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Category:SAFETY EVALUATION REPORT--LICENSING & RELATED ISSUES
MONTHYEARML20212C2921999-09-16016 September 1999 SER Accepting Licensee Request for Relief from ASME Code Section XI Requirements as Endorsed by 10CFR50.55a for Containment Insp for Pilgrim Nuclear Power Station ML20209C4731999-07-0707 July 1999 Addendum to SE on Proposed Transfer of Operating License & Matls License from Boston Edison Co to Entergy Nuclear Generation Co ML20196H2451999-06-29029 June 1999 SER Denying Licensee Proposed Alternative in Relief Request PRR-13,rev 2.Staff Determined That Proposed Alternative Provides Insufficient Info to Determine Adequacy of Scope of Implementation ML20209A8901999-06-28028 June 1999 SER Accepting Licensee Proposed Alternative to Use Code Case N-573 for Remainder of 10-year Interval Pursuant to 10CFR50.55a(a)(3)(i) ML20195K3431999-06-15015 June 1999 Safety Evaluation Granting Licensee Request to Use Guidance of GL 90-05 to Repair Flaws in ASME Class 3 Salt Svc Water System Piping for Plant ML20207E7471999-05-27027 May 1999 Safety Evaluation Granting Request Re Reduction of IGSCC Insp of Category D Welds Due to Implementation of HWC to License DPR-35 ML20206M1971999-05-11011 May 1999 SER Accepting Request for Approval to Repair Flaws in ASME Code Class 3 Salt Svc Water Piping at Plant ML20153D3901998-09-22022 September 1998 Safety Evaluation Granting 970707 Request to Use Guidance in GL 90-05 to Repair Flaws in ASME Class 3 Salt Svc Water Sys Piping for Pilgrim Nuclear Power Station ML20237E2251998-08-26026 August 1998 Suppl & Revs to SE for Amend 173 for Pigrim Nuclear Power Station ML20216J3741998-03-19019 March 1998 Safety Evaluation Accepting Licensee Request to Evaluate Elevated Tailpipe Temp on Safety Relief Valve SRV 203-3B ML20217D6431997-10-0101 October 1997 Safety Evaluation Granting Request for Approval to Repair Flaws in Accordance W/Gl 90-05 for ASME Class 3 SSW Piping for Pilgrim ML20137D0511997-03-20020 March 1997 Safety Evaluation Approving Third 10 Yr Interval ISI Program & Requests for Relief ML20134K2621997-02-10010 February 1997 Safety Evaluation Accepting Licensee one-time Request to Defer Insp of N2A & N2B safe-end Welds,Per GL 88-01 ML20129H3901996-10-30030 October 1996 Safety Evaluation Re Facility IPE Submittal for Internal Events & Internal Flood ML20129F4031996-09-27027 September 1996 Safety Evaluation Accepting Second ten-year Interval Inservice Insp Program Plan Request for Relief ML20059C3751993-12-29029 December 1993 Safety Evaluation Granting Exemption & Approving Alternative DAC Values for Use in Place of Generic Value for Radionuclides Specified in App B to 10CFR20.1001 - 20.2402 ML20058G2781993-11-29029 November 1993 Safety Evaluation Granting IST Program Relief Per 10CFR50.55a(f)(6)(i) & Approving Alternatives Per 10CFR50.55a(f)(4)(iv) ML20056F5301993-08-11011 August 1993 Safety Evaluation Re Licensee Response to Reg Guide 1.97, BWR Neutron Flux Monitoring. Criteria of NEDO-31558, Acceptable for Current BWR Operating License & Const Permit Holders ML20127P5431993-01-25025 January 1993 Safety Evaluation Supporting Amend 145 to License DPR-35 ML20126F8121992-12-23023 December 1992 Safety Evaluation Accepting Facility Design W/Respect to RG 1.97 ML20244C2901989-06-0606 June 1989 Draft Safety Evaluation of Util Compliance W/Atws Rule (10CFR50.62) Re Alternate Rod Injection & Recirculation Pump Trip Sys.Alternate Rod Injection Sys Not in Compliance W/Atws Rule Re Diversity ML20235V7341989-03-0303 March 1989 Safety Evaluation Accepting Util Revised Temp