IR 05000528/1993032
| ML20058H339 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 11/17/1993 |
| From: | Ang W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | |
| Shared Package | |
| ML20058H317 | List: |
| References | |
| 50-528-93-32, 50-529-93-32, 50-530-93-32, GL-89-10, NUDOCS 9312130051 | |
| Download: ML20058H339 (15) | |
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Y U. S. NUCLEAR REGULATORY COMMISSION
REGION V
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Report Nos.:
50-528/93-32, 50-529/93-32, 50-530/93-23
Docket Nos.:
50-528, 50-529, 50-530 License No.: NPF-41, NPF-51, NPF-74 i
Licensee: Arizona Public Service Company
P. O. Box 53999, Station 9082 l
Phoenix, AZ 85072-3999
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Facility Name:
Palo Verde Nuclear Generating Station Units 1, 2, and 3 Inspection Location:
Palo Verde Site, Wintersburg, Az.
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Inspection conducted: October 18 through 22, 1993
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Inspectors:
C. Myers, Reactor Inspector, Region V
Accompanying Personnel:
A. Trusty, Consultant, Idaho National Engineering i
Laboratory i
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Approved by:
W. P. Ang, Chief, Engineering Section Date Signed
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-i Inspection Summarv
Inspection durino the period October 18 - 22. 1993 (Report Nos. 50-528/93-32.
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50-529/93-32. 50-530/93-32)
l Areas Inspected:
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A special announced inspection of the implementation of the licensee's program to meet commitments to Generic Letter (GL) 89-10, " Safety-Related Motor-
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Operated Valve Testing and Surveillance," was conducted during the week of
October 18 through 22, 1993. Temporary Instruction 2515/109 was used as l
guidance during the inspection.
j Safety Issues Manaaement System (SIMS) Item:
SIMS Issue Number GL 89-10 was updated to reflect this TI 2525/109 Part 2
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inspection.-
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i 9312130051 931117 PDR ADOCPL 05000528
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r Pesults:
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General-Conclusions and Specific Findinas:
- The licensee's program was generally effective in establishing assurance of
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design basis capability for the sampled MOVs.
- The licensee was implementing a program consistent with their commitments
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- A licensee self-assessment of their program was comprehensive with
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. substantive findings.
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- Temperature effects on degraded voltage calculations and motor torque were l
not yet evaluated.
- Evaluation of the potential for pressure locking and thermal binding was not complete.
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- Reportability during MOV testing needed to be reviewed.
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Sionificant Safety Matters:
None.
Summary of Violation or Deviations:
None.
Open items Summary:
New Open Items:
l 93-32-01 FOLLOWUP Pressure Locking and Thermal Binding f
93-32-02 FOLLOWUP AC Motor Derating Due to Temperature
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93-32-03 FOLLOWUP Corrective Actions from Self-Assessment l
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Details 1.0 PERSONS CONTACTED Arizona Public Service Company
- R. Cherba, Manager, Independent Safety and Quality Engineering (ISQE)
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- S. Coppock, Supervisor, Valve Services Engineering (VSE)
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- R. Gouge, Director, Plant Support i
- M. Hooshmand, Engineer, VSE l
- W. Ide, Plant Manager, Unit 1 l
- J. Kriner, Engineer, Nuclear Engineering
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- W. Lui, Supervisor, Nuclear Engineering
- D. Maudlin, Director, Site Maintenance
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- P. Norton, Engineer, VSE
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- G. Overbeck, Director, Site Technical Support
- R. Prabhakar, Manager, ISQE l
- M. Radoccia, Supervisor, ISQE-
- C. Rath, Engineer, VSE
- M. Salazar, Supervisor, Valve Services i
- S. Scow, Engineer, ISQE
- W. Simko, Manager, Valve Services, Maintenance
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- E. Smith, Engineer, Nuclear Engineering
Others
- J. Draper, Site Representative, Southern California Edison l
- R. Henry, Site Representative, Salt River Project
- T. Scarbrough, NRC, Office of Nuclear Reactor Regula:, ion l
The inspectors also held discussions with other licensee and contractor personnel during the course of the inspection.
- Denotes those attending the exit meeting.
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2.0 GENERIC LETTER (GL) 89-10 " SAFETY-RELATED MOTOR-0PERATED VALVE TESTING
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AND SURVEILLANCE" (TI 2515/109)
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On June 28, 1989, the NRC issued Generic Letter (GL) 89-10 which requested
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licensees to' establish a. program to ensure that switch settings for safety-related motor-operated valves (MOVs) were selected, set, and maintained
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properly.
