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Category:SAFETY EVALUATION REPORT--LICENSING & RELATED ISSUES
MONTHYEARML20211A9791999-08-20020 August 1999 Safety Evaluation Granting Licensee Request for Approval of Proposed Relief from Volumetric Exam Requirements of ASME B&PV Code,Section Xi,For Plant,Unit 2 ML20209E4361999-07-0909 July 1999 SER Agreeing with Licensee General Interpretation of TS LCO 3.0.6,but Finds No Technical Basis or Guidance That Snubbers Could Be Treated as Exception to General Interpretation ML20196K6631999-07-0707 July 1999 Safety Evaluation Supporting Licensee 990520 Position Re Inoperable Snubbers ML20206P5201999-05-14014 May 1999 Safety Evaluation Accepting GL 96-05, Periodic Verification of Design-Basis Capability of Safety-Related Motor-Operated Valves ML20205S5551999-04-21021 April 1999 Safety Evaluation Accepting Response to GL 96-06, Assurance of Equipment Operability & Containment Integrity During Design Basis Accident Conditions ML20205N3651999-04-12012 April 1999 Safety Evaluation Accepting IPE of External Events Submittal ML20196J8351998-12-0808 December 1998 Safety Evaluation Granting Relief Request Re Relief Valves in Diesel Generator Fuel Oil Sys ML20196C0251998-11-27027 November 1998 SER Accepting Clarification on Calibration Tolerances on Trip Setpoints for Catawba Nuclear Station ML20196A6881998-11-25025 November 1998 Safety Evaluation Granting Relief Request 98-02 Re Limited Exam for Three Welds ML20247M0861998-05-21021 May 1998 SER Accepting 1997 Rev to Catawba UFSAR Submitted on 970925. Rev Added Analysis for Postulated Accident Involving Dropping of Sf Pool Weir Gate Onto Sf Assemblies ML20216E1771998-04-13013 April 1998 Safety Evaluation Accepting Relief Request 98-01 for Catawba Nuclear Station Units 1 & 2 from Requirements of ASME Boiler & PV Code for Second 10-year Interval Program for Inservice Testing of Pumps & Valves ML20217M4211998-04-0303 April 1998 Safety Evaluation Approving Request for Relief 97-04, non-code Repair Valves.Relief Granted Retroactively to Unit 1 & Expired Dec 1997.Relief for Unit 2 Will Expire at End of Cycle 9 Outage or Next Scheduled Outage Exceeding 30 Days ML20199A5521998-01-22022 January 1998 Safety Evaluation Re Licensee Response to GL 95-07, Pressure Locking & Thermal Binding of Safety-Related Power Operated Gate Valves, for Cns,Units 1 & 2 ML20199A6421998-01-22022 January 1998 Safety Evaluation Accepting Proposed EALs Changes for Plant, Units 1 & 2.Concludes That Changes Consistent W/Guidance in NUMARC/NESP-007,w/variations as Identified & Accepted in Review & Meets Requirements of 10CFR50.47(b)(4) ML20198P9641998-01-15015 January 1998 SE Granting Relief Request 97-03 for Second 10-yr Interval Inservice Insp Program ML20198R9951997-10-30030 October 1997 Safety Evaluation Authorizing Request for Approval of Alternative to Exam Requirement of Reactor Vessel Shell Weld,Per 10CFR50.55a(g)(6)(ii)(A)(5) ML20198J7651997-10-15015 October 1997 Safety Evaluation Accepting 10-yr Interval Insp Program Plan Alternatives for Listed Plants Units ML20211F8801997-09-22022 September 1997 Safety Evaluation Supporting Second ten-year Interval Inservice Inspection Program Plan & Associated Requests for Relief for Catawba Nuclear Station Unit 1 ML20149K8281997-07-29029 July 1997 SER Granting Request for Exemption from Requirements of 10CFR70.24 for Units 1 & 2 ML20141E1121997-06-16016 June 1997 Safety Evaluation Approving Licensee Position That UFSAR Table 6-77 Be Revised to Identify SA-1 & SA-4 Instead of SA-3 & SA-6 as Containment Isolation Valves ML20148H2501997-06-0505 June 1997 Safety Evaluation Accepting Proposed Restructuring of Util Through Acquisition Of,& Merger W/Panenergy Corp ML20141G6701997-05-20020 May 1997 Safety Evaluation Accepting Proposed Alternative Use of TS Requirement for Code Class Snubbers ML20135B3051997-02-27027 February 1997 Safety Evaluation Granting Second 10 Yr ISI Program Plan & Associated Requests for Relief ML20134P2421997-02-20020 February 