Profile,Per GE EAS-98-0887, Drywell Temp Analysis for Pilgrim Nuclear Power Station ML20154P6611988-09-28028 September 1988 SER Approving Rev 3 to Plant Second 10-yr Inservice Insp Program,Per 10CFR50.55a(g)(4) ML20151D0551988-07-18018 July 1988 Safety Evaluation Supporting Licensee Response to Generic Ltr 83-28,Item 2.2.1 Re Equipment Classification Programs for All safety-related Components ML20151E2041988-07-15015 July 1988 Safety Evaluation Supporting Incorporation of Reactor Protection Sys Circuitry Into Tech Specs & Deletion of 6- Month Channel Functional Test ML20154J9101988-05-17017 May 1988 Safety Evaluation Accepting Util Technical Evaluations & Acceptance Criteria Re Fire door-to-frame,frame-to-wall & Anchor Bolt Irregularities ML20155F8871988-03-24024 March 1988 Safety Evaluation Concluding That Internal Smoke Seals for Conduits Passing Through Fire Barriers from One Fire Area to Another Consistent W/Branch Technical Position 9.5-1 & Acceptable,Per Util 880203 Submittal ML20236Y3991987-11-10010 November 1987 SER Accepting Util Responses to Generic Ltr 83-28,Item 2.1, Part 1 Re Equipment Classification.Salp Input Encl ML20236V3081987-10-28028 October 1987 Safety Evaluation Supporting Acceptance of Offsite Dose Calculation Manual Updated Through Rev 1 on Interim Basis. App D to Technical Evaluation Rept EGG-PHY-7725 Encl ML20235M1611987-09-30030 September 1987 Safety Evaluation Supporting Util 870708 Proposed Change to Tech Specs Concerning LPCI Subsystem Testing ML20236Y3591987-07-22022 July 1987 Safety Evaluation Accepting Licensee Request to Modify Standby Liquid Control Sys Tech Specs,Per Requirements of ATWS rule,10CFR50.62.C.4.SALP Input Also Encl ML20206G8141987-03-26026 March 1987 Safety Evaluation Re Util Requests for Relief from Inservice Insp Requirements for Surface & Volumetric Exam of RHR Sys HX Nozzles & Exam of 100% Required Vol for nozzle-to-vessel Welds.Requests Granted W/Listed Conditions ML20215H9581987-03-17017 March 1987 Safety Evaluation Supporting Tech Spec Change Re Control Room High Efficiency Air Filter Sys.Salp Input Encl ML20212L8941987-01-15015 January 1987 Safety Evaluation Supporting Vacuum Breaker Analysis Performed to Predict Impact Velocities & Resulting Stresses ML20236Y3501986-09-0303 September 1986 Safety Evaluation Accepting Licensee 850813 Response Re Generic Ltr 83-28,Item 1.1 on post-trip Review.Salp Input Encl ML20212N8401986-08-22022 August 1986 SER Supporting Util Response to Item 1.C of NRC Re No Specific Time Limit Necessary on Containment Purging & Venting During Reactor Operation ML20155F8931986-08-20020 August 1986 Safety Evaluation Accepting Util 831116 Request for Four Exemptions from 10CFR50,App R,Section Iii.G.Level of Fire Safety in Listed Fire Zones Equivalent to Safety Achieved by Compliance W/Requirements ML20206L9511986-08-12012 August 1986 Safety Evaluation on Util Response to Generic Ltr 83-28, Items 3.1.1,3.1.2,.3.2.1,3.2.2 & 4.5.1 Re Maint & Test Procedures for safety-related Equipment & on-line Functional Testing of Reactor Trip Sys.Responses Acceptable ML20205C0621986-07-31031 July 1986 Safety Evaluation Accepting Util 831107 Response to Generic Ltr 83-28,Item 2.1, Post-Trip Review. BWR Parameter List Encl ML20236Y3361986-07-10010 July 1986 Safety Evaluation Supporting Util 831107 Response to Generic Ltr 83-28,Item 1.2 on post-trip Review & Data & Info Capability ML20199L2541986-07-0101 July 1986 Safety Evaluation Supporting Amend 96 to License DPR-35 ML20206D1741986-06-0606 June 1986 Safety Evaluation Supporting Util Response to IE Bulletin 80-11 Re Reevaluation & Testing Requirements in Items 2(b) & 3 Concerning Masonry Wall Design ML20203N3801986-04-30030 April 1986 Safety Evaluation Supporting Util 840625,1204,06,850521 & 1011 Responses to Generic Ltr 86-04 Concerning Recombiner Capability Requirements of 10CFR50.44(c)(3)(ii).Facility Does Not Require Recombiner Capability ML20236Y3711986-04-0101 April 1986 Safety Evaluation Accepting Util Response to Generic Ltr 83-28,Items 3.1.3 & 3.2.3 Re post-maint Testing of Reactor Trip Sys & All Other safety-related Components,Respectively. SALP Input Also Encl ML20137V7621986-02-12012 February 1986 SER Supporting Partial Relief from Generic Ltr 84-11 Re Performance of Visual Exam of Reactor Coolant Piping ML20135E5211985-09-11011 September 1985 Safety Evaluation Supporting post-trip Review Program & Procedures ML20134H3571985-08-13013 August 1985 Safety Evaluation Granting 821203,0804,831201,840628 & 850212 Relief Requests from ASME Code Requirements of Inservice Insp Program,Except for Items B9.10-B9.40 & C5.10-C5.32 Re Pressure Retaining Welds ML20140G1431985-07-0505 July 1985 Interim Safety Evaluation Supporting Util Response to Generic Ltr 83-36 Re NUREG-0737 Tech Specs ML20129C6901985-05-16016 May 1985 Safety Evaluation Re Dcrdr.Supplemental Rept Addressing Concerns Identified Necessary to Meet Requirements of NUREG-0737,Suppl 1 ML20206K6161985-03-13013 March 1985 SER Supporting Proposed Tech Spec Change to Permit Temporary Increase in Main Steam Line High Radiation Scram & Isolation Setpoints to Facilitate Testing of Hydrogen Addition Water Chemistry.Related Documentation Encl 1999-09-16
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARML20217E3021999-09-30030 September 1999 Monthly Operating Rept for Sept 1999 for Pilgrim Nuclear Station.With ML20212C2921999-09-16016 September 1999 SER Accepting Licensee Request for Relief from ASME Code Section XI Requirements as Endorsed by 10CFR50.55a for Containment Insp for Pilgrim Nuclear Power Station ML20216F3511999-09-0808 September 1999 ISI Summary Rept for Refuel Outage 12 at Pnps ML20216E6881999-08-31031 August 1999 Monthly Operating Rept for Aug 1999 for Pilgrim Nuclear Power Station.With ML20210R3401999-07-31031 July 1999 Monthly Operating Rept for July 1999 for Pilgrim Nuclear Power Station.With ML20209C4731999-07-0707 July 1999 Addendum to SE on Proposed Transfer of Operating License & Matls License from Boston Edison Co to Entergy Nuclear Generation Co ML20209H8251999-07-0101 July 1999 Provides Commission with Evaluation of & Recommendations for Improvement in Processes Used in Staff Review & Approval of Applications for Transfer of Operating Licenses of TMI-1 & Pilgrim Station ML20209E6191999-06-30030 June 1999 Monthly Operating Rept for June 1999 for Pilgrim Nuclear Power Station.With ML20196H2451999-06-29029 June 1999 SER Denying Licensee Proposed Alternative in Relief Request PRR-13,rev 2.Staff Determined That Proposed Alternative Provides Insufficient Info to Determine Adequacy of Scope of Implementation ML20209A8901999-06-28028 June 1999 SER Accepting Licensee Proposed Alternative to Use Code Case N-573 for Remainder of 10-year Interval Pursuant to 10CFR50.55a(a)(3)(i) ML20209B9861999-06-23023 June 1999 Rev 13A to Pilgrim Nuclear Power Station COLR for Cycle 13 ML20217N9061999-06-21021 June 1999 Rept of Changes,Tests & Experiments for Period of 970422-990621 ML20195K3431999-06-15015 June 1999 Safety Evaluation Granting Licensee Request to Use Guidance of GL 90-05 to Repair Flaws in ASME Class 3 Salt Svc Water System Piping for Plant ML20195G8231999-05-31031 May 1999 Monthly Operating