IR 05000361/1993036
| ML20059K633 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 01/04/1994 |
| From: | Ang W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | |
| Shared Package | |
| ML20059K602 | List: |
| References | |
| 50-361-93-36, 50-362-93-36, GL-89-10, NUDOCS 9402020191 | |
| Download: ML20059K633 (14) | |
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U. S. NUCLEAR REGULATORY COMMISSION
REGION V
Report Nos.: 50-361/93-36 and 50-362/93-36 Docket Nos.: 50-361 and 50-362 License Nos.: NPF-10 and NPF-15 Licensee: Southern California Edison Company Irvine Operations Center 23 Parker Street Irvine, California 92718 Facility Name: San Onofrc Units 2 and 3 Inspection at: San Onofre site, San Clemente, California Inspection conducted: December 6 through 10, 1993 Inspector: C. Myers, Reactor Inspector, Region V Approved by: -
'i H~D W. P. Ang, Chief, Engineering Section Date signed Inspection-Summary Inspection during the period December 6-10. 1993 (Report Nos. 50-361/93-36 and 50-362/93-36)
Areas Inspected:
A routine announced inspection of a licensee event report and followup of items from previous inspections was performed, Temporary Instruction 2515/109 and Inspection Modules 92700, 92701 and 92702 were used as guidance for this inspection.
Safety Issues Management S_ystem (SIMS) Item:
-l SIMS Issue Number GL 89-10 was updated to reflect this followup inspection-tmder TI 2515/109 Part 2.
9402020191 940106 PDR ADOCK 05000361 0 PDR
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Results:
General Conclusions and Soecific Findinasi Three MOVs in Unit 3 which the licensee had determined to be inoperable during i implementation of their Generic Letter 89-10 program were found to be ,
appropriately reported in licensee event report (LER) 93-3. ;
The licensee's degraded voltage calculations for DC MOVs did'not adequately justify the use of generic motor performance: curves. -
Significant Safety Matters:
None.
t Summary of Violations or Deviations:
i One deviation regarding MOV calculations under degraded voltage was ;
i denti fi ed. One non-c'ted violation regarding MOVs which were reported inoperable by the licensee was identified. ;
Open items Summary:
Open Items from Previous Inspections:
93-17-01:0 PEN Violation Failure to Document MOV Test Deficiencies 93-17-02: CLOSED Followup Two MOV Program Weaknesses 93-17-03: CLOSED Unresolved Reported MOV. Inoperability 92-02-01: CLOSED Followup M0V Capability under Degraded Voltage 92-02-02: CLOSED Followup Design Calculation Errors 92-02-03: CLOSED Followup' Previous NCR Operability Determin'ations 93-31-02:0 PEN Unresolved Failure of 3HV-6371 New Items identified During this Inspection: .
93-36-01:0 PEN Deviation MOV Capability under Degraded Voltage l 93-36-02: CLOSED Non-cited Reported MOV Inoperability Violation 1
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Details 1 1.0 PERSONS CONTACTED
Southern California Edison Company i
- D.Axline, Engineer,OnsiteNuclearLicensing(ONL)- :
- M. Anderson, Supervisor, Nuclear Engineering Design Organization (NED0) .
- P. Blakeslee, System Engineer, Station Technical (ST)
- D. Brieg, Manager, ST
- J. Curran, Program Manager, NEDO
- E. David, Lead Engineer, NEDO
- G. Gibson, Supervisor, ONL
- M. Herschthal, Assistant Manager, ST )
- R. Krieger, Vice President, Nuclear Generation
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- B. Joyce, Maintenance Manager, Units 2 and 3
- W. Marsh, Manager, Nuclear Regulatory Affairs
- R. McPherson, Engineer, Maintenance
- G. Plumlee, Engineer, ONL _
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- J. Reilly, Manager, Nuclear Engineering and Construction Others .