Five supplements to the generic letter have been subsequently issued. NRC inspections of licensee actions implementing commitments to GL 89-10 have been' conducted based on guidance provided in Temporary Instruction (TI) 2515/109, " Inspection Requirements for Generic Letter 89-10,. Safety-
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Related Motor-0perated Valve Testing and Surveillance." TI 2515/109 is divided into Part 1, " Program Review," and Part 2, " Verification of Program
Implementation." The Part 1 program review at Palo Verde was documented in.
NRC Inspcction Report 91-25. The current inspection was conducted using Part 2 of TI 2515/109.
The inspection consisted of a detailed review of the licensee's documentation i
of their GL 89-10 activities for selected MOVs. The inspectors selected a
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sample of MOVs from an information matrix provided by the licensee. The
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inspectors selected MOVs that appeared to have marginal actuator capacity and thrust settings compared to calculated requirements.
The sampled MOVs j
included a variety of actuator sizes. The selected MOVs included examples of
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testing under various differential pressure conditions.
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For each MOV selected, the inspectors reviewed the design basis calculations, the sizing and switch setting calculations, and the diagnostic test data. The inspectors reviewed the diagnostic test signatures using MOVATS (Motor Operator Valve Analysis and Test Sy:; tem, ITI-M0 VATS) Version 3000 software.
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l The licensee's program consisted of 351 MOVs (117 in each Unit). The j
following MOVs were selected for review:
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2JSGAUV0134 Steam Admission Valve to Auxiliary Feedwater Turbine i
2JAFBUV0034 Auxiliary Feedwater Isolation Valve
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2JSGNHVll42 Auxiliary Feedwater Discharge Block Valve
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3JAFAUV0037 Auxiliary feedwater Isolation Valve I
The selected MOVs were all gate valves, three with Limitorque actuators and one Rotork actuator. No globe or butterfly valves were selected. The sample MOVs were configured as shown below:
j Actuator Closure Control Valve Tvoe l
2JSGAUV0134 SB-0 Torque 6" - Anchor Darling i
2JAFBUV0034 SMB-1 Torque 6" - Anchor Darling
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2JSGNHV1142 Rotork Torque 6" - Anchor Darling 3JAFAUV0037 SMB-1 Torque 6" - Anchor Darling A summary of the test data for the sampled valves is provided in Attachment 1.
The inspectors concluded that the implementation of the licensee's MOV program i
was adequate for the sampled MOVs. Generally, the program appeared to
implement the licensee's commitments to the generic letter.
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2.1 Desion-Basis Reviews
The inspectors reviewed licensee procedure 81DP-4DC10, " Motor Operated Valve i
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Design Basis Review and Thrust / Torque Calculation," Rev. 00.03, dated February 2, 199?.. The licensee used this procedure to determine the worst case design i
basis conditions for each M0V. The inspectors reviewed the design basis l
calculations for each of the sampled MOVs. The design basis calculations for j
each of the sampled valves appeared to adequately evaluate the design basis
conditions consistent with licensee commitments in response to GL 89-10.
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2.1.a lack of Consideration of Flow and Temperature Effects l
The inspectors noted that flow and temperature parameters were not addressed
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in the design basis reviews. According to the licensee, flow and temperature l
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values were being incorporated into revised design basis review calculations.
- The inspectors found the licensee actions to be adequate.
2.1.D Test Conditions in Excess of Desian Basis Conditions
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The inspectors noted several examples where the test differential pressure and flow conditions exceeded the values assumed in the design basis review t
calculations. The inspectors were concerned that the design basis reviews may
be nonconservative if the design basis differential pressure and flow parameters were exceeded by dynamic testing conducted using normal system
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lineups. The licensee stated that the test results will be reviewed to assure l
that conditions achieved during dynamic testing are bounded by the design
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basis review calculation.
