SALEM TWP. – A buildup of toxic nitrogen gas during a pipe repair prompted officials to declare a more than five-hour alert Monday at the PPL nuclear power plant.
There was no radiological release and no one was injured, said plant spokesman Joe Scopelliti. The plant continued to operate as normal, he said.
“At 12:06 p.m. we declared an alert at the Susquehanna nuclear power plant when workers detected a low oxygen level in a pump room related to Unit 2,” Scopelliti said.
The alert, the second lowest of four emergency classification levels established by the U.S. Nuclear Regulatory Commission, was declared over at 5:26 p.m.
The NRC, as well as the Pennsylvania Emergency Management Agency and the state and Luzerne and Columbia EMAs, were notified.
Scopelliti said workers were placing a “freeze seal” on the pipe, a process that involves using liquid nitrogen to freeze the water in the pipe so it could be cut. The repair took place in the unit’s residual heat removal pump room.
“It houses a system that could be used to supply water if needed,” Scopelliti said. The equipment in the room was not in service.
NRC spokesman Neil Sheehan said the freezing procedure is common in the industry when a line cannot be isolated. A “jacket” or enclosed casing is placed over the line, freezing the water to allow workers to perform the maintenance.
The commission monitored the situation throughout the afternoon, Sheehan said. A worker was evacuated from the room at the time of the alert. PPL planned to send in personnel to investigate the source of the leak once the gas level was safe. A preliminary report indicated there was no leakage of nitrogen.
The NRC has two resident inspectors on site who followed the developments, Sheehan said.
The commission’s focus during the emergency was “to make sure the company is taking the appropriate steps to deal with the situation,” he said.
The power plant is owned jointly by PPL Susquehanna LLC and Allegheny Electric Cooperative Inc. Unit 2, which went on line in 1985, was operating at 100 percent power, and Unit 1, in operation since 1983, was at 94 percent, according to the NRC.
Earlier this month PPL Corp. filed an application with NRC to build a new reactor to be named the Bell Bend plant near the other units. That reactor would have a 1,600-megawatt capacity, higher than both the existing units.