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Category:SAFETY EVALUATION REPORT--LICENSING & RELATED ISSUES
MONTHYEARML20217K9441999-10-15015 October 1999 SER Accepting Util Alternative Proposed Relief Request RR-ENG-2-4 for Second 10-year ISI Interval at Stp,Units 1 & 2 Pursuant to 10CFR50.55a(a)(3)(i) ML20217K9151999-10-15015 October 1999 SER Authorizing Util Relief Request RR-ENG-2-3 for Second 10-year ISI Interval of Stp,Units 1 & 2 Pursuant to 10CFR50.55a(a)(3)(i) ML20211P7811999-09-0909 September 1999 SER Approving Second 10-year Interval Inservice Insp Program Plan Relief Request RR-ENG-2-8 (to Use Code Case N-491-2) for South Texas Project,Units 1 & 2 ML20211Q6731999-09-0909 September 1999 Safety Evaluation Accepting First 10-yr Interval ISI Program Plan Request for Relief from ASME Code Case N-498 ML20211P8411999-09-0909 September 1999 Safety Evaluation Supporting Alternative Proposed by Licensee to Surface Exam to Perform Boroscopic VT-1 Visual Exam of Pump Casing Welds within Pump Pits for Welds Covered by Relief Request RR-ENG-24 ML20211F4531999-08-24024 August 1999 Safety Evaluation Supporting Licensee Proposed Alternative to Defer Partial First Period Exams of flange-to-shell Weld to Third Period & Perform Required Ultrasonic Exams,Both Manual & Automated,During Third Period ML20211F5111999-08-23023 August 1999 Safety Evaluation Supporting Licensee Proposed Alternative Contained in Request for Relief RR-ENG-30 ML20210D9161999-07-23023 July 1999 Safety Evaluation Accepting Inservice Testing Relief Request RR-56 Re Component Cooling Water & Safety Injection Sys Containment Isolation Check Valve Closure Test Frequency ML20207H6361999-07-0808 July 1999 Safety Evaluation Approving 2nd 10 Yr Interval ISI Program Plan Request to Use ASME Section XI Code Case N-546 for Licenses NPF-76 & NPF-80,respectively ML20195J6871999-06-17017 June 1999 Safety Evaluation Supporting Proposed Alternative Contained in RR-ENG-2-5.Proposed Alternative Authorized Per 10CFR50.55a(a)(3)(i) for 2nd ISI Interval ML20204B2711999-03-15015 March 1999 Safety Evaluation Authorizing 990201 Request to Authorize Alternative to Regulations Per 10CFR50.55a(a)(3)(i) That Would Revise Start of Second 120-month IST Interval to No Later than 011201 ML20203H8361999-02-17017 February 1999 Safety Evaluation Supporting Request for Relief from ASME Code Requirements for Class 3 Piping for Plant ML20202H9621999-02-0303 February 1999 SER Accepting Change to EALs Used in Classification of Emergency Conditions ML20199K7711999-01-21021 January 1999 Safety Evaluation Accepting ISI Program Request for Relief for ASME Cose Repair Requirements for Code Class 3 Piping ML20199G8161999-01-19019 January 1999 SER Accepting Util 970707 Response to NRC 970509 RAI Re GL 92-08, Thermo-Lag 330-1 Fire Barriers. NRC Finds No Significant Safety Hazards Based on Application of Util Ampacity Derating Methodology ML20198M3431998-12-28028 December 1998 SER Accepting Util Request for Relief from ASME Code Repair Requirements for ASME Code Class 3 Piping for South Texas Project,Unit 2 ML20198B4111998-12-15015 December 1998 Staff Evaluation Rept of Individual Plant Exam of External Events (IPEEE) Submittal on South Texas Project,Units 1 & 2 ML20198B3491998-12-15015 December 1998 Safety Evaluation Accepting Relief Request to Use ASME Section XI Code Cases 2142-1 & 2143-1 for Replacement SGs ML20195B9601998-11-0606 November 1998 Safety Evaluation Accepting Proposed long-term C/As for Assuring Operability of MSSVs ML20195C8581998-11-0505 November 1998 SER Accepting Order Approving Application Re Proposed Corporate Merger of Central & South West Corp & American Electric Power Co,Inc