ML20035D941
| ML20035D941 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 04/08/1993 |
| From: | Collins S NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Hall D HOUSTON LIGHTING & POWER CO. |
| References | |
| NUDOCS 9304140137 | |
| Download: ML20035D941 (32) | |
See also: IR 05000498/1993008
Text
{{#Wiki_filter:- - _ _ _ . - - -_-. UNIVED ST ATES /jkaafGo , ?g NUCLEAR REGULATORY COMMISSION , )[ } REGION IV 8 611 RY AN PLAZA DRIVE. SUITE 400 o l Y, [ AR LINGTON, T E XAS 76011-8064 3 APR - 81993 ! ....* Dockets: 50-498 50-499 Licenses: NPF-76 NPF-80 EA 93-047 Houston Lighting & Power Company ATTN: Donald P. Hall, Group l Vice President, Nuclear P.O. Box 1700 Houston, Texas 77251 SUBJECT: ENFORCEMENT CONFERENCE CONDUCTED MARCH 25, 1993, (NRC INSPECTION , ' REPORT 50-498/93-08; 50-499/93-08) This refers to the enforcement conference conducted on March 25, 1993, at the , l Region IV office in Arlington, Texas, concerning activities authorized by NRC l License Numbers DPR-76 and DPR-80 for the South Texas Project Electric Generating Station, Units 1 and 2. The meeting was attended by those on the i attached Attendance List. The subjects discussed at this meeting are described in the enclosed meeting summary. l It is our opinion that this meeting was beneficial and has provided a better ' understanding of the apparent violations and your corrective actions. These ! violations were identified in NRC Inspection Report 50-498/93-08; 50-499/93-08. NRC's decision relative to these apparent violations will be communicated by separate correspondence. In accordance with Section 2.790 of the NRC's " Rules of Practice," Part 2, Title 10, Code of Federal Regulations, a copy of this letter will be placed in the NRC's Public Document Room. Should you have any questions concerning this matter, we will be pleased to discuss them with you. / , , Sincerel , . /1 (! $ LwQ T amuel J. Co' lins, Directe Division of eactor Safety Enclosure: Meeting Summary w/ attachments cc w/ enclosure: (see next page) i 9304140137 930408 1 // p PDR ADOCK 05000498 l G PDR l f l - -. . - .. .
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- Houston Lighting & Power Company
-2- 9 , cc w/ enclosure: - Houston Lighting & Power Company ATTN: William J. Jump, Manager , Nuclear Licensing P.O. Box 289 Wadsworth, Texas 77483 i City of Austin Electric Utility Department ' ATIN: J. C. Lanier/M. B. Lee P.O. Box 1088 Austin, Texas 78767 City Public Service Board ATTN: R. J. Costello/M. T. Hardt P.O. Box 1771 i San Antonio, Texas 78296 Newman & Holtzinger, P. C. ATTN: Jack R. Newman, Esq. 1615 L Street, NW > Washington, D.C. 20036 Central Power and Light Company ATTH: D. E. Ward /T. M. Puckett
P.O. Box 2121 Corpus Christi, Texas 78403
. INPO
Records Center . 1100 Circle 75 Parkway Atlanta, Georgia 30339-3064 Mr. Joseph M. Hendrie 50 Bellport Lane Bellport, New York 11713 , Bureau of Radiation Control State of Texas i 1101 West 49th Street Austin, Texas 78756 Judge, Matagorda County Matagorda County Courthouse 1700 Seventh Street Bay City, Texas 77414 i 1 ..0 . . . - - . . . - . - . - . - - . - - . - - - . - -
i 4 i e r ! a . , 1 . .
