The Oyster Creek Nuclear Generating Station in Lacey Township had four outages, or scrams,  during 2014, but only one of them was planned. A federal inspection in December found a July shutdown, which was among the three unplanned outages, has led to a downgrade in the facility's Performance Indicator from Green to White, or "very low safety significance" to "low to moderate," according a report from the U.S. Nuclear Regulatory Commission (NRC).

Oyster Creek nuclear plant (Excelon)

An NRC Supplemental Inspection team visited Oyster Creek from December 8-11, 2014.

"We wanted to really look at whether Exelon fully understood why it kept having these unplanned shutdowns and whether it had put in place corrective actions to make sure that they didn't continue to occur," said Neil Sheehan, NRC spokesman.

The inspection finding had to do with a failure to implement a temporary configuration change when a temporary repair was made on the plant's condenser, according to Sheehan.

"It basically takes the steam that's been created by the reactor and sends it into the turbine to spin it and then is condensed back into water via the condenser, " explained Sheehan, which contributed to the unplanned shutdown of the plant on July 11, 2014.

Sheehan said If the plant makes any modifications to that section of the condenser in the future, it has to ensure it will be carried out more carefully, so the problem doesn't happen again.

"We believe they have done a thorough evaluation of why these scrams kept occurring and that they have put in place changes to prevent recurrence in the future. We are satisfied with that, but we will not close out this White Performance Indicator until a certain amount of time has elapsed," he said.

The NRC uses a color-coded system that goes from Green, to White, to Yellow to Red.

"Anything above greater than Green, a plant gets additional NRC oversight," he added.

Sheehan also noted the NRC does not believe the July 11 shutdown posed any public safety threat or challenges to the safe operation of the reactor.

Sheehan did not give a specific date as to when a follow-up inspection would happen, but expects it to take place in the near future.