Event Notification Report for August 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.

* * * RETRACTION FROM MICHAEL FITZWATER TO JOHN SHOEMAKER AT 1437 EDT ON 10/19/10 * * *

"EN# 46194 made on August 21, 2010 at 1100 EDT is being retracted. Upon further Engineering review it was determined that the external flood barrier design deficiency in the Air Intake Tunnel (AIT) did not result in a condition that could have prevented the fulfillment of the safety function needed to remove residual heat. The AIT sump pump is in the cavity that had the degraded barrier where the in leakage of concern enters through conduits from yard electrical vaults. This pump starts automatically and has capacity in excess of the in leakage during the Probable Maximum Flood (PMF). The AIT sump pump's functional capability was confirmed to be available over the past three years. Therefore the ability to prevent flood water from the AIT reaching and impacting safety related equipment needed to remove residual heat was maintained. The event is therefore NOT reportable."

The Licensee has notified the Resident Inspector.

Notified R1DO.

NOTIFICATION OF STATE AGENCIES DUE LEAK OF A WATER TREATMENT CHEMICAL

"At 1509 on 08/21/2010, a notification to outside state agencies, Tennessee Department of Environment and Conservation (TDEC) and Tennessee Emergency Management Agency (TEMA), was made due to a Towerbrom 960 [a microbiocide] chemical leak that developed at the Essential Raw Cooling Water (ERCW) intake station. The leak occurred during scheduled chemical treatment of the ERCW system. The leak was identified at 1850 EDT on 08/20/2010 and terminated at 1955 EDT on 08/20/2010. Chemically treated ERCW containing 55 ppm total residual chlorine reached the waters of the US which is above the 0.1 ppm allowed by the plant's National Pollutant Discharge Elimination System (NPDES) permit. There have been no observable adverse effects to the environment at this time. This occurrence does not affect safety related or other plant equipment."

The licensee notified the NRC Resident Inspector.

ONE TRAIN ECCS DECLARED INOPERABLE DUE TO VOID IN "A" RHR HEAT EXCHANGER

"On 8/21/10 at 1700 [CDT] with the Unit in Mode 1, 100% power, Engineering personnel provided information to the Control Room that a known void in the 'A' Residual Heat Removal (RHR) heat exchanger could move from the heat exchanger to other locations in the Emergency Core Cooling System (ECCS). The analysis provided by a vendor indicates that during a specific RCS leak scenario with a failure of the A' RHR Pump, our [Unit 1] piping configuration could potentially allow the void to be swept from the 'A' RHR heat exchanger and be transported to the 'A' Centrifugal Charging Pump (CCP) and 'A' Safety Injection Pump (SIP) while in the cold leg recirculation mode of operation. This condition results in one train of ECCS being inoperable. The ECCS safety function is maintained due to redundant and interconnecting piping, in both injection and recirculation phases of operation.

"The NRC Resident has been informed."

The licensee declared one train of ECCS inoperable placing Unit 1 in the 72-hour Technical Specification [TS] 3.5.2, Condition A, Action A.1. Corrective actions are on going to remove the void and exit the TS Action Statement.

* * * RETRACTION FROM RICK HUBBARD TO JOHN SHOEMAKER ON 11/24/10 AT 12:24 EST * * *

"Additional information has been obtained by Engineering. The largest void identified in the 'A' RHR heat exchanger would not prevent the RHR system from performing its safety function. Hydraulic analysis models of this void moving through the system have shown that no pressure pulses will occur that could challenge the structural integrity of the system. The model results also show that ingestion of the void by the higher head ECCS pumps during the ECCS recirculation mode has no adverse affect on the ECCS high head pumps and they would remain capable of performing their safety function.

"As a result, this event is not reportable per 50.72(b)(3)(ii)(B). This event is being retracted."

The licensee notified the NRC Resident Inspector. R4DO (Lantz) has been notified.