IR 05000220/1993022
| ML20059G002 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 12/22/1993 |
| From: | Drysdale P, Eapen P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | |
| Shared Package | |
| ML20059F998 | List: |
| References | |
| 50-220-93-22, 50-410-93-22, NUDOCS 9401210043 | |
| Download: ML20059G002 (16) | |
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U.S. NUCLEAR REGULATORY COMMISSION ;
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Report No /93-22 and 50-410/93-21
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Docket No and 50-410 License No DPR-63 and NPF-69 Licensee: Niagara Mohawk Power Corporation !
301 Plainfield Road i Syracuse, New York 13212 i Facility Name: Nine Mile Point, Units 1 and 2 j Inspection At: Scriba, New York
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Inspection Conducted: October 4 - 8, 1993, at Nine Mile Point October 13 & 20, 1993, at King of Prussia, PA _
l INSPECTORS: Michael Buckley, Reactor Engineer ,
James Stewart, Reactor Engineer ,
LEAD INSPECTOR: I fMe -[b ' A I3 '
Peter Drysdale, }6nior Reactor Engineer Dat'e Systems Section, EB, DRS-l APPROVED BY: * / d f)
Dr. P. K. Eapen, Chiel Date '
Systems Section, EB, DRS
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.) I 9401210043 940105 ~
PDR ADOCK 0500022 G PDR:
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Areas Insnected: An announced safety inspection was conducted of the licensee's Generic Letter 89-10 program and related activities at Units 1 & 2. The motor-operated valve (MOV) program commitments and enhancements identified during the team inspections in June 1992 were reviewed for progress. Implementation of the licensee's MOV program requirements, including the test schedule and the results of tests were also reviewe Inspection Resultj: The MOV programs at both units were implemented in accordance with current commitments made under their Generic Letter 89-10 program, previous NRC inspections, and existing regulatory requirements. The Unit 1 program currently extends to early 1997. All design basis calculations and some static testing will be completed by 1 June 1994. The Unit 2 program currently includes an approved extension to their original l schedule beyond June 1994. Progress is being made on MOV design basis reviews and l I
dynamic testing. Several MOV program areas and commitments are complete, including fm' alizing the MOVs to be included in the scope of the 89-10 program, undervoltage t
calculations, and overhaul and stem lubrication frequency. The current test schedule provides for satisfactory completion of MOV testing by the revised commitment date of 90 ,
days after the fourth refuel outage following issuance of the Generic Lette !
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DETAILS INTRODUCTION
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On June 28,1989, the NRC issued Generic Letter (GL) 89-10, requesting licensees to
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establish a program to ensure that switch settings for safety-related motor-operated valves (MOVs) were selected, set, and maintained properly. Six supplements to the generic letter
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have been issued to clarify the NRC request. NRC inspections of licensee actions
. implementing the requirements of the generic letter and its supplements have been conducted
based on guidance provided in Temporary Instruction TI-109, " Inspection Requirements for
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Generic Letter 89-10, Revision 1," which is divided into Part 1, " Program Review," and Part 2, " Verification of Program Implementation."
The NRC conducted a Part 1 program review inspection at Nine Mile Point (NMP) in
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June 1992, as discussed in Inspection Report 50-220/92-82 and 50-410/92-82._ This inspection included an update to the program review conducted in the initial inspection and a .
- review of the Part 2 program implementation at both units.
f GL 89-10 PROGRAM STATUS Nine Mile Point Unit i The Generic Letter 89-10 program for Unit I has been finalized for 51 active motor-operated valves from an inclusive list of 80 plant motor-operated valves (MOVs). The justification for excluding 18 MOVs included the removal of 9 valves that perform no active safety function, 6 valves that are of the plug design and are not mentioned in the generic letter, three valves that modulate flow only, and one valve that had been removed from service. The inspectors found the justifications to be adequate and no deficiencies in program scope were identiGe Currently, the Unit 1 MOV program extends to early 1997. The Generic Letter requested that the program be completed in five years or three refueling outages, whichever is late Because Unit I was in an extended outage at the time of issuance of the generic letter and because the plant operates on a 24 month cycle, the third refueling outage will end in early 1997. The licensee currently plans to complete all calculations and initiate some static testing by June 1994. Completion of static testing and partial completion of dynamic testing is planned for refueling outage No.13 in 199 .1.1 GL 89-10 Program Progress Initial design basis review calculations have been performed for the 51 valves specified in the .
