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.


Palo Verde: Running Without a Backup Power Supply

, director, Nuclear Safety Project

The Arizona Public Service Company’s Palo Verde Generating Station about 60 miles west of Phoenix has three Combustion Engineering pressurized water reactors that began operating in the mid 1980s. In the early morning hours of Thursday, December 15, 2016, workers started one of two emergency diesel generators (EDGs) on the Unit 3 reactor for a routine test. The EDGs are the third tier of electrical power to emergency equipment for Unit 3. Read more >

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Columbia Generating Station: NRC’s Special Inspection of Self-Inflicted Safety Woes

, director, Nuclear Safety Project

Energy Northwest’s Columbia Generating Station near Richland, Washington has one General Electric boiling water reactor (BWR/5) with a Mark II containment design that began operating in 1984. In the late morning hours of Sunday, December 18, 2016, the station stopped generating electricity and began generating problems. Read more >

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Special Inspections: Safety Relief Valve Problems at Perry and Hatch

, director, Nuclear Safety Project

Near-Miss Summary

The Near-Miss

The Nuclear Regulatory Commission (NRC) sent special inspection teams to the Perry Nuclear Power Plant in Perry, Ohio and to the Edwin I. Hatch Nuclear Plant near Baxley, Georgia early this year. Both plants feature boiling water reactors (BWRs) and both experienced problems with safety relief valves that prompted the NRC’s reactions. Read more >

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Special Nuclear Inspection: River Bend Loss of Shutdown Cooling

, director, Nuclear Safety Project

The Nuclear Regulatory Commission (NRC) sent a special inspection team to the River Bend nuclear plant near St. Francisville, Louisiana on February 8, 2016, to investigate an event in which cooling of the reactor core was interrupted for over an hour on January 10 when the reactor was shut down. The NRC’s special inspection team identified four violations of regulatory requirements characterized as Green findings, the least serious among the agency’s green, white, yellow, and red classifications.

Read more >

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Special Inspection: Oconee Unplugged

, director, Nuclear Safety Project

Near-Miss Summary

The Near-Miss

The Nuclear Regulatory Commission (NRC) sent a special inspection team to the Oconee Nuclear Station in Seneca, South Carolina on January 5, 2016, after a worker found an electrical cable disconnected from a backup power supply for Unit 3. The following week, workers found a similarly disconnected cable on a backup power supply for Unit 1. Read more >

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