How Microsoft Is Restarting Three Mile Island for AI

On September 20, 2024, Constellation Energy announced the largest single-buyer corporate power purchase agreement ever signed. Microsoft buys 20 years of output — every megawatt-hour — from a restarted Three Mile Island Unit 1, renamed the Crane Clean Energy Center, targeting 2027 (originally 2028). Analysts model the price at $98 to $115 per MWh against $50/MWh PJM wholesale. The $1.6B restart works only because three subsidies stack: the IRA Section 45U PTC at up to $15/MWh, the 45Y clean energy credit, and a $1B DOE Loan Programs Office loan that closed November 18, 2025.But the plant being restarted is Unit 1. Unit 2 — the sister reactor — partially melted down on March 28, 1979. The cause was a Pilot-Operated Relief Valve that stuck open for 2 hours 22 minutes while a control-room indicator light, wired to the valve's command solenoid rather than its actual position, told operators it had closed.Eighteen months earlier at Davis-Besse — same Babcock & Wilcox PWR family — the same valve stuck open. Shift supervisor Mike Derivan diagnosed it in 20 minutes. The plant was at 9% power. B&W engineers Joseph Kelly (November 1, 1977) and Bert Dunn (February 9, 1978) wrote memos warning that "core uncovery and possible fuel damage would have resulted" at full power. Managers Don Hallman and Bruce Karrasch dismissed the warnings. Met-Ed was never notified.The Kemeny Commission found B&W's PORV had failed 11 prior times, 9 stuck open.The 2026 restart audits whether 47 years of post-1979 safety architecture — Kemeny, NUREG-0660, NUREG-0737, INPO, 10 CFR 50.155 — stuck. Up to 7,500 hours of NRC pre-restart inspection. Three license amendment requests pending hearing. Intervention petitions due April 27, 2026. A FERC waiver for 760 MW of capacity rights from retired Eddystone units, decision needed by June 1. PJM's June 30 base capacity auction as the operational hinge.And the grid math doesn't care. PJM's load forecast: 30 GW of data center growth between 2025 and 2030. The entire U.S. nuclear restart pipeline is 2.25 GW. Capacity auction prices hit the price cap in December 2025, falling 6,625 MW short of reliability targets for the first time in PJM history.CHAPTERS00:00 Disclaimer — none of this is investment advice00:08 Cold open — Davis-Besse, 197701:17 The 1977 warning that didn't stick01:49 How the PORV indicator failed02:34 The Kelly and Dunn memos03:29 March 28, 1979 — the partial meltdown04:23 Kemeny: people-related problems05:58 Unit 1 vs Unit 2, and the 2019 retirement06:57 The Microsoft–Constellation deal09:41 The $1 billion federal loan09:49 The FERC rejection and virtual PPA11:34 Grid math: 30 GW vs 2.25 GW14:21 Why not SMRs?16:07 The improvised regulatory path19:25 Spring 2026 hinge dates21:42 Closing — the price of certaintySOURCESConstellation — Crane Clean Energy Center announcement (Sept 2024); DOE $1B loan close (Nov 2025)NRC — Crane Clean Energy Center docketKemeny Commission report (Oct 1979)UCS / Dave Lochbaum — PORV indicator-light wiring + the Davis-Besse 1977 linkUtility Dive — Microsoft–Constellation PPA + FERC waiverBloomberg Businessweek — Bennett & Wade (May 2026)———This episode is for educational and informational purposes only and does not constitute financial, investment, or trading advice, nor a recommendation to buy or sell any security. Deep Dive is not a registered investment adviser. All investing involves risk. Consult a licensed financial professional before making investment decisions.