1997 Safety Evaluation Accepting TR BAW-10199P for Ref in Plants Licensing Documentation & Use in Licensing Applications ML20134L4081996-11-19019 November 1996 SER Accepting Performance of Plant Standby Nuclear Svc Water Pond ML20134G5551996-11-0707 November 1996 Safety Evaluation Accepting Proposed Application of BWU-Z CHF Correlation for Plants Mark-BW 17x17 Type Fuel ML20129E4851996-10-0101 October 1996 Safety Evaluation Recommending That Relief Request 96-02 Be Granted,Per 10CFR50.55a(g)(6)(i),per Request ML20056D9611993-07-30030 July 1993 SER Accepting Licensee 930325-0429 Submittals of Technical Info to Support Continued Operation of Facility for Remainder of Fuel Cycle 7 ML20055H9151990-07-27027 July 1990 Safety Evaluation Accepting Actions Taken to Resolve NRC Bulletin 88-002, Rapidly Propagating Fatigue Cracks in Steam Generators Tubes ML20248C0731989-08-0303 August 1989 Sser Accepting 880601,0909 & 890602 Changes to ATWS Mitigation Sys Actuation Circuitry for Plants ML20246L4221989-05-12012 May 1989 Safety Evaluation Supporting Revs 15 & 6 to Pump & Valve Inservice Testing Program & Relief Requests ML20150C2651988-06-28028 June 1988 Safety Evaluation Supporting Licensee Assessment to Fracture Toughness Requirements for Protection Against PTS Events,Per 10CFR50.61 ML20150C2611988-06-28028 June 1988 Safety Evaluation Supporting Licensee Assessment to Fracture Toughness Requirements for Protection Against PTS Events,Per 10CFR50.61 ML20154H2171988-05-18018 May 1988 Safety Evaluation Accepting Util 880414 Submittal Re Reload Startup Physics Test Program ML20148H1001988-01-22022 January 1988 Safety Evaluation Supporting Util 871113 Proposed Tech Spec Changes Reflecting Unit 2 Cycle 2 Refueling & Addition of Boron Dilution Mitigation Sys for Unit 2 ML20236M9631987-11-0606 November 1987 Safety Evaluation Accepting Util Proposed ATWS Mitigating Sys Actuation Circuitry for Facilities,Per 10CFR50.62(c)(1) & Pending Final Resolution of Tech Spec Issue ML20236D4451987-09-30030 September 1987 SER Re Licensee 870814 & 21 Responses Re Single Failure Potential in Nuclear Svc Water Sys.Nuclear Svc Water Sys Meets Requirements of GDC 5 & 44 Re Sharing & Provisions for Suitable Redundancy in Cooling Water Sys ML20236F5881987-07-29029 July 1987 Safety Evaluation Supporting Util 831104,841102,1231 & 851203 Responses to Items 3.1.1,3.1.2,3.2.1,3.2.2 & 4.5.1 of Generic Ltr 83-28 ML20215D2701987-06-11011 June 1987 SER Accepting Rev 13 to Unit 1 & Rev 4 to Unit 2 Pump & Valve Inservice Testing,Per Generic Ltr 83-28,Item 2.1 (Part 2) ML20214T4061987-06-0202 June 1987 Safety Evaluation Supporting Util 860424 Submittal Re Turbine Sys Maint Program for Early Detection of Cracking in Low Pressure Turbine Wheels ML20214M3361987-05-22022 May 1987 Safety Evaluation Supporting Util Rept Entitled, Rod Swap Methodology Rept for Startup Physics Testing ML20209B1511987-01-28028 January 1987 SER Supporting Util Responses to Generic Ltr 83-28,Item 4.5.2 Re Reactor Trip Sys on-line Testing ML20207Q5851987-01-15015 January 1987 SER Re Generic Ltr 83-28,Item 2.1 (Part 2) Concerning Vendor Interface Programs for Reactor Trip Sys Components.Util Response Acceptable.Item Closed ML20207N3011987-01-0808 January 1987 Safety Evaluation on Util 830309 & 851025 Requests for Relief from 10CFR50.55a Requirements Re Pump & Valve Inservice Testing Program.Relief Granted W/Listed Exceptions ML20207P6341986-08-31031 August 1986 Safety Evaluation Accepting Util 851120 & 860324 Proposals to Eliminate Arbitrary Intermediate Pipe Breaks in Select List of High Energy Piping Sys ML20199L3941986-07-0202 July 1986 SER Providing Final Conclusions & Recommendations from Evaluation of Tdi Owners Group Program to Validate & Update Quality of Tdi Diesel Generators ML20211E4251986-06-10010 June 1986 Draft SER Re Util 850624 Response to Generic Ltr 83-28,Items 4.1,4.2.1 & 4.2.2 Re Preventive Maint Program for Reactor Trip Breakers/Maint & Trending.Position on Item 4.1 Acceptable.Position on Items 4.2.1 & 