NOC-AE-000580, Forwards Response to NRC 990415 RAI Re Implementation of Commitments Related to GL 89-10, Safety-Related MOV Testing & Surveillance & GL 96-05, Periodic Verification of Design Basis Capability of Safety-Related Movs

Forwards Response to NRC 990415 RAI Re Implementation of Commitments Related to GL 89-10, Safety-Related MOV Testing & Surveillance & GL 96-05, Periodic Verification of Design Basis Capability of Safety-Related Movs

ML20209H289
Person / Time
Site:	South Texas
Issue date:	07/13/1999
From:	Thomas S HOUSTON LIGHTING & POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20209H296	List: ML20209H308 ML20209H315 ML20209H332 ML20209H337 NOC-AE-000580, Forwards Response to NRC 990415 RAI Re Implementation of Commitments Related to GL 89-10, Safety-Related MOV Testing & Surveillance & GL 96-05, Periodic Verification of Design Basis Capability of Safety-Related Movs
References
GL-89-10, GL-96-05, GL-96-5, NOC-AE-000580, NOC-AE-580, TAC-M97102, TAC-M97103, NUDOCS 9907200182
Download: ML20209H289 (11)

Text

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N am a r sam ramwseeaanmer sman m arm na.we roar 77m u July 13, 1999 NOC-AE-000580 File No.: G03.08 10CFR50 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 South Texas Pwject Units 1 and 2 -

Docket Nos. STN 50-498, STN 50-499 Response to Request for AdditionalInformation - Generic Letter 96-05,

" Periodic Verification of Design Basis Capability of Safety-Related Motor-Operated Valves"

References:

1. " Request for Additional Information - Generic Letter 96-05, South Texas Project, Units 1 and 2 (TAC Nos. M97102 and M97103)," NRC Letter to STP Nuclear Operating Company dated April 15,1999

2. Generic Letter 89-10, " Safety-Related Motor-Operated Valve Testing and Surveillance,"

dated June 28,1989

3. Generic I.etter 96-05, " Periodic Verification of Design Basis Capability of Safety-Related Motor-Operated Valves," dated September 18,1996 Pursuant to the request for additional information of tlie Nuclear Regulatory Commission (Reference 1), the South Texas Project submits this response regarding implementation of commitmete.s related to References 2 and 3.

If there are any questions, please contact either Mr. R. P. Murphy at (361) 972-8919 or me at (361) 972-7162.

I S. E. Thomas L

Manager, \

Design Engineering l

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Attachment:

Response to Request for AdditionalInformation dated April 15,1999 No'7200182990713 PDR ADOCK 05000498  !

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NOC-AE-000580 File No.: G03.08 Page 2 cc:

Ellis W. Merschoff - Jon C. Wood Regional Administrator, Region IV Matthews & Branscomb

.U. S. Nuclear Regulatory Commission One Alamo Center 611 Ryan Plaza Drive, Suite 400 106 S. St. Mary's Street, Suite 700 Arlington, TX 76011-8064- San Antonio, TX 78205-3692 Thomas W. Alexion Institute of Nuclear Power Project Manager, Mail Code'13H3 ' Operations - Records Center U. S. Nuclear Regulatory Commission - 700 Galleria Parkway Washington, DC 20555-0001 Atlanta, GA 30339-5957 Cornelius F. O'Keefe Richard A. Ratliff Sr. Resident Inspector Bureau of Radiation Control c/o U. S. Nuclear Regulatory Commission Texas Department of Health P. O. Box 910 1100 West 49th Street Bay City, TX .77404-0910 Austin, TX 78756-3189 J. R. Newman, Esquire D. G. Tees /R. L. Balcom Morgan, Lewis & Bockius Houston Lighting & Power Co.

1800 M. Street, N.W. P. O, Box 1700.

Washington, DC 20036-5869 Houston,TX 77251 M. T. Hardt/W. C. Gunst Central Power and Light Company City Public Service A7TN: G. E. Vaughn/C. A. Johnson

- P. O. Box 1771 .