- R. Erickson, Site Representative, San Diego Gas and Electric Co. '
- J. Russell, Resident Inspector, NRC
- D. Solario, Resident Inspector, NRC-The inspector 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 Followuo of Open Items from Previous Inspections (92701)_ .
2.1 (0 pen) Enforcement Item 50-361/93-17-01: -Inadeauate Documentation of MOV'
Test Signature Anomalies
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Oriainal Enforcement item
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This violation concerned a failure to identify and document the qualitative
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deficiencies in the GL 89-10 test data for 3HV-4705.
Auxiliary feedwater flow control valve 3HV-4705 failed to open'during routine :
testing in May,1993._ While no single root cause was identified,_ the licensee i concluded that the probable cause of the failure was due to misalignment of the actuator on the valve and internal degradation of the actuator. ;
The inspectors had noted that the diagnostic thrust signature for 3HV-4705 3 obtained during previous testing in March 1992 displayed significant. abnormal !
cyclic thrust loading at the initiation of the closing stroke. The ' unusual trace feature had not been identified or evaluated by the licensee.in the test 5
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procedure. The inspectors were concerned that the anomaly potentially indicated improper operation of the MOV. The licensee stated that the qualitative characteristics of the diagnostic signature had been evaluated informally by Maintenance personnel following the GL 89-10 testing, and had been judged to be acceptable at that time. Tb licensee had stated that, although unusual, they considered the irregularity to be a repeatable characteristic of the valve signature which was ;ncer. sequential to the proper valve operation.
The inspectors had also noted a large number of potential deficiencies in the material condition of MOVs which the licensee identified existing in many of the MOVs following the design basis testing during cycle 6 outages in both units. The licensee had identified that 53 of the 75 MOVs tested displayed anomalies in the diagnostic thrust signatures.
Licensee Actions in Response to the NOV in their response dated October 28, 1993, the licensee identified that they had revised their procedure for analysis of diagnostic test data to require documentation of evaluations of unusual diagnostic signature characteristics.
Observations durina this Inspection The inspector reviewed licensee procedure 5023-V-3.50. The inspector found that the procedure had been revised to require documentation of unusual qualitative characteristics observed in MOV diagnostic signatures.
The inspector reviewed the licensee's response dated October 28, 1993. The inspector found that the licensee had not addressed the generic implications of the numerous apparent deficiencies in the material coidition of the MOVs tested during the Cycle 6 outages. By NRC letter of November 22, 1993, additional information was requested regarding the basis for the licensee's conclusion that 3HV-4705 was an isolated occurrence and not indicative of a-programmatic problem. During telephone conversations subsequent to the inspection, the licensee committed to submit the results of their evaluation of the 53 MOVs with signature anomalies, and to review the results of maintenance observations of MOVs subsequent to indicated signature anomalies during testing. The licensee cnmitted to complete their reviews by January 31, 1994 and submit a report of their evaluation by February 15, 1994.
Another example of this program weakness is discussed in Paragraph 2.7.
Conclusion The inspector concluded that the licensee had not yet completed their qualitative evaluation of the Cycle 6 MOV signatures as part of their evaluation of the adequacy of their maintenance program. This item will remain open pending inspector review of the licensee evaluations.
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No violations or deviations were identified.
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2.2 (Closed) Followup Item 50-361/93-17-02: MOV Procram Weaknesses
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Oriainal Open Item a. Lack of Timely Generic Review During a previous NRC inspection, the inspectors considered the-lack of timely generic review of MOV test data in order to validate calculational assumptions
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to be a program weakness. The inspectors considered the proposed licensee .
actions to be adequate. This item was open pending confirmation of proposed licensee actions.
t The inspectors found that the licensee was not incorporating a generic review of the adequacy of their calculational assumptions as part of their evaluation of test data following each refueling outage. The licensee indicated that feedback of test data to revise their calculations will be conducted'as part of their final data reconciliation evaluation at the conclusion of their test schedule. The inspectors noted that the licensee's design standard MS-123-125, Attachment 6A, " Functional Margin Review," did. not specifically require an assessment of the generic implications of the test data that was applicable to other untested valves of the same type or manufacturer. Without a generic review of the test, the inspectors were concerned that consistently non- ;
conservative test results would not be promptly. identified. Furthermore, the
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implications of the generic applicability on MOVs which would not be practicable to test, but which used the same setpoint calculation method, would not be evaluated in a timely manner.
