In everyday English, decommissioned sounds like gone. In federal nuclear rules, it means something narrower.

by Compass Vermont

The company tearing down the Vermont Yankee nuclear plant in Vernon says the job is 99% done, three years ahead of its deadline, the Brattleboro Reformer reported. A Texas developer, PowerTransitions, wants to put a battery storage plant on part of the property.

But the fuel that ran the plant for 42 years isn’t going anywhere. It sits in 58 steel-and-concrete casks, each about 20 feet tall, at the north edge of the site. It stays until the federal government takes it, and there is still no place to send it.

So how does anyone reuse land that still holds nuclear fuel? The answer starts with what the word “decommissioned” actually means.

What “Decommissioned” Means

Decommissioning, as the Nuclear Regulatory Commission uses the word, means taking a plant out of service and cleaning up leftover radioactivity enough to end the reactor’s license. It covers the reactor, the buildings, the pipes and the soil. It does not cover the used fuel.

Vermont’s own 2018 agreement with NorthStar says so outright: as that agreement uses the word, decommissioning “does not include spent fuel management activities.” The same agreement set NorthStar’s 2030 cleanup deadline for everything on the site except the fuel storage area and the electric switchyard beside it.

What Stays Behind

The used fuel is 3,880 fuel assemblies, the bundles of uranium rods that powered the reactor, sealed in the 58 casks. A 59th cask holds reactor parts too radioactive for ordinary low-level waste disposal. The last of the fuel left the plant’s cooling pool for the casks in August 2018.

The fuel stays because the federal government never took it. Under contracts signed in 1983, the U.S. Department of Energy was supposed to start accepting used fuel from power plants in 1998. It has not taken any, from Vermont Yankee or anywhere else, because the country has no permanent disposal site.

The NRC’s page on Vermont Yankee assumes the fuel will be gone by 2052. That’s a planning assumption, not a pickup date. Only after the fuel leaves would the storage area itself be torn down and the site’s nuclear license end.

How the Rest of the Land Comes Back

Federal rules let an owner ask the NRC to release part of a nuclear site for any use while the rest stays under license. Once everything but the fuel storage is cleaned up, the license can shrink to just the ground around the casks.

That’s what happened at Maine Yankee in Wiscasset, Maine. In 2005 the NRC released all of that plant’s land except about 12 acres around its fuel storage, and the plant’s owner has since described its decommissioning as complete.

Vermont Yankee is on the same road. NorthStar expects its physical work to finish in 2027. The NRC then reviews the work before releasing the land, a review NorthStar expects to take a couple of years.

Why Regulators Say It’s Safe

The casks sit on concrete pads with nothing running inside them. State officials said in 2016 that, unlike the plant’s cooling pool, the dry casks have no moving parts to fail.

Federal rules cap the radiation anyone outside the storage area’s controlled zone can receive from it at 25 millirem a year. The edge of that zone must be at least 100 meters from the casks, a bit longer than a football field.

The average American receives about 620 millirem a year from natural and medical sources, according to the NRC. The cap on the casks is about 4% of that. A chest X-ray is about 10 millirem, so the yearly cap equals about two and a half chest X-rays.

A Battery Beside Nuclear Fuel Has Been Done Before

Rancho Seco, a closed nuclear plant southeast of Sacramento, California, is close to Vermont Yankee’s case. The NRC released most of that site in 2009. About 11 acres, including its used fuel storage, stayed under license.

The Sacramento Municipal Utility District has since put a solar farm and a public recreation park on the property. It is adding a 160-megawatt battery on about 15 acres inside the old plant’s fence, with construction scheduled to begin in June 2026.

That’s about the footprint PowerTransitions described for Vernon: roughly 15 of the site’s 140 acres, for a battery of 110 to 440 megawatts. Most battery storage in Vermont today holds 5 to 20 megawatts, according to Vermont Public.

Who Checks the Battery

The worry people raised at PowerTransitions’ recent community meeting in Vernon wasn’t radiation. It was fire: what happens to the casks if a battery burns?

When the NRC wrote its rule for releasing part of a nuclear site, it chose not to weigh the hazards of whatever gets built on the released land.

The casks are a separate matter. Under federal rules, NorthStar, as the holder of the cask license, must show that conditions at the site stay within what the casks were designed to withstand, and keep that review on file for NRC inspectors. Cask designs the NRC approves are analyzed for outside hazards, including explosions.

No public filing yet addresses a battery plant beside the Vermont Yankee casks. The battery would also need a certificate of public good from the Vermont Public Utility Commission, the state’s siting review for energy projects. PowerTransitions hasn’t filed, says it won’t without the town’s support, and expects any work to be three to five years off.

When that case is filed, what a battery fire could do to the casks is a question the public can put in front of the commission.

How to Weigh In

• The battery proposal. When PowerTransitions files for a certificate of public good, the case will be posted on ePUC, the Public Utility Commission’s online case system. Anyone can read the filings there and submit public comments. Search by the company name.
• The state’s Vermont Yankee oversight panel. The Nuclear Decommissioning Citizens Advisory Panel meets in public and posts its meetings and reports on the Department of Public Service site.