P. O. Box 289, Mail Code: N5012 San Antonio,TX 78296 Wadsworth,TX 77483 A. Ramirez/C. M. Canady U. S. Nuclear Regulatory Commission City of Austin - . Attention: Document Control Desk Electric Utility Department Washington, D.C. 20555-0001 721 Barton Springs Road Austin, TX 78704'

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O Attachment NOC-AE-000580 Page 1 of 9 South Texas Project l Units 1 and 2

! P==a== to Rean=* for Addide=1 Infor== tion datant Anril 15.1999 l

1. In NRC letter dated March 2,1995 (ACN 9503080315), the NRC staff closed its review of the motor-operated valve (MOV) program implemented at the South Texas Project (South Texas) in response to' Generic letter (GL) 89-10, " Safety-Related Motor Operated Valve Testing and Surveillance," based on the results of NRC Inspection Report No. 50-498 &

499/94-32 (dated November 10, 1994) and information contained in a letter from STP Nuclear Operating Company (the licensee) dated January 9,1995. In the inspection report, the NRC staff discussed certain aspects of the licensee's MOV program to be addressed over the long term. : For example, the inspectors noted that the licensee committed to apply results from the Electric Power Research Institute (EPRI) MOV Performance Prediction Model (PPM) for those MOVs that had no test data available to validate the assumed valve factor.

In addition, in the March 2,1995, letter, the staff noted that the licensee (1) committed to ,

dynamically test a minimum of eight MOVs (six gate valves, one globe valve, and one

. butterfly valve) with diagnostics each refueling outage; (2) agreed to revise the post maintenance test guidelines to review the need for dynamic testing regardless of valve type or achievable test differential pressure; and (3) committed to complete an MOV over-current protection review and to take appropriate actions, where necessary. The licensee should describe the actions taken to address the specific long-term aspects of the MOV program at South Texas noted in the NRC inspection report and the NRC staff's letter dated March 2, 1995.

Response

a) " Licensee committed to apply results from the Electric Power Research Institute (EPRI)

MOV Performance Prediction Model (PPlW) for those' MOVs that had no test data available to validate the assumed valve factor."

South Texas Project (STP) MOVs were evaluated using the EPRI Performance Prediction Model (PPM) for those MOVs that had no test data available to validate the assumed valve factor. The results of the PPM evaluation are being reviewed to assure that the assumed valve factors of the affected STP MOVs are acceptable. The STP Condition Reporting process will document the results. The review is expected to be complete by the end of 1999.

b) " Licensee committed to dynamically test a minimum of eight MOVs (six gate valves, one l globe valve, and one butterfly valve) with diagnostics each refueling outage."

The STP dynamic diagnostic testing program includes six gate valves, one globe valve, and one butterfly valve as mentioned above. At its own initiative, STP is also performing

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dynamic diagnostic testing on three additional gate valves representing additional valve groups. Each valve is tested on a frequency of 18 months or less during a refueling outage or during power operation if conditions allow.

t Anachment NOC-AE-000580 Page 2 of 9 c) " Licensee agreed to revise the post maintenance test guidelines to review the need for dynamic testing regardless of valve type or achievable test differential pressure."

STP revised the post-maintenance test guidelines to review the need for dynamic testing regardless of valve type or achievable test differential pressure. The revised guidelines are incorporated into both the engineering guidelines and the post-maintenance test manual.

d) " Licensee committed to complete an MOV over-current protection review and to take 4 appropriate actions, where necessary."

STP completed an MOV over-current protection review that is documented by the j Condition Reporting Process. MOVs in the STP GL 89-10/96-05 Program were reviewed to assure over-current protection for locked-rotor current. Modifications are being implemented to assure that circuit breaker setpoints will prevent inadvertent actuation (circuit breaker trip) under design basis conditions.

