Key facts
- Reactor decommissioning under NRC rules must generally be completed within 60 years of permanent shutdown.
- The two main strategies are DECON (prompt dismantlement) and SAFSTOR (deferred dismantlement).
- A licence termination plan must be submitted at least two years before the expected end of the licence.
- Maine Yankee's site was released from the NRC licence in 2005 and Yankee Rowe's in 2007, except for spent fuel storage areas.
- DOE, not the NRC, is responsible for legacy defence and enrichment sites.
The regulatory framework
Decommissioning in the United States means removing a facility from service and reducing residual radioactivity to a level that permits release of the property and termination of the NRC licence. For power reactors the main requirements are in 10 CFR 50.82, with financial rules in 10 CFR 50.75. Other fuel cycle and materials licensees, such as enrichment and fuel fabrication plants, are covered by other parts of the NRC rules; the commercial enrichment plant case is on the US enrichment page.
The licensee must notify the NRC when it permanently ceases operations and when fuel is removed from the reactor, after which the operating licence no longer authorises operation. The licensee submits a post-shutdown decommissioning activities report describing the planned activities, schedule and estimated costs. Later it submits a licence termination plan, which under 50.82 is a supplement to the final safety analysis report and must be submitted at least two years before the planned termination date. It includes a site characterisation and a description of the remaining dismantlement and the final radiation survey.
DECON, SAFSTOR and the 60-year limit
The NRC describes two main strategies. In DECON, equipment and structures are removed or decontaminated soon after shutdown so that the licence can be terminated. In SAFSTOR the plant is maintained and monitored in a safe, stable condition for a period, often decades, while radioactivity decays, then dismantled. A third option, entombment, is permitted by the rules but has seen little use.
The practical meaning of each phase is as follows. In the first phase after shutdown the fuel is removed from the reactor to the spent fuel pool and later, in many cases, to dry casks. In SAFSTOR the licensee keeps a reduced staff that maintains ventilation, monitors radiation, and provides security and fire protection. In DECON the licensee typically hires a decommissioning contractor, and the site is dismantled in stages: systems are drained and decontaminated, large components such as steam generators and the reactor vessel are cut up or removed whole, and buildings are surveyed and demolished or cleared for reuse.
Whichever route is chosen, NRC regulations require decommissioning to be completed within 60 years of permanent cessation of operations, unless the NRC approves a longer period for reasons specific to the site. NRC training slides illustrate the typical SAFSTOR case as about 50 years of storage with decay followed by about 10 years of dismantlement. Consider the trade-offs: deferral reduces worker doses and allows a decommissioning trust to grow, but extends security and monitoring costs and keeps the site out of other use. Prompt dismantlement uses current workers' knowledge of the plant and ends the burden sooner.
Funding assurance
The NRC requires licensees to demonstrate that they will have enough money to decommission. Under 10 CFR 50.75 the licensee must provide a certification of financial assurance, and the minimum amount is calculated using formulas in 50.75(c), which depend on reactor type and power level and are adjusted over time. The permitted assurance methods include prepayment, an external sinking fund, and, for some licensees, a surety, insurance or a parent guarantee. In practice, many utilities hold dedicated decommissioning trust funds, whose balances are reviewed periodically by the NRC and reported in biennial reports.
Reactor owners may also choose to sell a shut-down plant to a specialist decommissioning company that takes over the licence and the trust fund. Such transfers require NRC approval and review of the buyer's technical and financial capability, which is a point of regulatory attention because the trust fund is the primary protection against an unfunded liability. The NRC also requires licensees to report on the status of decommissioning funds at intervals.
Site-specific cost estimates are often higher than the generic formula, and licensees may seek to use trust funds for radiological decommissioning, spent fuel management and site restoration subject to NRC exemptions. The adequacy of funds is therefore a recurring regulatory topic. A 2024 Federal Register notice shows that even after a site has been released, the account for the spent fuel storage installation at Yankee Rowe has remained a subject of NRC action, here an exemption request.
Examples: Yankee Rowe and Maine Yankee
Two New England plants are among the first full-scale reactor decommissionings in the United States.
| Plant | State | Licence release | What remains |
|---|---|---|---|
| Yankee Rowe | Massachusetts | NRC approved release of most of the site in 2007 | Spent fuel storage installation (ISFSI) and surrounding area; company documents describe 15 canisters of spent fuel and one of greater-than-Class-C material |
| Maine Yankee | Maine | Notification of full site decommissioning in October 2005 | ISFSI area; cask counts differ between documents (60 to 64) |
Connecticut Yankee also completed decommissioning, with the reactor site released except for the storage area. In every case the remaining liability is spent fuel, which stays on site because no federal repository has opened. The NRC continues to oversee the ISFSIs under separate licence provisions, so the cost of guarding and monitoring the fuel continues after the plant is gone. See the DU inventories page for how DOE handles other material left from the fuel cycle.
DOE legacy sites
Defence-related and early commercial sites, including the three diffusion plants at Oak Ridge, Portsmouth and Paducah, are cleaned up by the Department of Energy under its Office of Environmental Management, funded by annual appropriations and not by NRC-style licensee trust funds. Cleanup standards are set through agreements with state and federal environmental regulators under laws such as CERCLA, and timelines run over decades. A comparison with Europe, where operators usually fund decommissioning through dedicated provisions, is on the European decommissioning page.
Frequently asked questions
What are DECON and SAFSTOR?
DECON is prompt dismantlement of a shut-down facility. SAFSTOR keeps it in safe storage for years and dismantles it later after radioactivity has decayed.
How long may decommissioning take?
NRC rules require completion within 60 years of permanent shutdown for reactors, unless the NRC approves a longer period for site-specific reasons.
How is decommissioning funded?
Licensees must provide financial assurance under 10 CFR 50.75, commonly through decommissioning trust funds, with a minimum amount calculated by NRC formulas.
Are Yankee Rowe and Maine Yankee fully cleared?
The plant sites were released from licence in 2007 and 2005, except for the on-site spent fuel storage installations, which remain under NRC oversight.
Who handles legacy sites like Paducah and Portsmouth?
The US Department of Energy, under its Office of Environmental Management.
Sources and further reading
- US Nuclear Regulatory Commission (eCFR) — 10 CFR 50.82 Termination of license (2024)
- Cornell Law School — 10 CFR 50.82 Termination of license (Legal Information Institute) (2024)
- US Nuclear Regulatory Commission — Fact sheet on decommissioning nuclear facilities (2024)
- US Nuclear Regulatory Commission — The NRC reactor decommissioning process (presentation) (2015)
- US Nuclear Regulatory Commission (archived) — Yankee Rowe decommissioning status (2008)
- US Federal Register — Exemption request for Yankee Atomic ISFSI decommissioning funding account (2024)
- World Nuclear News — Yankee site returned to public use (2007)
- World Nuclear News — Connecticut Yankee decommissioning complete (2007)
Related topics