ML20154N3371998-10-15015 October 1998 Safety Evaluation Re Licensee Request for Deviation from Fire Protection Program Incorporating Requirements of Section III.G.2.c of 10CFR50,App R ML20237D5281998-08-21021 August 1998 Safety Evaluation Re Proposed Increase in Sf Pool Heat Loads for Plant ML20237D4931998-08-21021 August 1998 Safety Evaluation Approving Request to Use ASME Section XI Code Case N-498-1 at STP ML20249A1831998-06-11011 June 1998 SER Accepting Request for Temporary Relief from ASME Code, Section XI Requirements,To Repair Flaws in Essential Cooling Water Sys Piping ML20217Q6881998-05-0606 May 1998 Safety Evaluation Accepting Monitoring for Leakage in Normal & Alternate Charging & Auxiliary Spray Lines at STP ML20199D0251997-11-17017 November 1997 SER Accepting Relief Requests for Inservice Testing Program for Pumps & Valves ML20199B2751997-11-0606 November 1997 Safety Evaluation Accepting Methodology for Graded QA Initiative in Operations QA Description for Plant ML20149E0741997-07-14014 July 1997 Safety Evaluation of First ten-year Interval Inservice Insp Program Plan Request to Use ASME Section XI Code Case N-416-1,Houston Lighting & Power Co,South Texas Projects, Units 1 & 2 ML20141A8531997-05-12012 May 1997 Safety Evaluation Accepting Licensee Request to Use ASME Section XI Code Case N-546, Alternative Requirements for Qualification of VT-2 Exam Personnel,Section XI Div 1, for First 10-yr Interval Inservice Insp Program Plan ML20137U3811997-04-0808 April 1997 Safety Evaluation Approving Transfer of Operating Authority to New Operating Company ML20137E4861997-03-24024 March 1997 Safety Evaluation Accepting Revised Response to NRC Bulletion 88-08, Thermal Stresses in Piping Connected to Reactor Coolant Sys, for Plant,Units 1 & 2 ML20132B0561996-12-11011 December 1996 Safety Evaluation Accepting Licensee Structural Integrity & Operability Assessments ML20059B8281993-10-21021 October 1993 SER Granting Relief & Concluding That Code Required Exam Impractical to Perform to Extent Required by Code & That Limited Section XI Surface Exam Provide Results Which Demonstrated to Be Superior or Equivalent to Surface Exam ML20057A0161993-08-31031 August 1993 Safety Evaluation Concluding That Licensee Has Demonstrated That External Events Not Major Contributor to Core Damage Scenarios at Plant ML20056C3231993-05-10010 May 1993 Supplemental SE Accepting Util Responses Re Operator Response Times During Sgtr.Licensee Satisfied All Four Criteria Required to Complete NRC Review ML20127M7241993-01-19019 January 1993 SE Concluding That Relief Requests Submitted on 920507 Are Covered by Rulemaking on 920908,which Was Incorporated Into 10CFR50.55a(b) ML20059N7881990-09-24024 September 1990 Safety Evaluation Accepting Util First 10-yr Inservice Insp Plan ML20248E6151989-09-21021 September 1989 Safety Evaluation Re Deletion of Dynamic Rod Drop Test, Static Rod Cluster Control Assembly (Rcca) Drop & Rcca below-bank Position Measurement Tests.Deletion Acceptable ML20246L6511989-02-22022 February 1989 Sser Accepting Util Efforts Re Action Items 1.a & 1.b of NRC Bulletin 88-011,per NRC Findings of Westinghouse & Plant Audit ML20207M4061988-10-0505 October 1988 Safety Evaluation Granting Util 880308 & 26 Requests to Increase Spent Fuel Pool Capacity Through Use of High Density Storage Racks ML20195G5531988-06-24024 June 1988 Safety Evaluation Accepting Proposed Reracking of Util Spent Fuel Storage Pools from Criticality Standpoint.Enrichment of Fuel to 4.5 Weight % U-235 May Be in Conflict W/ 10CFR51 Table S4 & Should Be Investigated by NRC ML20149M6941988-02-23023 February 1988 Safety Evaluation Supporting Proposals Re Personnel Air Lock Seal