In addition to the above commitments identified in the NRC RAI, the following commitments are included in the March 2,1995, letter:

l c) "We understand that you have committed to periodically verify the design-basis capability of motor-operated valves at South Texas Project within the scope of Generic Letter 89-  !

10. This process willinclude a static diagnostic test of each motor-operated valve within j the scope of Generic Letter 89-10 at least every 5 years to verify an acceptable capability j margin." I l

The STP Generic letter 89-10/ 96-05 Motor Operated Valve Program implements this commitment. At STP diagnostic testing of each MOV is performed at least every five years to verify an acceptable capability margin. In Attachment I to Generic Letter 96-05, the South Texas Project is cited as an example as having established an acceptable periodic verification program (PVP). The letter goes on to identify an acceptable approach to periodic verification based on diagnostically testing each safety-related MOV l every five years (or every three refueling outages).

For additional information, see the response to RAI # 2.

f) "For motor-operated gate valves, we understand that a margin will be maintained to account for possible increases in valve factor over time. This margin will be in addition to the margin allowed for uncertainties associated with instrument error, torque switch j repeatability, load sensitive behavior, and stem lubrication degradation." l A margin in the determination of valve factor is maintained to account for possible increases in valve factor o'ver time. This margin is in addition to the margin allowed for  !

uncertainties associated with instrument error, torque switch repeatability, load sensitive behavior, and stem lubrication degradation. Valve factors are monitored as a part of the evaluation of valve dynamic testing results.

Attachment NOC-AE-000580 Page 3 of 9

2. In a letter dated November 18,1998, the licensee updated its commitment to implement the JOG program. However, the licensee stated that it will " consider" the JOG program testing results. The NRC staff has determined that, when a licensee commits to the JOG Topical Report on the MOV Periodic Verification Program, the licensee is committing to implement each of the three phases of the described JOG program, including (1) JOG interim static diagnostic test program, (2) JOG 5-year dynamic test program, and (3) JOG long-term periodic test program. Where a licensee proposes to implement an approach different from any of these three phases of the JOG program, the licensee will be expected to notify the NRC and to provide justification for the proposed alternative approach. For example, if a licensee proposes not to implement the third phase of the JOG program (JOG long-term periodic test program) after the specific long-term test criteria have been established following the JOG 5-year dynamic test program, the licensee will be expected to notify the NRC and to justify its proposed alternative long-term test criteria. The South Texas licensee should discuss its commitment to the JOG long-term periodic test program and whether it is consistent with the NRC staff's interpretation of a commitment to all three phases of the JOG program.

Response

STP's commitme*t to the Joint Owners' Group (JOG) long-term periodic test program is consistent with tt NRC staff's interpretation of commitment to all three phases of the JOG program as it ht .en described above. STP will evaluate all data and specific long-term test criteria that ar- :stablished following the JOG five-year dynamic test plan for specific application to the iTP MOV program.

STP is committed to participation in the JOG five-year dynamic test program and is providing three sets of dynamic test results on each of four valves (a total of 12 tests) during this period. j To date, STP has provided the results of eight tests, and expects to complete this commitment in the year 2001, The South Texas Project is implementing diagnostic testing of its valves on a frequency of every five years or three refueling outages, which is consistent with the JOG interim static diagnostic test program. The STP program test frequencies will be adjusted, ifindicated, after the MOV risk categorization process is completed later this year.

STP will notify the NRC of any proposed alternatives or deviation from the JOG program and justify them.

The STP risk ranking approach is discussed in the response to question #3.

