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ACCESSION NBR:9612030141 DOC.DATE: 96/11/18 NOTARIZED: YES DOCKETFACIL:50-275 Diablo Canyon Nuclear Power Plant, Unit 1, Pacific Ga 05000275

50-323 Diablo Canyon Nuclear Power Plant, Unit 2, Pacific Ga 05000323AUTH. NAME AUTHOR AFFILIATION

WOMACK,L.F. Pacific Gas & Electric Co.RECIP.NAME RECIPIENT AFFILIATION

Document Control Branch (Document Control Desk)

SUBJECT: Forwards response to GL 96-05, "Periodic Verification forMotor Operated Valves."

DISTRIBUTION CODE: R073D COPIES RECEIVED:LTR I ENCL g SIZE: ATITLE: GL-96-05 Periodic Verif. of Design Basis Capability of Safety-Related TNOTES:

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Pacific Gas and Electric Company

November 18, 1996

PG8 E Letter DCL-96-223

245 Market Street, Room 836-N9BSan Francisco, CA 94105

,lrrrillrrgArldnmMail Code N9BP.O. Box 770000San Francisco, CA 94177415/973-0600 Fax 415/973-6567

Lawrence F. WomackVice PresidentNuclear Technical Services

U.S. Nuclear Regulatory CommissionATTN: Document Control DeskWashington, D.C. 20555-0001

Docket No. 50-275, OL-DPR-80Docket No. 50-323, OL-DPR-82Diablo Canyon Units 1 and 2Res onse to NRC Generic Letter 96-05 "Periodic Verificationfor Motor 0 crated Valves"

Gentlemen:

Generic Letter (GL) 96-05, "Periodic Verification for Motor Operated Valves," wasissued on September 13, 1996 and required a response under oath or affirmationwithin 60 days (Item 1) and 180 days (Item 2) of the date of the GL. PG8 E's responseto Items 1 and 2 of GL 96-05 is enclosed.

Sincerely,

Lawrence F. Womack

Subscribed and sworn to before methis 18th day of November 1996

Attorneys for Pacific Gas andElectric CompanyBruce R. WorthingtonRichar . Locke

Notary Public Richard F. Locke

cc: Steven D. BloomL. J. CallanKenneth E. PerkinsMichael D. TschiltzDiablo Distribution

Enclosure

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GRE Letter DCL-96-223

ENCLOSURE

RESPONSE TO NRC GENERIC LETTER 96-05, "PERIODIC VERIFICATIONFOR MOTOR OPERATED VALVES"

This enclosure provides PG8E's response to the information requested in Items 1 and2 of Generic Letter (GL) 96-05, dated September 13, 1996, for Diablo Canyon PowerPlant (DCPP), Units 1 and 2.

Re uested Actions

Each addressee of this generic letter is requested to establish a program, or to ensurethe effectiveness ofits current program, to verify on a periodic basis that safety-relatedMOVs conti'nue to be capable ofperforming their safety functions within the currentlicensing bases of the facility. The program should ensure that changes in performancerequirements resulting from degradation (such as those caused by age) can be properlyidentified and accounted for. Addressees that have developed periodic verificafionprogramsin response to GL 89-10 should review those programs to determine whetherany changes are appropriate in light of the informationin this generic letter.

Re uired Res onse

Alladdressees are required to submit the following written responses to this genericletter:

Within 60 days from the date of this generic letter, a written response indicatingwhether or not the addressee willimplement the action(s) requested herein. Ifthe addressee intends to implement the requested action(s), the addressee shallsubmit a schedule for completing implementation. Ifan addressee chooses notto implement the requested action(s), the addressee shall submit a description ofany proposed alternative course ofaction, the schedule for completing thealternative course of action (ifapplicable), and the safety basis for determiningthe acceptability of the planned alternative course of action.

