ML20216J904

Forwards Response to RAI Re GL 96-05, Periodic Verification of Design-Basis Capability of Safety-Related Motor-Operated Valves

ML20216J904
Person / Time
Site:	Vogtle
Issue date:	10/01/1999
From:	Beasley J SOUTHERN NUCLEAR OPERATING CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-96-05, LCV-904-E, NUDOCS 9910060316
Download: ML20216J904 (5)

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• J. Bernie Beasley.Jr., Pi Southern Nuclear

, . Vice President Operating Company,Inc.

Vogtle Project ' 40 invemess Center Parkway

, P.O. Box 1295 Binningham, Alabama 35201 Tel 205.992.7110 Fax 205.992.0403 SOUTHERN COMPANY Energy ro Serve YourWorld" October 1, 1999 Docket Nos. 50-424 50-425 LCV 904-E U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Ladies and Gentlemen:

Vogtle Electric Generating Plant Response to Request for Additional Information Regarding GL 96-05 By letters dated November 14,1996, March 12,1997, June 3,1998, and April 28, 1999, Southern Nuclear Operating Company (SNC) responded to the concerns identified in GL 96-05," Periodic Verification of Design-Basis Capability of Safety-Related Motor-Operated Valves." During a telephone discussion with the NRC Staff held on August 9,1999, additional information was requested. Attached are specific responses to the questions raised by the Staff.

Please contact this office if you have any questions.

Sincerely,

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. B. Beas) y, Jr JBB/BHW Attachment l

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9910060316 991001 PDR ADOCK 05000424 P PDR 0

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r U.S. Nuclear Regulatory Commission Page 2 cc: Southern Nuclear Operating Company Mr. J. T. Gasser Mr. M. Sheibani SNC Document Management-Vogtle U. S. Nuclear Regulatory Commission Mr. L. A. Reyes, Regional Administrator Mr. Ramin R. Assa, Vogtle Project Manager, NRR .

Mr. J. Zeiler, Senior Resident Inspector, Vogtle l

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4 Attachment Vogtle Electric Generating Plant Response to Request for Additional Information Regarding GL 96-05

- NRC Question 1:

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In its letter' dated July 17,1998, forwarding Technical Update 98-01, Limitorque indicated that a future technical update would be issued to address the application of de-powered MOVs. The BWROG is presently working on an evaluation methodology for de-powered Limitorque motor operated valvesi Discuss any preliminary actions that have been taken to review de-powered motor actuator capability for MOVs in your OL 96-05 program.

SNC Response to Question 1:

As part of the GL 89-10 and 96-05 programs, the de-powered MOVs were included in the design review. Based on these reviews, the de-powered MOVs at Vogtle Electric Generr. ting Plant (VEGP) are high margin MOVs. The Westinghouse Owners Group (WOG) has elected to participate in the BWROG evaluation. The results of the BWROG program will be monitored via VEGP's particip, tion in the WOG. ,

It is VEGP's practice in the GL 89-10 program to apply the pull out efficiency in determining motor torque available for de-powered MOVs. Also noteworthy is that the application factor used for the VEGP de-powered MOVs is 0.9.

NRC Question 2:

The submittal dated April 28,1999, states that the containment spray pump RWST and containment sump suction valves and the SI pump mini-flow valves were listed as medium or high safety significant in the WOG generic list of MOVs. At Vogtle the safety significance of these valves is considered low. Verify that the GL 96-05 safety significance classification of these valves is consistent with the Maintenance Rule safety significance classification. l SNC Response to Question 2:

The VEGP Probabilistic Safety Assessment (PSA) model is evaluated and updated based on plant and industry experience. The valves identified in this request for information were assessed based on the best information available at the time of the assessment. The PSA model and related assessments are evaluated for updates as new data, experience,  !

and/or information becomes available.

Containment Spray Pump RWST and Containment Sump Suction Valves 1 The VEGP Maintenance Rule Program assessed the containment spray system as not ,

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. safety significant. The assessment was determined based on the VEGP PSA model

• showing containment spray as not safety significant because of Vogtle's large, dry

. containment and subsequent Maintenance Rule Expert Panel review which similarly concluded containment spray system as not safety significant.

A review of the MOVs was performed based on insights from the VEGP PSA for risk significance assessment to support VEGP's conversion to risk significance and valve margin based MOV static testing frequencies as discussed in letter LCV-0904-D, dated ~AMI 28,1999. This PSA review ofindividual MOV risk significance was perfora .ising methods to quantify the risk significance that is consistent with the Westinghouse Owners Group PSA methodology document, V-EC-1658-A, Rev. 2.

The PSA review of the MOVs determined the containment spray pump RWST and containment sump suction valves met the criteria for low safety significant valves.

c The MOV expert panel also assessed these MOVs as low. safety significance, with i

inputs in that determination being the Maintenance Rule safety significance and the results of the PSA review of these specific MOVs.

SI Pun p Mini-flow Valves The VEGP PSA, used as the basis for the Maintenance Rule Program safety significance ranking, assessed the intermediate head safety injection (SI) pumps as contributing negligibly to the safety significance of the safety injection system. The SI pump mini-flow valves are required to function to support SI pump operation.

However, because the pumps are not safety significant in the PSA model, the valves are likewise not safety significant with respect to supporting the safety injection pumps. 'Ihe safety injection system is assessed in the Maintenance Rule Program as

- safety significant because PSA modeling of other components within the system results in a RAW and RRW which meet the criteria for safety significance.

When the Si pump mini-flow valves were reviewed by the MOV expert panel, the PSA model importance factors for the valves showed them as low safety significant valves. The expert panel concluded, based on the PSA ranking and the safety functions of the valves, that the valves were low safety significant. However, as a result of work with the PSA model to confirm the GL 96-05 risk significance assessments for these valves, an additional safety function was identified which resulted in the PSA assessing the valves as high safety significant. As a result, the SI pump mini-flow valves will be assessed in the GL 96-05 Program as high-safety significant valves. It is possible that the basis may be changed which may result in a revision of the safety significance, however these valves are currently assessed as high-safety .significant.

NRC Question 3:

The submittal dated March 12,1997, states that the EPRI MOV PPM was applied to specific valve groups at Vogtle. Discuss the static test interval for GL 96-05 MOVs that i was set up using the EPRI MOV PPM.  !

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. SNC Response to Question 33

- Current static test intervals were determined using the risk significance and valve margin

. approach described in the letter LCV-0904-D, dated April 28,1999, with no special consideration given based on MOV setup using EPRI MOV PPM.

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