Anachment NOC-AE-000580 Page4 of 9

3. The licensee's updated commitment stated that the South Texas MOV risk-ranking approach differs in some respects from the program described in the Westinghouse Owners Group (WOG) Engineering Report V-EC-1658-A (Revision 2, dated August 13,1998), " Risk Ranking Approach for Motor-Operated Valves in Response to Generic 1.etter 90-05," and the NRC safety evaluation dated April 14,1998, on Revision 1 of WOG Engineering Report V-EC-1658. The licensee intends to substitute its own risk-informed performance-based approach to address the safety significance of MOVs at South Texas. The licensee should describe the methodology used for risk rankmg MOVs at South Texas in more detail, -

including (1) a description of how the South Texas methodology differs from the method described in WOG Engineering Report V-EC-1658-A and the NRC safety evaluation; (2) a

- discussion of the applicability of the' conditions and limitations contained in the NRC safety evaluation of WOG Engineering Report V-EC-1658-A; (3) the process used to develop a sample list of high-risk MOVs from other Westinghouse plants; (4) how expert panels were used to evaluate MOV risk significance; and (5) a discussion of the static test frequency that will result from application of the South Texas risk-ranking methodology.

Response

(a)"The licensee should describe the methodology used for risk ranking.MOVs at South Texas in more detail, including . . . a description of how the South Texas methodology differs from the method described in WOG Engineering Report V-EC-1658-A and the NRC safety evaluation."

The STP Probabilistic. Safety Assessment (PSA) is a fully integrated, detailed Level 2 analysis of plant risk incorporating large early release frequency and core damage frequency. The STP PSA includes an integrated and detailed analysis of common cause events, containment bypass (interfacing systems LOCA), and internal and external events (fires, internal and external floods, seismic events, high winds (including tornado),

tsunami, spatial interactions, and other initiators). The PSA uses plant specific data for equipment failure rates, which are updated periodically. Intra- and intersystem common cause failures resulting from maintenance and testing activities are also integrated. As such, the STP PSA is substantially more comprehensive in its analysis and modeling than the more high level methodologies developed specifically -for Independent Plant Examination (IPE) and external events IPE (IPEEE) used to satisfy Generic Letter 88-20.

The STP PSA pre-dates the regulatory requirement for performing a separate internal events IPE and IPEEE, was used to satisfy IPE and IPEEE requirements, and is maintained as a "living PRA." Safety evaluations of the STP PSA are documented by Refemnces 1 through 4.

' The STP PSA, along with deterministic evaluations and assessments, has been used to enhance STP licensing basis documents based on a comprehensive risk management philosophy, including changes to technical specifications and plant changes. Some of these are documented in References 5 and 6.

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4 Attachment NOC-AE-000580 Page 5 of 9 4

Since 1995, the South Texas Project has worked closely with the NRC on an industry initiative to- allow an approach to quality. assurance' for grading the application of previously approved ' quality assurance controls to safety-related plant structures, systems and components (SSCs). The NRC issued a safety evaluation '(Reference 7) which approved changes to the STP Operations Quality Assurance Plan (OQAP) to address Graded Quality Assurance (GQA) concepts.

- A graded approach to quality assurance requires a well-documented, proceduralized, and i reviewed and _ accepted program for determining equipment safety significance. The STP program, which has been reviewed by the NRC, is documented in procedures related to the_ Probabilistic Risk Assessment . Program (Reference 8), Comprehensive Risk Management (Reference 9), Probabilistic Safety Assessment Risk Rankmg (ref.10), and

-_ Station' Performance Data Collection, Categorization, and Reporting (Reference 11).

Current revisions of these procedures are attached.

With the exception of the actual criteria used in the risk categorization process, the methods described in the Westinghouse document and the STP program documents are identical. Section 3 of the Westinghouse document describes a risk ranking approach that is similar to that used in the STP Maintenance Rule program and is identical to the process

- used by the Graded QA working group (Reference 9).

The actual risk ranking criteria used at STP are based on information provided in the Probabilistic Safety Assessment Risk Ranking Program (Reference 10). Use of plant actual criteria is consistent with the process described in the Westinghouse document (Section 3.0). The NRC safety evaluation on Graded Quality Assurance reviews STP's quantitative and qualitative categorization process, including the PSA ranking and expert panel review processes in detail, and finds that "the licensee has developed an acceptable methodology to determine the relative safety significance of plant SSCs."

