Constellation Energy is actively exploring regulatory pathways to potentially deploy advanced nuclear reactors at its Clinton Clean Energy Center, marking a significant step toward next-generation nuclear development. The company is evaluating whether to extend the site’s existing Early Site Permit (ESP) or pursue a new construction permit from the Nuclear Regulatory Commission (NRC) to enable the deployment of an advanced reactor or small modular reactor (SMR). This announcement comes on the heels of Constellation finalizing a landmark 20-year power purchase agreement (PPA) with Meta, which guarantees the tech giant’s offtake of the entire 1,121 MW of emissions-free electricity produced by the Clinton Nuclear Power Plant starting in June 2027.
The regulatory strategy represents a more concrete plan than the broad advanced reactor “considerations” mentioned when the Meta PPA was first announced in June. Constellation’s current ESP for the site, adjacent to the Clinton nuclear plant, expires on March 15, 2027, indicating some regulatory urgency around the expansion plans. The company received NRC approval in April to submit a renewal application 45 days before expiration, following a December 2024 exemption request. Originally issued in March 2007, the ESP allows deployment of up to 6,800 MWth of nuclear capacity at the site, independent of specific reactor designs.
Constellation’s PPA with Meta, announced on June 3, 2025, includes a 30-MW uprate at Clinton, which Constellation expects to be fully complete in 2029 and to qualify for the federal technology-neutral 45Y clean electricity production tax credit preserved under the One Big Beautiful Bill Act. When it announced the deal in June, Constellation said the agreement would support the “relicensing and continued operations of Constellation’s high-performing Clinton nuclear facility for another two decades after the state’s ratepayer-funded zero emission credit (ZEC) program expires.”
The Clinton Nuclear Power Plant, now known as the Clinton Clean Energy Center, entered commercial operation in 1987 and has long played a critical role in powering central Illinois. The power plant faced potential early retirement in 2017 due to market pressures and persistent financial losses. Its closure was averted by state intervention through the 2016 Future Energy Jobs Act, which established the Illinois Zero Emission Credit (ZEC) program. The program, in effect from June 2017 through May 2027, requires utilities to purchase all eligible credits each planning year (June–May). To limit costs for consumers, the Illinois Power Agency (IPA) caps total annual payments.
In its latest quarterly filing, Constellation reported recognizing $201 million in revenue for ZECs delivered in prior years, with payment expected in 2026. For the 2025–2026 planning year, the IPA set the ZEC price at $1.17 per credit with a cap of $224 million. By contrast, for 2024–2025 the ZEC price was $9.38 per credit with a $222 million cap, but revenue recognized for earlier credits was minimal given the lower price and cap structure.
“With the future of the plant secure, Constellation can evaluate opportunities for additional nuclear capacity at the site,” the company said on Tuesday. “With confidence in the plant’s continued operation, Constellation is also evaluating opportunities to extend the site’s early site permit or pursue a new construction permit from the U.S. Nuclear Regulatory Commission to enable the potential development of an advanced reactor or small modular reactor at the Clinton site,” it noted. The deal with Meta also enables additions of “new clean energy to the grid in the Midcontinent Independent System Operator’s (MISO) Zone 4 territory, which spans central and southern Illinois,” it said.
According to Kathleen Barrón, executive vice president and chief strategy and growth officer at Constellation Energy, the Meta investment has provided the crucial certainty necessary for the prospective expansion. “Now more than ever, it’s critical that we maintain and expand all sources of clean, reliable energy, and thanks to Meta’s investment, the future of the Clinton Clean Energy Center and its contributions to this community are secure,” she said.
The Clinton plans reflect broader industry momentum as technology companies seek reliable clean power for AI and data center operations. Meta, in a blog post published in December 2024, said it expects to source 1-4 GW of nuclear energy across multiple states starting in the early 2030s. “We are looking to identify developers that can help accelerate the availability of new nuclear generators and create sufficient scale to achieve material cost reductions by deploying