ML20205N430

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

ML20205N430
Person / Time
Site:	Waterford
Issue date:	04/12/1999
From:	Ewing E ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-96-05, GL-96-5, TAC-M97117, W3F1-99-0065, W3F1-99-65, NUDOCS 9904160274
Download: ML20205N430 (7)

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cp Ent+rgy Operttions, Inc.

Killona LA 70066 Tel 504 739 6242 r C. Ewing. til Ns ear Sa'ety & Regulatory Affairs W3F1-99-0065 A4.05 PR 1

l April 12,1999 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555

Subject:

Waterford 3 SES Docket No. 50-382 License No. NPF-38 1 Request for Additional Information Regarding Generic Letter (GL) 96-05, " Periodic Verification of Design-Basis Capability of Safety-Related Motor-Operated Valves" .

Gentlemen: 1 Entergy is hereby providing the attached response to the Request for Additional Information regarding the Generic Letter (GL) 96-05 Program at Waterford Steam Electric Station Unit 3 (TAC No. M97117).

Should you have any questions or comments concerning this response, please J contact me at (504) 739-6242 or David Young at (504) 739-6363.

Very truly yours, 1

E.d. Ewing Director ,f Nuclear Safety & Regulatory Affairs ECE/ DAY /rtk I (

Attachment

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cc: E.W. Merschoff (NRC Region IV), C.P. Patel (NRC-NRR),

J. Smith, N.S. Reynolds, NRC Resident inspectors Office 33 T,d"Io$5 %*g2 -

Attachmsnt to W3F1-99-0065 Page 1 Gi6 REQUEST FOR ADDITIONAL INFORMATION ON RESPONSE OF WATERFORD STEAM ELECTRIC STATION, UNIT 3 TO GENERIC LETTER 96-05 Question

1. In the Nucleer Regulatory Commission (NRC) Inspection Repcrt No. 50-382/94-23, the NRC staff closed its review of the motor-operated valve (NIOV) program implemented at Waterford Steam Electric Station, Unit 3 (Waterford 3) in response to Generic Letter (GL) 89-10 " Safety-Related Motor-Operated Valve Testing and Surveillance," based on the results of the inspection and the licensee's commitment to resolve outstanding MOV issues as described in a l

letter dated November 11,1994. In the inspection report, the NRC staff discussed certain aspects of the licensee's MOV program to be addressed cver the long term. For example, the inspectors noted that (1) the licensee agreed to update thrust calculations to include load sensitive behavior and stem friction j coefficient test resu%n that exceeded assumed values; and (2) the licensee's trending program ww rudimentary and required additional enhancements. In addition to the NRC inspection report items, the licensee committed in its November 11,1994, letter to take specific actions, including updating its l Planning Information Guide Notebook (PIGN) to identify maintenance activities  ;

that would require performance of a post-maintenance differential pressure test. l The licensee should describe the actions taken to address the specific long-term aspects of the MOV program at Waterford 3 noted in the NRC inspection report  ;

and its letter dated November 11,1994. '

Response

The W3 letter dated November 11,1994 (W3F1-94-0174) documented two commitments related to periodic verification and post-maintenance differential i pressure testing for MOVs in the scope of the GL 89-10 program. The periodic i verification program as committed to per GL 89-10 has been superceded by the I commitments associated with GL 96-05 as stated in the Updated GL 96-05 response dated January 11,1999.

As agreed to during the GL 89-10 closure inspection, the MOV setpoint calculations have been revised to fully incorporate the test results 'Or each MOV including load sensitive behavior values that exceeded assumed values.

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c Attachment to W3F1-99-0065 Page 2 of 6 The MOV Trending Program, which consists of both failure and performance trending, is currently maintained in a computer database. MOV trending is performed each quarter ar.d is included in the W3 global trending program. i Failure trending includes component failures, procedure deficiencies, and personnel errors. Performance trending, which utilizes data collected during diagnostic testing, monitors MOV performance to detect any degradation or adverse trend and compares the data to the ap9able design basis values. For example, valve stem coefficients of friction are calculated from the diagnostic test data and trended to both identify degradation and to compare against the design basis values used in the design calculations. A formal MOV Trending Report is i prepared after each refuel as required by Procedure PE-001-017 "MOV Setting, 1 Signature Analysis, and Trend Evaluation". It is recognized that further I strengthening in this area would provide additional benefit and therefore will be pursued consistent with the overall W3 effort in the area of performance indication and trending.

