BRATTLEBORO -- When Entergy officials announced in August they were closing Vermont Yankee nuclear power plant in Vernon, the debate about its future quickly shifted from whether it should be allowed to continue operating to how long it will take to clean up the site.

On Aug. 27, Entergy called a surprise press conference to announce its Board of Directors had concluded the plant was no longer financially viable and would be shutting down at the end of its current 18-month operating cycle, which means sometime in late 2014.

Entergy representatives indicated following its final power down, the plant would be placed in SAFSTOR, a decommissioning option that would allow the site to remain untouched for up to 60 years. This would not only allow the plant time to decontaminate naturally, but would also allow the decommissioning fund to build to the level necessary for complete mitigation of the site.

Currently, Yankee's decommissioning fund contains about $580 million, which is $40 million less than the Nuclear Regulatory Commission's minimum for site reclamation.

However, the NRC recently concluded that given the way the money is invested, it is "adequate" for eventual decommissioning, a total cost it has estimated to be a little more than $854 million.

The decommissioning fund was created through a surcharge on the electric bills of Vermonters. The surcharge was discontinued after Entergy bought the plant in 2002 from a consortium of public utilities, known as the Vermont Yankee Nuclear Power Corp., which included Central Vermont Public Service, Green Mountain Power and Public Service of New Hampshire.

Because of the Wall Street crash, the decommissioning fund fell to $347 million in February 2009. Since then, it has grown by nearly $240 million. If the fund follows the same trajectory, it could have the NRC minimum sometime in 2018. The NRC requires only that the site be returned to brownfield status, which might include leaving some of the below-ground structures.

However, according to memorandums of agreement signed when Entergy bought the plant in 2002, Entergy promised it would return the site to a greenfield, essentially the way it was prior to Yankee's construction. That could drive the cost of decommissioning to $1 billion or more.

The Vermont Public Service Board is currently reviewing testimony and evidence on whether Entergy should receive a certificate of public good allowing it to operate the plant for the time being. The current certificate expired in March 2012, but the PSB's hearing process was put on hold while a suit filed by Entergy against the state of Vermont wended its way through the federal court system. In January 2012, a judge in the U.S. District Court for the District of Vermont ruled in Entergy's favor, concluding the state Legislature had crossed over into federal territory when it considered safety during hearings to craft legislation affecting the future of the plant. The state appealed the ruling to the Second Circuit Court of Appeals, but in August 2013, it affirmed most of the district court's ruling.

Chris Recchia, the commissioner of the Vermont Department of Public Service, told the Vermont Public Service Board it's the Shumlin administration's position that the plant should be granted a certificate allowing Entergy to operate the plant for another 14 months, but only if it agrees to place $60 million in a separate fund for site restoration. In documents filed with the PSB, the administration expressed its belief that site restoration up to Vermont standards would cost an additional $120 million.

Critics of Entergy's plan to place the plant in SAFSTOR are concerned about what corporate structure might exist 20, 30 or 60 years after closure. If the corporate owner no longer exists and the plant still hasn't been decommissioned, said Neil Sheehan, spokesman for the NRC, the five-member Commission that oversees the NRC, with input from the staff, would have to come to a decision on an approach going forward.

"The scenario you're presenting would be new territory for the NRC," said Sheehan. "However, other agencies have dealt with such situations, especially the EPA. If there was insufficient funding to complete the radiological decommissioning work, the NRC would seek a remedy involving the parent company. It's not clear who would want to buy a permanently shutdown nuclear power plant but certainly the parent company has other assets."

But SAFSTOR isn't the only option available to plant owners. There is also DECON, which the state of Vermont prefers and entails an immediate dismantling of the plant and remediation of the site. And then there is ENTOMB, the enclosure of contaminated parts of the plant in a permanent layer of concrete. Entergy has indicated that neither of those options is appropriate for Yankee.

Bob Audette can be reached at raudette@reformer.com, or at 802-254-2311, ext. 160. Follow Bob on Twitter @audette.reformer.