The licensee committed to initiate generic evaluation of test data' following the U3C7 outage. The licensee stated that their functional assessment will '
evaluate the generic implications of the high valve factors observed during the Cycle 7. testing.
b. Timeliness of MOV Test Data Review During a previous NRC inspection, the inspectors found a lack of specific. test acceptance criteria for determining design basis capability and the untimely completion of NEDO reviews of the test. data to be. a program weakness. The proposed licensee action appeared adequate. This item was considered open pending implementation of the licensee's proposed actions.
The inspectors noted the MOV test procedure did not require evaluation of the MOV diagnostic signature data prior to returning the MOV.to service in-an operational mode in which the M0V was required to be operable. For Cycle 7 1r testing, the licensee completed the NED0 review of the test data by close of ~ '
breakers following the outage.
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The licensee committed to formally require the completion of the NED0 review i prior to close of breakers. In addition, the. licensee committed to include specific acceptance criteria-in the GL 89-10 test procedures to evaluate design b' asis capability based on the test data. The licensee planned to . >
establish a design basis screening criteria using an extrapolation of the ~ test'
data.
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Licensee Action on this Open item ;
a. The licensee implemented procedure changes to begin generic evaluation of test data following .the Cycle 7 outage. l
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b. The licensee implemented changes to their procedure for MOV test- data evaluation to include saecific acceptance criteria to extrapolate the test results to full design aasis conditions to verify adequate actuator
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Observations Durina this Inspection Through discussions with licensee personnel, the inspector found that the licensee had initiated their functional margin review of MOV test data. The- '
inspector reviewed the licensee's. MOV test data evaluation procedures and found that they incorporated adequate acceptance criteria.
Conclusions The inspector concluded that the licensee had implemented procedural changes to assure timely test data review and appropriate test acceptance criteria.
This item is closed.
No violations or deviations were identified.
2.3 (Closed) Followup Item 50-361/93-17-03: Reported MOV Inonerabilit_y Original Open Item In Licensee Event Report (LER) 93-03, dated' June 28, 1993, the licensee reported that three safety related MOVs in Unit 3 were inoperable for a period of 14 months from the time of testing until the test data was evaluated.
During this period the plant was operated in a mode in which the MOVs were ,
required to be operable. During a previous NRC inspection, this reported-condition which was prohibited by the plant's Technical Specifications was '
considered an unresolved item pending inspector evaluation of the' MOV test-data and the licensee's basis for determining the operability of the reported MOVs. .
Two of the MOVs (3HV-6366 & 3HV-6368) were component cooling water (CCW)
supply valves in separate trains for the containment emergency cooling unit a which were required to open on receipt of a containment cooling actuation signal. The other MOV (3HV-0510) was a pressurizer steam sample isolation . '
valve which was required to close on a containment isolation actuation signal.
The licensee declared the valves inoperable in June 1993 after evaluating test-data obtained from GL 89-10 testing in March 1992. The licensee concluded that the test data indicated that the switch settings for'the valves were non-conservative. )
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5 Licensee Action' to Address this Open Item The licensee had further evaluated the data for MOV 3HV-0510 and determined '
that the operability of the MOV could be justified.
Observations Durina this inspection The inspector reviewed the diagnostic thrust signatures and MOV setpoint requirements for 3HV-6366 and 3HV-6368. The inspector found that in both cases, the MOV close torque switch setting had been slightly below the mi_nimum ,
required setpoint. The inspector found that there appeared to be conservative margin in the established setpoints which were based on worst case design basis conditions. The-inspector found that the licensee had declared the MOVs to be inoperable based on a reduction in the required margin established by design for worst case design basis conditions. The inspector noted that the valves had operated successfully during differential pressure testing. The valves were normally aligned open to perform their safety function for containment cooling.