The licensee based their determination of maximum expected differential l
pressure (MEDP) under design basis conditions on the system valve alignments
specified in normal, abnormal and emergency operating procedures. The licensee identified that several system valve alignments in the operations
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procedures had been revised by opera: ions after preparation of the MOV design basis calculations. However, the consequences of the change in the valve
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lineup in the MOV design basis calculations had not been reviewed. The i
licensee reviewed the affected MOV calculations and revised the MEDP.
i Furthermore the licensee revised procedure OlAC-0AP02, " Review and Approval of l
Nuclear Administrative," to require that the nuclear engineering department
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(NED) review changes in operations valve lineups or operational sequences that may effect the design basis conditions of safety related M0Vs. NED was a
currently reviewing all MOV manipulations to ensure that differential l
pressures, design temperatures, and flow were bounded by existing design basis
conditions. The inspectors found the licensee actions to be adequate.
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2.1.c Pressure lockina and Thermal Bindina
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e The inspectors found that the licensee's design basis review did not include
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evaluation of the potential for pressure locking and thermal binding..The
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licensee had previously evaluated the potential for pressure locking and
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thermal binding in response to an industry report and identified two safety
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related gate valves in each unit that were considered to be susceptible.
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According to the licensee, the identified valves were tested during the plant conditions which made them susceptible to pressure locking. No indication of
l pressure locking was observed by the licenste during their testing. The licensee had concluded that no modifications of the susceptible valves were warranted.
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The licensee stated that additional engineering evaluation was required to
more thoroughly address the issue in light of increased occurrences of the problem in the industry.
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The inspectors noted that the licensee's self-assessment (discussed in
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Paragraph 2.6) also identified that additional engineering evaluation was in
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progress.
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The licensee committed to complete their evaluation for pressure locking and thermal binding by. April 1994.
Furthermore the licensee indicated that i
modifications of susceptible valves would be implemented during the next available refueling outage for each Unit. This item will be open pending inspector review of the completed licensee. evaluation of the potential for pressure locking and thermal binding (93-32-01:0 PEN).
l 2.2 MOV Sizino and Switch Settina Calculations I
i The inspectors found that the licensee had established specific procedures for conducting calculations within their GL 89-10 program. The inspectors
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reviewed licensee procedure 13-JC-ZZ-201, "MOV Thrust, Torque and Actuator
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Sizing Calculation," Rev. 1, dated September 21, 1992.
The licensee used this
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procedure to determine adequate actuator sizing and required torque switch
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thrust setpoints. The inspectors reviewed the sizing and setpoint
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calculations for the sampled valves. The licensse's calculations for the
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sampled valves appeared to be adequate. The inspectors independently
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calculated the minimum thrust for opening and closing the valves.
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significant errors were identified by the inspectors.
2.2.a Calculation Method
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The inspectors noted the following features of the licensee's method.
l (1) Valve Factor Assumption (VF) - (Valve factor was defined as the ratio of the stem thrust to the differential pressure force acting on the valve disk.) The licensee assumed a valve factor of 0.4 for gate valves and 1.1 for globe valves.
The licensee used the mean seat diameter of
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the valve in their calculation of valve factors.
i (2) Stem Friction Coefficient Assumption (C0F) -
A stem friction coefficient of 0.20 was assumed in the licensee's determination of output thrust capability under degraded voltage conditions. A stem friction coefficient of 0.10 was assumed in the licensee's determination that structure limits were not exceeded.
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Load Sensitive Behavior Assumption (lSB) - (LSB is defined as the percentage difference between the valve stem thrust at torque switch trip under static and dynamic conditions for a given torque switch setting.)
For untested valves, no specific thrust margin was incorporated in the thrust setpoint calculations _ to address possible MOV load sensitive behavior (also known as " rate of loading").
If LSB was displayed by a valve during testing, the valve specific thrust difference was added to minimum calculated required thrust. This issue is further discussed in Paragraph 2.2.b.
(4) Stem Lubrication Dearadation - No specific margin was included as a
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thrust margin in the setpoint calculation to account for stem lubrication degradation between periodic verification testing.
This issue is further discussed in Paragraph 2.2.b.
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(5) Minimum Thrust Setpoint - The minimum required thrust setpoint specified in the licensee's Interim Controlled Motor Operated Valve Data Base included an allowance for diagnostic equipment inaccuracy and torque j
switch repeatability.
(6) Maximum Allowable Thrust Setpoint - The maximum allowable thrust
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setpoint was established based on either degraded voltage considerations j
or weak link structural limitations.
j 2.2.b Lack of Specific Marain For load Sensitive Behavior and Deoradation For untested valves, the licensee did not specifically account for uncertainties such as load sensitive behavior (also known as " rate of
loading") and stem lubricant degradation in their setpoint calculations.
i Instead, the licensee attempted to set the torque switch "as high as j
practicable" within the specified setpoint range as a' conservative technique
to accommodate potential LSB and lubricant degradation.
l During their evaluation of the dynamic test data for each valve,.the licensee
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determined if load sensitive behavior was displayed.