Unit 1 MOV program. These calculations included stem friction coef6cients of 0.15, valve factors of 0.3 (gate valves), and a 10 percent allowance for rate-of-loading. Further, the calculations included consideration of degraded voltage, torque switch repeatability, stroke time, and temperature-torque degradation of DC motors. Of the initial calculations,4 of 51 valves were identined with operating vulnerabilities due to estimated torque or thrust. These valves were 83.1-09, drywell inboard sump isolation; 83.1-11, floor drain inboard isolation; L 33-01 reactor water cleanup (RWCU) return isolation; and 33-02, RWCU inboard suction isolation. The licensee repeated the calculations in each case and established that current
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switch settings were adequate to meet operational requirements. The inspectors reviewed six of the design basis calculations for completeness and consistency with the program l assumptions and no discrepancies were identified. The licensee had not completed 1 independent reviews of the calculations. The licensee intends to repeat all calculations usmg l 0.2 stem friction coefficient and 0.5 valve factor. The upgraded calculations will be used to prioritize testing of valve actuators. The revision; to the calculations are expected to be .
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complete prior to the 1995 refueling outag :
Niagara Mohawk stated that preliminary operability determinations have been completed with regard to MOV motor torque degradation (Limitorque Technical Update 93-03) for all safety- ,
related MOVs. However, initial design basis reviews did not consider the effects of pressure locking in establishing operating requirements for MOVs. Niagara Mohawk stated that action was in progress for resolution of pressure locking at Nine Mile Point Unit 1. Because pressure locking has the potential for prevention of an MOV to complete its design function, t the NRC considers this issue unresolved pending completion of the evaluation by Niagara 1 Mohawk and review by NRC inspectors (UNR 50-220/93-22-01).
2.1.2 (Closed) NOV 50-220/92-82-01: Inadequate MOV Preventive Maintenance :
Procedure NRC Inspection Report 50-220/92-82 identified a violation of NRC requirements when it was determined that Unit 1 Preventative Maintenance Procedures N1-EMP-GEN-R120 and N1-EMP-GEN-R121, did not provide sufficient detail for a qualified individual to perform verification of torque switch settings when performing maintenance on MOVs. The licensee responded to the notice of violation in correspondence NMP87236, dated August 19, 1992, and the inspectors reviewed the corrective actions specified in the response. The specified -
electrical maintenance procedures were revised to clarify and improve the level of detail necessary to identify and establish correct torque switch settings. Further, the inspectors observed that NMP drawing E21.6 F-42124-C, which specified torque switch settings for all ,
Unit 1 MOVs, had been revised to provide better clarity of switch setting requirements. The inspectors reviewed the current torque switch settings for two valves; 81-02, containment spray suction isolation, and 05-07, emergency condenser vent valve to torus, and determined that the settings were within design specifications. These two valves had been overhauled since the notice of violation was issued. No deficiencies were identified and violation 50-220/92-82-01 is close .1.3 (Closed) URI 50-220/92-82-02: Torque Switch Setting Control During NRC inspection 50-220/92-82, nine valves were identified as being in operation with incorrect torque switch settings. Unresolved item 50-220/92-82-02 was established by the NRC to ensure a follow-up review of the licensee's evaluation and corrective actions specified for the nine valve ,
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The licensee reviewed each incorrect torque switch setting in Deviation Event Report
< 1-92-271. 9 In each case, the licensee established operability for the systems involved by ,
evaluating the actual switch settings using maximum differential pressure requirements. The >
inspectors reviewed the operability determinations and no deficiencies were identifie Unresolved Item 50-220/92-82-02 is close P Nine Mile Point Unit 2
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The Unit 2 MOV program scope includes 177 valves. Design basis reviews for each of the valves were completed using 0.3 valve factor and 0.15 stem friction coefficient. The licensee stated that they would validate the assumed factors using the results of dynamic ;
testing. The inspectors reviewed the current version of the MOV Program Plan and the draft ,
version for the next revision. The licensee agreed to consider the following enhancements for the MOV program: Expand the defined criteria for generating a Deviation / Event Report (DER) for unacceptable dynamic test problems and anomalies. The Program Plan only addresses .,
test " failures." l Provide an explicit definition of the minimum conditions for the extrapolation of dynamic test result l Define the training and qualification requirements for MOV engineers, test technicians, and other technical MOV personne . Define the requirements for periodic reverification including dynamic reverification tests, if necessar ,
-1 I Update the current Master Program Schedule to reflect the Program Extensio .2.1 Follow-up to the GL 89-10 Part 1 Inspection (Section numbers in parentheses refer to the related section numbers in Inspection Report 50-410/92-82)
Determine the Final Program Scope (Section 2.1)
The initial Program Plan Description, 2 PPD-GL-89-10, " Motor-Operated Valve Program Plan Description for Nine Mile Point Nuclear Station Unit 2," included safety-related MOVs l that did not have an active safety function but that were subject to inadvertent mispositionin Supplement 4 to GL 89-10 allowed these MOVs to be excluded from the program for BWR In June 1992, the licensee issued Revision 1 to the program plan. This revision to the plan ,
specified a total of 203 MOVs within the program. A draft version of Revision 2 to the Program Plan was prepared prior to this inspection and it further modified the total number within the scope to 177 MOVs. This number was determined in a systematic review in NER-2M-001, " Determination of Motor-Operated Valves Within the Scope of NRC Generic Letter 89-10," issued on 10/6/92. Revision 1 to the NER was issued on 3/23/93. The document provided the methodology used to determine the final scope of MOVs in the GL 89-10 program and a final list of active MOVs in the program after all non-active MOVs
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were eliminated and justiDed. The initial scope contained all safety-related MOVs with .