4.2.2 Unacceptable ML20207T4241985-12-30030 December 1985 SER Re SPDS Based on Documentation & 850513-15 Audit.Spds Does Not Fully Meet Requirements of Suppl 1 to NUREG-0737. Five Listed Variables Should Be Added to Spds.Interim Implementation Acceptable ML20138M9011985-12-17017 December 1985 Draft SER on Util 850329 Response to 841003 Request for Addl Info Re Hydrogen Control Measures for Plant.Addl Info & Analyses Required Re Effect of Upper Compartment Burns on Air Return Fan ML20128F9921985-06-21021 June 1985 SER Based on Util 831104 Response to Generic Ltr 83-28,Item 1.1 Re post-trip Review Program Description & Procedures. Program & Procedures Acceptable 1999-08-20
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARML20217H0201999-09-30030 September 1999 Monthly Operating Repts for Sept 1999 for Catawba Nuclear Station,Units 1 & 2 ML20216E5401999-09-0707 September 1999 Special Rept:On 990826,discovered That Meteorological Sys Upper Wind Speed Cup Set Broken,Causing Upper Wind Channel to Be Inoperable.Cup Set Replaced & Channel Restored to Operable Status on 990826 ML20212B4711999-08-31031 August 1999 Monthly Operating Repts for Aug 1999 for Catawba Nuclear Station,Units 1 & 2 ML20217H0321999-08-31031 August 1999 Revised Monthly Operating Rept for Aug 1999 for Catawba Nuclear Station,Units 1 & 2 ML20211B1281999-08-31031 August 1999 Dynamic Rod Worth Measurement Using Casmo/Simulate ML20211A9791999-08-20020 August 1999 Safety Evaluation Granting Licensee Request for Approval of Proposed Relief from Volumetric Exam Requirements of ASME B&PV Code,Section Xi,For Plant,Unit 2 ML20211F3441999-08-17017 August 1999 Updated non-proprietary Page 2-4 of TR DPC-NE-2009 ML20211C1291999-08-17017 August 1999 ISI Rept Unit 1 Catawba 1999 RFO 11 ML20210R1051999-08-0606 August 1999 Special Rept:On 990628,cathodic Protection Sys Was Declared Inoperable After Sys Did Not Pass Acceptance Criteria of Bimonthly Surveillance.Work Request 98085802 Was Initiated & Connections on Well Anode Were Cleaned or Replaced ML20210S2891999-07-31031 July 1999 Monthly Operating Repts for July 1999 for Catawba Nuclear Station,Units 1 & 2 ML20212B4871999-07-31031 July 1999 Revised Monthly Operating Rept for July 1999 for Catawba Nuclear Station,Units 1 & 2 ML20209E4361999-07-0909 July 1999 SER Agreeing with Licensee General Interpretation of TS LCO 3.0.6,but Finds No Technical Basis or Guidance That Snubbers Could Be Treated as Exception to General Interpretation ML20196K6631999-07-0707 July 1999 Safety Evaluation Supporting Licensee 990520 Position Re Inoperable Snubbers ML20210S2951999-06-30030 June 1999 Revised Monthly Operating Rept for June 1999 for Catawba Nuclear Station,Units 1 & 2 ML20209H4501999-06-30030 June 1999 Monthly Operating Repts for June 1999 for Catawba Nuclear Station,Units 1 & 2 ML20209H4561999-05-31031 May 1999 Revised Monthly Operating Rept for May 1999 for Catawba Nuclear Station,Units 1 & 2 ML20206T4771999-05-31031 May 1999 Rev 3 to UFSAR Chapter 15 Sys Transient Analysis Methodology ML20196L1881999-05-31031 May 1999 Non-proprietary Rev 1 to DPC-NE-3004, Mass & Energy Release & Containment Response Methodology ML20196A0001999-05-31031 May 1999 Monthly Operating Repts for May 1999 for Catawba Nuclear Station,Units 1 & 2 ML20206P5201999-05-14014 May 1999 Safety Evaluation Accepting GL 96-05, Periodic Verification of Design-Basis Capability of Safety-Related Motor-Operated Valves ML20206N8391999-05-0404 May 1999 Rev 16 to CNEI-0400-24, Catawba Unit 1 Cycle 12 Colr ML20206R1811999-04-30030 April 1999 Monthly Operating Repts for Apr 1999 for Catawba Nuclear Station,Units 1 & 2 ML20196A0041999-04-30030 April 1999 Revised Monthly Operating Repts for Apr 1999 for Catawba Nuclear Station,Units 1 & 2 ML20206N8261999-04-22022 April 1999 Rev 15 to CNEI-0400-24, Catawba Unit 1 Cycle 12 Colr. Page 145 of 270 of Incoming Submittal Not Included ML20205S5551999-04-21021 April 1999 Safety Evaluation Accepting Response to GL 96-06, Assurance of Equipment Operability & Containment Integrity During Design Basis Accident Conditions ML20205N3651999-04-12012 April 1999 Safety Evaluation Accepting IPE of External Events Submittal ML18016A9011999-04-12012 April 1999 Part 21 Rept Re Defect in Component of DSRV-16-4,Enterprise DG Sys.Caused by Potential Problem with Connecting Rod Assemblies Built Since 1986,that Have Been Converted to Use Prestressed Fasteners.Affected Rods Should Be Inspected ML20206R1931999-03-31031 March 1999 Revised Monthly Operating Repts for Apr 1999 for Catawba Nuclear Station,Units 1 & 2 ML20205P9521999-03-31031 March 1999 Monthly Operating Repts for Mar 1999 for Catawba Nuclear Station,Units 1 & 2 ML20205P9561999-02-28028 February 1999 Revised Monthly Operating Repts for Feb 1999 for Catawba Nuclear Station,Units 1 & 2 ML20204C9111999-02-28028 February 1999 Monthly Operating Repts for Feb 1999 for Catawba Nuclear Station,Units 1 & 2 ML20203A2581999-02-0505 February 1999 Safety Evaluation of TR DPC-NE-3002-A,Rev 2, UFSAR Chapter 15 Sys Transient Analysis Methodology. Rept Acceptable. Staff Requests Duke Energy Corp to Publish Accepted Version of TR within 3 Months of Receipt of SE ML20204C9161999-01-31031 January 1999 Revised Monthly Operating Repts for Jan 1999 for Catawba Nuclear Station,Units 1 & 2 ML20199K8711999-01-13013 January 1999 Inservice Insp Rept for Unit 2 Catawba 1998 Refueling Outage 9 ML20199E3071998-12-31031 December 1998 Monthly Operating Repts for Dec 1998 for Catawba Nuclear Station,Units 1 & 2 ML20216F9931998-12-31031 December 1998 Piedmont Municipal Power Agency 1998 Annual Rept ML20205E9441998-12-31031 December 1998 1998 10CFR50.59 Rept for Catawba Nuclear Station,Units 1 & 2, Containing Brief Description of Changes,Tests & Experiments,Including Summary of Ses.With ML20206P2081998-12-31031 December 1998 Special Rept:On 981218,inoperability of Meteorological Monitoring Instrumentation Channels,Was Observed.Caused by Data Logger Overloading Circuit.Replaced & Repaired Temp Signal Processor ML20203A4101998-12-22022 December 1998 Rev 16 to CNEI-0400-25, Catawba Unit 2 Cycle 10 Colr ML20203A4041998-12-22022 December 1998 Rev 14 to CNEI-0400-24, Catawba Unit 1 Cycle 11 Colr ML20198B1341998-12-14014 December 1998 Revised Special Rept:On 980505,discovered That Certain Fire Barriers Appeared to Be Degraded.Caused by Removal of Firestop Damming Boards.Hourly Fire Watches Established in Affected Areas ML20196J8351998-12-0808 December 1998 Safety Evaluation Granting Relief Request Re Relief Valves in Diesel Generator Fuel Oil Sys ML20199E3221998-11-30030 November 1998 Revised MOR for Nov 1998 for Catawba Nuclear Station,Units 1 & 2 Re Personnel Exposure ML20198E3151998-11-30030 November 1998 Monthly Operating Repts for Nov 1998 for Catawba Nuclear Station,Units 1 & 2 ML20196C0251998-11-27027 November 1998 SER Accepting Clarification on Calibration Tolerances on Trip Setpoints for Catawba Nuclear Station ML20196A6881998-11-25025 November 1998 Safety Evaluation Granting Relief Request 98-02 Re Limited Exam for Three Welds ML20196D4041998-11-19019 November 1998 Rev 1 to Special Rept:On 980618,determined That Method Used to Calibrate Wind Speed Instrumentation Loops of Meteorological Monitoring Instrumentation Sys Does Not Meet TS Definition for Channel Calibration.Procedure Revised ML20195E5521998-10-31031 October 1998 Monthly Operating Repts for Oct 1998 for Catawba Nuclear Station,Units 1 & 2 ML20198E3261998-10-31031 October 1998 Revised Monthly Operating Repts for Oct 1998 for Catawba Nuclear Station,Units 1 & 2 ML20154M7661998-10-12012 October 1998 LER 98-S01-00:on 980913,terminated Vendor Employee Entered Protected Area.Caused by Computer Interface Malfunction. Security Retained Vendor Employee Badge to Prevent Further Access & Computer Malfunction Was Repaired.With 1999-09-07
[Table view] |
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p eut y* t UNITED STATES g ,j
't NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 3066H001