2. Within 180 days from the date of this generic letter, or upon notificafion to NRCof completion of GL 89-10 (whicheveris later), the addressee shall submit awritten summary description ofits MOVperiodic verification program establishedin accordance with the Requested Actions paragraph or the alternative course ofaction established by the addressee in response to item 1 above.

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RESPONSE

PG&E believes that the actions requested by GL 96-05 are substantially complete forDCPP and that the Motor-Operated Valve (MOV) Program established in accordance withGL 89-10, "Safety-Related Motor Operated Valve Testing and Surveillance," meets theGL 96-05 requirements. A verification program is in place to ensure on a periodic basisthat safety-related MOVs continue to be capable of performing their safety functions. TheMOV Program ensures that changes in performance requirements resulting fromdegradation are properly identified and accounted for. Additionally, as noted below, testingto determine stability of valve performance will be completed by the end of the upcomingUnit 1 eighth refueling outage scheduled for completion in May 1997.

In addition to its requested actions, GL 96-05 notes that licensees optionally may alsosubmit an application to the NRC to credit an MOV Program as an alternative to the currentInservice Test (IST) requirements for stroke-time testing, provided an acceptable level ofquality and safety is maintained. PG&E is presently reviewing its MOV Program withrespect to GL 96-05 and the IST Plan and may submit an application to the NRC in thefuture based on the provisions of GL 96-05. PG&E expects to make a decision in thisregard by the end of March 1997.

PREVIOUS SUBMITTALS

PG&E submitted several letters to the NRC in response to GL 89-10. These lettersdescribe the program PG&E undertook in response to GL 89-10, plus responses toNRC Inspection Reports.

~ PG&E Letter DCL-89-324, dated December 27, 1989, provided an initial responseto GL 89-10.

~ PG&E Letter DCL-92-176, dated July 30, 1992, responded to NRC findings asdocumented in NRC Inspection Report (IR) 91-39/91-39, dated January 24, 1992.

~ PG&E Letter DCL-92-182, dated August 12, 1992, extended the scheduledcompletion for PG&E's MOV Program.

~ PG&E Letter DCL-93-234, dated October 4, 1993, provided a response toSupplement 5 of GL 89-10.

~ PG&E Letter DCL-94-262, dated November 28, 1994 provided notification of MOVProgram completion.

~ NRC IR 95-01/95-01, dated March 2, 1995, reviewed PG&E's MOV Program, andPG&E Letter DCL-95-103, dated May 5, 1995, provided a response toIR 95-01/95-01.

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~ NRC Letter dated August 3, 1995, provided a closure to NRC review of PG8 E'sGL 89-10 MOV Program.

~ Additionally, PG8E Letters DCL-95-205, dated October 11, 1995, and DCL-96-140,dated July 12, 1996, provided PG8E's response to GL 95-07, "Pressure Lockingand Thermal Binding of Safety-Related Power-Operated Gate Valves."

PG&E Letter DCL-94-262 noted that there was a population of 165 MOVs (122 gate valves,26 globe valves, and 17 butterfly valves) included in the MOV Program. Currently, thereare 155 MOVs in the MOV Program (112 gate valves, 26 globe valves, and 17 butterflyvalves). Subsequent to issuance of DCL-94-262, PG8 E re-reviewed the MOVs againstthe requirements of GL 89-10 and determined that 10 gate valves (a total of five valves,MOVs 8808A, 8808B, 8808C, 8808D, and 8992 for each unit), did not need to beincluded in the MOV Program. Removal of these MOVs from the MOV Program wasreviewed with the NRC during their inspection activities as documented inIR 95-01/95-01 (this IR notes that there are 155 MOVs in the MOV Program).