Air Sys Isolation ML20207K1081986-12-31031 December 1986 Safety Evaluation Re Cumulative Usage Factor Criterion for Pipe Break Postulation.Proposal Not to Postulate Pipe Breaks for SI Injection Lines & Pressurizer Surge Line Approved, Pending Resolution of Confirmatory Item Re Vibratory Stress ML20154M2201986-03-0707 March 1986 SER Supporting Licensee Mods,Per Generic Ltr 83-28,Item 4.3, Reactor Trip Breaker Automatic Shunt Trip ML20138N8121985-10-30030 October 1985 SER Supporting Util 850717 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 ML20134L5551985-07-31031 July 1985 Draft Safety Evaluation Re Elimination of Arbitrary Intermediate Pipe Breaks ML20137G8061985-07-31031 July 1985 Safety Evaluation Supporting Util Proposal for Elimination of Arbitrary Intermediate Pipe Breaks in High Energy Piping Sys from Design Considerations in SRP Section 3.6.2 ML20140B7991977-06-0606 June 1977 Safety Evaluation Supporting Subcompartment Pressure Analysis & Proposed Valve Room Design,Per Low Stress Superpipe Requirements of Branch Technical Position Meb 3-1 Re Protection Against Main Steam or Feedwater Line Breaks 1999-09-09
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARML20217K9441999-10-15015 October 1999 SER Accepting Util Alternative Proposed Relief Request RR-ENG-2-4 for Second 10-year ISI Interval at Stp,Units 1 & 2 Pursuant to 10CFR50.55a(a)(3)(i) ML20217K9151999-10-15015 October 1999 SER Authorizing Util Relief Request RR-ENG-2-3 for Second 10-year ISI Interval of Stp,Units 1 & 2 Pursuant to 10CFR50.55a(a)(3)(i) NOC-AE-000676, Monthly Operating Repts for Sept 1999 for South Texas Project,Units 1 & 2.With1999-09-30030 September 1999 Monthly Operating Repts for Sept 1999 for South Texas Project,Units 1 & 2.With ML20217D0531999-09-30030 September 1999 Rev 1 to STP Electric Generating Station Unit 2 Cycle 7 Colr ML20217D0481999-09-30030 September 1999 Rev 1 to STP Electric Generating Station Unit 1 Cycle 9 Colr ML20211P8411999-09-0909 September 1999 Safety Evaluation Supporting Alternative Proposed by Licensee to Surface Exam to Perform Boroscopic VT-1 Visual Exam of Pump Casing Welds within Pump Pits for Welds Covered by Relief Request RR-ENG-24 ML20211P7811999-09-0909 September 1999 SER Approving Second 10-year Interval Inservice Insp Program Plan Relief Request RR-ENG-2-8 (to Use Code Case N-491-2) for South Texas Project,Units 1 & 2 ML20211Q6731999-09-0909 September 1999 Safety Evaluation Accepting First 10-yr Interval ISI Program Plan Request for Relief from ASME Code Case N-498 NOC-AE-000643, Monthly Operating Repts for Aug 1999 for South Texas Project,Units 1 & 2.With1999-08-31031 August 1999 Monthly Operating Repts for Aug 1999 for South Texas Project,Units 1 & 2.With ML20212E5191999-08-31031 August 1999 Rev 3 to SG-99-04-005, STP 1RE08 Outage Condition Monitoring Rept & Final Operational Assessment ML20211F4531999-08-24024 August 1999 Safety Evaluation Supporting Licensee Proposed Alternative to Defer Partial First Period Exams of flange-to-shell Weld to Third Period & Perform Required Ultrasonic Exams,Both Manual & Automated,During Third Period ML20211F5111999-08-23023 August 1999 Safety Evaluation Supporting Licensee Proposed Alternative Contained in Request for Relief RR-ENG-30 ML20210C9411999-07-31031 July 1999 Rev 1 to SG-99-07-002, South Tx,Unit 1 Cycle 9 Voltage- Based Repair Criteria 90-Day Rept, Jul 1999 ML20210R3631999-07-31031 July 1999 Monthly Operating Repts for July 1999 for South Tx Project, Units 1 & 2.With ML20210D9161999-07-23023 July 1999 Safety Evaluation Accepting Inservice Testing Relief Request RR-56 Re Component Cooling Water & Safety Injection Sys Containment Isolation Check Valve