- Houston Lighting & Power Company
-3- [ < .
i ! Licensing Representative ' Houston Lighting & Power Company Suite 610 Three Metro Center , Bethesda, Maryland 20814 Houston Lighting & Power Company l
, ATTN: Rufus S. Scott, Associate I General Counsel P.O. Box 61867 Houston, Texas 77208
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- Houston Lighting & Power Company
-4- i bcc to DMB (IE14) - DRS bcc distrib. by RIV: J. L. Milhoan Resident Inspector DRP Section Chief (DRP/D) Lisa Shea, RM/ALF, MS: MNBB 4S03 MIS System DRSS-FIPS RIV File Project Engineer (DRP/D) R. Bachmann, OGC, MS: 15-B-18 DRS l Section Chief (DRP/TSS)
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- previously concurred
i , _ , - - - . _ . . __, _ _ , _ _ . , . _ _ _ _ _ , , _ _ _ , _ , , . . _ . _ , _ . .
- - . - _ _ - O ! , , , , Houston Lighting & Power Company -4- bcc to DMB (IE14) - DRS bcc distrib. by RIV: J. L. Milhoan Resident Inspector DRP Section Chief (DRP/D) Lisa Shea, RM/ALF, MS: MNBB 4503 MIS System DRSS-FIPS RIV File Project Engineer (DRP/D) R. Bachmann, OGC, MS: 15-B-18 DRS Section Chief (DRP/TSS) l > l l i . {
RIV:RI:ES* C:ES* DD:DRS* D:DRP* D:DRSr..fk' SJColkin[ys- MFRunyan/lb TFWesterman ATHowell ABBeach / /93 / /93 / /93 / /93 If/d,/93 I
- previously concurred
l 130025 - . - . . - - - - . - . - - - -
___ ' - , , . . MEETING SUMMARY . Licensee: Houston Lighting & Power Company (HL&P) Facility: South Texas Project (STP), Units 1 and 2 Licenses: DPR-76 and DPR-80 Dockets: 50-498 and 50-499 SUBJECT: ENFORCEMENT CONFERENCE (50-498/93-08; 50-499/93-08) , On March 25, 1993, representatives of HL&P met with Region IV personnel in
' Arlington, Texas, to discuss the apparent violations identified in NRC Inspection Report 50-498/93-08; 50-499/93-08. The conference was held at the request of Region IV. The licensee presented a summary of the causes for the apparent violations and their corrective actions. ' The attendance list and licensee presentation are attached to this summary. , Attachments: 1. Attendance List 2. Licensee Presentation (NRC distribution only) l l l ~ ___ . . _ - . - _ _ . . _ _ _ _ _ . . _ , _.. _ _ _ _ _ _ _ _
_ __ _ _ _ i 4 . . . ATTACHMENT 1 , ' ATTENDANCE LIST l Houston Lighting & Power Company ! D. Hall, Group Vice President - Nuclear W. Kinsey, Vice President, Nuclear Generation S. Head, Deputy Licensing Manager C. Keen, Construction Engineering Specialist - Licensing C. Walker, Manager, Public Information , M. McBurnett, Manager, Integrated Planning and Scheduling T. Jordan, General Manager, Nuclear Engineering i i K. Christian, Manager Plant Operation C. Albury, Principal Engineer V. Patil, Motor-0perated Valve Program , Sargent and Lundy
! 1. Garza City of Austin Electric Utility , P. Golde, Manager, Joint Projects City Public Service - San Antonio " M. Hardt, Director, Nuclear Division Central Power & Light l B. McLauchlin, Senior Operations Engineer Nuclear Regulatory Commission J. Milhoan, Regional Administrator, Region IV . 4 ' A. Beach, Director, Division of Reactor Projects (DRP) A. Howell, Deputy Director, Division of Reactor Safety (DRS) T. Stetka, Chief, Project Section D, DRP G. Sanborn, Enforcement Officer, Region IV W. Brown, Regional Counsel ! T. Westerman, Chief, Engineering Section, DRS
M. Satorius, Project Engineer, Project Section D, DRP l M. Runyan, Reactor Inspector, Engineering Section, DRS } W. Reckley, Project Manager, Project Directorate IV-2, Office of Nuclear Reactor Regualtion , i . -_- - , _ - - _ _ _ . _ ._, . . _ - , , . _ . . _- - -
. . .-_ . . . . .-- - ..... - -. ...._. - . . - - - .... . .. .- - - - .- _ . - . . , . ATTACHMENT 2 SOUTH TEXAS PROJECT HL&P- NRC ENFORCEMENT CONFERENCE , MOTOR OPERATED VALVES MARCH 25,1993
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"4 - , l &ccI!ence l Through i l Senvice, TEAMWORK, Pnios i $ ! ! I i ' . . . . . .. . . . .