electric motors on the Unit 2 Master Equipment List. Nonsafety-related valves that must function within the plant's design basis, as required by EOPs, were also included in the initial scope even if the plant's accident analysis did not take credit for these valve ,
NER-2M-001 also provided guidance to justify deletion of MOVs from the nnal scop l Design Basis Review (DBR) documents for most MOVs currently provide a detailed evaluation of an MOV's design parameters and operating function and determine if the MOV is active or passive. MOVs with no active function were deleted from the initial program scope. MOVs with no DBR have preliminary evaluations for their function. NER-2M-001 .!
contains the initial scope of 204 MOVs and also the justifications for 27 MOVs deleted i leaving 177 MOVs in the final scope. The inspector considered the justifications for deletion j
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to be adequate in that they were for non-safety MOVs, or with no active safety function or Class 1E power source. This item is adequately resolve Document Justi6 cation for AC Undervoltace Calculation Assumptions (Section 2.2)
During the Part 1 inspection, the licensee lacked justi6 cation for assumptions used for degraded voltage calculations and indicated that the GL 89-10 program will reflect the BWR Owners Group position on undervoltage. Nuclear Engineering Report NER-2E-002, "Use of Degraded Voltage Relay Setting as the Starting Point for Calculation EC-154," was completed on 7/14/93. The report contains a position paper to justify assumptions for basing degraded motor voltage upon degraded voltage relay settings as the starting point for the calculations. EC-154 was initiated to determine the actual starting voltage available at the terminals of all active safety-related MOVs. NER-2E-002 justified the use of the degraded voltage relay setpoint as a conservative starting point for EC-154 based, in part, on the following reasons: 1) The voltage used in EC-154 at the switchgear was 90.5% of nominal, and 2) EC-154 used the BWR Owners Group assumption for voltage drop calculations, that the MOV draws locked rotor current for the duration of the strok '
Calculation EC-154 determined the voltage available at the motor terminals during starting beginning with the degraded voltage relay setpoint and then calculated the voltage drop to the MOV motor. This is consistent with GL 89-10 and the NRC letter of 4/30/93, " Guidance for Inspection of Programs in Response to GL 89-10," which states that licensees should use the degraded grid voltage setpoint as the starting point for determining the minimum voltage at the motor terminals for AC motors. This item is satisfactorily resolve Document Justification for DC Undervoltage Calculation Assumptions (Section 2.2)
The licensee initiated calculation A10.1-H-046 to address this item after the Part 1 inspection and to account for the effects of reduced voltage on DC motors in establishing MOV stroke times. The calculation considered the effects of reduced voltage in a linear derating of the motor speed from rated voltage. The derating was accomplished by multiplying the percent voltage available at the motor terminals (80%) by motor speed at the rated voltage for the required stem torque value. Stem torque was converted into motor torque at running efficiency, and the adjusted stroke time was calculated using the reduced voltage at the running motor torque. The adjusted stroke time attributed 10% of the total stroke to be under the effects of valve differential pressure, packing load, and stem rejection forces. 90%
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of the stroke used the running motor torque at a derated RPM that excluded forces related to differential pressure. The calculation tabulated the adjusted stroke times for 11 MOVs with q DC motors and listed the design and licensing documents affected by each adjustment. Three MOV specification data sheets, three Updated Safety Analysis Report (USAR) specifications, and no Technical Specification revisions were required. The licensee cross referenced the ;
adjusted stroke times in the degraded voltage calculations for each MOV, but revisions to the .
