Equipment malfunctions during 2014 at the Oyster Creek Nuclear Power Plant in Lacey Township result in more intensive scrutiny by the Nuclear Regulatory Commission (NRC).

Oyster Creek Nuclear Power Plant (Exelon)

Federal regulators Monday released finalized findings of incidents that led to elevated safety-risk determinations. Exelon, which owns and operates the plant, initiated corrective action.

The increased oversight, said NRC in a prepared release, are to "ensure the underlying issues have been fully addressed."

Findings fall into four color categories - green for satisfactory, followed by white, yellow and red in ascending order related to safety risks.

The "yellow" finding regards design aspects of electromagnetic relief valves (EMRV), which allow coolant to be injected into the reactor core during a shutdown.

In June 2014, two valves that were removed for repairs did not open during testing, a condition attributed to misalignment with the valve actuator, NRC said.

Exelon workers tested five of its installed EMRVs, which functioned, NRC said. Exelon installed redesigned actuators during October 2014 refueling.

NRC designated the "yellow" finding to an old-design issue, not reflective of procedures, programs, policies or performance since Exelon has owned the generating station.

The "white" finding refers to a malfunctioning backup diesel generator. During a bi-weekly test in July 2014, operators discovered that the fan which would keep it from overheating was inoperable. This was attributed to a belt-driven fan drive shaft that had sheared in two.

The breakage was attributed to fatigue, and the shaft was replaced. The agency says that, unlike the valve malfunction, the broken shaft was discovered by NRC inspectors.

According to information from NRC, federal inspectors learned that Exelon had changed its tensioning methods for the fan belts but had not verified the acceptance criteria necessary for the alteration, leading to the equipment fatigue and failure.

The inoperability extended beyond its permitted outage time in violation of the plant's technical specifications, NRC said.

Team inspections will begin once Exelon notifies NRC that it is prepared for them.

In response, Exelon issued the following:

"The issues at Oyster Creek were all self-identified by Exelon, immediately addressed and brought to the NRC’s attention at that time. That is how our regulatory process works. Exelon expeditiously and thoroughly completed a comprehensive review of each issue to identify its root cause, develop and implement corrective actions and then shared that very important information with not only the other Exelon stations, but the industry as a whole to prevent reoccurrence.

We remain committed to operating Oyster Creek safely and reliably until 2019 and we have demonstrated how our corrective actions are appropriate to ensure the continued safety of the facility."

The finalized findings were reviewed in NRC's webinar on April 27. They will be revisited during their annual safety assessment geared toward public participation, May 28 at the Holiday Inn of Manahawkin.

More details are available in the ADAMS electronic documents system at the NRC web page.