__ _ -_ ___ _-_ _____-_________ ____ _ _ __ ____ _ _________ ._ . . , NRC - HL&P ENFORCEMENT CONFERENCE . MOTOR OPERATED VALVES - . March 25,1993 Aaenda Opening Remarks D. P. Hall SI-MOV-31 A M. A. McBurnett/K. J. Christian Apparent violations - System overview - Chronology - Causes - Safety significance - Corrective actions / Enhancements - Conclusions - l RHR Suction Valves M. A. McBurnett/T. J. Jordan Apparent violation - System overview - 4' Chronology - Cause - Operability determination - Safety significance - Corrective actions - , Conclusions - Additional information -
Closing Remarks D. P. Hall I 4 ' , . . . . . . . . . . . ._ _ - - - - - - - - - - . - - .+,m_-. .-.-
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. . ^ NRC .HL&P ENFORCEMENT CONFERENCE . LOW HEAD COLD LEG INJECTION ISOLATION VALVE ISSUE ~' (SI-MOV-31 A) Apparent Violations 1. Unit 2 operated from April 1989 to October 1990 with the Train A low head safety injection isolation valve to reactor coolant system cold leg, SI-MOV-31 A, inoperable in violation of Technical Specification 3.5.2. , 2. Failure to take appropriate corrective actions following the initial failure of SI-MOV-31 A to prevent recurrence pursuant to 10 CFR 50, Appendix B, Criterion XVI. .
i i ,' ! 2 -..
___ ______ _ _ __ _ _ _____ __ __ - _ _ __ _ _ _ _ - _ _ _ _ _ _____ _ _ _ _ _ _ - _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ - _ _ _ - _ _ _ . . , NRC - HL&P ENFORCEMENT CONFERENCE . LOW HEAD COLD LEG INJECTION ISOLATION VALVE ISSUE ~~ (Sl-MOV-31 A) Overview of Safety Iniection System Safety functions performed by the system (Schematic Nos.1 & 2)
normal position of SI-MOV-31 A is open with power removed (breaker open) - three 100% trains - each high head safety injection and low head safety injection train designed to deliver flow to - ' hot and cold legs
one high head safety injection pump minimum requirement for hot leg injection - , ! .
i i ! ! 3 . . . . . . . . . . . . . . . . . - . - --
L . . , . SCHEMATIC NO.1 SIS MECHANICAL INTERFACES HHSI AND LHSI PUMPS AND ASSOCIATED PIPING, TRAIN A COLD LEG INJECTION NORMAL LINEUP _______.x l I 3s n l b' - L2 -
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, 8 HMSI e ' , _ _ PUMPIA I .____ __ ________ e i , I 8 SI 6A I I I I I I I I I I ' I l kt2 8 . , r, SIISA Q l y RHR HEAT I , EXCHANGER I yl l i n
________-___________ __..___- _ _, , ___ _ ______ ___ ____ ___ L O St31A h ~_ _ _ % _ _ _ _ _ _8 o c RHR PUMP [3; PUMP 1A EMERGENCY SUMP A - - - - - _ >- FLOW PATH SSCOLD
' . M SCHEMATIC NO. 2 SIS MECHANICAL INTERFACES HHSI AND LHSI PUMPS AND ASSOCIATED PIPING, TRAIN A HOT LEG RECIRCULATION D 0 U D g-------r -
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a PUMP 1A I I L 2, 8 a ym' ' SI 6A , , , , I t I I i , 1 1 I 9____ , __g.__, I I p l St IM 8 RHR HEAT , , EXCHANGER l , l ' i i__. . _ _ _ ________________________________ _, g' . m, , 8 F7 , o 1- a O S131A i. .-. ________ _. g i e . 1 RHR PUMP [3: PUMP 1 A , EMERGENCY SUMP A . _____________________________________ ,___,_. i - - + FLOW PATH SIS-HOT