Closure Test Frequency ML20210D4821999-07-21021 July 1999 1RE08 ISI Summary Rept for Steam Generator Tubing of South Texas Project Electric Generating Station Unit 1 ML20210D4491999-07-21021 July 1999 Revised Chapters to Operations QA Plan, Including Rev 9 to Chapter 1.0, Organization & Rev 6 to Chapter 16.0, Independent Technical Review NOC-AE-000583, LER 99-S03-00:on 990619,failure to Revitalize Sdg Number 11 Was Noted.Caused by Failure to Communicate Status of Sdg. Subject Sdg Revitalized on 990619 & Licensee Will Develop Security Force Instruction Re Sdgs.With1999-07-15015 July 1999 LER 99-S03-00:on 990619,failure to Revitalize Sdg Number 11 Was Noted.Caused by Failure to Communicate Status of Sdg. Subject Sdg Revitalized on 990619 & Licensee Will Develop Security Force Instruction Re Sdgs.With ML20207H6361999-07-0808 July 1999 Safety Evaluation Approving 2nd 10 Yr Interval ISI Program Plan Request to Use ASME Section XI Code Case N-546 for Licenses NPF-76 & NPF-80,respectively ML20216D7481999-07-0707 July 1999 1RE08 ISI Summary Rept for Welds & Component Supports of STP Electric Generating Station,Unit 1 NOC-AE-000593, Monthly Operating Repts for June 1999 for Stp,Units 1 & 2. with1999-06-30030 June 1999 Monthly Operating Repts for June 1999 for Stp,Units 1 & 2. with NOC-AE-000570, LER 99-S01-00:on 990527,discovered That Unescorted Access Had Been Inappropriately Granted.Caused by Failure to Follow Procedure.Util Verified That Individual Did Not Have Current Unescorted Access at STP or Any Other Util.With1999-06-28028 June 1999 LER 99-S01-00:on 990527,discovered That Unescorted Access Had Been Inappropriately Granted.Caused by Failure to Follow Procedure.Util Verified That Individual Did Not Have Current Unescorted Access at STP or Any Other Util.With ML20196G5821999-06-23023 June 1999 LER 99-S02-00:on 990601,failure to Maintain Positive Control of Vital Area Security Key Was Noted.Caused by Lack of Attention to Detail.Discussed Event with Operator Involved IAW Constructive Discipline Program ML20195J6871999-06-17017 June 1999 Safety Evaluation Supporting Proposed Alternative Contained in RR-ENG-2-5.Proposed Alternative Authorized Per 10CFR50.55a(a)(3)(i) for 2nd ISI Interval ML20196A2391999-06-15015 June 1999 Change QA-042 to Rev 13 of Operations QAP, Reflecting Current Organizational Alignment for South Texas Project & Culminating Organizational Realigment That Has Been Taking Place During Past Several Months NOC-AE-000563, Monthly Operating Repts for May 1999 for Stp,Units 1 & 2. with1999-05-31031 May 1999 Monthly Operating Repts for May 1999 for Stp,Units 1 & 2. with ML20206U5411999-05-18018 May 1999 Non-proprietary Errata Pages for Rev 2,Addendum 1 to WCAP-13699, Laser Welded Sleeves for 3/4 Inch Diamete Tube Feedring Type & W Preheater SGs Generic Sleeving Rept ML20206A7721999-04-30030 April 1999 STP Electric Generating Station Unit 1 Cycle 9 Colr NOC-AE-000543, Monthly Operating Repts for Apr 1999 for Stp,Units 1 & 2. with1999-04-30030 April 1999 Monthly Operating Repts for Apr 1999 for Stp,Units 1 & 2. with ML20205H0321999-03-31031 March 1999 Change QA-040 to Rev 13 of Operations QA Plan NOC-AE-000507, Monthly Operating Repts for Mar 1999 for Stp,Units 1 & 2. with1999-03-31031 March 1999 Monthly Operating Repts for Mar 1999 for Stp,Units 1 & 2. with ML20205A3781999-03-22022 March 1999 STP Electric Generating Station Simulator Certification Four Yr Rept for Units 1 & 2 ML20204B2711999-03-15015 March 1999 Safety Evaluation Authorizing 990201 Request to Authorize Alternative to Regulations Per 10CFR50.55a(a)(3)(i) That Would Revise Start of Second 120-month IST Interval to No Later than 011201 ML20207M9231999-03-12012 