I related specification sheets and USAR sections are still in progress. Since the necessary revisions have been identified, this item is satisfactorily resolve Include Undervoltage for Manually Actuated Valves (Section 2.2) j i
Nuclear Engineering Guideline NEG-2M-001, " Design Basis Review for Safety-Related Motor-Operated Valves," originally excluded consideration of degraded voltage for manually actuated active safety valves that are required to be operated during or after an acciden Justification for this position was not documented, but this exclusion was not being used in the GL 89-10 program. The licensee issued Revision 3 to NEG-2M-001 on 8/18/92. The revision included a requirement to use the minimum available starting voltage (reduced voltage) at the motor terminal in the actuator sizing calculations for all active MOVs. This item is satisfactorily resolve Include Temocrature Effects on AC Motors (Para 2.2)
The licensee made a preliminary evaluation of the Limitorque Part 21 Notice on potential degradation of MOV motor torque due to elevated ambient temperatures. The evaluation determined the maximum operating and accident temperatures for all GL 89-10 MOVs; calculated gross torque losses, locked rotor current, and motor terminal voltages at these temperatures; then recalculated the available torque during these conditions. Their review of torque losses in 99 MOVs concluded that no immediate operability concerns existed. The licensee also stated that the effects of high ambient temperature on AC motor torque will be further evaluated as additional motor-specific information becomes available. Limitorque issued additional guidance on its Part 21 notice in Technical Update 93-03 in September 1993. This item remains open pending completion of the licensee's final evaluation Evaluate Industry Diagnostic Equipment Validation Results (Section 2.3)
The licensee completed Revision 4 to Nuclear Engineering Guideline NEG-2M-002,
"Limitorque Motor-Operated Valve Torque Switch Setting Confirmation," on 1/26/93. The guideline outlined steps to verify torque switch setpoints at NMP2. For each GL 89-10 MOV at NMP2, a calculation was performed to verify the normal and maximum torque i switch settings recommended by Limitorque and/or the valve manufacturer and to verify that i the correct design conditions were used for the actuator design. The calculation provided a -l thrust window that incorporated the VOTES diagnostic instrument inaccuracies published by Liberty Technologies, and also the torque switch repeatability errors published by :
Limitorque. The stated VOTES inaccuracy,9.0% or 12.0%, was multiplied by a torque correction factor supplied by Liberty before combining it with the torque switch repeatability error. The calculation lacked specific guidance for when to use 5% or 10% torque switch
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repeatability, or when the 9.0% or 12.0% VOTES inaccuracy was applicable. However, it did indicate that a decision must be made when the VOTES instrumentation is calibrate The licensee indicated that the specific conditions for torque switch and instrumentation accuracies will be added to NEG-2M-002. This item remains open pending further review of NEG-2M-00 The licensee responded to Generic Letter 89-10, Supplement 5, "lnaccuracy of Motor-Operated Valve Diagnostic Equipment," on 9/27/93, to provide information requested on actions planned or taken to address reported inaccuracies of MOV diagnostic equipmen In its correspondence, NMPC indicated that it reviewed all MOVs in the GL 89-10 program and adjusted thrust values as necessary to update the results of previous tests. In addition, the licensee is using new software for the VOTES equipment that will automatically apply
the necessary correction factors to the thrust data for future test Document Justifications for Switch Setting Calculation Assumptions (Section 2.4)
NEG-2M-002 provided the methodology for performing MOV sizing and switch setting calculations, but only the Supplement 3 MOV calculations were complete as of the Part 1 inspection. The schedule at that time indicated that these calculations would be completed by the end of 1992. Subsequent revisions to the guideline and individual MOV calculations contained assumptions and justifications for switch settings as follows: 1) The minimum required thrust and torque is calculated using the valve design conditions such as line pressure, maximum differential pressure, etc.,2) The stuffing box load used shall be the higher of the Limitorque vahies or the thrust provided by the valve manufacturer, 3) The existing actuator and motor size will be used initially to verify the size, and 4) The valve design input data is obtained from manufacturer's documents. The NEG assumptions have been incorporated into the switch setting calculations performed to date. However, not all MOV switch setting calculations have been finalized. Therefore, the data used to support the !
assumptions for each MOV are not yet complete. The licensee stated that these calculations would be completed prior to June 1994. This item remains open pending the licensee's completion of these calculation Establish a Feedback Processes for Dynamic Test Results (Section 2.4)
The MOV program did not provide a feedback process where an evaluation of differential pressure test results would be performed to determine available thrust margins. Additionally, the licensee did not have a mechanism to validate assumptions in the thrust calculations using dynamic test results. NEG-2M-010, " Motor-Operated Valve Static Test Review Guideline for Liberty Technology VOTES Diagnostic Equipment," provides guidance for evaluating dynamic test data and for validating the assumptions used in calculations for determining -
torque switch settings. Feedback mechanisms specified in the procedure currently contain criteria for verifying valve factors and stem factors, and for computing rate-of-loading !
effects. By this procedure, verification of MOV sizing calculations are considered acceptable l if 1) the as-tested valve factor is less than or equal to the factor assumed in the sizing j calculation; and 2) the stem factor is less than or equal to the value originally assume !