. - . NRC - HL&P ENFORCEMENT CONFERENCE . LOW HEAD COLD LEG INJECTION ISOLATION VALVE ISSUE ^~ (SI-MOV-31 A) Chronoloav 4 Unit 2 April 1989 Failure and Operability Determination (Apparent Violation No.1) ! 9 Apr 89 2119 Unit 2 SI-MOV-31 A closed remotely 9 Apr 89 2128 Secured RHR cool down . 9 Apr 89 2135 SI-MOV-31 A would not open remotely i ! 9 Apr 89 2240 Power removed from actuator and valve opened manually I 9 Apr 89 2248 Determination that valve was in required position for operability and Unit 2 enters Mode 3 l 5 Nov 89 Unit 2 enters Mode 5 for bottom mounted instrumentation outage
20 Nov 89 SI-MOV-31 A placed on Operability Tracking Log i- 21 Nov 89 Valve operator motor determined to be shorted 4 i 27 Nov 89 "A" train Si declared operable i
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- .- . -- _ . _ . ._. . . . . . , NRC - HL&P ENFORCEMENT CONFERENCE . LOW HEAD COLD LEG INJECTION ISOLATION VALVE ISSUE ' (SI-MOV-31 A)
Chronoloav (Cont'd) , . 13 Jan 90 Unit 2 enters Mode 3 after outage activities , 29 Sep 90 Unit 2 enters 2REO1 8 Nov 90 SI-MOV-31 A Valve operator motor repaired February 1993 Failure and Operability Determination , 9 Feb 93 2306 SI-MOV-31 A failed to open ! 9 Feb 93 2306 SI-MOV-31 A declared inoperable 11 Feb 931115 Review of prior history reveals motor failure in April 1989 ' SPR written on repeat failure of SI-MOV-31 A motor -
- l SPR written on April 1989 operability determination -
l 17 Feb 93 Reportability evaluation complete 18 Feb 93 Reported to NRC i l 19 Feb 93 SI-MOV-31 A valve operator motor repaired i 19 Mar 93 LER submitted to the NRC 6' , - . .
_ - - . NRC - HL&P ENFORCEMENT CONFERENCE - . LOW HEAD COLD LEG INJECTION ISOLATION VALVE ISSUE (SI-MOV-31 A)
Chronoloav (Cont'd) Previous SI-MOV-31 A Failures (Apparent Violation No. 2) Three occurrences prior to April 1989 failure - Unit 1 in January 1988 (prior to initial criticality) - Unit 2 in July 1988 (hot functional testing in progress) - Unit 2 in August 1988 (hot functional testing in progress) - ' No failures on Unit 2 from November 1990 until February 1993
Unit 1 operated SI-MOV-31 A sinco January 1988 without failure - Approximately 50 open and close cycles on Unit 1 - Approximately 30 open and close cycles on Unit 2 - ! i 6 - . -- . - . - - ..- . - .--. - ._ -
.. . . . - - . . . . . - . . _ . - ' ' ' NRC - HL&P ENFORCEMENT CONFERENCE . LOW HEAD COLD LEG INJECTION ISOLATION VALVE ISSUE - (SI-MOV-31 A) Causes April 1989 Operability Determination (Apparent Violation No.1) Misinterpretation of Technical Specification 3.5.2 requirements
Weak programmatic controls for operability determination - ! i February 1993 Failure
1993 failure is due to grease lock in spring pack (Picture No.1 )
l Previous SI-MOV-31 A Failures (Apparent Violation No. 2) ! Possible causes of four previous failures (valve to be disassembled in 2RE03) -
j thermal binding (Picture No. 2) - , I improper actuator set up -
wedging of the valve stem bearing block (Picture No. 3) . - excessive stroking over short period of time - grease lock in spring pack - , I
! 7 !