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RESPONSE TO GENERIC LETTER 95-07. " PRESSURE LOCKING AND THERMAL BINDING OF SAFETY-RELATED POWER-OPERATED GATE VALVES" CATAWBA NUCLEAR STATION. UNITS 1 AND 2 DOCKET NOS. 50413 AND 414
1.0 INTRODUCTION
Pressure locking and thermal binding represent potential common cause failure mechanisms, which can render redundant safety systems incapable of performing their safety functions. The identification of susceptible valves and the determination of when the phenomena might occur require a thorough knowledge of components, systems, and plant operationt. Presture locking occurs in flexible-wedge and double-disk gate valves when fluid becomes pressurized inside the valve bonnet and the actuator is not capable of overcoming the additional thrust requirements resulting froin the differential pressure created across both valve disks by the pressurized tiuid in the valve borinet. Thermal binding is generally associated with a wedge gate valve that is closed while the system is hot and then is allowed to cool before an attempt is made to open the valve.
Pressure locking or thermal binding occurs as a result of the valve design characteristics (wedge and valve body configuration, flexibility, and material thermal coefficients) when the valve is subjected to specific pressures and temperatures during various modes of plant operation. Operating experience indicates that these situations were not always considered as part of the design basis for valves in many plants.
2.0 REGULATORY REQUIREMENTS Part 50 of Title 10 of the Code of Federal Reaulations (10 CFR) (Appendix A, General Design Criteria 1 and 4) and plant licensing safety analyses require and/or commit that licensees design and test safety-related components and systems to provide adequate assurance that those systems can perform their safety functions. Other individual criteria in Appendix A to 10 CFR Part 50 apply to sp3cific systems. In accordance with those regulations and licensing commitments, and under the additional provisions of 10 CFR Part 50 (Appendix B, Criterion XVI), licensees are expected to take actions to ensure that safety-related power-operated gate valves susceptible to pressure locking or thermal binding are capable of performing their required safety functions. l On August 17,1995, the NRC issued Generic Letter (GL) 95-07, " Pressure Locking and Thermal Binding of Safety-Related Power-Operated Gate Valves," requesting licensees to take certain actions to ensure that safety-related power-operated gate velves that are susceptible to pressure locking or thermal binding are capable of performing their safety functions within the l
9901200019 900122 PDR ADOCK 05000413 p PDH _
l 1
g current licensing basis of the facility, GL 95-07 requested that each licensee, within 180 days of 3 the date of issuance, (1) evaluate the operational configurations of safety-related power-l operated gate valves in its plant to identify valves that are susceptible to pressure locking or _
thermal binding, and (2) perform further analyses, and take needed corrective actions (or justify longer schedules), to ensure that the susceptible valves identified in item (1) are capable of performing their intended safety functions under all modes of plant oporation, including test configuration. In addition, GL 95-07 requested that licensees, within 180 days of the date of j
4 issuance, provide to the NRC a summary description of (a) the susceptibility evaluation used to
- determine that valves are or are not susceptible to pressure locking or thermal binding, (b) the ,
c results of the susceptibility evaluation, including a listing of the susceptible valves ider,tified, and 4
(c) the corrective actions, or other dispositioning, for the valves identified as susceptible to r pressure locking or thermal binding. The NRC issued GL 95-07 as a " compliance backfit" p pursuant to 10 CW 50.109(a)(4)(i) because modification may be necessary to bring facilities
- L into compliance with the rules referenced above.
