During a fire safety inspection yesterday afternoon at the Calvert Cliff nuclear power plant in Maryland, operators discovered a fire safety barrier problem that could have rendered the Control Room inoperable. Inspectors found a breach in the fire barrier that, in the event of a High Energy Line Break, “could allow steam from a high energy line break in the Unit 2 Steam Generator Blowdown system to potentially impact equipment in the Control Room. The Control Room is not analyzed for a steam environment.” Calvert Cliffs reported such a scenario could “could likely affect the safety related equipment in the Control Room.” Further, the breach is ” is believed to have existed from initial plant construction.” (Unit 2 has been in operation since 1977.) Initial reaction from Calvert Cliffs was to isolate a steam line: “At 1803 on 12/8/11, Unit 2 Steam Generator Blowdown was secured to eliminate the potential for a HELB in the affected area which eliminated the potential unanalyzed condition.”
The problem is confined to the Unit 2 reactor, but both units share a single Control Room, meaning that a break in the steam line in Unit 2 could have affected both units by rendering the Control Room inoperable. In Nuke Speak, this is called a co-location problem. To cut costs, nuclear operators like to group together new units with existing units. Opponents have raised co-location issues in response to expansion applications of a number of nuclear plants including the South Texas Project.