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. ' . PICTURE NO. 3 j
. EXPLODED VIEW FLEXIBLE WEDGE GATE VALVE u
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1. Body 13. Glan'd Follower 28. Packing Gland Nut 3. Disc 14. Yoke 29. Spherical Washer 4. Main Flange Gasket 17. Operator Cap Screw 31. Guide " 5. Bonnet 18. Leak-Off Pipe 32. Torque Arm 6. Stem 19. Main Flange Stud 33. Stem Pin 8. Primary Packing 20. Main Flange Nut 34. Disc Pin Ba. Secondary Packing 21. Link 35. Lock Pin 9. Lantern Ring 22. Pin 36. Bearing Block 10. Yoke-Bonnet Nut 23. Torque Key 37. Lock Pin 11. Yoke-Bonnet Stud 24. Torque Arm Set Screw 38. Lock Ring .12. ..Gla nd 27. Packing Gland S,tud - ,. _ . _ . _ _ _ . ~ . . , _ _ _ , - _ - . _ - - . . _ . _ . . _ _ _ _ . . . . _ _ _ - . . _ . . . . . _ . . _ . . . _ .
. . . NRC - HL&P ENFORCEMENT CONFERENCE . LOW HEAD COLD LEG INJECTION ISOLATION VALVE ISSUE (S!-MOV-31 A) initial Corrective Actions (Apparent Violation No. 2) - Initial corrective actions reasonable in light of information available in 1989
Occurred almost 4 years ago - More knowledge about MOVs available today than at time of prior failures a Knowledge used in failure analysis of February 1993 event - Knowledge available at time of prior failures - 8
. . , NRC - HL&P ENFORCEMENT CONFERENCE . LOW HEAD COLD LEG INJECTION ISOLATION VALVE ISSUE ~~ (SI-MOV-31 A) Safety Sianificance (Apparent Violation No.1) , Violation of Technical Specification is significant - Actual safety significance is minimal
' System has redundancy such that operation with one cold jeg injection isolation valve inoperable - and open, safety function is met including single failure consideration
(Schematic No. 3) . i e I i . . 4 9 . - - - - - - - - _ ~ .- - .
' . . SCHEMATIC NO. 3 REACTOR COOLANT SYSTEM HHSI RH tHSi HHSI RH Si m SI190 SI19C m I" M 1B [ Stsa l Si sc -u -vs B C , m m REACTOR REACTOR COOLANT COOLANT PUMP 1C PUMP 18 i i ' ' , , SI 68 31-31B REACTOR SI-31C "" I HHSI RHRtHS1 RHRtHSI HHSI RH tHS1 SI-31A REACTOR l SisA REACTOR COOLANT COOLANT PUMP 1A PUMP 10 > i = 1 _ l S1 R,tHSI A SI19A A SM) 1A Si BA ' n D ACC -vs /vs RCS . - - . - . - __
' ' ' NRC - HL&P ENFORCEMENT CONFERENCE
. LOW HEAD COLD LEG INJECTION ISOLATION VALVE ISSUE - (SI-MOV-31 A) , 1 . Safety Sionificance (Cont'd) (Apparent Violation No.1)
! Violation would not occur today - , February 1993 SI-MOV-31 A failure declared inoperable - 3 1 Programs / controls in place (Diagram Nos.1 & 2) - Station problem reporting process - . 4 !