Conclusion The inspector concluded that the licensee actions in response to their evaluation of the test data had been conservative. The inspector also concluded that the period of operation with the MOVs in an inoperable condition had been appropriately reported in LER 93-03 as a condition p prohibited by Technical Specifications. This violation is not being cited l
because it meets the' enforcement criteria of 10 CFR Part 2, Appendix C, VII.B.
(Closed - Non-cited Violation 50-361/93-36-02)
l~ One ncn-cited violation was identified.
l 2.4 (Closed) Followup Item 50-361/92-02-01: MOV Capability Under Dearaded <
Voltage Conditions Oriainal'Onen Item
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During a previous NRC inspection, the inspectors noted that.the design. basis degraded voltage condition for four MOVs was calculated to be as low as 40Fs of the rated DC voltage for the motors of the actuators. The licensee had stated -
that they would contact the actuator vendor (Limitorque) regarding the acceptability of the application under very low voltage conditions. As an-alternative, at the time of the inspection, the licensee was considering ,
additional testing and analytical measures. Review of the vendor correspondence and other licensee actions -to demonstrate MOV capability under degraded voltage conditions was considered to be an open item. ,
licensee Action on this Item The licensee revised their method for calculating MOV capability under degraded voltage conditions in design standard MS-123-125. The licensee
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obtain concurrence in their low voltage applications. According to licensee !
personnel, Limitorque had been contacted sometime in the past but had not .,
specifically concurred with the licensee's low DC voltage application. .j The inspector reviewed the licensee's calculation method for determining M0V d
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actuator output torque capability under degraded voltage which was identified in design standard MS-123-125. The licensee utilized the calculated actuator i output torque under degraded voltage conditions to assure minimum actuator-capability under design basis differential pressure and to limit the maximum allowable torque switch settings to prevent motor stall. The licensee based their calculation method on a method identified by Limitorque in their 1988 7 publication " Notes from the Field."
The inspector found that the licensee's calculation method differed from the standard Limitorque sizing method for determining actuator output torque capability under degraded voltage conditions. Tha standard Limitorque method was based on the use of rated motor starting torque and the voltage available at the mo;or terminals. In the standard Limitorque method, the actuator output torque capability was calculated including a degraded voltage factor (DV). Limitorque defined the DV for DC motors as the ratio of the minimum voltage at the motor terminals to the rated motor voltage.
The inspector found that the licensee's calculation method was based on the motor locked rotor current. After determining the locked rotor motor current .
available under degraded voltage conditions, the licensee used generic motor - l curves published by Limitorque to determine the motor torque available. -The inspector found that the licensee method did not incorporate any tolerance for 3 individual motor deviation from the published motor curves. . The licensee's
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method utilized the motor output torque over the entire speed range of the motor including zero revolutions per minute stall conditions. The inspector noted that the licensee's method predicted significantly greater actuator output torque than the standard Limitorque method.
The inspector noted tha' the licensee's degraded voltage calculations for some DC motors predicted higher available torque under degraded voltage conditions; .
i that the rated motor torque under nominal voltage conditions. ~ According to
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the licensee, their degraded voltage calculations for four.DC motors, .'
predicted an output torque capability under degraded voltage-conditions which exceeded the start torque rating of two foot-pounds. In comparison, the standard Limitorque calculation would have predicted output torque capability o (available starting torque) less than two foot-pounds under degraded voltage conditions. ,
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The inspector found that the licensee method effectively utilized stall torque !
as the basis for determining actuator capability under degraded voltage conditions. The licensee had previously committed not to use stall torque as -
the basis for actuator capability determination. Furthermore, in Maintenance Update 92-1, limitorque stated that stall torque was to be used for overload analysis only and not for determining reliable actuator output or maximum 1 torque switch settings.