If so, the specific LSB
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value displayed during testing was fedback as a " Dynamic Test Correction l
Factor" and the minimum required setpoint was revised.
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The inspectors reviewed the licensee's justification for their treatment of
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LSB. The inspectors emphasized that, for MOVs that will not be dynamically
tested and MOVs that will not be tested under sufficient differential pressure
to exhibit LSB, the licensee will need to ensure that their qualitative method
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of accounting for these uncertainties is adequate based on the best available
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data.
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2.2.c Setooint Control The design requirements for actuator thrust and torque calculated from the l
licensee's calculation 13-JC-ZZ-201 were adjusted by the licensee to account
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for instrument inaccuracy and torque switch repeatability.
The licensee
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incorporated the torque switch repeatability information contained in j
Limitorque Maintenance Update 92-2.
The resulting setpoints were specified
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and controlled in the licensee's Interim Controlled Motor Operator Data Base
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(ICMODB).
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According to the licensee, the ICMODB was being progressively revised to j
incorporate the results of the dynamic testing for each valve and valve group.
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Test based allowances for LSB and VF were incorporated as a " Test Correction
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Factor" for each valve.
After the completion of each refueling outage, the-
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highest valve factor considered by the licensee as representative of each j
valve group was incorporated into the ICMODB setpoints for all untested valves
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in that valve group. After completion of scheduled testing, the licensee
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intended to perform a comprehensive review of the test data from Units 1, 2,
and 3, and to apply this data to similar valve groups. The licensee stated
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that the setpoint calculation 13-JC-ZZ-201 would be revised to incorporate
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test based allowances for uncertainties after the comprehensive review at the
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completion of their test program. The inspectors found the licensee's method l
of progressive incorporation of the best available data in the control of MOV
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setpoints to be adequate.
l 2.2.d Dearaded Voltaae The inspectors reviewed Programmatic Assessment 93-02 which was a self-I assessment of the licensee's GL 89-10 program conducted by the licensee's
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Independent Safety Engineering group.
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The licensee revised their degraded voltage calculation 13-EC-MA-221 in July 1993. Although the results of this calculation indicated lower bus voltages.
than previously determined, the licensee determined that there were no
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immediate operability problems. At the time of the inspection, the licensee
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was in the process of revising their MOV sizing calculation 13-JC-ZZ-201 to
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incorporate the lower bus voltages. The licensee stated that they would
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complete a preliminary evaluation of the adequacy of MOV motor sizing by l
November 30, 1993. The inspectors concluded that this commitment was
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acceptable, j
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As part of the revision of calculation 13-JC-ZZ-210, the licensee was evaluating Limitorque's notification of a potential 10 CFR 21 condition,
" Reliance 3 Phase A.C Actuator Motors (Starting Torque at Elevated i
Temperature)", dated May 13, 1993. The vendor notification addressed the
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effect of elevated temperature on the output of AC motors. The licensee
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indicated that they would perform an operability determination for affected M0Vs and update 13-JC-ZZ-201 and ICMODB accordingly. The licensee committed to complete their evaluation of the Limitorque notification by April 30, 1994.
This item will be open pending inspector review of the completed licensee i
evaluation of the Limitorque notification. (93-32-02:0 PEN)
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2.3 Testina and Data Analysis
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The inspectors reviewed licensee procedure 39DP-9ZZZ01, "PVNGS Guidelines for l
Evaluation of Motor Operated Valve Dynamic Test Data," Rev. 2, dated April l
21, 1993. The licensee used this procedure to evaluate the results of their i
dynamic testing under differential pressure conditions.
The procedure
included the determination of apparent valve factor, stem factor, and load
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sensitive behavior for both the opening and closing direction. The inspectors i
observed that instrument inaccuracies were included in the determination of i
valve factor and stem factor.
l The inspectors noted that the data evaluation procedure compared the test l
results to the assumed values in the licensee's setpoint cilculations. The
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data evaluation procedure did not extrapolate test data fr>>m testing under at i
partial MEDP to design basis conditions.
If the test restits were not bounded j
by the assumed values, the licensee initiated a Condition Report _ Disposition Request (CRDR) to document and evaluate the condition.