I Procecure UNT-005-024, "MOV Testing, Maintenance, and Trending Program," was l revised (Rev. 2) to include the DP Post Maintenance Test Matrix as submitted to the NRC in the W3 letter dated November 11,1994. This matrix identifies the maintenance activities that require performance of a post-maintenance differential pressure test.

Also the PIGN Tab 6 was revised (Rev. 4) to include the same DP Post Maintenance Test Matrix as contained in UNT-005-024 Rev. 2. {

The NRC staff closed its review of the MOV program implemented at W3 in response to GL 89-10 in a letter dated December 21,1994. The letter identified five issues that would receive particular attention. These five issues are discussed below including the current status of each.

1. The Electric Power Rescarch Institute (EPRI) Performance Prediction Program Methodology (PPPM) will be applied to valves SI-602A&B to more precisely determine the performance requirements.

ER-W3-98-0869 upgraded the limitorque HBC Unit and revised the MOV Design Basis Review calculation to incorporate the EPRI PPPM. The HBC Unit was replaced to accommodate the greater torque requirements as a result of the EPRI PPPM. SI-602A&B meet the EPRI PPPM torque requirements.

2. The need to perform post-maintenance differential testing following disc and seat lapping will be evaluated by engineering on a case-by-case basis taking into consideration the overall maintenance history of the valve. j I

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Attachment to W3F1-99-0065 Page 3 of 6 Procedure UNT-005-024, Revision 2, "MOV Testing, Maintenance, and Trending Program," contains a " Note" which requires an engineering input (evaluation) following disc or seat lapping to determine the need to perform a post-maintenance differential test. Consideration of the overall maintenance history in the engineering input is discussed in the note.

3. For cases where post-maintenance differential testing is deferred, the use of an assumed valve factor will be accompanied by an engineering evaluation. i Procedure UNT-005-024, Revision 2, MOV Testing, Maintenance, and Trending Program," contains a " Note" which requires the use of an assumed valve factor to be  ;

accompanied by an engineering input (evaluation).  !

4. The issue of pressure locking and thermal binding of gate valves will be reviewed in connection with a new generic letter.

W3 has submitted a response to GL 95-07 " Pressure Locking and Thermal Binding of  !

Safety-Re.ated Power-Operated Gate Valves".

5. W3 will review the implications of an emerging issue related to actuator torque capability under in situ thrust loadings, as appropriate to your program, to determine if additional action is necessary to ensure adequate design basis capability,

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This issue is discussed in the response to Question 3.

Question

2. In a letter dated March 17,1997, the licensee stated that it is participating in the  !

Joint Owners Group (JOG) program on MOV Periodic Verification in response to GL 96-05. On August 6,1997, the Combustion Engineering Owners' Group  ;

submitted Revision 2 of Topical Report MPR-1807 on the JOG program on MOV l Periodic Verification. On October 30,1997, the NRC staff completed a safety evaluation concluding that the JOG program is an acceptable industry-wide ,

response to GL 96-05, with certain conditions and limitations. The JOG program specifies that the methodology and discrimination enteria for ranking MOVs according to th9 safety significance are the responsibility of each participating licensee. In its letter dated March 17,1997, the licensee stated that static diagnostic testing would be based, in part, on an expert review and the Probabilistic Safety Assessment (PSA) for Waterford 3. The licensee should describe its methodology used for risk ranking MOVs at Waterford 3 in more i

Attachm:nt to W3F1-99-0065 Page 4 of 6 datail. Although Waterford 3 is a pressurized water reactor (PWR) designed by Combustion Engineering, the licensee could obtain insights from the methodologies for MOV risk ranking provided by the Boiling Water Reactor Owners' Group (BWROG)in Topical Report NEDC 32264 (Revision 2, dated feeptember 1996) and by the Westinghouse Owners Group (WOG) in Engineering Report V-EC-16E8-A (Revision 2, dated August 13,1998), and the NRC safety evaluations on the BWROG and WOG methodologies dated February 27,1996, and April 14,1998, respectively. For example, key aspects  ;

of the BWROG and WOG methodologies are the comparison of the licensee's MOV risk-ranking results to a sample list of MOVs identified as high risk at other plants designed by the applicable Nuclear Steam System Supplier, and the determination of the bases for differences in the MOV rankings.

