‘Substantial’ safety violation alleged at SC nuclear plant after 20 years of problems

Federal regulators have cited Dominion Energy for what they say is a substantial safety violation after finding that utility workers failed for 20 years to resolve cracking problems at the company’s V.C. Summer nuclear power plant northwest of Columbia.

This past week, the U.S. Nuclear Regulatory Commission issued what’s known as a preliminary “yellow’’ safety assessment, a measure of how serious an atomic safety problem is considered at a power plant. Yellow assessments are the second most serious on an NRC scale of severity.

The NRC, which rarely issues yellow findings, said nuclear plant operators did not resolve cracking problems from 2003 to 2022 in V.C. Summer’s diesel generator system, one of the most important backup safety systems at an atomic power plant.

NRC officials were not available Friday to explain their concerns with the backup diesel generator system, but an Oct. 4 enforcement letter to Dominion nuclear operations president Eric Carr said the utility violated an atomic safety standard that could result in more scrutiny of the power plant.

“We are considering escalated enforcement for the apparent violation,’’ according to the letter signed by LaDonna Suggs, acting director of the NRC’s division of reactor projects.

That’s no surprise to one nuclear safety advocate. Yellow designations often spark additional investigation and scrutiny of atomic power plants like the one in Fairfield County, said David Lochbaum, a former NRC official and expert on the inner workings of nuclear plants.

“The NRC feels this was avoidable,’’ Lochbaum said, when asked why the agency issued a yellow finding. “There were signs of problems that were overlooked. Because of that, the problem grew to a point where the diesel generator’’ system did not work during testing.

“You’re supposed to find and fix problems that occur,’’ he said.

Since 2009, the NRC has issued seven yellow findings against the nation’s nuclear power plants, Lochbaum said, after reviewing agency records. Only a red designation is considered worse, with white and green findings less significant. The United States has nearly 100 nuclear plants.

The NRC’s determination is not final and is listed as an “apparent’’ violation. Dominion will have an opportunity to explain more about the diesel generator system issues, according to the NRC. Dominion spokesman Darryl Huger said the company “has implemented a plan to improve the system’s reliability.’’

Huger, in an email to The State, said V.C. Summer has a history of operating safely, maintaining what he said was an “exemplary’’ record. The recent NRC concern centers on a pipe that delivers fuel to one of the power plant’s two emergency diesel generators, he said. Dominion found problems after testing the piping system, according to the NRC.

The power company, which acquired former V.C. Summer plant owner SCE&G after a failed effort to build two additional reactors at the site, plans to install thicker piping in the generator system, Huger said.

Dominion’s backup diesel generator system, like those at other nuclear plants, is designed to provide power to parts of the plant that need electricity in the event power is knocked out during an emergency, such as a storm or earthquake.

That’s important because power is needed to keep water running through the nuclear reactor core to prevent it from overheating. If power is lost, the nuclear fuel can melt, causing radiation to be released into the surrounding community.

In this case, officials at the V.C. Summer plant learned about cracks in fuel pipes in the facility’s diesel generator system in 2003. Utility workers fixed the initial crack, as well as other cracks four different times in the years after the initial work was done.

But the NRC says the utility never adequately assessed what could be done to make sure the diesel piping system did not experience more cracking. The most recent cracks were identified in November 2022 during a 24-hour test of the system. Workers found a small leak on one of two diesel generator systems. The leak increased over time and workers discovered a 140-degree crack around a pipe, records show.

The cracking occurred mostly in the power plant’s “A” diesel generator system, although one problem occurred in the plant’s “B” generator system. The plant has two backup diesel generators.

The cracking that led to the yellow safety finding follows separate, electrical problems with the plant’s diesel generator system in 2022. The NRC said the company, in that case, also failed to promptly resolve problems, issuing a white finding last year. White is lower in safety significant than yellow, but still considered notable.

Tom Clements, a long-time nuclear safety advocate, said the NRC’s recent yellow safety assessment reveals a violation “too egregious to ignore.’’ He called for a “severe monetary fine’’ against Dominion, which he said ignored preventative maintenance through the years.

Dominion’s problems are noteworthy in light of the company’s recent request to renew its V.C. Summer operating license another 40 years, Clements said. The power plant, which cranked up operations in the early 1980s, is about 25 miles northwest of Columbia in rural Fairfield County.

“Hopefully, serious safety problems don’t lurk in other reactor safety systems at the reactor,’’ Clements said in an email to The State. “This incident serves as a wake-up call to fully analyze all such systems prior to a license-renewal determination.’’