Procedure used several times in violation of federal regulations.
PLYMOUTH — Pilgrim Nuclear Power Station operators recently discovered that their procedure for testing an emergency system used to contain radiation violated federal regulations and could have left the public unprotected if a radiological release had occurred while the test was being done.
In a letter sent to the Nuclear Regulatory Commission in late January, officials from Entergy Corp., Pilgrim’s owner and operator, said the flaw was discovered Nov. 26 as workers prepared to test the standby gas treatment system.
Entergy said the test had been done with the procedural error several times in the past three years.
The standby gas treatment system, located in the reactor building, consists of two trains of gas treatment, which each contain large fans for driving contaminated air through filters in an emergency before it is sent into the atmosphere from a tall stack.
The filters help minimize the amount of radioactivity being released.
During testing of the gas treatment system, operators would disable both trains simultaneously, according to the report Entergy submitted to the NRC on Jan. 25. Under federal regulations, however, at least one train must be available in case an emergency occurs.
“In an emergency, when we most needed radiation filtered, we would have been out of luck,” said Mary Lampert, a Pilgrim opponent and president of Pilgrim Watch.
Entergy spokesman Patrick O’Brien acknowledged the flawed test method.
“The test procedure has been placed on hold and is being revised to ensure compliance with applicable regulations,” O’Brien wrote via email. “There was no adverse impact to the plant or safety as a result of the previously performed testing, nor would one have been expected.”
David Lochbaum, director of the Nuclear Safety Program for the Union of Concerned Scientists, agreed that the danger to the public was minimal since the testing does not take long.
“Test miscues like this also happen at nuclear plants not owned by Entergy,” Lochbaum said. “The difference is that they happen without all the other problems that seem to inflict Entergy's reactors.”
One of Entergy’s proposed solutions to the testing mistake, as stated in the company’s letter to the NRC, is to train operations personnel and maintenance coordinators that voluntarily compromising a safety system needed in an emergency “is not allowed.”
Normally, the gas treatment system is kept in standby mode while the reactor building’s regular ventilation system is used.
In a nuclear incident, the regular ventilation system shuts down and the standby system kicks in to clean the gases leaking from the reactor into the secondary containment area before they are released.
Because the system would be essential to public safety in an emergency, it must be operational whenever the nuclear reactor is running, at startup and in hot shutdown mode, during the movement of irradiated fuel assemblies in the secondary containment area and during movement of new fuel over the spent-fuel pool.
Technical specifications for the operation of the plant’s nuclear reactor require that at least one of the two trains be operational. If one goes down, it must be working again within seven days or operators must shut down the reactor.
If both trains are down, operators must immediately begin shutdown and have the reactor in cold shutdown within 36 hours.
“In this instance, the company identified that a procedure/test that plant personnel were getting ready to perform was written such that the system would be disabled, though it’s important to note they identified the issue before the test actually commenced,” NRC spokesman Neil Sheehan wrote of Entergy’s discovery of the testing flaw in late November.
“However, in realizing that this test would disable the standby gas treatment system, they also realized that performing the test had disabled the system in the past, on occasions when the test was previously performed,” Sheehan said.
Federal inspectors will review the information sent Jan. 25 and document their conclusions in a future quarterly report.
Pilgrim is classified by federal standards as one of the worst-performing reactors in the nation, one step above mandatory shutdown.
The reactor is scheduled for shutdown by May 31, 2019.
— Follow Christine Legere on Twitter: @ChrisLegereCCT.