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On 2-21-06, during a tour of containment during normal operation at 100% power, a small leak (one (1) to three (3) drops per second) was noted from a 1/2 inch line connected to the decay heat removal (DHR) drop line. It was identified as being a body-bonnet leak on valve 1LP-167 subject to a TS limit of 10 gpm. At approximately 1400 hours on 6-14-06 following a shutdown for an unrelated issue, the source was identified as a leak at a weld in a "tee" joint adjacent to 1LP-167. This is considered RCS pressure boundary leakage, subject to a TS limit of zero leakage. The leak was isolated by closing a normally open valve in the 1/2 inch line and the leakage stopped. Initial Safety Significance: The leak is in a 1/2 inch line which provides over pressure protection from thermal expansion in the volume between 1LP-1 and 1LP-2 (the main pressure boundary isolation valves between the high pressure RCS and the LPI (DHR) system). The leak rate (1 to 3 drops per second) was not significant, except that it was RCS pressure boundary leakage. 1LP-1 is normally closed, but must be opened to establish a DHR path. Valve 1LP-167 is a 1/2 inch check valve which would have limited RCS leakage. Thus, if the leak had grown, it would have been limited to the amount of seat leakage past either 1LP-167 or 1LP-1. It would also have been limited by the 1/2 inch size of the line containing the leak." Technical Specification LCO 3.4.13 applies to RCS leakage in modes 1 to 4. The licensee plans to fix the leak prior to entry into mode 4. The licensee notified the NRC Resident Inspector.

• * * RETRACTION AT 00:15 ON 6/16/2006 FROM SAM LARK TO ABRAMOVITZ * * *

On 6-14-06 at 1908 hours Oconee reported an RCS pressure boundary leak in a 1/2 inch line connected to the decay heat removal (DHR) line near valve 1LP-1 inside containment. Oconee has reviewed the event in greater detail and has concluded that the event is not reportable. The Basis for TS 3.4.13 states that RCS LEAKAGE includes leakage from connected systems up to and including the second normally closed valve (or outermost isolation valve for systems penetrating containment). However TS 1.1 contains a definition of LEAKAGE which includes 'Pressure Boundary LEAKAGE: LEAKAGE (except SG LEAKAGE) through a nonisolable fault in an RCS component body, pipe wall, or vessel wall.' The leakage in this event was isolable, and therefore does not meet the definition of Pressure Boundary LEAKAGE. Therefore the zero leakage criterion of TS 3.4.13 does not apply to this leak. The applicable criterion is 10 gpm identified LEAKAGE. Since the leak does not meet the criterion as Pressure Boundary LEAKAGE, the leak was isolable, and the applicable TS LEAKAGE limit was not exceeded, this event does not meet the reportability criteria for 10 CFR 50.72 or 50.73 and event notification 42641 is hereby RETRACTED. Additional information and clarification: "During normal operation the leak was isolated by one barrier (valves 1LP-167 and 1LP-1, closed in parallel). The leakage observed on 2-21-06 during a containment tour at Mode 1 was recorded as 1 drop per second. As stated in the initial notification, at that time the leak was believed to be a body-bonnet leak. It was observed at Mode 1 again on 5-25-06 and recorded as 3 drops/second. On 6-14-06, the leakage was recorded as one drop/second while at reduced pressure in Mode 4, before the DHR systems was placed in service. At that point, the leak was isolated by closing an additional valve (1LP-166, normally open), and the leak stopped. The Low Pressure Injection system was placed in service for DHR, which opened 1 LP-1. Later, with system pressure at approximately 285 psig in Mode 5 (outside the applicability of TS 3.4.13), 1LP-166 was reopened to allow additional verification of the leak location. At that time the leak was described as a 'spray' but no leak rate was measured before 1LP-166 was reclosed. The leak rate at that time was estimated as well less than 10 GPM. Corrective Action: The affective section of 1/2 inch pipe and associated fittings have been removed for transfer to a Duke laboratory for analysis. Repairs will be completed prior to return to mode 4. The licensee notified the NRC Resident Inspector. Notified the R2DO (Bonser).