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The licensee developed Engineering Specification NMP2-386M, " Dynamic Flow Testing of Safety-Related MotoriOperated Valves to Comply With GL 89-10," which establishes '
requirements for in-situ dynamic testing of MOVs and provides guidance for selecting the parent valves for testing to qualify non-testable valves in representative groups. The '
specification also contains a requirement to verify original valve factor assumptions and to '
reevaluate the thrust margin at design basis condition A feedback process has been established by the licensee and verification of assumed parameters is performed on an ongoing basis as testing is completed. This item has been satisfactorily resolve l
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Complete Weak Link Analyses (Section 2.4)
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NEG-2M-002 contains instructions to calculate the maximum permitted thrust for an actuator ?
based upon it's manufacturer's rating, and to calculate the maximum permitted thrust to meet ,
ASME allowable stress criteria for the valve. The licensee indicated during the Part 1
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inspection that weak-link information was being sought from the valve manufacturer Manufacturers have provided weak link information on valves, but information for all GL
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89-10 valves had not yet been obtained. The weak link thrust for the actuator is determined by the manufacturer's maximum rating. The licensee indicated that valve and actuator ,
information is included in calculations for maximum torque switch settings when it is available. This item remains open pending incorporation of weak link data for all GL 89-10 MOV Evahtate Industry Test Results (Section 2.5)
The licensee used a 0.3 valve factor for GL Supplement 3 MOV capability calculations and apparently did not review the applicability of NRC-sponsored testing for Supplement 3 valves. This was particularly significant for the test results of 10" Velan valves. The licensee subsequently completed Nuclear Engineering Report NER-2M-004, " Impact of NRC Sponsored MOV Dynamic Test Results On Valve Factor Used in Gate Valve Actuator i
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Sizing," on 10/29/92. The report reviewed the NRC sponsored testing conducted by the Idaho National Engineering Laboratory, but determined that a 0.3 valve' factor was appropriate for the capability calculations on Supplement 3 MOVs at NMP2. NRR noted that the use of a 0.3 valve factor for Supplement 3 had produced insufficient results at various power facilities. NRR further expressed reservations that the licensee must validate all valve factor assumptions using test results at NMP2 or the best industry data available for MOVs only statically tested after the schedule extension. The licenesee revised NEG-2M-002_ which contains requirements to revise the initially assumed valve factors based upon the results of dynamic testing. This item is complete; however, final revisions to the assumed valve factors will be necessary based on actual test results and other available industry dat ,
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Justification of Capability Assumptions (Section 2.5)
This section initially dealt only with GL Supplement 3 valves during the Part 1 inspectio ' The standard Limitorque equations were revised to determine the allowable upper range for ,
setting torque switches. The available window for torque switch setup may be reduced significantly if the method requires modification. To date, the allowable upper _ range for )
torque switch settings has not been determined for all Supplement 3 MOVs. This item 1 remains open until all MOVs have the maximum torque switch settings for all of the GL .
89-10 MOVs have been calculated in accordance with the guidance in NEG-2M-00 :
l Reevaluation to Periodically Test Motor-cocrated Valves Following a Dynamic Test Program (Section 2.7)
The licensee planned to periodically test MOVs by stroking them under static condition The relationship between static performance and performance under design basis conditions was not clearly established. The licensee agreed that static periodic reverification tests would be reevaluated following dynamic testing and that they would consider the BWR Owners Group position on periodic reverification testing. Sufficient dynamic testing has been completed to determine the extent that dynamic reverification testing that may be necessar .i However, the criteria for this determination has not been incorporated into the MOV program procedures. This item remains ope Document Position on Valve Overhauls (Section 2.8)
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The licensee documented their basis for conducting periodic MOV overhauls in an intemal memorandum, dated July 22,1993. The memorandum indicated that NMP2 does not intend .