March 1999 Amended Part 21 Rept Re Cooper-Bessemer Ksv EDG Power Piston Failure.Total of 198 or More Pistons Have Been Measured at Seven Different Sites.All Potentially Defective Pistons Have Been Removed from Svc Based on Encl Results NOC-AE-000468, Monthly Operating Repts for Feb 1999 for South Texas Project Electric Generating Station.With1999-02-28028 February 1999 Monthly Operating Repts for Feb 1999 for South Texas Project Electric Generating Station.With ML20207D1101999-02-24024 February 1999 Change QA-039 to Rev 13 of Operations QA Plan, for STP ML20203H8361999-02-17017 February 1999 Safety Evaluation Supporting Request for Relief from ASME Code Requirements for Class 3 Piping for Plant ML20202H9621999-02-0303 February 1999 SER Accepting Change to EALs Used in Classification of Emergency Conditions ML20202E8471999-01-31031 January 1999 2RE06 ISI Summary Rept for SG Tubing of STP Electric Generating Station,Unit 2 ML20216G2011999-01-31031 January 1999 City Public Svc of San Antonio Annual Rept 1998-1999 ML20199G5961999-01-31031 January 1999 Cycle 7 Voltage-Based Repair Criteria Rept for Jan 1999 ML20199K7711999-01-21021 January 1999 Safety Evaluation Accepting ISI Program Request for Relief for ASME Cose Repair Requirements for Code Class 3 Piping ML20199G8161999-01-19019 January 1999 SER Accepting Util 970707 Response to NRC 970509 RAI Re GL 92-08, Thermo-Lag 330-1 Fire Barriers. NRC Finds No Significant Safety Hazards Based on Application of Util Ampacity Derating Methodology ML20199H4981999-01-11011 January 1999 2RE06 ISI Summary Rept for Welds & Component Supports of Stp,Unit 2 ML20206Q3751999-01-0404 January 1999 2RE06 ISI Summary Rept for Sys Pressure Tests (Class 1 & 2) ML20206Q3721999-01-0404 January 1999 2RE06 ISI Summary Rept for Repairs & Replacements ML20216G2171998-12-31031 December 1998 Houston Industries 1998 Annual Rept. App a 1998 Financial Statements & Us Securities & Exchange Commission Form 10-K Encl NOC-AE-000403, Monthly Operating Repts for Dec 1998 for South Texas Project Unit 1 & 2.With1998-12-31031 December 1998 Monthly Operating Repts for Dec 1998 for South Texas Project Unit 1 & 2.With ML20216G1521998-12-31031 December 1998 Central & South West Corp 1998 Summary Annual Rept & Securities & Exchange Commission Form 10-K ML20198M3431998-12-28028 December 1998 SER Accepting Util Request for Relief from ASME Code Repair Requirements for ASME Code Class 3 Piping for South Texas Project,Unit 2 1999-09-09
[Table view] |
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- AR Ry UNITED STATES l
s* j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. - aaai
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l l SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO THE INSERVICE INSPECTION PROGRAM
- REQUEST FOR RELIEF FROM ASME CODE REPAIR REQUIREMENTS FOR ASME CODE CLASS 3 PIPING
! HOUSTON LIGHTING & POWER COMPANY 1
! CITY PUBLIC SERVICE BOARD OF SAN ANTONIO i
f CENTRAL POWER AND LIGHT COMPANY i
CITY OF AUSTIN. TEXA1 SOUTH TEXAS PROJECT UNITS I AND 2 DOCKET NOS. 50-498 AND 50-499
1.0 INTRODUCTION
10 CFR 50.55a(g) requires nuclear power facility piping and components to meet the applicable requirements of Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (hereafter referred as the Code).Section XI of the Code specifies Code-acceptable repair methods for flaws that exceed Code acceptance limits in piping that is in-service. A Code repair is required to restore the structural integrity of flawed Code piping,-independent of the operational mode of the plant when the flaw is detected. Those repairs not in compliance with Section XI of the Code are non-Code repairs. However, the implementation of required Code (weld) repairs to ASME Code Class 1, 2 or 3 systems is often impractical for nuclear licensees since the repairs normally require an isolation of the system requiring the repair, and often a shutdewn of the nuclear power plant.
