|BIOFOULING OF INTAKE STRUCTURE LEADS TO MANUAL REACTOR SCRAM OF UNIT 2 AND DOWNPOWER OF UNITS 1 & 3
"On July 20, 2020, at 1325 hours Central Daylight Time, Brown's Ferry Unit 2 inserted a manual reactor scram due to degrading main condenser vacuum from marine biofouling at the intake structure. Brown's Ferry Unit 1 performed a down power to 43% and Unit 3 down powered to 76%. Conditions are stable on both Unit 1 and 3 following unit down power.
"Primary Containment Isolations Systems received an actuation signal for groups 2, 3, 6, and 8 on reactor water level below +2". All Primary Containment Isolations System groups that received an actuation signal performed as designed. Additionally, all other systems functioned as designed.
"This event is reportable within 4 hours per 10CFR50.72(b)(2)(iv)(B) - Any event or condition that results in actuation of the reactor protection system (RPS) when the reactor is critical except when the actuation results from and is part of a pre-planned sequence during testing or reactor operation.
"This event also requires an 8 hour report per 10CFR 50.72(b)(3)(iv)(A), "Any event or condition that results in valid actuation of any of the systems listed in paragraph (b)(3)(iv)(B), (1) Reactor protection system (RPS) including: reactor scram or reactor trip, except when the actuation results from and is part of a pre-planned sequence during testing or reactor operation and (2) General containment isolation signals affecting containment isolation valves in more than one system or multiple main steam isolation valves (MSIVs).
"The NRC Resident Inspector has been notified."
All control rods fully inserted and decay heat is being removed via normal feedwater and condenser.