DESCRIPTION OF MOV PROGRAM

Initial Establishment of MOV Pro ram

PG8 E's MOV Program for ongoing periodic verification of MOVperformance has been inplace for approximately two years (following completion of the initial program, asdocumented in DCL-94-262) and is described in Interdepartmental AdministrativeProcedure (IDAP) MA1.ID1, "Program Plan for Compliance with Generic Letter 89-10(MOV Surveillance and Testing)." All MOV Program valve tag numbers are listed inPG8E Procedure ICE-12, "I8C Engineering Procedure for Preparation of Motor-OperatedValve Sizing and Switch Setpoint Calculations."

Procedure ICE-12 describes the methods that were used to:

(1) Determine minimum required thrust and maximum allowable thrust for rising-stem MOVs to ensure that the MOVs will operate under the most severeoperating conditions without overstressing the MOV or the weakest actuatorcomponent.

(2) Determine the required operating torque and maximum allowable torque for1/4-turn MOVs.

(3) Establish the control requirements for MOVs.

(4) Size the actuators of both rising-stem and 1/4-turn MOVs.

(5) Evaluate the results of in-situ "flow"tests using diagnostic equipment todetermine whether the torque/limit switches are correctly set and to determinethe performance adequacy of the MOV under test and extrapolated design basisconditions.

Calculations of required actuator thrust values and the limiting allowable thrust for allrising-stem MOVs were documented in PGKE Calculation J-031. These calculationswere performed using Procedure ICE-12 requirements. Using ICE-12 requirements,calculations of minimum required valve torque, maximum allowable valve torque, andmotor operator capability for motor operators installed on butterfly valves weredocumented in PGRE Calculation J-042.

Maximum d P and flow for all MOV Program valves were reviewed using DCPP designbasis documents, operating procedures, emergency procedures, and the criteriacontained in GL 89-10 and its Supplements. The criteria, assumptions, design input,and the results of this review are documented in various PGRE documents.

As part of the establishment of the MOV Program, the MOVs were d,P tested if it waspractical to test and if meaningful results could be obtained. The MOV Program usesthe valve operation test and evaluation systems (VOTES) diagnostic system suppliedby Liberty Technologies. The MOVs were tested at the maximum practical hP and flowconditions. Ninety-nine MOVs (66 gate valves, 22 globe valves, and 11 butterflyvalves) were d P tested. In addition, all MOVs were tested under static conditions. TheMOVs that were tested only under static conditions were qualified using conservativeassumptions. The assumptions were determined based on DCPP test data, industrydata, and EPRI test results. Also, PG&E engineering reports are issued after eachrefueling outage to address the generic implications of MOV testing (both static andb,P). The valve factor and rate of loading results from d P testing were compared to theoriginal design assumptions, and potential impacts of the b,P testing on similar MOVswere also reviewed, and corrective actions were taken as applicable.

As discussed in IR 95-01, to verify that valve performance was stable (e.g., that thevalve factor for gate valves was stable), eight MOVs were scheduled for future b,Ptesting (one of them to be done twice, for a total of nine tests). As of the date of thisLetter, five rising stem valves and one butterfly valve have been tested, with valvefactor results stable or lower than the original d,P test, with the exception of one valve(which is scheduled for a follow-up d P test in the Unit 2 eighth refueling outage,scheduled for early 1998). The remaining three MOV tests will be completed by theend of the upcoming Unit 1 eighth refueling outage.

PGRE considered valve mispositioning during the design basis review of the MOVs.The rules to determine valve mispositioning are addressed in IDAP MA1.ID1.Supplement 7 of GL 89-10, dated January 24, 1996, discussed a new NRC staffposition that mispositioning need not be considered as part of the design basis.However, PG8 E chose at that time to keep the previously determined design bases to

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provide more margin in the MOV setup. In the future, PGKE may make use of theguidance provided in Supplement 7 and the resulting margin on a case-by-case basisfor operability determinations or other MOV issues.

On oin MOV Pro ram

PGKE's MOV Periodic Verification Program is a static test based plan. IDAPAD13.ID4, "Post-Maintenance Testing," identifies the appropriate test(s) after each typeof maintenance. IDAP MA1.ID4, "Control and Trending of Motor-Operating ValveDiagnostic Information," implements a trending program that compiles and trends MOVperformance data and failures.