. By letter dated February 13,1996, Duke Energy Corporation (Duke Energy or DEC) (previously
- Duke Power Company) submitted its 180-day response to GL 95-07 for Catawba Nuclear
. Station -The NRC staff reviewed the licensee's February 13,1996, submittal, and requested
' additional information in letters dated July 1,1996, and February 19,1997. By letters dated July 31,1996, and April 4,1997, DEC provided additiona! information in response to the staff's request. The staff has reviewed DEC submittals of February 13 and July 31,1996, and April 4, 1997, as discussed in this safety evaluation.
e 3.0 EVALUATION 3,1 : - Scope of Licensee's Review GL 95-07 requested that licensees evalusts the operational configurations of safety-related L'
power-operated gate valves in their plants to identify valves that are susceptible to pressure ,
lockin0 or thermal binding. DEC letters dated February 13 and July 31,1996, and April 4,1997, 4
described the scope of valves evaluated in response to GL 95-07. The staff has reviewed the scope of DEC susceptibility evaluation performed in response to GL 95-07 and found it to be j_ . complete and acceptable.
- Duke Energy did not include the residual heat removal pump suction valves,1,2 ND1B, 2A,
- '36B,' 37A, and 1,2 FWO27A,055B in the scope of GL 95-07 because these valves are used
. during plant conditions below hot standby, Section 5.4.7.2.6 of the Final Safety Analysis Report 4 - states that the safe shutdown design basis for Catawba is hot standby. Duke Energy did not include the residual heat removal pump hot leg injection valves,1,2 ND032A, 0658, and 1,2 N11838, in the scope of GL 95-07 because ths Final Safety Analysis Report Chapter 15
^
accident analysis credits the safety lnjection pumps for providing hot leg injection. The criteria for determining the scope of power-operated valves for GL 95-07 are consistent with the staff's
. accep'ance of the scope of motor-operated valves associated with GL 89-10, " Safety-Re!sted Motor-Operated Valve Testing and Surveillance."
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l 4
3- !
- 3.2 Corrective Actions 4
- , GL 95-07 requested that each iicenses, within 180 days, perform fudher analyses as
_ appropriate, and take appropriate corrective actions (or justify longer schedules), to ensure that '
the susceptible valves identified are capable of performing their intended safety function under ,
i all modes of plant operation, including test configuration. Duke Energy's submittals of '
February 13 and July 31,1996, and April 4,1997, discuss DEC proposed corrective actions to l address potential pressure locking and thermal binding problems. The submittels stated that no -
s valves were identified as susceptible to thermally induced pressure locking. The staff's '
p evaluation of DEC actions is discussed in the following paragraphs.
4
- a. Duke Energy stated that the following vailves were evaluated for pressure locking and l modified to eliminate the potential for pressure locking:
l 1,2 CA038A,042B,046B,050A,0548,058A,062A,0668, Aux!!!ary Feedwater Pump Discharge to Steam Generators
- 1,2 NC031B, 033A, 0358, Pressurizer Power Operated Relief Valve Block
' 2 N11848,185A, Containment Recirculation Sump to Nuclear Decay 1,2 SA002,005, Main Steam to Turbine Driven Auxiliary Feedwater Pump n .
- The staff finds that physical modification to valves susceptible to pressure locking is an appropriate corrective action to ensure operability of the valves and is thus acceptable,
- b. Duke Energy stated that the following valves will be modified to eliminate the potential for pressure locking during the Unit i refueling outages, cycles 9,10,11, and 12, scheduled for i
mid-1996, fall 1997, spring 1999 and fall 2vJO, and the Unit 2 refueling outages, cycles 9 and i 10, scheduled for fall 1998, and spring 2000:
1,2 ND02c Low Head injection Pump to Charging System
- 1,2 NID09A,0108, High Head injection Pump to Cold Leg l .
