Operators at Exelon’s 890-MW Calvert Cliffs-1 units in Lusby, Maryland, shut the unit early Monday morning because of a technical issue.
The move came after a down power to about 10 percent of capacity from 100 percent on Sunday when workers found a main transformer cable disconnected, a Nuclear Regulatory Commission (NRC) spokesman said Monday.
“Icy conditions and 60 mph winds [from the weekend blizzard] caused a high voltage line in Calvert Cliffs’ switchyard to disconnect,” said Lacey Dean, a Calvert Cliffs spokeswoman. Operators “reduced power on Unit 1 and took the generator offline to allow BGE crews to repair the line safely and effectively.”
The 880-MW unit 2 continues to operate at 100 percent of capacity, she said.
Operators shut the unit early that day “after elevated sodium levels were identified in the condenser. Plant personnel will be checking for condenser tube leakage,” said Neil Sheehan, an NRC Region I spokesman.
In addition, operators at Entergy’s 849-MW FitzPatrick nuclear power plant in Scriba, New York, manually shut at 10:41 pm EST [0341 GMT] Saturday from 89 percent of capacity “due to lowering [water] intake level,” the company said in an event notification report filed that day with NRC.
“The lowering intake level indication was a result of frazil ice, which is a slushy ice condition that occurs in Lake Ontario under … meteorological conditions involving water temperature, air temperature, and wind speed and direction,” said FitzPatrick spokeswoman Tammy Holden. “Frazil ice can create a blockage at the [water] intake structure.”
“There was one complication during shutdown: A power transfer glitch knocked the circulating-water pumps out of service, but other systems were used for the cooldown,” Sheehan said.
Operators early Friday had reduced the unit’s output to 60 percent of capacity from 100 percent early in order to conduct unrelated “planned maintenance,” Holden said.