ML090760975

Generic Letter 2008-01, Supplemental Response

ML090760975
Person / Time
Site:	Oconee
Issue date:	03/12/2009
From:	Baxter D Duke Energy Carolinas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GL-08-001
Download: ML090760975 (5)

Text

S Duke DAVE BAXTER Vice President'Energy Oconee Nuclear Station Duke Energy ON01 VP / 7800 Rochester Highway Seneca, SC 29672 864-873-4460 864-873-4208 fax dabaxter@dukeenergy.

corn March 12, 2009 U. S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 ATTENTION:

Document Control Desk

Subject:

Duke Energy Carolinas, LLC (Duke)Oconee Nuclear Station, Unit 2 Docket No. 50-270 Generic Letter 2008-01, Supplemental Response On January 11, 2008, the NRC issued Generic Letter (GL) 2008-01, Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems. A written response consistent with the requested actions and information was requested within 9 months of the date of the GL. If the requested response date could not be met, a 3 month response was requested to provide the proposed alternative course of action.By letter dated May 8, 2008, Duke provided an alternative course of action for Oconee as well as Catawba and McGuire. Because some of the system piping referenced in the GL is located in areas inaccessible during power operation (i.e., Containment), the field verifications could not be completed until the upcoming refueling outages. Once the outage related field verifications were complete, the results would be provided to the NRC within 90 days of the end of the refueling outage. By letter dated September 25, 2008, the NRC accepted Duke's alternative course of action.The attachment to this letter provides the Oconee Unit 2 post outage supplemental response to Duke's GL 2008-01 9-month response dated October 13, 2008.AML www. duke-energy, com U.S. Nuclear Regulatory Commission March 12, 2009 Page 2 There are no new commitments contained in this supplemental response.Please contact Russ Oakley at (864) 873-3829 if additional questions arise.I declare under penalty of perjury that the foregoing is true and correct. Executed on March 12, 2009.Sincerely, Dave Baxter, Vice President Oconee Nuclear Site Attachment U.S. Nuclear Regulatory Commission March 12, 2009 Page 3 cc: w/attachment Mr. Luis Reyes Regional Administrator, Region II U.S. Nuclear Regulatory Commission Sam Nunn Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, GA 30303-8931 Mr. Jon Thompson (addressee only)Project Manager U.S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Mail Stop 0-8 G9A Washington, D.C. 20555 Mr. John Stang Project Manager U. S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Mail Stop 0-8 G9A Washington, D. C. 20555 Mr. Andy Hutto NRC Senior Resident Inspector Oconee Nuclear Station Attachment Oconee Unit 2 Generic Letter (GL).2008-01 9-Month Supplemental Response This attachment contains the results of walk-downs and surveys performed during-the Oconee Unit 2 fall 2008 refueling outage for the Low Pressure Injection (LPI), Core Flood (CF), and High Pressure Injection (HPI) systems piping inside the Unit 2 Containment and Unit 2 Letdown Storage Tank Room (deemed inaccessible for the GL 08-01 initial 9-month response).

The Unit 2 Building Spray (BS) system piping did not require any further walk-downs or surveys due to the design of the system. Piping for this system inside containment is open to the building atmosphere and is normally empty.System Walk-downs System piping walk-downs were performed inside Containment and Letdown Storage Tank Room to verify design drawings were accurate, and that there were no indications of support, restraint, or insulation damage indicative of past water hammer events.No significant drawing discrepancies were identified.

Also, no past evidence of water hammer was identified for piping inside of Containment or Letdown Storage Tank Room during the performance of the walk-downs.

Survey Measurements Field surveys were performed inside Containment and Letdown Storage Tank Room to verify the relative slope of the horizontal piping sections.

The piping slope surveys were performed by site personnel.

Survey acceptance criteria were the same as described in Oconee's October 13, 2008 GL response.Based upon piping configuration review, selected confirmatory Ultrasonic Testing (UT) locations were inspected and were verified to be water solid. Surveys identified ten locations which could be potential gas accumulation sites due to adverse pipe slope conditions.

Based on review of the slope survey results, two additional high point locations on the HPI supply header from the Letdown Storage Tank and one location on the discharge piping inside containment were identified which warrant installation of an effective vent valve. One additional program monitoring location was also identified.

These actions are not required as conditions of operability.

Operability is assured by current venting procedures without additional changes to system configuration or vent valve additions.

The vent valve additions are an enhancement to current venting capability.

Corrective Actions No corrective actions were identified which are needed to ensure continued operability of these systems.Conclusion Walk-downs and pipe slope surveys were performed during the Oconee Unit 2 fall outage for the inaccessible portions of High Pressure Injection, Low Pressure Injection, and Core Flood systems. The results of this effort did not change the conclusions of Oconee's October 13, 2008 GL response or result in any additional corrective actions required for continued operability.