WINNSBORO – For the second time in 12 months, federal nuclear inspectors have noted defects in critical hardware at the V.C. Summer nuclear plant in Fairfield County.
On October 4, the Nuclear Regulatory Commission (NRC) informed Dominion Energy, which operates V.C. Summer, of an apparent violation of “substantial safety significance.”
The NRC issued a preliminary “Yellow” assessment, the second most serious level, involving an emergency diesel generator. The generators provide emergency power during blackouts.
Red assessments are the most serious, followed by Yellow, White, and Green.
Yellow assessments indicate a “substantial safety or security significance finding,” according to the NRC.
NRC spokesman Dave Gasperson estimated the agency would probably make a final determination sometime in November after holding a public regulatory meeting.
V.C. Summer will have an opportunity to respond to the Yellow assessment, he said.
“It’s up to V.C. Summer if they want to present information during a conference or submit a written response,” Gasperson said.
In a prepared statement, Dominion acknowledged that backup systems are critical in the operation of nuclear power plants.
“At Dominion Energy, safety is our top priority,” the statement says. “Rigorous internal and external controls are in place to ensure all equipment is maintained and operates as designed.”
According to the NRC report, federal inspectors found defects that left the generator vulnerable to piping cracks. The report also stated that pipe cracks had been detected during prior testing.
“Despite the challenge to maintain leak-tight connections and repeat occurrences of cracked piping, no significant changes were made to maintenance practices, procedures or system design, and the licensee continued to reactively monitor for leakage even after vulnerabilities were identified,” the report states.
Documented issues of cracking had been reported as far back as 2003, the report continues.
“The licensee treated individual pipe failures as ‘broke/fix’ rather than identifying the system vulnerability,” the report states. “The licensee fixed the cracked piping/fittings but failed to identify and correct the failure mechanism that affected the fuel oil system piping.”
In its statement, Dominion said it would continue to work on maintaining compliance with federal nuclear regulations.
“With a commitment to continued safe operations, we are inspecting and maintaining our generator and related components,” the statement said. “We will continue to keep the NRC updated on our future strategy to further enhance our diesel generators.”
The preliminary Yellow assessment comes almost exactly a year after the NRC noted safety defects in another V.C. Summer emergency diesel generator, prompting the federal agency to issue a White assessment, according to documents obtained by The Voice.
White assessments are less serious than Yellow assessments. They indicate a “low to moderate safety or security significance finding,” according to the NRC.
Specifically, Dominion failed “to adequately assess erratic emergency diesel generator governor operation, which resulted in an inoperable [generator],” according to the 2022 violation.
“The [generator] was exhibiting other-than-expected and non-routine conditions in the form of significant fuel rack and kilowatt swings,” the violation letter states. “These conditions resulted in a condition of the indeterminate cause and other-than expected equipment performance found during surveillance testing.”
V.C. Summer has received at least two other White assessment violations since 2000, according to the NRC database.
Both occurred when SCANA ran V.C. Summer.
In 2006, the NRC issued a violation notice when V.C. Summer received a shipment of radioactive material “in a package with radiation levels on an external surface that exceeded applicable regulatory requirements.”
The package was then taken from V.C. Summer to an unnamed offsite waste processing vendor, according to the NRC.
The second White assessment was issued in 2000 after the NRC discovered a turbine driven emergency feed water pump had become inoperable, records show.
Emergency water pumps help to cool reactors in the event of a shutdown.