For example, during
the licensee's evaluation of the test data for MOV 3JAFAUV0037, the apparent i
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I valve factor was. greater than the assumed valve factor of 0.40.
The licensee.
l initiated a CRDR to evaluate th.is test result.
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The CRDR evaluation included a straight line extrapolation of the thrust to
overcome differential pressure by using the ratio of design basis differential
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pressure to the test differential pressure.
The inspectors observed that the licensee's self-assessment (discussed in
Paragraph 2.6) also identified that the licensee's data evaluation procedure i
39DP-9ZZ01 did not require extrapolation adjustments for evaluation of dynamic
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test data collected at less than design basis conditions. The self-assessment
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-found that the extrapolation process should be contained in the licensee's data evaluation procedure 390P-9ZZ01.
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liowever, the licensee had not justified the long-term acceptability of their
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a extrapolation method. Tb e s nsee planned to justify their method of i
extrapolation within the'..
h' uled completion of their GL 89-10 prograu.
j The inspectors found the licensee's data evaluation to be adequate.
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2.3.a.
Chances in Diaanostic Eauipment
For the design basis testing conducted through 1991, the licensee used the ITI
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M0 VATS Series 3000/3386 Diagnostic Test System as its primary diagnostic
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system with the MOVATS thrust measuring device (TMD) which measured spring pack displacement as the basis for thrust determination.
For design basis testing conducted after 1991, the licensee continued to use
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the MOVATS Data Acquisition Module, but changed to the use of transducers
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which measure thrust and torque directly. The licensee utilized stem mounted
strain gages as the primary thrust transducer. When access did not permit the use of stem mounted strain gages, other transducers were used including the
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MOVATS torque thrust cell (TTC), M0 VATS stem strain ring (SSR) and yoke
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mounted strain gages. V0TES software was also utilized in the analysis of thrust signatures obtained from yoke mounted strain gages. The inspectors did not review the licensee's use of the VOTES software nor any data from yoke mounted strain gages. The strain gages were thrust calibrated in-situ using a Teledyne calibration rig capable of calibrating the transducers in both the opening and closing direction.
In-situ torque calibration of stem mounted strain gages was also performed using a calibrated torque wrench.
TMD data continued to be used in cases where strain gage data was unavailable.
i The licensee used M0VAls Engineering Report ER-5.2, Revision C, "Limito 'que
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Actuator Open vs. Closed TMD Data Analysis Procedure," to adjust TMD static i
test thrust data for measurement error. ER-5.2 identified increased thrust
measurement error attributable to directional effects and rate of loading.
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2.3.b.
Lack of Testina at Desian Casis F ow Rates i
The inspectors reviewed a summary of all GL 89-10 testing performed by the
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licensee and noted that a majority of the differential pressure tests did not
achieve maximum expected flow (MEF) conditions. Further, the percentage of l
MEF attained during testing was sometimes much less than the percentage of the
maximum expected differential pressure (MEDP). The inspectors were concerned that testing under low flow conditions may not be conservative. The licensee r
did not include a consideration of flow rate in the test acceptance criteria or their setpoint calculations. The inspectors emphasized-that the licensee should justify all testing performed at less than design basis differential pressure and flow. The licensee committed to established adequate justification for their treatment of flow effects. The inspectors found the licensee proposed actions to be adequate.
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2.3.c.
Timeliness of Data Review i
i The inspectors reviewed the licensee's dynamic test procedures. The inspectors observed that the test acceptance criteria stated that a valve would be
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considered operable provided the valve stroked during the test pending an
engineering evaluation of the test data. At the time of the inspection, the licensee's practice was to complete the engineering ~ evaluation of the MOVs prior to plant start-up. The licensee had previously committed to complete the engineering evaluation of the test data within 7 days after completing the test. According to the licensee, all test data from testing conducted while shutdown had been evaluated prior to restart.
For testing conducted at power
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for the AFW steam admission valves, the engineering evaluation of the test data was completed within 7 days.
The inspectors discussed the need it performed an operability evaluation prior to returning M0Vs to service.
In response to the inspectors' concern, prior to further differential pressure testing, the licensee committed to revise
their procedures to assure adequate data review prior to returning the MOV to i
service. The licensee stated that sufficient data review would be performed
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to provide reasonable assurance of valve operability for the mode or operating condition including evaluation of design basis capability.