to routinely perform actuator refurbishments, but will perform selective maintenance based ~ ,
on the results of MOV inspections and evaluations. Revision 2 of the NMP2 MOV Program Plan outlines the Upgraded MOV Preventive Maintenance Program. The program provides for periodic MOV inspections,' maintenance, and testing as part of the overall program pla Controlled maintenance procedures have been developed and implemented to clean' and lubricate valve stems and the actuator upper bearings, to examine the operator gear box grease condition, and to evaluate the condition of the stem nut. The licensee stated that PM activities will be performed on all GL 89-10 actuators inside containment at least every 18 months (i.e., each refueling outage) and on all others at least once every 24 months. Each actuator will be tested with diagnostic equipment at least once every three fuel cycles and corrective and preventive maintenance records will be evaluated and diagnostic test results will be used to trend the physical condition of each MOV. The licensee also stated that they will reevaluate their position on scheduled MOV overhauls as trending data is acquired and ,
as those results dictate. This item is complet i l
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Document Justification for Stem Lubrication Selection and Frequency (Section 2.8)
The licensee was previously using a nickel based anti-seize lubricant ("NEVER-SEEZ") for stem lubrication. Limitorque recommended that this lubricant be replaced with Nebula EP- '
or EP-1, or a similar compound for all MOV stem lubrication in order to av'oid the dryout and cracking that has been observed in service. The licensee reviewed the results ofindustry - >
test data on approximately twenty different lubricants for the stem / stem nut interface and '
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concluded that Nebula EP-0 will be used for all MOV stem lubrication at NMP2. Three preventive maintenance procedures governing the use of lubricants were subsequently revised to require the exclusive use of EP-0 for MOV stem The licensee indicated that GL 89-10 MOVs will have their stems lubricated prior to diagnostic testing. The MOVs inside the containment will have stem lubrication scheduled for every 18 months and the MOVs outside the containment will be done every 24 month '
The spring packs for MOVs tested will be removed and tested to determine their response curve so that further performance of the spring pack can be tracked against the baseline ;
diagnostic test. The vendor recommendation for stem lubrication is every 18 months; however, the licensee plans to adjust the frequency as necessary to maintain proper operation of the MOVs. This item is complet ,
Develon MOV Post-maintenance Test Criteria (Section 2.3)
The licensee developed Procedure GAP-SAT-02, " Post-Maintenance Test Requirements."
This procedure identified specific work activities such as modifications, preventive and !
corrective maintenance, and troubleshooting that may have impaired proper functioning of I plant equipment. The procedure contained guidance in a matrix table with 6 general valve maintenance tasks, each corresponding to specific post-maintenance tests (PMTs) that should
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be performed before returning a valve to service. The guidelines for MOVs specified static
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VOTES tests following certain maintenance on valves or their actuators. However, no guidelines were provided for performing a dynamic VOTES tests, for example after :
significant repair or replacement of a containment isolation valve. Revision 1 to the procedure was in progress during this inspection and the licensee indicated that they will ,
include guidelines and criteria for dynamic VOTES tests where appropriate following MOV l maintenance. This item remains ope Evaluate the Potential for Mixed Grease (Section 2.9)
l In May of 1990, the licensee completed a preventive maintenance degreasing effort at i
, NMP2. A total of 232 grease sampics were taken from installed actuators and were subjected to laboratory analysis to determine the composition and condition of the greas i Based upon the lab results, 23 actuators were completely degreased and regreased in order to l
correct identified problems. Three nonconformance reports, three problem reports, and one engineering and design coordination report were generated to address mixed grease problems i identified during this process. The licensee subsequently developed preventive maintenance procedures that contain steps to evaluate the texture, color, smell, and consistency of actuator
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grease during maintenance inspections. This item is acceptabl __ , .
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Develop a GL 89-10 Valve Trending Program (Section 2.9)
The MOV Program Plan only makes an indirect reference to trending of test results and reviewing valve history following failures. No specific activity within the program scope has yet been defined for MOV trending and a formal trending program has not yet been developed. The licensee is collecting data from MOV testing and maintenance activities that can be used for trending purposes in the future. The licensee expects that the specific parameters useful for trending will be identified and the available data will be used in a trending program that will be in place by June 1994. This item remains ope Evaluate MOVs for Hydraulic Lock (Section 2.11) ;j
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l The licensee reviewed Limitorque Maintenance Update 88-02 and evaluated the potential for hydraulic lock in MOV spring packs. Results of the evaluation were documented in an intemal memorandum, dated July 2'2,1993, indicating that all actuators at NMP2 are of a vintage equipped with internal grease relief ports in the spring cartridge housing. The licensee issued Preventive Maintenance Procedure N2-EPM-GEN-V534 to conduct "as installed" tests of all spring packs, followed by cleaning and subsequent retesting. These tests were scheduled to be conducted every third fuel cycle in conjunction with MOV y diagnostic tests. The spring pack test results are then compared to the calculated torque l output. Incompatible test results require replacement of the spring pack with an improved i design that includes a grooved limiter sleeve for the relief of potential hydraulic pressure 1 internal to the spring pack cartridge. This item is acceptabl .2.2 Unit 2 GL 89-10 Program Schedule Extension In a letter, dated April 15, 1993, NMPC requested the NRC to approve a schedule extension beyond June 28,1994 for completing the recommended actions of GL 89-10. The extension was granted in an NRC letter, dated August 26,1993, with the following conditions: Partially dynamic tested MOVs must be justified operable at maximum dynamic condition . NMPC must use the best industry data to show that MOVs only statically tested are operable (a 0.3 Valve factor has been shown to be generally not acceptable). NMPC must demonstrate that conservative predictions are used to set up MOVs not tested before June of 199 . NMPC must justify the grouping methodology used to avoid dynamic testing of some MOVs. Justification for MOV grouping for dynamic testing should be provided before the extension dat Forty-one low priority MOVs are affected by the extension request. Within the group of 41 valves,15 gate valves will be tested during the current outage. The 26 remaining will be tested this outage if the outage schedule permits. The licensee further indicated that 16 MOVs have been tested since the Part 1 inspectio _- . . _ _ , . __ . _ . _ ._ . .
