Three Mile Island's Reactor Faces Grid Delays Despite 2027 Restart Plans | The Calibre Brief Ep. 19
About this episode
This episode of The Calibre Brief examines the complexities surrounding the planned restart of the former Three Mile Island Unit 1, now called the Crane Clean Energy Center. Constellation aims to restart the reactor in 2027 under a long-term agreement with Microsoft. However, PJM, the regional grid operator, has raised concerns about significant transmission work, potentially delaying full grid deliverability until 2031.
We explore the distinction between restarting a nuclear plant and achieving full firm capacity. While the plant's technical readiness could align with the 2027 target, PJM's 2031 timeline creates uncertainty over when the output will be considered dependable by the grid.
The June 2026 transfer of capacity interconnection rights from the Eddystone gas plant to Crane offers potential relief, yet it remains unclear if this measure will resolve all transmission constraints. This situation highlights the broader challenge facing data centers and AI power consumers: securing clean energy contracts does not guarantee immediate transmission readiness.
Join us as we delve deeper into how transmission constraints are shaping the landscape of energy delivery in the era of expanding data-center demand.
Key topics
Key moments
- 0:07 An old nuclear reactor has a customer and a return date
- 0:17 At the former Three Mile Island site, Unit 1 sits at the center of…
- 0:42 Restarting the reactor means refueling, repair, testing, and…
- 1:10 June brought a possible shortcut: FERC approved moving 760 megawatts…
- 1:44 The constraint reaches beyond one reactor
- 2:10 Crane may show that the bottleneck in the AI power race is not always…
- 2:25 You've been listening to The Calibre Brief from Calibre Code USA
Transcript
Show transcript
Welcome to The Calibre Brief, a Calibre Code USA production.
An old nuclear reactor has a customer and a return date. Yet the harder question is whether the wires will be ready.
At the former Three Mile Island site, Unit 1 sits at the center of that puzzle. The 835-megawatt reactor retired in 2019 is being prepared to return as the Crane Clean Energy Center. Constellation aims for 2027 and has a 20-year agreement to sell its output to Microsoft. A restart date, though, is one clock.
Restarting the reactor means refueling, repair, testing, and regulatory review. Deliverability is different. PJM must determine whether power can reach customers at peak demand without overloading lines or substations. In March 2026, a Constellation executive said PJM had indicated a possible 2031 connection, and a filing described significant transmission work before full deliverability.
June brought a possible shortcut: FERC approved moving 760 megawatts of capacity interconnection rights from the Eddystone gas plant to Crane. FERC said that transfer could reduce or eliminate some contingent facilities and improve interim deliverability. That is not a final answer. The record establishes an approved tool, not a completed grid path. It does not prove full firm service in 2027.
The constraint reaches beyond one reactor. In 2026, large substation transformers could take more than 160 weeks to arrive. PJM also reported more than 21 gigawatts in engineering and procurement, with 8.2 gigawatts under construction. A private power contract can support a restart. It cannot, by itself, make the transmission system ready.
Crane may show that the bottleneck in the AI power race is not always a generator. It may be the grid's ability to treat generation as dependable.
You've been listening to The Calibre Brief from Calibre Code USA. Should large power users secure private generation before transmission is complete? Comment, like and subscribe on YouTube, and follow the podcast.