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The inspectors concluded that the licensee had been meeting their previous commitment regarding the timeliness of test data evaluation. The inspectors
i found the licensee commitment to perform a preliminary assessment of design basis capability prior to returning valves to service to be adequate.
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Desian-Basis Capability The inspectors reviewed the design basis calculations and test packages for
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the subject valves. The selected valves were dynamically tested under the following conditions.
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i VALVE CLOSE MAX D/P
" 0SE TEST D/P
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2JSGAUV0134 1355 psid 623 psid 40%
2JAFBUV0034 1740 psid 1740 psid 100%
i 2JSGNHV1142 1590 psid 1558 psid 98.6%
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3JAFAUV0037 1810 psid 615 psid 34%
l The inspectors reviewed the dynamic test data using the industry standard
equation, the valve mean's seat diameter and the dynamic test conditions for the selected valves. The valve factors in the closing direction ranged from i
approximately 0.50 to 0.65.
In the opening direction, the apparent valve factor ranged from 0.12 to 0.62 (see Attachment 1).
Stem friction
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coefficients were observed from 0.07 to 0.15.
Load sensitive behavior
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(defined in Paragraph 2.2.a.3) was observed as high as 21%.
l The inspectors reviewed the differential pressure test results for all MOVs i
which the licensee considered to have been aaequately tested to determine
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specific valve factors. The inspectors observed that several MOVs tested
under high closing differential pressure conditions had valve factors above
0.60, which was greater than the value of 0.40 assumed by the licensee.
According to the licensee, the torque switch setting for each of the MOVs was j
adequate to accommodate the higher valve factor.
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2.3.e Determination of Flow isolation To evaluate valve factors which exceed design assumptions during testing under r
partial differential pressure conditions, the licensee extrapolated the force to overcome the test differential pressure to design basis differential
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pressure conditions. The licensee identified the force to overcome
differential pressure as the force measured at flow isolation. The inspectors found that the licensee did not use the maximum force occurring before seat
contact in their extrapolation to design basis conditions. The inspectors
found that the licensee determined flow isolation at the point of leveling of
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the pressure traces also recorded during the testing. The inspectors i
discussed with the licensee the uncertainty in the use of pressure traces in
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the determination of flow isolation. Recent results of testing conducted as
part of the Electric Power Research Institute (EPRI) Performance Prediction
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Program indicated that pressures can converge before flow isolation. The r
inspectors found the licensee method to be potentially nonconservative for
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cases in which flow isolation was not clearly distinguishable.
For each of the MOVs sampled, the inspectors found that flow isolation was evident. The-i licensee acknowledged the inspectors' concern and indicated that they were
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following the development of this industry 1ssue.
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2.3.f Butterfly Valve Testina
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The inspectors discussed the results of licensee testing of butterfly valves.
The licensee indicated that they had experienced consistently high operai.ing torque requirements for Posi-seal (tradename) butterfly valves.
The licensee
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indicated that they were preparing to notify the manufacturer and industry user's group of the results of their testing. The inspectors found the licensee actions to be adequate, j
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2.3 9 Evaluation of Diaanostic Sianature Anomalies
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The inspectors found that the licensee's test data evaluation procedures
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L required the evaluation of anomalies in the diagnostic signatures obtained l
l from differential pressure testing. The inspectors reviewed an example of the
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licensee's evaluation.
The example involved a documented identification and evaluation of cyclic running load in the signature of a butter #1y valve. The licensee further investigated the condition and identified a u. ective bearing in the actuator as the cause of the anomaly. The inspectors found that the
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licensee's treatmant 'of anomalies in diagnostic signatures appeared to be-l l
adequate.
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2.3.h Reportability
The inspectors noted that the licensee had not yet submitted any licensee i
event reports (LERs) related to'their M0V test results. The inspectors
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emphasized that the reporting-requirements of 10 CFR 50.73 apply during the i
conduct of the licensee's GL 89-10 program.
In response to the inspectors'
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concern, by November 5,1993, the licensee committed to complete a review of
the reportability of all as found thrust data which had been~ found to be below
calculated thrust requirements. The inspector found the licensee commitment j
to be adequate.
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2.3.i Lack of inherent Stall Protection
The licensee identified that as a result of increased thrust requirements
identified through their GL 89-10 program, many of their MOVs were no longer
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inherently stall protected by design. As a result, if an actuator motor stall l
was experienced during MOV operation, forces may exceed allowable structural j
limits for the weak link component of the MOV. The licensee identified that a
this was also a particular concern during valve opening when the torque switch.
j was bypassed and the stem-to-disk connection was the weak link. The
inspectors noted that unseating force, occurring during the opening stroke j
when the torque switch was bypassed, was evaluated by the licensee to assure
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that it did not exceed the structural limits for the weak link component.