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1 l-L Three globe valves with large thrust margin will not be statically or dynamically tested before June 1994. All gate valves will be tested before June 94; however,29 other MOVs may not be tested before June 9 .2.3 Grouping Methodology The licensee submitted their plan to assign GL 89-10 MOV groups in order to minimize the total amount of testing necessary among valves with virtually identical designs and function l
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The grouping methodology was defined in Nuclear Engineering Report NER-2M-003,
" Dynamic Testing Valve Grouping," and Engineering Specification NMP2-386M, " Dynamic Flow Testing of Safety-Related Motor-Operated Valves to Comply With GL 89-10." The inspectors observed that the valves in the designated groups were, for the most part, identical in design and safety function during accident condition A conference Call between Niagara Mohawk, NRR, and Region I was held on October 13, 1993, to review the licensee's proposed plan for grouping MOVs for dynamic j testin Thirty-two groups are defined for all 177 valves. Most groups contain 2 - 4 MOVs. The largest group contained 16 MOVs,10 of which will be dynamically tested. The grouping i methodology was considered adequate for the licensee to proceed with the MOV test schedule defined for the current outage. Final approval of the licensee's grouping will-require additional NRC review of the details of the valves in each group and the applicability of test data from parent MOVs to the other non-tested valves in each grou .3 Unit 2 MOV Test Witnessing During this inspection, the inspectors observed dynamic tests of valves 2CSH*MOV105, -l 2CSH*MOV107, and 2CSH*MOVill. The testing was performed in accordance with the licensee's procedures and valid test data were obtained. A thorough pretest briefing was held by control room personnel and by test supervisors for persons involved with the test. The inspector's observations are as follows:
l 2CSH*MOVill. " Test Return to Suppression Pool"-
This valve is a 12 inch Anchor Darling globe valve with an SMB-4 Limitorque actuator installed. It is in the charging system test return line to the suppression pool and is required j to automatically close when the system responds to a loss of coolant accident. During testing of this valve on October 5,1993, the control room switch was released prematurely so that full valve closure was not achieved. The licensee identified this condition as a test technique and coordination problem and took actions to improve both and repeated the test successfully as allowed by the test procedur i i
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2CSH*MOV107. " Pump 1 Iniection Valve"-
During a dynamic test on October 5,1993, valve 2CSH*MOV107 was stroked closed and failed to indicate fully shut. No injection flow was indicated where valve motion stopped, but the valve fully closed when the control switch was later positioned to close a second time. The test observers noted a chatter in the torque switch during this test. The torque switch was checked for anomalies on October 6,1993, and none were foun Historically, the torque switch for this MOV was set at 2.5, but was recently decreased to 2.25 in order to obtain a better margin to overthrust. The licensee considered that the problem with valve closure could have been attributed to the lower torque switch settin This valve was subsequently disassembled for inspection. The actuator was eventually rebuilt and overhauled due to some defective mechanical components. In order to obtain greater thrust values and to raise the weak link value, the valve's stem and disc were replaced. The torque switch setting was then increased to 2.5. The licensee performed a static retest of the MOV with satisfactory results. Before the end of the refueling outage in November 1993, a successful dynamic test of this MOV was also completed and positive flow cutoff was indicated by the test of this MOV before the end of the refueling outage in November 199 CSH*MOV105. " Minimum Flow Bypass Valve":
This gate valve is a four inch Anchor Darling with an SB-0 Limitorque actuator installed. It is required to open when the high pressure charging pump starts to maintain a minimum flow though the charging pump and to automatically close when injection flow is initiated. During the first test on October 5,1993, a pressure transmitter problem caused a data acquisition problem. The problem was corrected and a retest was completed the following day. The j
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measured stem thrust was within the licensees stated criteria and the final engineering
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- evaluations were ongoing at the end of this inspectio MOV Dynamic Test Results Review The test results for 2RHS*MOV4C were reviewed to deterniine if this valve met the !
