A glitch with an emergency diesel generator at the Davis-Besse reactor should be classified as a low-to-moderate safety problem, Energy Harbor Corp. staff argued at a Tuesday hearing held by the Nuclear Regulatory Commission.
On May 27, 2021, a field flash selector switch on an emergency diesel generator at the Ohio plant failed a test. The problem was fixed the next day. The switch, last successfully checked on Nov.12, 2020, is part of the ramp-up procedure in turning on the emergency generator, which would be used during power blackouts or fires.
NRC officials gave no indication Tuesday on whether they would agree with Energy Harbor’s contention. The NRC also did not say when it would make a decision on the matter, the latest at the financially troubled power plant at the center of a pay-to-play scandal that in the past several years has rocked the Ohio legislature and former plant owner FirstEnergy.
The NRC has contended that the switches degraded without anyone’s knowledge between the November and May checks, which could have been prevented with a better preventive maintenance program schedule. Tuesday’s hearing was Energy Harbor’s opportunity to provide feedback to the NRC. No other agencies or members of the public testified.
The NRC said the glitch should be classified as “greater than green.” The NRC has four levels of classifications for safety problems. Green means a finding of very low safety significance . White means a finding of low to moderate safety significance. Yellow translates to a substantial safety problem. Red indicates a great safety problem.
On Tuesday, Energy Harbor argued that white is the most appropriate classification for the switch failure, while green is the most appropriate classification for the lack of a preventative maintenance schedule.
Cleve Wilson, strategic engineering manager for Energy Harbor, and Alan Filipiak, the site’s assistant operations manager, said Davis-Besse’s staff determined that a preventative maintenance check between November 2020 and May 2021 would likely not have prevented the May 27 test failure.
The failure was blamed on foreign material — likely nickel — found on the switch’s electrical contacts, they said. Energy Harbor — and independent analytical firms MPR and Exelon Power Labs — have not been able to identify where that foreign material came from. There are small openings in the switch equipment where foreign material could enter.
“Presence of foreign materials is a unique and unpredictable incident and not the result of a performance deficiency,” said a slide in Energy Harbor’s presentation.
Kevin Barclay, an NRC reactor inspector, voiced concerns about wear-and-tear found on some of the switch’s electrical contacts.
Since 2019, Davis-Besse has had four failures of emergency diesel generators to meet NRC standards and one failure of a backup diesel generator during maintenance. The reactor site has two emergency diesel generators to provide power during a loss of offsite electricity plus a third back-up generator in case the two emergency generators fail. One diesel generator is supposed to be sufficient to enable the plant to shut down and remain in a stable condition.
Energy Harbor used to be a subsidiary of FirstEnergy Corp. called FirstEnergy Solutions. It owns the Davis-Besse Nuclear Power Station in Oak Harbor, Ohio, and the Perry Nuclear Power Plant in Perry, Ohio.
FirstEnergy Solutions declared Chapter 11 bankruptcy in 2018 and later emerged for that condition. It also split from FirstEnergy Corp and became an independent corporation after the bankruptcy.
