Lacy said Vermont Yankee has three decommissioning options: Immediate decommissioning, which would take six to eight years; mothballing the facility and decommissioning over a 60-year period; and filling the structure with concrete and waiting until the radioactive material decays completely.

There have been 11 nuclear facilities that have undergone immediate decommissioning, Lacy said, with two more now in progress. Eleven sites in the country have been mothballed and two more - which he described as early, prototype reactors - have been filled with concrete and shut down.

Each option has its own costs and benefits, although the true costs of shutting down a power plant for good fluctuate and are hard to pin down. Decommissioning the facility immediately would cost between $655 million and $893 million; mothballing it for a few decades would cost between $717 million and $991 million.

Vermont Yankee's owners have a trust fund set up to pay for decommissioning, but that account has dropped in recent months as troubles began on Wall Street. In September 2007, the fund was $440 million. In December 2008, it was $372 million.

"Like all trust funds in the United States, this has been in decline," Lacy said.

Because of the uncertainties of the final decommissioning costs, Lacy recommended that lawmakers insist that the owners of Vermont Yankee put more money in that account.

"You can't sharpen your pencils enough," he said. "You don't want to be in a position 60 years from now where there is not enough money left in that fund."

Lacy Consulting, which bills itself as a non-partisan source of information on nuclear issues, was hired by the Vermont Legislature as consultants during the Vermont Yankee debate.