(b)'The licensee should describe the methodology used for risk rankmg MOVs at South Texas in more detail, including . . . a discussion of the applicability of the conditions and limitations contained in the NRC safety evaluation of WOG Engineering Report V-EC-1658-A."

STP considers the conditions and limitations contained in the NRC safety evaluation on pages 9 and 10 of WOG Engineering Report V-EC-1658-A to be applicable.

The STP PSA is a fully _ integrated, detailed Level 2 analysis of plant risk. Based on a j review of the NRC's expressed concerns noted in the conditions and limitations, it appears  ;

that those concerns follow from a set of assumptions that are not applicable to the STP j PSA by virtue ofits methods and detail. However, STP believes that the issues identified l by the NRCare, .in general, appropriate for consideration by the Expert Panel. '

Containment bypass and the potential for radioactive release, data accuracy and the use of generic failure rates, the potential for intra- and intersystem common-cause failures, and MOVs identified as medium to high risk in other plant PRAs/IPEs will be considered as a i

Attachment NOC-AE-000580 Page 6 of 9 l

l part of the panel review. An approach to documentation similar to that suggested in the Engineering Report V-EC-1658-A, Revision 2, will be utilized at STP.

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l l Note: Additional discussion of Condition (c) on page 9 of WOG Engineering Report V-EC-1658-A, Revision 2, is provided in part C below. Additional discussion of Condition 1

(g) on page 10 of WOG Engineering Report V-EC-1658-A, Revision 2, is provided in part E below.

(c) 'The licensee should describe the methodology used for risk ranking MOVs at South Texas in more detail, including . . . the process used to develop a sample list of high-risk MOVs from other Westinghouse plants."

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The list of risk-significant MOVs in Westinghouse NSSS plants identified in Appendix A to V-EC-1658-A, Revision 2, will be reviewed and evaluated by the STP MOV working group and Expert Panet The NRC in its Safety Evaluation dated April 14,1998, of the WOG report stated that it "did not identify any additional MOVs to be included in the WOG generallist."

(d)'The licensee should describe the methodology used for risk ranking MOVs at South Texas in more detail, including . . . how expert panels were used to evaluate MOV risk significance."

STP is in the process of completing a risk-informed performance-based evaluation of i MOVs in the STP PVP, including the use of an expert panel that will determine the safety significance categorization of MOVs. The process of categorization will be completed in 1999, and will provide an optimized MOV testing strategy.

The process used at STP for safety significance categorization, including the use of an expert panel, is discussed in section (a) of this RAI.

(e) 'The licensee should describe the methodology used for risk ranking MOVs at South Texas in more detail, including. . . a discussion of the static test frequency that will result from application of the South Texas risk-ranking methodology."

STP is implementing the JOG interim static diagnostic test program in lieu of the earlier commitment to test each MOV at least every five years after the MOV risk categorization process is completed later this year. Specifically, Table 4-1 of the JOG Program Document MPR 1807, Rev. 2, allows static testing of STP MOVs on a frequency from once every cycle to once every six cycles, depending on their margin and risk category.

STP expects that the application of its risk-ranking methodology will result in a testing  ;

frequency for a few valves on a more frequent basis, and on a number of valves it may extend to every six cycles (not to exceed 10 years). STP's testing frequencies are expected to be similar to other plants in the program.

As noted by the NRC in its Safety Evaluation of the JOG program dated October 30, 1997, the South Texas Project must evaluate information obtained from diagnostic MOV

I- ..

Attachment NOC-AE-000580 Page 7 of 9 testing conducted during the first five-year period to validate assumptions made in

. justifying the longer test interval where a selected test interval extends beyond five years.

