Three Mile Island Restart
837 MW AI data center in Middletown, PA, United States: under construction.
- Capacity: 837 MW
- Location: Middletown, PA, United States
- Developer: Constellation
- Tenant: Microsoft
- Status: under construction
- Estimated cost: $1.6B
- Energy source: Nuclear power from the Crane Clean Energy Center / Three Mile Island Unit 1 restart.
Three Mile Island Restart is a 837 MW AI data center project located in Middletown, PA, United States, currently under construction. It is being built by Constellation for tenant Microsoft. The estimated build cost is $1.6B. Its energy source is listed as Nuclear power from the Crane Clean Energy Center / Three Mile Island Unit 1 restart.. This project is one of thousands of data-center facilities tracked by Data Center Index across PA, United States, covering operational, under-construction, announced, and permitted sites.
Project description
Constellation is restarting Three Mile Island Unit 1 in Middletown, Pennsylvania. The 837 MW, $1.6 billion project is under construction and its output is contracted to Microsoft. Emerson is linked on the instrumentation side.
Public companies linked to Three Mile Island Restart
Developers, tenants, and suppliers tracked by Data Center Index with exposure to this project:
- Constellation Energy (CEG), developer · energy · high DC exposure
- Microsoft (MSFT), tenant · hyperscaler
- Emerson Electric (EMR), power management · power equipment · mid DC exposure
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Frequently asked questions
- What is Three Mile Island Restart?
- Three Mile Island Restart is a power generation asset feeding AI data center demand in Middletown, Pennsylvania tracked by Data Center Index. Its status is under construction.
- Where is Three Mile Island Restart?
- Three Mile Island Restart is in Middletown, Pennsylvania. Every tracked Pennsylvania campus, with counts and capacity, is at https://datacenterindex.ai/markets/pennsylvania.
- How big is Three Mile Island Restart?
- Data Center Index tracks Three Mile Island Restart at 837 MW, on an estimated $1.6B build. That capacity is an estimate. We modeled or inferred it, and no source states it. This entry is a power generation asset, not a data center hall.
- Who is building Three Mile Island Restart?
- Constellation is developing Three Mile Island Restart, with Microsoft named as the tenant.
- Which public companies are linked to Three Mile Island Restart?
- Data Center Index links 3 tracked public companies to Three Mile Island Restart: Constellation Energy (CEG), Microsoft (MSFT), Emerson Electric (EMR). Each is a developer, tenant or supplier with a sourced link to the project.
Sources
- AI Data Center Index facility profile: Three Mile Island Reactivation (aidci · aggregator · 2026-04-29)