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addition, the inspectors found that the licensee had established appropriate j
administrative controls to assure that stall events during operations or testing were reported and evaluated by engineering.
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i The inspectors found that the licensee had implemented preventative maintenance tasks to periodically perform static testing.
2.5 Schedule Of a total of 277 MOVs in each Unit, the licensee's GL 89-10 program applied to 117 MOVs (42%). The licensee had planned to dynamically test 109 (93%) of the MOVs within their program.
The licensee has completed baseline (static)
j testing of 116 MOVs (99%). The licensee has completed dynamic testing of 45
MOVs (41%) in Unit 1, 81 MOVs (74%) in Unit 2 and 58 MOVs (53%) in Unit 3.
In their' letter dated January 10, 1992, the licensee had revised its schedule for completion of their GL 89-10 program testing. The licensee committed to complete testing in Unit 1 by the end of the IR5 refueling outage schedulsd
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for early 1995, to complete testing in Unit 2 by the end of the 2R5 refueling
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outage scheduled for late 1994, and to complete testing in Unit 3 by the end
of the 3R4 refueling outage scheduled for mid 1994.
The licensee completed 37 dynamic tests during the current IR4 outage. The inspectors noted that following the current IR4 refueling outage, one outage i
remained in each Unit to complete testing. The licensee has scheduled 31, 30.
and 54 dynamic tests for each of the remaining outages in Unit 1, 2 and 3
respectively.
The licensee was evaluating the elimination of 20 MOVs (18%) per Unit from their test schedule, leaving only 15, 8 and 31 MOVs in Unit 1, 2 and 3,
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respectively, to be dynamically tested following the current Unit I refueling outage.
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The inspectors found that the licensee was meeting its committed schedule for
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completion of their GL89-10 program.
2.6 OA Involvement
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The inspectors reviewed Technical Quality Assessment (TQE) 93-02, " Generic Letter 89-10 Motor Operated Valves Program Assessment," dated September 21,
1993. The'self-assessment of the licensee's MOV program was conducted by the
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licensee's Independent Safety and Quality Engineering grora (ISQE). The inspectors found the self-assessment to be a comprehensive overview of the licensee's MOV program with substantive technical and programmatic findings.
l In particular, the inspectors noted that four of the seven deficiencies
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identified in the licensee's self-assessment involved weaknesses in the i
control and documentation of test data and engineering calculations. At the
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time of this inspection, the plant had not yet responded to the findings of the self-assessament.
This item will be open pending inspector review of the licensee's corrective actions for the deficiencies identified in the self-assessment. (93-32-03:0 PEN)
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No violations or deviations were identified.
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3.0 EXIT MEETING l
An exit meeting was conducted on October 22, 1993. During this meeting, the
inspectors reviewed the scope and findings of the inspection. The licensee I
acknowledged the inspectors' findings. The licensee did not identify as
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proprietary any information provided to or reviewed by the inspector.
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Attachment 1
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PALO VERDE GATE VALVE DATA
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I Valve Number Valve Size &'
Test Dynamic Stem Friction Lead Manufacturer Conditions Valve Coefficient'
Sensitive
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(Open & Close)
Factor Behaviors
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2]SGAUV0134 6"-1900 psi 0.59 Close j
Anchor Darling 623 psid 0.62 Open Unavailabic Unavailable Gate 2JAFBUV0034 6*-1600 psi 0.50 Close 0.07 Close Anchor Darling 1740 psid 0.31 Open 0.11 Open 10.3 %
Gate
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3JAFAUV0037 6*-1600 psi 0.65 Close Anchor Darling 615 psid 0.12 Open Unavailabic
.7.6 %
Gate
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2JSGNHV1142 6"
0.54 Close 0.15 Close Anchor Darling 1558 psid 0.46 Open 0.10 Open
- 21 %
Gate 1. The dynamic valve factors listed were calculated by the licensee using a mean seat diameter.
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i 2. A negative number indicates that the thrust observed at control switch trip (CST) during the dynamic test was greater
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than the thrust observed at CST during the static test.
3. Nickel Never Seize No.165 used for stem lubricant.
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