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_ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ' . . , . . l .. l DIAGRAM NO.1 l OLD ' 1 OPERABILITY DETERMINATION PROCESS ON 4/9/89
1 STATION PROBLEM MAINTENANCE
REPORT IF REQUIRED WORK REQUEST SHIFT SUPERVISOR i ' l , I 4 t If , ENTERIN OTL STATION PROBLEM STATION PROBLEM ASSIGN PRIORITY IF REQUIRED j _ REPORT REVIEW - 1I REPORT WTTHOUT MAINTENANCE j. SHIFT SUPERVISOR SHIFT SUPERVISOR SHIFT SUPERVISOR WORK REQUEST i , t i ! If , j IF REQUIRED j JCO I { ENGINEERING s 4
) ! 4
' 1 corse 1 4 ! I ? . . . . . . . . . . . ~ . . . . - . - . . , _ _ _ _ _ . . . . . . . - _ - . . . , _ _ . . _ , . ._ . _ . . _ - . - . . - . - . . ,_ _ _ , _ _
_ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . . , , DIAGRAM NO. 2 '~ CURRENT OPERABILITY DETERMINATION PROCESS 3/93 SERVICE REQUEST gpmONMRSE Th d? INmATED ANYONE N ANYONO- ^ 1r if REVIEW OF STATION PROBLEM SERVICE REQUEST ORT INmAWD = r IF REQUIRED
sHrT StFEN9m M ONE If 'I DECLARE INOPERABLE OPERABILITY OPERABLE TECH CS
DECISION i s>in SUPENSOR SHFT 8tPEN90R sten SUPEN90R DOCUMENT RATKNUE FOR OPERMHUTY qp ON SENCE F1EQUEST p sten SUPENSOR ENTER IN 1f 1f 1I 3 OTL [[Wg{g' INOPERABLE DECLARE , sHWT SUPEN90R 3 cs OPERABLE 1P m ENtaMesme se sHFT sUPENeOR eten SUPEN90R ': REQUIRE 1 . CONDITIONAL..it! - - j e pgg pgg : ' - ' TE1G NEE 7qPs3 V 1f i JCO POSSIBLE neutvtoTose OPEevura TO SUPPORT ~ 2. auf spartemi , j OPERABILITY oence ct a squouwet ) oo EEn~o %y 4 ! , i . . . . . . .
_ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ - _ - _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _____ __-_ _ _ _ _ _ _ _ _ _ _ . . - ' ' NRC - HL&P ENFORCEMENT CONFERENCE ~ ' . LOW HEAD COLD LEG INJECTION ISOLATION VALVE ISSUE - (Sl-MOV-31 A) Corrective Actions Remedial Actions SI-MOV-31 A declared inoperable and repaired - SI-MOV-31 A changed from torqued closed to limit closed to prevent thermal binding or wedging of - the valve stem bearing block and eliminates motor control function of spring pack Spring pack cleaned and will be replaced in 2RE03 - A review was performed to verify that other torque closed valves have spring packs with grease - relief paths 11
_ - _ _ _ _ _-_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . ' ' NRC - HL&P ENFORCEMENT CONFERENCE . LOW HEAD COLD LEG INJECTION ISOLATION VALVE ISSUE (SI-MOV-31 A) Corrective Actions Actions to Address Potential Generic implications Review Operability Tracking Log and open service requests on Unit 1 prior to start up '
Event to be included in Licensed Operator re-qualification training (8/10/93)
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~ ' NRC - HL&P ENFORCEMENT CONFERENCE . LOW HEAD COLD LEG INJECTION ISOLATION VALVE ISSUE (SI-MOV-31 A) Enhancements to Address Potential Generic implications Identify enhancements for programmatic controls regarding operability determinations (3/30/93) - Formalize triage process to include a review of operability decisions - Identify additional tools for Conditional Release Authorizations to provide more guidance and - support { Identify additional tools for shift supervisor operability decisions - Identify any other reportable conditions related to past operability determinations (6/1/93) - ! Identify other key safety related equipment reliability trends (6/1/93) - Upgrade the program to analyze and effectively trend equipment history to identify repetitive - - component degradation and failures, and to take effective corrective action to prevent recurrence. (plan developed by 6/17/93 complete implementation by 3/31/94)
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._ . . _ - . _- . . . , NRC - HL&P ENFORCEMENT CONFERENCE . LOW HEAD COLD LEG INJECTION ISOLATION VALVE ISSUE (SI-MOV-31 A) Conclusions Technical Specification violation occurred
Operation with SI-MOV-31 A inoperable had minimal actual safety significance - Same valve failed but not appropriately cited as a corrective action violation