The licensee provided the following information via facsimile: Event: On February 16, 2005 at 1331 hours EST, Operations discovered that the Oconee Unit 3 Reactor Building Normal Sump (RBNS) level was increasing. Chemistry sampled the containment normal sump to determine the water source and could not conclusively rule out Low Pressure Service Water (LPSW). The leak rate into the sump is approximately 1.9 gpm. LPSW is the cooling medium used for the Reactor Cooling Pump (RCP) motor coolers, the Reactor Building Cooling Units (RBCU), and the Reactor Building Auxiliary Cooling Units (RBACU). Unit 3 entered Technical Specification 3.6.1.A at 1331. This requires restoring containment to Operable status within 1 hour. The approximately 1.9 gpm leakage is above the leakage allowed in calculation OSC-7005 "LPSW Allowable Leakage Inside Containment". At 1431 Unit 3 entered Technical Specification 3.6.1 B which requires being in mode 3 in 12 hours. Initial Safety Significance: By limiting the amount of LPSW leakage inside containment then containment operability is ensured. Above the calculated LPSW leakage as stated in OSC-7005, containment operability is in question. The LPSW system pressure could be less than containment LOCA peak pressure. Therefore containment atmosphere has the potential to leak through the LPSW system, during a LOCA, and out the return line resulting in a containment leak path. Collective Action(s): Additional sampling and process indications suggest that the cause of the Reactor Building Normal Sump rate increase is feedwater or main steam. A power reduction to 18% has been completed and a reactor building entry is in progress to confirm the source of the leakage. If the source is confirmed to be feedwater or main steam, Technical Specification 3.6.1 will be exited. The turbine is still loaded and the electrical grid was not affected by the power decrease to 18%. All systems functioned as required and other units at Oconee were not affected by this event. NRC Resident Inspector was notified.

• * * UPDATE ON 2/17/05 @ 0018 BY JOHN COLLINS TO CHAUNCEY GOULD * * * UPDATE

They entered the containment and verified a steam leak off the impulse line for the "3B" steam generator main steam pressure transmitters. They are currently at 18% power and making a decisions on repair options. The NRC Resident Inspector will be informed. The Reg 2 RDO(Bernhard) was notified.

• * * UPDATE ON 2/17/05 @ 0139 BY JOHN COLLINS TO CHAUNCEY GOULD * * * RETRACTION

At 0012 on February 17, 2005 entry into the Unit 3 reactor building confirmed that the source of leakage into the reactor building normal sump was the Main Steam system. Specifically, the location of the leak appears to be a fitting downstream of an instrument root valve off the 3B Main Steam line. Based on this information, Technical Specification 3.6.1 was exited and this event is not reportable per 10CFR50.72. and therefore being retracted. A shutdown to MODE 3 will be conducted to facilitate repairing the leak. The NRC Resident Inspector will be informed. Reg 2 RDO(Bernhard) was notified.

Event: At 08:00 hours Oconee Unit 1 initiated a unit shutdown per Technical Specification (TS) 3.0.3. Unit 2 initiated shutdown at 0900 (ET). It is expected that Unit 3 will initiate shutdown at 1000 hours. Target for entry into Mode 3 is 1300 hours on all units. At 0129 hours all three Oconee units received a number of alarms related to power to the 230 KV switchyard (SWYD) battery chargers. At 0200 hours Operations determined that both AC power sources to the SWYD battery chargers required by TS 3.8.3 had tripped and declared entry into TS 3.0.3 because no specific condition of TS 3.8.3 applied. Evaluation for potential applicability of other reporting criteria is still in progress. Initial Safety Significance: The SWYD batteries currently have normal voltage (being monitored hourly) but are NOT considered operable per TS 3.8.5 at this time, which would also require TS 3.0.3 entry. However, if voltage drops too low the ability to remotely operate SWYD power circuit breakers would be affected, which would impact SWYD isolation capability. Local manual operation would still be possible, and operations personnel are stationed in the SWYD as a contingency. Corrective Action: 1. Maintenance has identified a fault in a power transfer switch. Actions have been completed to isolate the fault and restore power to the battery chargers. 2. Measurements of battery voltages are being taken hourly. A surveillance will be performed to verify TS 3.8.5 compliance after the charger power supply is restored. 3. Shutdown of Oconee units will follow schedule above unless power and battery voltages are restored sooner (as expected). The electrical grid is stable and standby emergency power remains operable. The NRC Resident Inspector has been informed. The licensee does not intend to make any State, local or other Federal notifications or issue any press release at this time.

• * * UPDATE AT 1400 EDT ON 7/28/04 FROM PHIL NORTH TO S. SANDIN * * *

At 0945 EDT both SWYD battery chargers were energized to restore battery parameters. At 1205 EDT the affected batteries were declared operable and all three (3) Units exited their respective LCOs. Units 1, 2, and 3 are currently holding at 80%, 84% and 89% power, respectively, and will commence power escalation after review and closeout of their paperwork. Notified R2DO (Decker).