Fermi 1 was built to prove an audacious idea: a reactor that creates more fuel than it consumes. Sitting on the western shore of Lake Erie south of Detroit, Michigan, the plant used liquid sodium metal -- heated to temperatures that would make it burst into flame on contact with water or air -- instead of ordinary water as its coolant. This allowed the reactor to run without slowing down its neutrons, a trick that converted a surrounding blanket of uranium-238 into plutonium-239, a fresh fissile fuel. In theory, breeder reactors offered an effectively limitless energy supply. Walker Lee Cisler, president of Detroit Edison, championed the project starting in 1951, convinced the breeder cycle would dominate commercial nuclear power. The U.S. Atomic Energy Commission approved the concept on December 19, 1951 -- just one day before the world's first power-producing reactor, the experimental EBR-I in Idaho, lit its first light bulbs.

The warnings came early and from the top. On November 29, 1955, EBR-I suffered a partial meltdown when an operator hit the wrong button during a temperature test, and half the core melted in seconds. Despite this, Cisler applied for Fermi 1's construction permit in January 1956. The AEC's own Advisory Committee on Reactor Safeguards, a blue-ribbon panel that included Nobel laureate Hans Bethe, concluded there was "insufficient information available at this time to give assurance that the PRDC reactor can be operated at this site without a public hazard." AEC chairman Lewis Strauss classified the review as confidential and approved construction anyway. The United Auto Workers, led by Walter Reuther, sued to stop the project. A federal court revoked the construction license in 1960, but the Supreme Court reversed the decision, and construction continued. The budget doubled from $35 million to $70 million. Criticality, planned for 1959, was not achieved until August 23, 1963.

October 5, 1966 began routinely. Operators started ramping Fermi 1 toward 20,000 kilowatts of thermal power for a test run. At 3:05 PM, operator Mike Weber noticed the control rods were withdrawn further than they should have been -- the automatic system was compensating for something wrong inside the core. He crossed the room to the temperature display panel and saw two fuel assemblies burning far hotter than the rest. At 3:09, radiation alarms sounded. A Class I emergency sealed the reactor building. At 3:20, the decision was made to scram. The meltdown was caught early enough that no radioactive material escaped the containment building. Four fuel assemblies had melted; two had fused together. The cause would take months to uncover -- those forgotten zirconium shield plates, added in 1959 and never documented, had broken free and blocked sodium flow to the fuel.

Fermi 1 spent four years in repair. It restarted in July 1970 and ran until November 1972, when the AEC denied its license extension. By then the project had consumed $132 million. Shutting the reactor down created its own disasters: the company hired to dispose of non-radioactive sodium simply dumped it in open World War I bunkers in Nitro, West Virginia. Rain reached the sodium, igniting it and forcing the town to shelter in place. The site became a notorious EPA Superfund cleanup. The radioactive sodium, originally intended for the never-built Clinch River Breeder Reactor, sat on-site until 1984. The reactor vessel itself was not removed and cut up until 2012. The AEC had budgeted $4 million for decommissioning; actual costs reached $130 million by 1974.

In 1975, journalist John Fuller published "We Almost Lost Detroit," its title drawn from an anonymous plant operator's remark. Fuller argued the design was inherently unsafe and that only luck prevented catastrophe. Detroit Edison countered with its own publication: "We Did Not Almost Lose Detroit." By any technical measure, the accident was contained -- the worst-case scenarios never came close to materializing. But the debate over Fermi 1 shaped American nuclear policy for decades. The plant demonstrated both the promise and peril of sodium-cooled fast reactors: extraordinary energy potential married to extraordinary complexity. The site remains in SAFSTOR decommissioning status today, the reactor, fuel, and coolant all removed, leaving only the containment shell on the flat Michigan shoreline where Cisler once dreamed of limitless power.