Near Misses at U.S. Nuclear Power Plants

The Nuclear Regulatory Commission (NRC) is the arm of the federal government charged with enforcing safety regulations at U.S. nuclear power plants. Every year they respond to safety and security “near misses,” defined as events that increased the risk of reactor core damage by at least 10 times. This series catalogs those near misses.


Clinton Power Station: Déjà vu Transformer Problems

, director, Nuclear Safety Project

The Clinton Power Station located 23 miles southeast of Bloomington, Illinois has one General Electric boiling water reactor with a Mark III containment that began operating in 1987.

On December 8, 2013, an electrical fault on a power transformer stopped the flow of electricity to some equipment with the reactor operating near full power. The de-energized equipment caused conditions within the plant to degrade. A few minutes later, the control room operators manually scrammed the reactor per procedures in response to the deteriorating conditions. The NRC dispatched a special inspection team to investigate the cause and its corrective actions.

On December 9, 2017, an electrical fault on a power transformer stopped the flow of electricity to some equipment with the reactor operating near full power. The de-energized equipment caused conditions within the plant to degrade. A few minutes later, the control room operators manually scrammed the reactor per procedures in response to the deteriorating conditions. The NRC dispatched a special inspection team to investigate the cause and its corrective actions. The NRC’s special inspection team issued its report on January 29, 2018.

Same reactor. Same month. Nearly the same day. Same transformer. Same problem. Same outcome. Same NRC response.

Coincidence? Nope. When one does nothing to solve a problem, one invites the problem back. And problems accept the invitations too often. Read more >

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Grand Gulf: Three Nuclear Safety Miscues in Mississippi Warranting NRC’s Attention

, director, Nuclear Safety Project

The Nuclear Regulatory Commission (NRC) reacted to a trio of miscues at the Grand Gulf nuclear plant in Mississippi by sending a special inspection team to investigate. While none of the events had adverse nuclear safety consequences, the NRC team identified significantly poor performance by the operators in all three. The recurring performance shortfalls instill little confidence that the operators would perform successfully in event of a design basis or beyond design basis accident. Read more >

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Broken Valve in Emergency System at LaSalle Nuclear Plant

, director, Nuclear Safety Project

An NRC Special Inspection Team (SIT) conducted an inspection at the LaSalle Nuclear Plant this spring to investigate the cause of a valve’s failure and assess the effectiveness of the corrective actions taken. Read more >

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Cooper: Nuclear Plant Operated 89 Days with Key Safety System Impaired

, director, Nuclear Safety Project

The Nebraska Public Power District’s Cooper Nuclear Station about 23 miles south of Nebraska City has one boiling water reactor that began operating in the mid-1970s to add about 800 megawatts of electricity to the power grid. Workers shut down the reactor on September 24, 2016, to enter a scheduled refueling outage. That process eventually led to NRC special inspections. Read more >

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Turkey Point: Fire and Explosion at the Nuclear Plant

, director, Nuclear Safety Project

The Florida Power & Light Company’s Turkey Point Nuclear Generating Station about 20 miles south of Miami has two Westinghouse pressurized water reactors that began operating in the early 1970s. Built next to two fossil-fired generating units, Units 3 and 4 each add about 875 megawatts of nuclear-generated electricity to the power grid.

Both reactors hummed along at full power on the morning of Saturday, March 18, 2017, when problems arose. Read more >

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