The MOVs in the MOV Program are statically tested at a frequency based on availablemargin, performance history, whether or not a torque switch or limit switch is used, anda probabilistic risk assessment (PRA) that was performed specifically for the MOVs.The PRA results were reviewed by an expert panel, and the MOVs were prioritized withrespect to their risk significance. The MOVs were divided into high, medium, and lowsafety significance categories based on the PRA results and the input from the expertpanel. The resulting MOV surveillance/test frequencies determined by PG8E vary fromtwo to six fuel cycles (this is also noted in IR 95-01). It should be noted that thesefrequencies only apply to testing the MOVs with the VOTES equipment installed, not toany other testing that may be performed on the MOVs (such as stroke time testing).

The highest risk and low margin safety-related MOVs are tested every other fuel cycle.The lowest risk and high margin safety-related MOVs are tested every 6 fuel cycles.The remainder of the safety-related MOVs are tested on a frequency between these.The testing of the lowest risk and high margin MOVs at a frequency greater than5 years (as allowed by Code Case OMN-1 and GL 96-05, Attachment 1) is consideredappropriate as the MOV setup is based on conservative bounding factors. The post-outage generic evaluations will detect any need for increased test frequency.

IDAP MA1.ID4 provides guidance for identification of MOV operating trends due to theeffects of aging and maintenance activities. MA1.ID4 indicates that reviews should beperformed at a minimum of every two years to tabulate the types and number of MOVfailures (ifany), any cases of accelerated wear and degradation, and problems thatoccurred during maintenance activities and normal operation. These data are enteredinto a database that facilitates MOV trending by valve number, operator and type ofMOV, type of failure, and service application. MA1.ID1 provides that the followinggrouping rules should be applied: (1) MOVs should be grouped by similarities such asvalve manufacturer, valve model, and valve size; (2) each MOV in a group shall betested at least under static conditions; (3) design adequacy for each group should beverified through review and analysis of DCPP and industry data; (4) a representativesample (nominally 30 percent, and no less than two MOVs ifpossible) of each groupshould be tested at or near design basis conditions as a benchmark to qualify the otherMOVs in the group; (5) ifan MOV in a group fails or exhibits adverse performance

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during testing or operation, applicability of that information shall be evaluated for eachMOV in the group.

As part of the grouping analysis, a minimum valve factor degradation margin of5 percent is used in the evaluations. PG&E MOV test data indicate that the 5 percentmargin is bounding for MOVs at DCPP since there is little MOV operation at anysignificant d,P loading during testing or normal operation and MOV trends as a part ofthe MOV Program have not indicated any significant degradation. MA1.ID1 notes thata preventive maintenance inspection should be performed at least once every otherfuel cycle for each MOV, which includes a thorough check of the actuator and valvestem. The limit and torque switch condition is visually verified, the motor cavity, maingearbox, and limit switch grease conditions and levels are checked, the valve stemlubrication is checked (and relubricated as needed), and all accessible actuatorsubcomponents are inspected.

CONCLUSIONS

PG&E believes that the actions requested by GL 96-05 are substantially complete forDCPP and that the GL 89-1 0 MOV Program meets the GL 96-05 requirements. Averification program is in place that ensures on a periodic basis that safety-related MOVscontinue to be capable of performing their safety functions. The MOV Program ensuresthat changes in performance requirements resulting from degradation are properlyidentified and accounted for. Additionally, testing to determine stability of valveperformance will be completed by the end of the upcoming Unit 1 eighth refuelingoutage scheduled for completion in May 1997.

PG&E is presently reviewing GL 96-05 for application to the Inservice Testing Plan, andmay submit a relief request to the NRC in the future based on the provisions of GL 96-05.PG&E expects to make a decision in this regard by the end of March 1997.

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