Technical Specification (TS) 4.0.5 says, in part, that inservice inspection of ASME Code Class 1, 2 and 3 components shall be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel Code and applicable Addenda as required by 10 CFR Part 50, Section 50.55a(g), except where specific written relief has been granted by the Commission pursuant to 10 CFR Part 50, Section 50.55a(g)(6)(1).
9612170014 961211 PDR ADOCK 05000498 P PDR
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- 1 i l l Alternatives-to Code requirements may be used by nuclear licensees when i authorized by the Commission if the proposed alternatives to the requirements i are such that they are shown to provide an acceptable level of quality and safety in lieu of the Code requirements (10 CFR 50.55a(a)(3)(i)], or if j compliance with the Code requirements would result in hardship or unusual
! difficulty without a compensating increase in the level of quality and safety l [10 CFR 50.55a(a)(3)(ii)].
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- A licensee may also submit requests for relief from certain Code requirements l when a licensee has determined that conformance with certain Code requirements i is impractical for its facility [10 CFR 50.55a(g)(5)(iii)]. Pursuant to 10 CFR 50.55a(g)(6)(i), the Commission may grant such relief and may impose
- such alternative requirements as it determines is authorized by law and will not endanger life or property or the common defense and security and is otherwise in the public interest giving due consideration to the burden upon i the licensee that could result if the requirements were imposed on the
! facility.
{ Generic Letter (GL) 90-05, entitled " Guidance for Performing Temporary Non-Code Repair of ASME Code Class 1, 2 and 3 Piping," and dated June 15, 1990, provides guidance for the staff in evaluating relief requests submitted by
, licensees for temporary non-Code repairs of Code Class 3 piping. For the j purpose of this generic letter, impracticality is defined to exist if the flaw
- detected during plant operation is in a section of Class 3 piping that cannot be isolated for completing a code repair within the time period permitted by
, the limiting condition for operation of the affected system as specified in i the plant TSs, and performance of code repair necessitates a plant shutdown.
2.0 BACKGROUND
During routine system inspections, members of the Houston Lighting & Power Company's South Texas Project (the licensee) staff discovered flaws in the 1 Essential Cooling Water System (ECWS) at the South Texas Project. The ECWS is
- a low pressure system with normal operating pressures of approximately 50 psig and the design pressure is 120 psig. The flaws are located in Unit 1 on 8
! inch line EW-1186-WT3 and in Unit 2 on 8 inch line EW-2186-WT3. In both cases
- the flaws are located immediately above the weld joint in the cast material.
i Another flaw was found in Unit 2 on 6 inch line EW-2221-WT3 at field weld EW2221 FW0004. In all cases the flawed pipe material was identified to be cast aluminum-bronze (ASME SB 271 CA 952 material for the 8 inch cast flanges and ASME SB 148 CA 952 material for the 6 inch cast tee). The cast materials i were welded with filler metal SFA 5.7 CuAl-A2 weld material. By letter dated
- May 31, 1996, the licensee requested relief from the ASME Code,Section XI
{ repair or replacement requirements under the provisions of 10 CFR 50.55a(g).
