Oyster Creek nuclear power plant oversight will increase after an inspection found deficient maintenance work on a safety-related relief valve, federal officials said.
The finding ended up identified during a 2016 NRC inspection of the Lacey Township, NJ-based Oyster Creek. The facility is owned and operated by Exelon. The Nuclear Regulatory Commission (NRC) placed a white safety on the facility, which indicates a low to moderate safety significance.
The NRC uses a color-coded system to categorize inspection findings, with colors ranging from green, for very low safety or security significance, to white, yellow or red, for substantial safety or security significance. Findings determined to be greater than green result in additional NRC scrutiny.
This finding involves a problem with one of the plant’s electromatic relief valves (EMRV).
EMRVs end up used to depressurize the reactor during a pipe break. Oyster Creek has five of these valves.
“These valves serve a key safety function and therefore it is important that they be available to help mitigate severe accidents at the plant,” said NRC Region I Administrator Dan Dorman. “We will conduct a supplemental inspection at Oyster Creek to ensure the underlying problems that led to this issue have been appropriately addressed.”
Depressurizing the reactor during a pipe break is needed to inject coolant into the reactor core, according to the NRC. The valves play an important role in keeping the fuel covered and cooled during the shutdown process, according to the commission. If nuclear fuel overheats, it can result in a nuclear meltdown.
Staff at Exelon, Oyster Creek’s parent company, “failed to follow procedures” during the valve reassembly by not locking washers on the valve’s cut-off switch lever, according to Sheehan. The resulting friction caused the valve to malfunction, despite the requirement that the valves work properly in order for the plant to be online, according to the NRC. If one of the valves is inoperable for more than three days, the plant is required to shut down the reactor and reduce its pressure, according to the commission.
Despite the requirements, the valve was inoperable for nearly two years, between Oct. 11, 2014, and Sept. 19, 2016, said NRC spokesman Neil Sheehan.
In March, Exelon and the commission held a conference on the inspection finding and confirmed that the valves had since been correctly assembled.
“Exelon Generation and the NRC share a common goal of safe and excellent operations,” plant spokeswoman Suzanne D’Ambrosio said. “The conference was a productive and open dialogue between Exelon Generation and NRC staff. While we appreciated the opportunity to discuss our concerns with this potential white finding, we are disappointed in the results. As always, we will continue to work alongside the NRC to ensure that Oyster Creek is operated with the highest level of safety and precision.”
In terms of corrective actions, Exelon verified correct assembly of the valves following the most recent refueling and maintenance outage at the plant.
This is the second time in two years the plant has received a safety finding from the NRC for problems related to the electromatic relief valves. In April 2015, the commission issued a “yellow” finding, one of “substantial safety significance,” for a design problem in the valve actuator. The two issues are not related, Sheehan said.
“In that (previous) case, the issue was deemed to be an old design issue … (and) did not reflect a performance deficiency with existing licensee programs, policies or procedures,” Sheehan said in an email. “However, the current EMRV (electromatic relief valve) issue is not considered an old design issue because it is not a design-related problem and was the result of a current performance deficiency – the incorrect reassembly of the valve.”