STP identified (not self-revealing) - Promptly reported - Prompt and comprehensive corrective actions
,
Event occurred almost 4 years ago - i Both apparent violations would not occur today - l
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__. . . . . . . , NRC - HL&P ENFORCEMENT CONFERENCE . RHR SYSTEM SUCTION ISOLATION VALVES -- ACTUATOR OVER TORQUE ISSUE Apparent Violation 3. Failure to perform a proper operability determination of five Residual Heat Removal Suction isolation Motor Operated Valves that were operated with torque loading in excess of the vendor rating. The
initial corrective action response to this appeared contrary to 10 CFR 50, Appendix B, Criterion XVI. The NRC considers the apparent violation to be similar to a previous violation which involved - excessive application of thrust in Motor Operated Valves. , i T i 4
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NRC - HL&P ENFORCEMENT CONFERENCE . RHR SYSTEM SUCTION ISOLATION VALVES - ACTUATOR OVER TORQUE ISSUE , Overview of the System Valve actuator operation (Picture No. 4)
4 Safety function of RHR valves (Schematic No. 4) - , consequences of failure to meet thrust requirements - i consequences of failure to meet torque requirements - differences between overthrust and overtorque - Limitorque SB-2 actuator
Limitorque rating for thrust - 70,000 lbs - . Limitorque rating for torque - 1250 ft Ibs -
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. . , . SCHEMATIC NO. 4 .. RESIDUAL HEAT REMOVAL SYSTEM MECHANICAL INTERFACES , TRAIN A i i RCS , HOT ' XRH4020A ~ ~ DO I e .p, p' . . . . FCV451 SI- 0019A di HHS! PUMP ! ! O >9 15xf RHR n' O RCS PUMP bU A l XRH4032A ,. .., COLD LEO . , g l I l . - t ...I HCV. St. RCS 864 0031A HOT 'M ' " W 8' 7 LEO NMP * * * ~ SRH- SRH- 0060A 0061A PUMP RHRS 4 . 4 i _ _ _ _ _ _ _ _ _ _ _ _ , _ _ - _ . . _ _ _ _ _ _ . _ _ . _ _ _ _ _ _ - _ _ _ _ . _ . _ . . _ _ _ _ . _ _ _ _ _ _ . . . _ . _ . . _ . . . . . . . . . . . . . . - - _
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NRC - HL&P ENFORCEMENT CONFERENCE . RHR SYSTEM SUCTION ISOLATION VALVES -. ACTUATOR OVER TORQUE ISSUE Chronoloav of Event (Apparent Violation No. 3) L 4 Dec 92 Decision to operate Motor Operated Valves based on thrust data , 2 Feb 93 Review of RHR test results revealed overtorqued condition 2 Feb 93 Operability evaluation completed 4 Feb 93 Unit shutdown for other reasons , 2 9 Feb 93 MOVATS testing commenced i 27 Feb 93 Replaced torque affected parts, restored margin ! ! Cause of Overtorque Condition -' , e Marginal stem factors on subject valve actuators '
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i i < 4 l l 17 ! !
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NRC - HL&P ENFORCEMENT CONFERENCE RHR SYSTEM SUCTION ISOLATION VALVES .. ACTUATOR OVER TORQUE ISSUE
l l l Basis for February 2.1993 Operability Determination i 1 Site specific data supported operability -
Successful operation of actuators in overtorqued condition since 1RE02 (Spring 1990) - ! Actuators disassembled and inspected during the last outage (Fall 1992)
MOVATS testing demonstrated acceptable thrust - ' Overtorque is a wear (cycle life) issue
Minimal number of cycles expected prior to next outage -
MOV would have performed intended safety function - ! The operability determination was proper -
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NRC - HL&P ENFORCEMENT CONFERENCE . RHR SYSTEM SUCTION ISOLATION VALVES - ACTUATOR OVER TORQUE ISSUE Safety Sionificance Motor Operated Valves had sufficient thrust to perform intended safety function -
Motor Operated Valves were operable and capable of performing their intended safety functions
test history - number of cycles expected until next testing interval - number of cycles on Motor Operated Valves
- inspection of components removed from the Motor Operated Valves revealed only wear from - operation due to overtorque Recent Kalsi high torque qualification evaluation - Actuator from Unit 1 was tested to 75 cycles and did not fail - .
