TMI missing flood barriers to protect safety related equipment

Facility: THREE MILE ISLAND

Event Number: 46194

Event Date: 08/21/2010

FLOOD BARRIERS NEEDED TO PROTECT SAFETY RELATED EQUIPMENT MISSING

"On August 21, 2010 an inspection of the Air Intake Tunnel (AIT) sump identified missing flood barriers needed to protect safety related equipment in the plant. If enough flood water had entered into the AIT, water could have entered into the Auxiliary Building (AB) through the ventilation ductwork that connects the AIT and the AB. If flood water continued to enter the AB, then safety related equipment in the AB could have been affected.

"This condition could have resulted in the unavailability of equipment in the Auxiliary Building including the 1A and 1B Decay Heat pumps, the 1A and 1B Building Spray pumps and 1A, 1B and 1C Make-up Pumps. This is reportable as an 8 hour ENS notification under 10CFR50.72(b)(3)(v)(B) and 10CFR50.72(a)(1)(ii) as a condition that at the time of discovery could have prevented the fulfillment of the safety function of structures or systems that are needed to remove residual heat.

"Flood protection barriers have been established for the affected penetrations. Inspections of the flood protection barriers are ongoing. Further engineering review is being performed to determine the impact of the potential water intrusion into the AIT and AB."

The licensee notified the NRC Resident Inspector. The licensee will notify the Pennsylvania Bureau of Radiation Protection.