! The licensee based its request for relief on the results of a flaw evaluation that was performed by the licensee in accordance with the guidelines and
! acceptance criteria contained in GL 90-05.
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3.0 LICENSEE'S RELIEF REQUEST 3.1 Components for Which Relief is Reauested ASME Code Class 3 essential cooling water system piping (two eight inch cast I pipe flanges and one six inch cast pipe tee). l 3.2 Section XI Edition for South Texas Proiect. Units 1 and 2 l 1983 Edition including Summer 1983 Addenda of the ASME Code,Section XI.
3.3 ASME Section XI Code Reauirement The ASME Code Section XI requires that repairs or replacements of ASME Code Class components be performed in accordance with rules found in Articles IWA-4000 or IWA-7000, respectively. The intent of these rules serve to provide an acceptable means of restoring the structural integrity of a degraded Code Class system back to the original design requirements.
3.4 Content of the Relief Reauest Relief is sought from performing a repair or replacement of two eight inch cast pipe flanges (Unit 1 ECW line 8"-EW-1186-WT3 and Unit 2 ECW line 8"-EW- '
2185-WT3) and one six inch cast pipe tee (Unit 2 ECW line 6"-EW-2221-WT3) per the requirements of Article IWA-4000 or IWA-7000, respectively. Relief is being sought until the next South Texas, Units 1 and 2, scheduled outage for the affected unit. At that time, the licensee will perform a Code repair to return the system to compliance with the Code.
3.5 Basis for Relief Request for relief has been submitted under the impracticality provisions of 10 CFR 50.55a(g). The licensee stated that performance of a Code repair during power operations within the time permitted by the TS limiting condition for operation may not be practical due to potential for fit-up problems during repair, potential need for access to the inside surface, and extended time required for draining.
The licensee has analyzed the effect of through-wall flaws in ECWS piping and found that the pipe degradation is slow and, therefore, rapid or catastrophic failure is not a consideration. Further, the licensee has also determined that the leakage can be detected before flaw reaches a limiting size that would affect the operability of the ECWS (currently there is no measurable leakage). Also because there is no measurable leak there is no adverse effect on any safety-related equipment in the surrounding area.
3.6 Licensee's Alternative Proaram
- 1. Visual inspection of the affected areas to detect possible leakage will be performed weekly. Operators will be able to identify any significant leakage during normal rounds.
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- 2. The integrity of the piping will be assessed every month until a 1 permanent repair can be completed. Radiographs or ultrasonic
. examination will be performed of the degraded areas every month to i assess the piping.
- 3. Performance of an engineering evaluation of the structural integrity of I the system based on the results of the visual, radiographic and/or !
ultrasonic examinations. I
- 4. Continuation of the ECWS monthly walkdowns. This walkdown is a I j regularly scheduled VT-2 examination of the ECWS and includes all cast
! components.
- 5. - Performing a Code repair during the next refueling outage for the
! affected unit.
4.0 STAFF EVALUATION AND CONCLUSIONS i
j 4.1 Operability Determination. Root Cause Analysis and Structural Intearity Evaluation
- The licensee determined that the flaws were located in the ECWS which is
- classified as ASME Code Class 3 system. The flaws are located in Unit 1 on 8 j inch line EW-1186-WT3 and in Unit 2 on 8 inch line EW-2186-WT3 and 6 inch line
! EW-2221-WT3. In all cases the flawed pipe material was identified to be cast l aluminum-bronze which is inherently ductile material (ASME SB 271 CA 952
- material for the 8 inch cast flanges and ASME SB 148 CA 952 material for the 6 1 inch cast tee). Upon discovery of the flaws, the licensee performed an
. evaluation of the flaws using the guidance provided in GL 90-05 and found that l the flaws satisfy the through-wall criteria prescribed in GL 90-05 and that j the flaws meet the criteria for a non-Code repair. The licensee determined d that the operability of the system will not be impaired because currently there is no measurable leak. Also because currently there is no measurable leak there will be no adverse effect on any other safety-related equipment in the surrounding area.