75 cycles exceeds operating cycle requirements - l - examination of actuator used during the test revealed significant wear but no cracking 4 testing of actuator cenfirmed operability determination - , No other cases of torq ?e exceeding allowable when thrust is within specifications
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. . ' NRC - HL&P ENFORCEMENT CONFERENCE
RHR SYSTEM SUCTION ISOLATION VALVES -- ACTUATOR OVER TORQUE ISSUE Corrective Actions l Remedial Actions An independent review of MOVATS program was conducted by IMPELL, Kalsi and Sargent & Lundy - , Torque-bearing components have been replaced and the actuators re-tested satisfactorily on - Unit 1 Motor Operated Valves with overforque conditions outside industry guidance
A checl. list that identifies attributes key to evaluation of MOV operability has been developed and
will be used to guide further engineering evaluations Engineering review of MOVATS data will be completed prior to declaring valves operable in future .
} 1 l Actions to Address Potential Generic Implications ! ! Unit 1 test data has been reviewed to identify other cases of overtorque (complete) - l Unit 2 test data will be reviewed prior to start up (ongoing)
, ) Residual Heat Removal Suction isolation Valves will be retested in the nec refueling outage to - establish the long term maintenance of stem factor margin (planned) , , i if maintenance of stem factor proves to be an ongoing problem with these Motor Operated Valves,
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additional actions will be considered as appropriate (planned)
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NRC - HL&P ENFORCEMENT CONFERENCE . RHR SYSTEM SUCTION ISOLATION VALVES - ACTUATOR OVER TORQUE ISSUE , Conclusions Actuators exceeded vendor values for overtorque - Actuators met thrust requirements
, Actuators repeatedly tested and confirmed operable
Residual Heat Removal Suction isolation Valves functioned when called upon '
Actuators would have performed intended safety function
Operability determination supported by site data
i STP identified (not self-revealing)
, Comprehensive corrective actions
Operability determination was proper
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NRC - HL&P ENFORCEMENT CONFERENCE . RHR SYSTEM SUCTION ISOLATION VALVES - ACTUATOR OVER TORQUE ISSUE Additional Information Actions taken to assure long-term operability of RHR Suction Isolation Motor Operated Valves stem factors currently acceptable + current thrust and torque values are satisfactory - degradation not expected to exceed as found conditions - Kalsi testing confirmed operability of valves in as found conditions - Motor Operated Valves to be retested during next refueling outage to establish long-term stem factor
trends Maximum Expected Differential Pressure Safety Function of RHR Suction Valves - - maintain reactor coolant pressure boundary integrity during Mode 1,2 and 3 operations open to provide decay heat removal for normal shutdown, safety grade cold shutdown, small -
break LOCA may be closed by the plant operators to isolate a failure in the RHR System - i , 22
s ' NRC - HLGP ENFORCEMENT CONFERENCE . RHR SYSTEM SUCTION ISOLATION VALVES - ACTUATOR OVER TORQUE ISSUE Additional Information (Cont'd) Maximum expected differential pressure (MEDP)
opening MEDP has not changed - closing MEDP has been lowered from 700 psid to 450 psid - ,. Basis for original closing MEDP - - setpoint for Auto Closure Interlock was 700 psig j to achieve MEDP of 700 psid the following have to occur - line break in RHR ' - low pressure set point PORV fails or out of service - , inadvertent increase in RCS pressure - i $ i 1 l 23 i
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NRC - HL&P ENFORCEMENT CONFERENCE , . RHR SYSTEM SUCTION ISOLATION VALVES - ACTUATOR OVER TORQUE ISSUE Additional :nformation (Cont'd) Justification for revising closing MEDP - - Auto Closure Interlock function deleted Note: STP RHR system is entirely in the Containment Building Existing administrative controls limit RHR System pressure to 450 psig - ' This limit is established based on the setpoint of the RHR system relief valve pressure setpoint (600 psig) less the RHR pump head (100 psig) and 50 psig margin Based on Design Basis Small Break Analysis,line breaks sufficient to produce high MEDP on - these valves will depressurize the RCS to below 450 psig in about 20 seconds
Considering plant operator action time and valve closure time (80 seconds), it is not reasonable to expect the valves to experience MEDP greater than 450 psid 24 . . --- -- -- -. . -. . . . . . . - - . - }}