1,2 N1121 A,152B, Medium Hearl injection Pump to Hot Leg 1,2 N11368, Low Head injection Pump to Charging System 1 N11848,185A, Containment Recirculation Sump to Nuclear Dec.ay
~
1,2 NS001B,018A, Containment Spray Pump Sump Suction 1,2 NS038B, 043A, Low Head injection to Auxiliary Spray 1,2 NV252A,2538, Charging Pump Suction
>- - Until these valves are modified, a pressure locking prediction methodology developed by the Commonwealth Edison Company (Comed) was used to demonstrate operability for valves 1,2
- ND028A; 1,2 N1136B; 1,2 N1009A, 010B; 1,2 N1121 A,~ _152B; 1,2 NS001B, 018A; 1,2 NS0588,
'043A; and 1,2 NV252A,2538.4 Pockets of air in the bonnets 'were used to demonstrate
' operability for valves 1 N11848,'185A. The staff finds that the Comed pressure !ocking o
i-
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. . . i 4
4 i
prediction methodology and reliance on air in the bonnets of the valves provide reasonablel assurance of operability of the valves until the planned modifications to prevent pressure locking are completed as scheduled. Duke Energy's commitment to modify these valves in the
. long term is an scooptable finc! resolution.
With certain conditions, the staff finds that the Comed methodology provides a technically .
sound basis for assuring that valves susceptible to pressure locking are capable of performing - !
their intended safety related function. On April 9,19g7, a public meeting was conducted to __
discuss the Comed pressure locking thrust prediction methodology presented in GL 95-07 submittels. The minutes of the public meeting were issued on April 25,19g7. During the public meeting, Comed recommended that, when using the Comed pressure lockbg prediction _ 4 methodology, minimum margins should be applied between calculated pressure locking thrust and actuator capability. For those valves identified in this safety evaluation that use the Comed pressure locking prediction methodology, licensees should ensure that the margin between calculated pressure locking thrust and actuator capability meets or exceeds these minimum requirements. At the meeting, Comed indicated that its methodology is undergoing review and may be revised or enhanced. Licensees are responsible for ensuring that the thrust values
- - calculated to overcome pressure locking for these valves remain valid following implementation l
of any revisions or enhancements to the Comed pressure locking prediction methodology. The ,
staff's review of the Comed methodology is ongoing and a safety evaluation for the methodology will be issued in the future.
- c. Duke Energy stated that procedures were modified to cycle the following valves following evolutions that could potentially create a pressure locking condition:
1,2 NS0128,0158, Containment Spray Pump Discharge to Header B 1,2 NS029A,032A, Containment Spray Pump Discharge to Header A The staff finds that DEC's procedural changes to require cycling the valves provide assurance that pressure locking conditions are adequately identified and eliminated, and are thus acceptable.'
d, Duke Energy stated that all flexible and solid wedge gate valves in the scope of GL 95-07 were evaluated for thermal binding. When evaluating whether valves were susceptible to thermal binding, DEC assumed that thermal binding would not occur below specific temperature
. thresholds. There assumptions were based on industry experience. Gate valves in systems
' with a normal operating temperature less than 200*F were not considered by DEC to be susceptible to thermal binding. Further, flexible wedge gate valves that are shut and i
- experience a cooldown differential temperatures of less than 100'F and solid wedge gate
! valves that are shut end experience a cooldown differential temperature of less than SG'F prior L > to opening were not considered by DEC to be susceptible to thermal binding. The screening cnteria used by DEC appear to provide a reasonable approach to identify those valvet, that might be susceptible to thermal binding. Until more definitive industry criteria are developed, the staff concludes that DEC's actions to address thermal binding of gate valves are scooptable.-
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4.0 CONCLUSION
l Based on the preceding evaluation, the staff finds that DEC has performed appropriate evaluations of the operational configurations of safety-related power-operated gate valves to ident4y valves tnat are susceptible to pressure locking or thermal binding for Catawba Nuclear !
Station, Units 1 and 2. In addition, the staff finds that DEC has taken, or is scheduled to take, appi:priate corrective actions to ensure that these valves are capable of performing their intended safety functions. Therefore, the staff concludes that DEC has adequately addressed the requested actions discussed in GL 95-07.
Principal Contributor: Stephen G. Tingen Dated: January 22, 1998
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