Yesterday’s severe weather in parts of the southeast caused a number of problems for the region’s nuclear power plants, according to today’s NRC Event Reports. The most serious incidents involved the Browns Ferry nuclear plant in Alabama.
High winds and severe weather yesterday afternoon caused loss of offsite power to Browns Ferry. This resulted in an automatic shutdown of all three reactors. This morning’s Reactor Status Report shows all three units at 0% output.
The reactor trip caused activation of the Reactor Protection System, the Primary Containment System and the Emergency Diesel Generators. (One of the plant’s Emergency Diesel Generators was out of service for maintenance when the storm hit.) Falling water levels in the Unit 1 reactor also caused the actuation of the High Pressure Coolant Injection system.
That wasn’t the end of the Unusual Event at Browns Ferry, however. Plant operators reported that only 12 of the plant’s 100 offsite emergency sirens were operable at the time of the incident. Additionally, the plant suffered an oil spill when the diesel-powered Fire Pump activated. This leak was into the cold water channel, which discharges into navigable waterways, requiring a report to the state of Alabama.
Later that evening, operators of Unit 1 noticed a drop in water level, causing an RPS scram signal, and opened relief valves to put more water over the reactor core.
In other storm-related incidents, Seqouyah nuclear in Tennessee reported that 35 of its offsite sirens were knocked out by high winds and severe weather. Later that evening, the plant reported loss of all offsite power due to storms. Unlike Browns Ferry, Seqouyah kept its reactors running during the event, declaring a Limiting Condition of Operation (LCO) rather than a shutdown. Offsite power has since been restored, and the LCO lifted.
Sirens at Ft. Calhoun in Nebraska were also out last night, but it was for planned maintenance.