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As noted in the previous inspection, the licensee had conducted static testing at degraded voltage conditions to demonstrate that the motor would trip'the torque switch and not stall. The inspector noted, however, that the testing was performed with the torque switch nominally adjusted within its setpoint !
band and not at the maximum setpoint. Under the licensee's setpoint method, the maximum torque switch thrust setting was typically limited by the degraded voltage capability of the motor. The inspector found that the licensee's. ;
degraded voltage testing did support the existing torque switch settings but not the allowable setpoint range. .
The inspector contacted Limitorque and discussed the use of published motor '
curves in determining motor performance under degraded voltage conditions.
While considered a technically sound approach in determining available motor current under degraded voltage cenditions, Limitorque did not recommend the- .
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use of the generic motor curves w;thout specific validation for individual motors. Limitorque considered the motor curves to be representative of'a limited sample of production tests of motors. Individual motor performance ',
was expected to differ from the published curves.
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Furthermore, Limitorque stated that the calculation method published in their 1988 " Notes from the Field" was intended for use in cable sizing and not as an alternative to the standard Limitorque actuator sizing method without specific i actuator testing. Limitorque stated that published actuator efficiencies were only valid for use with the standard Limitorque sizing method, 1;onclusions Based on the MOV testing under degraded voltage conditions and the calculations performed by the licensee, the original open item (50-361/92-02-01) is closed.
The inspector found the lack of vendor contact and use of stall torque.in determining the MOV degraded voltage capability to be a program weakness and a -
deviation from previous licensee commitments (Deviation 50-361/93-36-01).
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The -inspector found that the licensee had not adequately justified the use~ of.
generic motor curves without specific validation for individual motors. The inspector considered this a . weakness in the licensee's GL 89-10. program. j
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P 2.5 (Closed) Followun item 50-361/92-02-02: Desian Calculation Errors ;
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Oriainal Open Item During a previous NRC inspection, the inspectors noted numerous errors.in the design calculations for MOV sizing and setpoints conducted by the licensee as. ,
part of their GL 89-10 program. The inspectors found that there were no specific procedures established for the GL89-10 calculations. In response to '
the inspectors' concerns,'the licensee had initiated an investigation to .
determine the extent of the problem. This item was considered an open item ?
pending inspector review of the results of the licensee investigation'and :
corrective actions.
Licensee Action on this Item -
The licensee conducted a root cause analysis of the errors found in the !
engineering calculations. In a letter dated May 26, 1992, the licensee responded to the NRC concerns and identified corrective actions. :
Observation Durina this Insnection 1 The inspector reviewed the Nuclear Engineering Design Organization (NEDO).
Design Standard MS-123-125 which was used by the licensee. to performed ,
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calculations for their GL 89-10 program. The inspector found that specific guidance had been established for the conduct of the calculations. ;
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'The inspector reviewed Surveillance Report SOS-140-93,. dated May 27, 1993, which was conducted by the licensee's quality assurance organization. ,
Significant improvements in the control and quality of engineering ,
calculations were identified by the licensee audit. The inspector found the-licensee audit to be adequate.
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The inspector sampled two calculations conducted by the licensee for MOV ;
sizing and setpoints and found no errors. j
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Conclusions
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The inspector concluded that the licensee actions in response to the ;
inspectors concerns had been adequate. This item is closed. !
No violations or deviations were identified.
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2.6 (Closed) Followup Item 50-361/92-02-03: MOV Operability Determinations-Oriainal Open item
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During a previous.NRC inspection, the inspectors observed that- the licensee had initiated non-conformance reports (NCRs) for M0V. setpoints.which did not .
meet the calculated requirements of the licensee's GL 89-10 program. -The
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insnactors observed several instances where M0V operability determinations ~ in NCR dispositions were not based on the design criteria established by the
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licensee's_GL 89-10 program. In response to the inspector's concern, the
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licensee committed to review all previous NCR operability determinations for MOVs to assure consistent application of GL 89-10 criteria as the basis for -
the operability of the MOVs.
