ML083470246

Submittal of Auxiliary Service Water System Outage Report

ML083470246
Person / Time
Site:	Oconee
Issue date:	12/09/2008
From:	Baxter D Duke Energy Corp
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
Download: ML083470246 (7)

Text

Duke Ener DAVE BAXTER Vice President Energy, Oconee Nuclear Station Duke Energy Corporation ON01 VP17800 Rochester Highway Seneca, SC 29672 864-885-4460 864-885-4208 fax dabaxter@dukeenergy.com December 9, 2008 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555

Subject:

Oconee Nuclear Station Docket Nos. 50-269, -270, -287 Oconee Auxiliary Service Water System Outage In accordance with Selected Licensee Commitment (SLC) 16.9.9, please find attached a copy of a report which details the outage of the Oconee Unit 2 Auxiliary Service Water (ASW) System. SLC 16.9.9 requires that a report be submitted to the Nuclear Regulatory Commission (NRC) if the station ASW System and the Standby Shutdown Facility (SSF) ASW System are inoperable for greater than 7 days. The report provides reasons for the outage and outlines plans and procedures used to provide for the loss of the system during the outage.

No NRC commitments are contained in this report.

Sincerely, Dave axter Site Vice President Oconee Nuclear Station Attachment

,4oo/

www. duke-energy.com

U. S. Nuclear Regulatory Commission December 9, 2008 Page 2 of 2 CC: Luis Reyes, Regional Administrator Region II Andy Hutto, Senior Resident Inspector Oconee Nuclear Site John Stang, Project Manager NRR BCC :

D. A. Baxter T. P. Gillespie S. A. Batson R. J. Freudenberger B. G. Davenport K. R. Alter K. R. Ashe R. D. Hart R. L. Gill L. A. Vaughn ELL NSRB

ATTACHMENT Selected Licensee Commitment 16.9.9 Auxiliary Service Water System Outage Report

Selected Licensee Commitment 16.9.9 Auxiliary Service Water System Outage Report Purpose This report provides information about the Auxiliary Service Water (ASW) System outage that occurred during the current Oconee Unit 2 refueling outage.

System Description

The ASW System is designed to remove decay heat in the absence of the Main Feedwater (MFDW) System, Emergency Feedwater (EFW) System and Decay Heat Removal (DHR) Systems. DHR is accomplished by supplying water to the steam generators through the EFW headers.

The water supply for the ASW System is provided by the Oconee Unit 2 Condenser Circulating Water (CCW) System intake.

Another alternate and independent means of DHR is provided by the Standby Shutdown Facility (SSF) ASW System. Similar to the ASW System, the SSF ASW System removes decay heat by supplying water to the .steam generators through the EFW headers. In addition, the water supply for the SSF ASW System is provided by the Oconee Unit 2 CCW System intake.

Selected Licensee Commitments Condition B of Selected Licensee Commitment (SLC) 16.9.9 allows the ASW system and the SSF ASW system to be simultaneously inoperable for a period of 7 days. If one of the systems cannot be returned to service within that time period, then condition C states that a report be submitted to the Nuclear Regulatory Commission (NRC) within 30 days outlining plans and procedures to be used to provide for the loss of the system.

ASW System Outage Information A. During the current Unit 2 refueling outage, the CCW system inlet piping was dewatered to allow for maintenance and modification activities. The major activities that required dewatering included the following:

" Replace 2A and 2B CCW pump discharge expansion joints

" Repair seats on 2CCW-12 and 2CCW-13 (CCW pump discharge valves)

Selected Licensee Commitment 16.9.9 Auxiliary Service Water System Outage Report Page 2 of 4

• Rebuild 2CCW-30 (condenser inlet unwatering block valve) 0 Modifications to tie in the Protected Service Water (PSW) recirculation line into the CCW piping and replace CCW-99 (ASW pump suction) with a new valve. These modifications were necessary to support eventual replacement of the Station ASW pump with the new PSW pump in 2010.