acceptance criteria established by the licensee and the NRC to ensure its operation during normal and accident conditions. This valve is the minimum flow bypass line isolation valve for the residual heat removal system. During testing on July 20,1993, test personnel used an incorrect calibrator sensitivity. This resulted in the computer trace indicating a thrust at torque switch trip that was within the established thrust criteria, while the measured actual thrust was not. The valve was declared operable on July 21,1993, although under degaded-voltage conditions it may not have operated as designed. During the licensee's post-test engineering review, the incorrect calibrator sensitivity was identified and corrected. The correction required that this MOV be retested and torque switch setting lowered. A Deviation / Event Report (DER) 2-93-1699 was written to provide disposition and corrective action. A retest was satisfactorily completed on July 22,199 _ - _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ - _ .
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15 Mov Pressure Locking and Thennal Binding In March 1991, the licensee evaluated INPO Significant Event Report 08-88 that identified certain MOV gate valves that experienced pressure locking and/or thermal binding to the extent that they could not be operated. The licensee also responded to General Electric Service Information Letter No. 368 and initiated Deviation Report DER-2-91-Q-1557 to evaluate the susceptibility of NMP2 valves to these phenomena and to recommend and track corrective actions to alleviate the condition. The evaluation was documented in Niagara Mohawk Internal Correspondence NMP74764 which reported reviews of forty-five MOV Fourteen MOVs were considered susceptible to pressure locking and thirteen to thermal binding. Six of all these cases were susceptible to both conditions. The report further identified four MOVs with a high priority, two MOVs with medium, and eight MOVs with a low priority with regard to plant safety and for pursuing corrective action To prevent pressure locking and thermal binding, report NMP74764 recommended actions to modify four high priority, two medium priority, and one low priority MOV. MOVs 2CSL*MOV104,2RHS*MOV24A,2RHS*MOV24B, and 2RHS*MOV24C were modi 6ed during the recent Unit 2 refueling outage by providing an external pressure relief path from the valve bonnet to the upstream pipe. However, the remaining three MOVs will not be -
modi 6ed since subsequent engineering evaluation determined that these MOVs have v experienced operating problems or exhibited any conditions that represent hydraulic locx or thermal binding. The licensee stated that they will establish justifications for not modifying the remaining three MOVs by December 31,1993, during Snal closeout of the DER.-
Pending the licensee's completion of this justi6 cation and its subsequent review by the NRC, this item is unresolved (UNR 50-410/93-21-01). EXIT MEETING The inspectors met with licensee personnel, denoted in Attachment 1 of this report, at the -
conclusion of the onsite inspection on October 8,1993. At that time, the scope of the inspection and the inspection results were summarized. A follow-up telephone conference between the licensee, NRR, and Region I was conducted on October 13, 1993, to clarify certain aspects of the licensee's MOV Grouping Plan for Unit 2. A final closcout meeting was conducted via telephone conference between Region I and the licensee on October 20,1993. The licensee acknowledged the inspection findings as detailed in this report and had no additional comments regarding the inspection result .. -. -- - - .- - . . . . _
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ATTACIIMENT 1 ,
Persons Contacted <
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Niacara Mohawk Power Cornoration. Corporate and Station Personnel T. Aiken Electrical Design H. Barrett Site Licensing J. Bunyan Engineering Project Manager
- K. Dahlberg Plant Manager, Unit 1 J. Halusic . Lead Design Engineer K. Johnson Electrical Maintenance Unit 1
- M. Jones Project Manager, G.L. 89-10 N. Kollengode Project Manager, Unit 1
- R. Magnant Site Licensing
R.- M ain MOV Maintenance Engineer
- M. McCormick Gen Manager, Safety Assessment, Licensing & Training
- R. Morey Lead Engineer, Unit 1 .
- J. Mueller Plant Manager, Unit 2
- L. Pisano Manager, Work Control / Outage Management, Unit 1
- N. Rademacher Operations Manager, Unit 1 K. Sweet Technical Manager, Unit 1 B. Tessier Manager Maintenance, Unit 1 G. Thompson Supervisor System Engineering, Unit 2
- K. W ard Manager, Unit 2 Engineering U. S. Nuclear Regulatory Commission B. Norris Sr. Resident Inspector, Nine Mile Point R. Plasse Resident Inspector, Nine Mile Point, Unit 1 W. Mattingly Resident Inspector, Nine Mile Point, Unit 2
- Denotes those present at the exit meeting held October 8,1993.