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Licensee Actions on this Item The licensee identified 38 NCRs which had been issued previously for MOV setpoint problems during the Unit 3 Cycle 6 refueling outage. The licensee reviewed 25 of the 38 NCRs and found that the operability of all could be ,
justified within the criteria of their GL 89-10 program. The. remaining 13 ;
NCRs were not reevaluated because the M0V setpoints had been readjusted during subsequent outages to- eliminate the nonconforming condition. The licensee: ;
contacted the NRC on July 27, 1993,- informing them of the results of their review. The inspectors agreed that further review of the remaining 13 NCRs was not necessary, >
Observations Durina this Inspection l The inspector reviewed the 25 revised NCR operability evaluations and fotnd that GL 89-10 criteria were consistently used as the basis for operability.
The inspector sampled two recent NCRs concerning MOV setpoint problems a1d found the operability evaluations to be adequate.
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Conclusions The inspector concluded that the licensee had adequately established GL 89-10 criteria for assurance of design basis capability as the basis' for MOV ,
operability determinations. Because all the torque switch settings for the 38_ ,
MOVs had been readjusted during subsequent testing within the licensee's GL 89-10 program, this item is closed. ,
No violations or deviations were identified. '!
2.7 (0 pen) Unresolved item 50-361/93-31-02: Failure of 3HV-6371 ,
Oriainal Open Item
During a previous NRC inspection, the inspector reviewed the licensee's actions following their discovery on November 12, 1993, of. a misassembled valve disk.in 3HV-6371, the component cooling water (CCW) outlet valve for the emergency cooling unit ME399. Upon scheduled disassembly of the valve during i the U3C7 outage, the licensee had identified damage 'on certain internal ' parts ;
of the disk assembly apparently caused by previous misassembly. of the disk. -
The: inspector reviewed the maintenance history for the valve and the results -
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of prior testing of the valve. The inspector had noted abnormal diagnostic ,
test- signatures in March 1992 and reoccurring operational. problems since t January 1993. . The inspector was concerned that prior repetitive maintenance had apparently not identified nor corrected the root cause of the problem. .
The adequacy of the licensee's configuration control and control of maintenance activities was an unresolved item pending further inspector review-
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- of ongoing licensee investigations into the root cause of the valve mi sassembly. _
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Licensee Actions on this Item ,
i The licensee initiated non conformance report (NCR) 9311005502 to document the valve misassembly and corrective actions. The licensee initiated a maintenance division investigation report to determine the root cause of the (
valve misassembly. .
a 0bservations Durino this inspection ,
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The inspector reviewed the maintenance and testing previously performed by.the -
i licensee for 3HV-6371. The inspector also reviewed the diagnostic signatures '
obtained during testing for 3HV-6371. The inspector found the following
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3/5/92 Diagnostic testing under static conditions was conducted during the' i V3C6 outage. Significant abnormal running loads were indicated in the diagnostic signatures. ;
1/19/93 3HV-6371 failt ' , open during testing. Motor breakers tripped. ;
NCR 93010041 wa. aitiated to document the failure. The NCR' !
indicated tisat the M0V had a history of high running current. The 'j valve stem and actuator motor were replaced. Diagnostic signatures' :
taken post maintenance indicated continued abnormal running loads which the licensee considered indicative of a bent stem despite -
having replaced the valve stem. j 2/24/93 Additional actuator maintenance trouM, hooting performed under Revision 1 to NCR 93010041, f
3/31/93 Additional actuator maintenance performed under Revision 2 to NCR 93010041. Torque switch replaced. Worm and worm gear found damaged i and overheated. Actuator grease found hardened around worm :
indicating inadequate lubrication. Diagnostic signatures obtained t using calibrated strain gages.
