FERC Approves Critical Grid-Rights Waiver for Constellation-Microsoft Three Mile Island Nuclear Restart
A major regulatory hurdle has been cleared for the resurrection of Three Mile Island Unit 1 (now renamed the Crane Clean Energy Center). On June 1, 2026, the Federal Energy Regulatory Commission (FERC) approved a critical waiver from PJM Interconnection rules, keeping Constellation Energy and Microsoft on track for their targeted second-half 2027 restart timeline to power regional AI data centers.
Bypassing the 2030 Transmission Gridlock
Constellation’s $1.6 billion plan to restart the 835-megawatt (MW) Crane nuclear unit in Pennsylvania had run into severe grid interconnection bottlenecks. The regional grid operator, PJM, determined that necessary high-voltage transmission upgrades (including 765-kV and 500-kV projects) would not be completed until at least December 2030, which would have restricted the plant from delivering its full power output for years.
To bypass this gridlock, Constellation requested a waiver to transfer 760 MW of Capacity Interconnection Rights (CIRs) from its Eddystone natural gas-fired power plant outside Philadelphia to the Crane nuclear plant.
- The Eddystone Loophole: Eddystone was scheduled to retire in May 2025, but the Department of Energy (DOE) ordered Constellation to keep the gas plant running under an emergency energy order. Because Eddystone operates as an "energy-only" resource under the emergency order, its valuable capacity rights (CIRs) were left unused and eligible for transfer.
- FERC's Approval: FERC approved the transfer over objections from PJM's independent market monitor, concluding that the waiver solved a concrete problem and made efficient use of existing grid rights:
"The requested waiver will allow for the transfer of CIRs between the Eddystone units and Crane, which may reduce or eliminate the number of Contingent Facilities for Crane and thereby potentially increase Crane’s interim deliverability and enable Crane to be fully operational before December 31, 2030." — FERC Order, June 1, 2026
Technical and Commercial Implications
The waiver is a major victory for Microsoft (MSFT), which signed a landmark 20-year power purchase agreement (PPA) to buy 100% of the Crane unit's energy, capacity, and carbon-free attributes.1
From an operational standpoint, full deliverability is vital for nuclear reactors. If forced to run below their rated power output for extended periods due to grid constraints, nuclear turbine equipment faces heightened risks of elevated vibration, mechanical wear, and long-term reliability issues. Securing the 760 MW of capacity rights ensures that Crane can run at its optimal, high-capacity baseline from day one of its restart.
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An instance of The commercial leverage of clean electricity shifts from discount seeking to long-term asset underwriting. — Microsoft secured its energy future by signing a multi-decade agreement that directly underwrites the restart and operation of the Crane Clean Energy Center. ↩︎