ML053340283

High Energy Line Break and Tornado Mitigation Strategy

ML053340283
Person / Time
Site:	Oconee
Issue date:	11/21/2005
From:	Rosalyn Jones Duke Energy Corp
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML053340283 (6)

Text

RONALD A JONES

_oDuke Vice President ParPowere Oconee Nuclear Site Duke Power ONO1VP / 7800 Rochester Hwy.

Seneca, SC 29672 November 21, 2005 864 885 3158 864 885 3564 fax U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 ATTENTION: Document Control Desk

SUBJECT:

Duke Energy Corporation Oconee Nuclear Station Units 1, 2 and 3 Docket Nos: 50-269, 270 and 287 High Energy Line Break and Tornado Mitigation Strategy On November 14, 2005, representatives from Duke Energy Corporation's (Duke) Oconee Nuclear Station met with the Nuclear Regulatory Commission (NRC) to provide progress updates on both the Tornado and High Energy Line Break (HELB) projects. A brief overview of the proposed Tornado License Amendment Request was provided, focusing on the general approach and logic used to create the methodology document. Submittal schedule information was also provided to the NRC.

HELB discussions focused on ultrasonic examinations (UT) of selected portions of feedwater piping in the East Penetration Room (EPR), and restoration of electrical penetration termination enclosures to their correct configuration. The UT examinations are intended to provide a high degree of confidence in the continued structural integrity of the piping, while the electrical penetration restoration work will better protect the associated terminal strips from wetting. This discussion concluded with a brief overview of planned EPR modifications to mitigate the effects of flood water accumulation following a HELB event. A list of specific commitments, as discussed during the meeting, is included as an attachment to this letter.

Duke continues to evaluate additional modifications that would improve our Tornado and HELB mitigation strategies, and will submit a letter to the NRC on or before January 31, 2006, providing modification scope and schedule details.

www.dukepower.corn

U.S. Nuclear Regulatory Commission November 21, 2005 Page 2 If you have any questions or comments regarding these issues, please contact Graham Davenport of the Oconee Nuclear Site Regulatory Compliance Group at 864-885-3044.

Very r ly yours, RA nes, Vice President Oconee Nuclear Site Enclosure

U.S. Nuclear Regulatory Commission November 21, 2005 Page 3 cc: Mr. L. N. Olshan, Project Manager Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 0-14 H25 Washington, D.C. 20555 Dr. W. D. Travers, Regional Administrator U.S. Nuclear Regulatory Commission - Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, Georgia 30303 Mr. M. E. Ernstes, Chief Branch 1 DRP U.S. Nuclear Regulatory Commission - Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, Georgia 30303 Mr. M. C. Shannon Senior Resident Inspector Oconee Nuclear Station

ATTACHMENT LISTING OF COMMITMENTS MADE DURING A NOVEMBER 14, 2005 MEETING BETWEEN DUKE ENERGY CORPORATION AND NUCLEAR REGULATORY COMMISSION REPRESENTATIVES RELATIVE TO TORNADO AND HELB MITIGATION STRATIGIES

ATTACHMENT LISTING OF COMMITMENTS MADE DURING A NOVEMBER 14, 2005 MEETING BETWEEN DUKE ENERGY CORPORATION AND NUCLEAR REGULATORY COMMISSION REPRESENTATIVES RELATIVE TO TORNADO AND HELB MITIGATION STRATIGIES Main Feedwater and Main Steam Piping Inspection Program:

1.Complete ASME Section XI ISI UT of all East Penetration Room (EPR) Main Steam (MS) and Main Feedwater (MFDW) girth and attachment welds in all Oconee units by the Spring of 2008 (completion of Unit 1 End Of Cycle (EOC) 24 refueling outage (RFO)).

2. Implement an inspection schedule that ensures all EPR MS and MFDW girth and attachment welds are re-inspected at least once during each subsequent 10-year inspection interval. (This inspection schedule has been implemented) 3.Implement an inspection program that ensures selected piping base metal downstream of feedwater isolation valves located in the EPR, and not enclosed by the guard pipe, receives a UT examination at least once every 10 years. Initial inspections will occur during the Spring 2006, Unit 3 EOC22 RFO; the Fall 2006, Unit 1 EOC23 RFO; and the Spring 2007, Unit 2 EOC22 RFO.

4.Visually inspect attachment welds at the terminal end inside the guard pipe at least once every 10 years.

This inspection will occur externally to the feedwater pipe using an appropriate inspection technique, such as borescope. Initial inspections will occur during the Spring 2006, Unit 3 EOC22 RFO; the Fall 2006, Unit 1 EOC23 RFO; and the Spring 2007, Unit 2 EOC22 RFO.

Electrical Penetration Termination Enclosures Located in the Penetration Rooms:

1.Complete restoration of the Oconee Unit 2 EPR-enclosures to their correct configuration by 12/31/2005. Missing and/or damaged covers, gaskets, and fasteners will be repaired or replaced.

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LISTING OF COMMITMENTS MADE DURING A NOVEMBER 14, 2005 MEETING BETWEEN DUKE ENERGY CORPORATION AND NUCLEAR REGULATORY COMMISSION REPRESENTATIVES RELATIVE TO TORNADO AND HELB MITIGATION STRATIGIES

2. Inspect and restore the Oconee Unit 1 and Unit 3 enclosures to their correct configuration by 12/31/2006. Missing and/or damaged covers, gaskets, and fasteners will be repaired or replaced. This activity will occur during the scheduled Spring and Fall RFOs. To the extent practical, this work will be accomplished prior to the RFOs. Portions of this work may require an outage to perform.

3 Create an inspection plan to select a portion of enclosures to open and inspect for signs of internal debris/corrosion by 1/31/2006. Fully implement this inspection plan during the Spring 2006, Unit 3 EOC22 RFO; the Fall 2006, Unit 1 EOC23 RFO; and the Spring 2007, Unit 2 EOC22 RFO. Ten selected EPR penetration enclosures were opened and inspected during the current Unit 2 EOC21 RFO. No electrical termination degradation was observed.

4 Revise station procedures and processes as needed, by 12/31/2006, to ensure penetration termination enclosures are maintained in their correct configuration.

EPR Flood Prevention Modifications 1.Complete the design and installation of flood outlet devices for each Oconee Unit EPR by 5/31/2007.

Installation will occur during the Spring 2006, Unit 3 EOC22 RFO; the Fall 2006, Unit 1 EOC23 RFO; and the Spring 2007, Unit 2 EOC22 RFO. To the extent practical, installation will be accomplished before the respective refueling outages.-

2. Complete the design and installation of flood impoundment features for each Oconee unit EPR by 12/31/2007.

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