Decommissioning the Vermont Yankee nuclear plant will cost up to $1.24 billion, owner Entergy Corp. said in a study submitted to Vermont regulators on Friday.

Entergy Nuclear Vermont Yankee (ENVY) plans to shutter the reactor in late 2014. The decision to close the plant stems from a settlement agreement negotiated by several Vermont state agencies and ENVY in December 2013.

The site assessment study submitted to Vermont’s Public Service Department, Agency of Natural Resources, Department of Health, and Public Service Board on Friday includes a description of existing radiological and non-radiological conditions at the site, a description of the decommissioning process, a description of steps required to move spent nuclear fuel to dry storage and to close the spent fuel pool, and information on the likely cost and schedule of decommissioning.

It shows that ENVY expects to immediately begin transitioning the 1972-built plant from operations to dormancy after shutdown at the end of 2014, a transition period that is expected to last until about 2020.

The company will use the SAFSTOR decommissioning option—which means that the plant will remain in safe condition until decommissioning work is completed. Total decommissioning costs include $817 million to terminate an operating license with the Nuclear Regulatory Commission (NRC), $368 million for spent fuel management, and $57 million for site restoration.

“The need for a spent fuel management plan is largely driven by the U.S. Department of Energy’s [DOE’s] failure to remove and dispose spent nuclear fuel, for which ENVY and prior owners of VY have already paid the DOE more than $119 million. ENVY has prevailed in past litigation for recovery of the large majority of its claimed spent fuel storage costs,” Entergy said.

“In the meantime, we believe that moving all of the [Vermont Yankee] spent nuclear fuel into robust dry fuel storage containers on a seismically-hardened Independent Spent Fuel Storage Installation (ISFSI) in the short-term is in the best interest of all parties, and that will be our primary focus over the next several years.”

Under the SAFSTOR scenario, dismantling and decontamination of the plant would not begin until about 2069, and the site would not be released for unrestricted use until about 2075.

Vermont Yankee will join 17 16 reactors in the U.S. that are in some stage of decommissioning. Ten are using or transitioning to the SAFSTOR, option, four are using the DECON (decontamination) option, and two that have not yet chosen a decommissioning option.

Like Vermont Yankee, these include plants that shut down over the past two years, before their licenses expired: Kewaunee in Carlton, Wis.; Crystal River Unit 3 in Crystal River, Fla.; and SONGS Units 2 and 3 in California. Between 2014 and 2050, meanwhile, nearly all of the current fleet of U.S. reactors is slated for retirements unless there is another round of 20-year extensions.

—Sonal Patel, associate editor (@POWERmagazine, @sonalcpatel)