Three Mile Island Nuclear Reactor Shuts Down

Three Mile Island, the money-losing nuclear facility in Pennsylvania, has shut down its remaining reactor, ending its 45-year electricity-producing career. Three Mile Island’s Unit 1 opened in 1974 and was licensed to operate through 2034. Its energy giant owner, Chicago-based Exelon Corp. (NYSE: EXC) decided to close before the end of the license.

Three Mile Island was the site of the worst civilian nuclear accident in U.S. history. On March 28, 1979, the second reactor experienced a cooling problem that resulted in the partial melting of the reactor. The meltdown prompted the quick evacuation of 14,000 people and exposed nearly 2 million people to radiation. There were no casualties and there has not been any publicly disclosed health effects associated with the incident.

The incident led to the definitive closure of the reactor and stricter oversight of the nuclear power industry. As a result, no nuclear plant proposed after the accident in 1979 has been successfully completed and put into operation in the United States.

The plant has been losing money for many years. The 1979 accident that destroyed Unit 2 left it with just one reactor and competitive electricity markets limited its ability to increase earnings. Exelon tried to get financial aid from Pennsylvania last spring, but the bailout attempted by Pennsylvania officials was ultimately unsuccessful.

According to a statement from Exelon, the site will start being dismantled in the coming weeks. The first phase will be removing the reactor’s fuel supply and storing it in the used fuel pool. The dismantling of the main components, including the cooling towers, will not begin for years.

Out of the 675 people employed at Three Mile Island, roughly 300 will remain at the site during the first phase of decommissioning. That number will drop to 50 starting in 2022.