Response

The risk importance rankings for the Category 1 and safety-related Category 2 motor operated valves (MOVs) in the Waterford 3 MOV Program Plan were determined by an ad hoc expert panel using preliminary risk rankings from the Waterford 3 PSA. The risk categories (ranks) of HIGH, MEDIUM, and LOW were used, consistent with the MOV Program Plan.

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Fussell-Vesely and risk achievement worth (RAW) importances were calculated '

for the Category 1 and safety-related Category 2 MOVs using the Waterford 3 PSA model. Fault tree requantification was used for the RAW calculation to eliminate the error involved in using pre-existing cut sets for calculating RAW values. The resulting importances were used to create a preliminary ranking according to the criteria of an Entergy Operations-wide PSA guideline for component risk importance ranking. The criteria were:

F-V RAW >= 0.005 < 0.005 ~

>= 2 HIGH MEDIUM

<2 MEDIUM LOW The PSA rankings were then reviewed by the expert p .el, which made the final  !

determination of the risk categories. The panel members represented the I disciplines of operations, maintenance, engineering, and safety analysis /PSA.

All had at least 9 years of experience in their disciplines. The expert panel

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compensated for any PSA modeling limitations and determined the risk category for valves not in the PSA model.

Question

3. The JOG program focuses on the potential age-related increase in the thrust or torque required to operate valves under their design-basis conditions. In the NRC safety evaluation dated October 30,1997, on the JOG program, the NRC staff specified that licensees are responsible for addressing the thrust or torque delivered by the MOV motor actuator and its potential degradation. The licensee should describe the plan at Waterford 3 for ensuring adequate AC and DC MOV motor actuator output capability, including consideration of recent guidance in Lirnitorque Technical Update 98-01 and its Supplement 1.

Response

in response to the recent guidance in Limitorque Technical Update 98-01 for AC motor operated valves, Condition Report (CR) 98-0988 was issued to identify the potential adverse condition and justify operability of the affected MOVs. As part of the corrective actions to this CR, all affected MOV Design Basis Review calculations were revised with the exception of the calculations for the ten MOVs identified as requiring modification to re-establish sufficient design margin.

Modification package ER-W3-98-1220-00 for these ten MOVs has been prepared and approved. Two of the ten MOVs were modified during Refuel 9 and the balance are currently planned to be modified during Cycle 10.

With regard to the two safety related DC MOVs at Waterford 3, mod;iicaiion package ER-W3-98-0789-02 was prepared and implemented during Refuel 9 to provide additional margin to account for the findings in NUREG/CR 6478, "MOV Actuator Motor and Gearbox Testing," which states that the method for predicting torque loss due to the operation of DC motors at reduced voltage under-estimates actual torque losses. Entergy is aware that additional NRC sponsored DC motor testing is ongoing. Although Limitorque has not issued any technical . l guidance related to these findings pending the results of the additional testing, Entergy took a proactive approach by providing auditional margin to account for these findings. If the conclusions of NUREGICR 6478 are further supported by th,e additional testing, any Limitorque or regulatory guidance related to DC motor output at reduced voltage will not adversely impact the two safety related DC MOVs at W3 when considering the implementation of the above modification.

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.- Attachm:nt to W3F1-99-0065 Page 6 of 6 Therefore, Entergy is taking the necessary actions to ensure adequate AC and DC MOV motor output capability is maintained. Entergy will continue to monitor the NRC sponsored DC motor testing and take any actions necessary in response to future Limitorque or regulatory guidance related to the thrust or torque delivered by the motor actuator and its potential degradation.

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