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< a Auachment NOC-AE-000580 Page 8 of 9

4. The JOG program focuses on the potential age-related increase in the thmst or teque 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 South Texas for ensuring adequate ac and de MOV motor actuator output capability, including consideration of recent guidance in Limitorque Technical Update 98-01 and its Supplement I dated July 17. IN8.

l Resnonse:

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The STP MOV program ensures systematic monitoring and evaluation of MOV motor actuator capability by diagnostically testing each program MOV as provided by the program (currently every five years). Additionally, the motor actuator mechanical condition and lubrication is routinely inspected and maintained to enhance the continued satisfactory performance of the MOVs.

Diagnostic test results are input to the STP MOV Tracking and Trending Progr .m to evaluate for adverse trends and predict valve performance. Performance of an MOV outside the acceptance criteria of the Diagnostic Testing Program or the Tracking and Trending program requires an ' engineering evaluation to determine if the MOV is degraded. The engineering j evaluation will result in an initiation of corrective actions or a justification to allow continued {

operation based on adequate operating margin.

Engineering evaluation and/or calculation is used to determine motor actuator capability as an input to calculate deterministic MOV margin used in the Diagnostic Test and Tracking and Trending Programs. As new industry information becomes available, it is evaluated and applied to motor actuator capability.

The output capability of DC motor MOVs at STP was evaluated considering Limitorque Technical Update 98-01 with supplement I dated July 17,1998. The potential temperature-related DC motor performance degradation shown in the Idaho National Engineering and Environmental Laboratory preliminary test result presentation, " Preliminary Results of Direct Current Motor Actuator Testing," by Kevin G. DeWall and John C. Watkins was also  !

considered. In all cases, output capability for the STP DC motors is acceptable.

The output capability of AC motor MOVs at STP was evaluated using the results of the Commonwealth Edison MOV AC Motor Test Program (Comed methodology). Specific validated engineering data as allowed by the methodology and pullout efficiency were utilized for the evaluation. In all cases, output capability for the STP AC motors is acceptable. i i

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Attachment NOC-AE-000580 Page 9 of 9

References:

1. " Safety Evaluation by the OfHee of Nuclear Reactor Regulation Related to the Probabilistic

~ Safety Analysis Evaluation,".sent to the Houston Lighting & Power Company under cover letter dated January 21,1992.

2. - " Safety Evaluation by the Office of Nuclear Reactor Regulation Related to the Probabilistic Safety Assessment - External Events," sent to the Houston Lighting & Power Company L under cover letter dated August 31,1993.

3. " Staff Evaluation of South Texas Project Individual Plant Examination (Internal Events Only)," sent to the Houston Lighting & Power Company under cover letter dated August 9, 1995.

4. " Staff Evaluation Report of Individual Plant Examination of External Events (IPEEE) submittal on South Texas Project (STP), Units 1 and 2," sent to the Houston Lighting &

Power Company under cover letter dated December 15,1998.

5. Ietter ST-HL-AE-5076 dated 5/1/1995 from Houston Lighting & Power to USNRC requesting changes to Technical Specification 3.10.8 to allow extension of the Standby Diesel Generator Allowed Outage Time for a cumulative 21 days on each Standby Diesel Generator once per fuel cycle.

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6. Letter ST-HL-AE-3283 dated 2/1/1990 from Houston Lighting & Power to USNRC requesting changes to 22 Technical Specifications.

7. . " Safety Evaluation by the Office of Nuclear Reactor Regulation, Houston Lighting and Power Company, South Texas Project, Units 1 and 2, Graded Quality Assurance Program, Dockets Nos. 50-498 & 50-499," sent to the Houston Lighting & Power Company under cover letter dated November 6,1997.

8. OPGPO4-ZA-0604, Rev. 3. "Probabilistic Risk Assessment Program."

9. OPGP02-ZA-0003, Rev. 4, " Comprehensive Risk Management." l

10. OPGP01-ZA-0304, Rev. 2, "Probabilistic Safety Assessment Risk Ranking."

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11. OPGP02-ZA-0004, Draft, '" Station Performance Data Collection, Categorization, and l Reporting."

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