0 Major maintenance activities were performed for the SSF diesel generator, SSF diesel air system, SSF ASW pump air ejector, various SSF pumps, breakers, and instruments.

As a result of the CCW System intake dewatering, the suction source for the station ASW System and the SSF ASW System was removed from service. Thus, the ASW System was placed in a 7 day action statement per SLC 16.9.9, Condition B.

B. Originally, this work evolution was scheduled for a planned duration of 14 days, thereby exceeding the SLC Allowed Outage Time (AOT) of 7 days. This duration was due to the increased scope of work, modifications, and complex nature of the evolution. Contingencies were incorporated into the maintenance evolution plan because of the planned duration.

This work evolution plan was reviewed and approved by the Plant Operations Review Committee (PORC) on October 29, 2008 prior to initiation of the work.

C. The following information outlines the maintenance evolution plans and procedures that were in place at the start of the AOT to provide for the loss of the system as specified in Condition C.

Once the SSF was taken out of service, all work activities were performed continuously until the CCW Inlet piping was.

refilled and the SSF deemed available.

Critical Action Plans were developed and implemented to help minimize the duration of the unavailability and provide contingency plans to reduce or mitigate plant risk.

No activities were scheduled to adversely affect the operability/availability of Keowee emergency power paths or other protected train components on operating Units while the SSF was out of service. Other protected trains included Emergency Feedwater (EFW), Low Pressure Service Water (LPSW),

and High Pressure Injection (HPI).

Selected Licensee Commitment 16.9.9 Auxiliary Service Water System Outage Report Page 3 of 4 Some of the other major risk mitigation/contingency actions are listed as follows:

" Keowee lake level was maintained below the level of the CCW inlet piping at the intake to prevent potential water intrusion into the Turbine Building.

" An assessment was conducted each shift to evaluate work progress and risk to the extent that they affected the projected unavailability. The outage manager was notified of any potential negative impacts.

" To avoid extending the duration of the work, scheduled tasks were assigned higher priority than other outage work.

Any emergent tasks were given high priority. Risk assessments were performed daily. An SSF outage coordinator was assigned to track work progress and ensure appropriate priorities were established for the work tasks.

D. The action statement was entered for the ASW System and the SSF ASW System becoming inoperable at 0127 hours0.00147 days <br />0.0353 hours <br />2.099868e-4 weeks <br />4.83235e-5 months <br /> on November 6, 2008.

Because of the complex nature and increased scope of these activities, additional time was required to complete this work. The 7 day action statement expired on November 13, 2008 at 0127 hours0.00147 days <br />0.0353 hours <br />2.099868e-4 weeks <br />4.83235e-5 months <br />; thus, Condition C was entered to generate the report to the NRC within 30 days.

Condition B for the ASW system and SSF ASW system inoperable was exited on November 24, 2008 at 2235 hours0.0259 days <br />0.621 hours <br />0.0037 weeks <br />8.504175e-4 months <br />.

Note that the original scheduled 14 day duration was exceeded in part due to problems encountered during system isolation and dewatering.

E. It is important to note that the benefits of performing the work include improved reliability of the affected systems and equipment. Also, overall plant risk will be reduced for the remaining life of the plant after final installation of the new PSW system.

==

Conclusion:==

As described above, the reason that the ASW System outage exceeded the 7 day AOT in SLC 16.9.9 Condition B was due to the complexity and increased scope of the planned maintenance evolution and

Selected Licensee Commitment 16.9.9 Auxiliary Service Water System Outage Report Page 4 of 4 modifications which required that the CCW inlet piping remain dewatered. These activities were deemed necessary to maintain the long-term reliability of the ASW system. Appropriate risk management actions were implemented within Oconee's Maintenance Rule a(4) program to provide for the loss of the system and assure the availability of redundant accident mitigation systems throughout the entire duration of the system outage.