The licensee performed a root cause analysis of the flaw, and determined that the degradation resulted from dealloying. The licensee believes that a preexisting flaw was present to enable initiation of the dealloying process.
The dealloying process normally initiates from a crevice such as a backing ring, a fabrication-induced flaw, or a casting flaw. A dealloying area may include cracks as those identified on the 8 inch flanges. Failure analysis indicates that the crack propagation occurred by a process of dealloying along the crack. front. Previous examples of such cracks were found to have initiated from pre-existing flaws exposed to the ECWS cooling water. The problem of dealloying of castings has been also described in previous comunications with the NRC. The flaws were inspected using visual and radiographic examinations to assess overall degradation of the affected castings. The examination of the flaw areas indicated that the flaw in Unit 1, 8 inch cast flange measured 4-1/16 inches and the flaw in Unit 2, 1
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i i 8 inch flange measured 3-1/16 inches. The radiographic examination of the l Unit 2, 6 inch tee to flange joint found no linear indications. An evaluation
- of the ultrasonic and radiographic examination results and calculation of
- ' structural integrity confirmed that the flawed piping satisfies the "through-wall flaw" approach described in NRC GL 90-05.
l 4.2 Auamented Insnection
- The flaws are located in two 8 inch pipe flanges and one 6 inch pipe tee weld l Joint. The flaw areas were visually and radiographically examined to assess i the flaws. No further areas of degradation were observed and the flaws were i determined to be localized and caused by dealloying. Previous cases of
- dealloying has been described in previous communications with the NRC staff.
The ECWS will be visually inspected monthly for leaks or indications of
- dealloying including all castings.
4.3 Proposed Temoorary Noncode Repair and Monitorina Provisions l
l At this time, the licensee is monitoring the flawed areas every week. If measurable leak is identified quantitative assessment of the leak will be j . performed. The licensee has committed to perform ultrasonic or radiographic j examination of the flawed area every month to assess the castings wall
- degradation rate. Based on the results of the examinations, an engineering evaluation will be performed to determine if further remedial measures or j
corrective actions are needed until Code repair is completed.
! 4.4 Staff Conclusions
! The staff has determined that the licensee's flaw evaluation has been
! consistent with the guidelines and acceptance criteria of GL 90-05. The
, staff, therefore, finds the licensees' structural integrity and operability
, assessments to be acceptable. The licensee has established a periodic inspection program to monitor flaw growth and ensure continued operability.
The licensee ic also monitoring the condition of the flaws by visual i inspection every week to ascertain that no measurable leak exist of the flawed j areas. If measurable leak is identified quantitative assessment of the leak i will be performed. The licensees actions constitute an ccceptable temporary alternative to the Code requirements.
Furthermore, the staff finds that performance of an immediste Code repair is impractical since it would require an isolation of the affected ECWS piping and a plant shutdown, since performance of a Code repair would take longer than allowed by the limiting condition for operation. This meets the GL 90-05 definition of impracticality. Such an isolation is not in the best interest of plant safety, given the magnitude of the flaw and the licensee's alternative program. The staff, therefore, concludes that the licensee's proposed alternative is authorized by law and will not endanger life or property or the common defense and security and is otherwise in the public
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j interest giving due consideration to the burden upon the licensee that could i
result if the Code requirements were imposed on the facility. Pursuant to 10 CFR 50.55a(g)(6)(1) the alternative is imposed until the next scheduled j outage exceeding 30 days, but no later than the next refueling outage, for the
- affected unit. At that time a Code repair will be performed.
Principal Contributor: G. Georgiev, NRR Date: December 11, 1996 i
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