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4/8/93 Operations declared 3HV-6371 inoperable and issued a change 'to the system lineup to secure the valve in its safety features position in l accordance with plant. Technical O 'cifications. Additional actuator "
maintenance performed under Revisjun 3 to NCR 93010041. Actuator -
overhauled with change 'of type of grease.
4/28/93 Torque switch adjusted to new Unit 2 setpoints. Diagnostic i signature continues to indicate abnormal high running loads.
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11/12/93 Disassembly of the valve- during the V3C7 outage identified damaged internals and improper ass?mbly. NCR 93110055 initiated. .Po s t - ;
maintenance diagnostic testing indicated no abnormal running loads.
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-i The inspector noted that 3HV-6371 was a WKM 10"-150# gate valve with a high ;
speed SB-00S-15-3600 Limitorque actuator. The licensee identified that WKM.
was the tradename for a Pow-R-Seal gate valve manufactured by the WKM valve ' i division of Cooper Indust' r ies, Inc. The split gate, lever-lock design .of the i valve disk incorporated an assembly of parts which allowed the disk faces to- .
be wedged outward against the valve seating rings only after flow cutoff. l The inspector noted that the static diagnostic signatures from March 1992 2 indicated a significant abnormal running load potentially indicating a -!
severely bent valve stem. The licensee had recognized the unusual-indication ;
but had considered the indication to be inconsequential to the proper ;
operation of the valve at that time.
The' inspector noted that the running load increased in both the opening and closing direction up to approximately half of the thrust setting of the torque switch. The torque switch setting had been establirhed by the licensee to ,
provide sufficient thrust to operate the valve under worst case design basis '
differential pressure. However, the signature indicated that almost half of i the available thrust eas requirt d to operate the valve under static (zero ;
differential pressure) conditions. The inspector noted that the licensee's ;
calculations had assumed only a nominal running load in establishing the !
allowable torque switch setpoints. i The inspector noted that similar valve 2HV-6371 had been dynamically tested at l 91% design basis differential pressure during the U2C7 outage. The results of that testing indicated that the valve displayed a valve factor (VF) of 0.53 '
which exceeded the 0.4 VF assumed by the licensee in their setpoint calculations. j The inspector noted that no root cause was required for NCR 93110055. ;
. According to the licensee, a root cause analysis would evaluate the generic implications of the valve misassembly. Despite the NCR- disposition, the inspecton 9ted that a root cause investigation was underway by the licensee. '
The inspe. a reviewed licensee maintenance procedure S0123-I-6.75, " Valve-WKM' l Model D-2 Gate Valve Disassembly, Cleaning, inspection and Reassembly,"
Revision 0, TCN 2, dated October 8, 1993. The inspector found the procedure ,
had been recently revised to incorporate detailed instructions for~ the proper assembly of the valve disk. :
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Conclusions -
The inspector concluded that indications of abnormal MOV operation t 1d not ~
been thoroughly investigated prior to the MOV failure in January 1993. The inspector was concerned that observations of degraded material conditions in i the valve and actuator continued to be observed following diagnostic. testing. :
The inspector found the failure of 3HV-6371 to exhibit maintenance program 1 deficiencies similar to those discussed in Paragraph 2.1. . .
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This item will remain unresolved pending inspector review of the results of- l the licensce investigation into the root cause' for the misassembly of 3HV-6371. '
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No violations or deviations were identified. ,
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3.0 UNRESOLVED ITEMS !
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Unresolved items are matters about which -o information is required in' order -
to ascertain whether they are acceptabla : .as, items of noncompliance or ni deviations. A previously identified anresolved item is discussed in Paragraph' -l 2.7 of this repnrt.
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4.0 EXIT MEETING i
The inspector conducted an exit meeting on December 10, 1993, with members of-the licensee staff as indicated in paragraph 1.0. During the exit'meeti19, .
the inspector reviewed the inspection findings as described in this reptct.
The-licensee acknowledged the concerns identified in the report. )
The licensee did not identify as proprietary any information provided to, or j reviewed by, the inspector during this inspection. j
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