NRC: Oyster Creek Emergency Diesel Generator Cooling System Failed During Test Due To Aging Hose

by Patricia A. Miller

The Oyster Creek Nuclear Generating Station could face additional oversite from the federal Nuclear Regulatory Commission, based on the latest quarterly inspection of the plant in Lacey Township.

The NRC's latest inspection of the plant's performance found a "White" violation because Exelon did not provide instructions or procedures for maintenance on the plant's emergency diesel generator cooling water system, according to an NRC letter sent to the plant manager and the site vice president.

The NRC's inspection was completed on March 31, 2016. A "White" finding is a finding of low to moderate safety significance, according to the letter.

Exelon did not appropriately prescribe instructions or procedures for maintenance on the emergency diesel generator cooling water system to ensure that a three-inch cooling flexible coupling hose was maintained to support the EDG safety function.

"As a result, the flexible coupling hose was in service for approximately 22 years and subjected to thermal degradation and aging that eventually led to failure of EDG No. 1 during operating conditions on January 4, 2016, " the letter states.

The system was inoperable for greater than the allowed outage time.

If it is finalized as “White,” the plant would move to Column 2 (the Regulatory Response Column) of the NRC’s Action Matrix and receive additional oversight from the agency.

"The emergency diesel generators serve an important safety function in that they are activated to provide power to key plant safety systems in the event that power to the plant from the grid is interrupted," NRC spokesman Neil Sheean said.

Exelon had 10 days from the receipt of the letter to either contest or accept the findings.

"We believe that we have sufficient information to make a final significance determination," the NRC said.

The inspectors also found two violations of NRC requirements, both of which were of very low safety significance during the visit, and a licensee-identified violation of very low safety significance, according to the letter.

Oyster Creek was taken offline recently for a planned maintenance outage, Exelon spokesperson Suzanne D'Ambrosio said.

"During the outage, technicians repaired and tested several pumps and seals that control water flow and performed maintenance on a control rod drive mechanism," she said. "Many of these activities could not be performed while the unit was generating electricity."

The plant is now back online.

Oyster Creek is the oldest nuclear plant in the United States. It went online on Dec. 23, 1969.

Photo credit: Exelon Corporation