Rept for May 1999 for Pnps.With ML20207E7471999-05-27027 May 1999 Safety Evaluation Granting Request Re Reduction of IGSCC Insp of Category D Welds Due to Implementation of HWC to License DPR-35 ML20206M1971999-05-11011 May 1999 SER Accepting Request for Approval to Repair Flaws in ASME Code Class 3 Salt Svc Water Piping at Plant ML20206J6611999-04-30030 April 1999 Monthly Operating Rept for Apr 1999 for Pilgrim Nuclear Power Station.With ML20205L0221999-03-31031 March 1999 Monthly Operating Rept for Mar 1999 for Pilgrim Nuclear Power Station.With ML20207J5471999-03-0909 March 1999 Training Simulator,1999 4-Yr Certification Rept ML20207F9401999-03-0101 March 1999 Long Term Program Semi-Annual Rept for Pilgrim Nuclear Power Station ML20207H5451999-02-28028 February 1999 Monthly Operating Rept for Feb 1999 for Pilgrim Nuclear Power Station.With ML20196E2151998-12-31031 December 1998 1998 Annual Rept for Boston Edison & Securities & Exchange Commission Form 10-K Rept.With ML20206Q2741998-12-31031 December 1998 Monthly Operating Rept for Dec 1998 for Pilgrim Nuclear Power Station.With ML20197J3591998-11-30030 November 1998 Monthly Operating Rept for Nov 1998 for Pilgrim Nuclear Power Station.With ML20195C9951998-10-31031 October 1998 Monthly Operating Rept for Oct 1998 for Pilgrim Nuclear Power Station.With ML20154K0721998-09-30030 September 1998 Monthly Operating Rept for Sept 1998 for Pilgrim Nuclear Power Station.With ML20153D3901998-09-22022 September 1998 Safety Evaluation Granting 970707 Request to Use Guidance in GL 90-05 to Repair Flaws in ASME Class 3 Salt Svc Water Sys Piping for Pilgrim Nuclear Power Station ML20197C5011998-09-0404 September 1998 Rev 12C,Pages 4 & 5 to Pilgrim Nuclear Power Station Colr ML20197C5471998-08-31031 August 1998 Rev 12C to Pilgrim Nuclear Power Station Colr ML20151W8231998-08-31031 August 1998 Monthly Operating Rept for Aug 1998 for Pilgrim Nuclear Power Station.With ML20237E2251998-08-26026 August 1998 Suppl & Revs to SE for Amend 173 for Pigrim Nuclear Power Station ML20237A9941998-07-31031 July 1998 Monthly Operating Rept for Pilgrim Nuclear Power Station ML20236U8201998-07-13013 July 1998 Rev 12B to Pilgrim Nuclear Power Station COLR (Cycle 12) ML20236P0151998-06-30030 June 1998 Monthly Operating Rept for June 1998 for Pilgrim Nuclear Power Station ML20249A3741998-05-31031 May 1998 Monthly Operating Rept for May 1998 for Pilgrim Nuclear Power Station.W/Undated Ltr ML20247H2081998-04-30030 April 1998 Monthly Operating Rept for Apr 1998 for Pilgrim Nuclear Power Station ML20207B7601998-03-31031 March 1998 Final Rept, Pilgrim Nuclear Power Station Site-Specific Offsite Radiological Emergency Preparedenss Prompt Alert & Notification System Quality Assurance Verification, Prepared for FEMA ML20216G3911998-03-31031 March 1998 Monthly Operating Rept for Mar 1998 for Pilgrim Nuclear Power Station ML20216J3741998-03-19019 March 1998 Safety Evaluation Accepting Licensee Request to Evaluate Elevated Tailpipe Temp on Safety Relief Valve SRV 203-3B ML20248L2241998-02-28028 February 1998 Monthly Operating Rept for Feb 1998 for Pilgrim Nuclear Station ML20202G5251998-01-31031 January 1998 Monthly Operating Rept for Jan 1998 for Pilgrim Nuclear Power Station ML20236M8511997-12-31031 December 1997 1997 Annual Rept for Boston Edison & Securities & Exchange Commission Form 10-K Rept ML20198L7701997-12-31031 December 1997 Monthly Operating Rept for Dec 1997 for Pilgrim Nuclear Power Station ML20203D6101997-11-30030 November 1997 Monthly Operating Rept for Nov 1997 for Pilgrim Nuclear Power Station ML20202D5761997-11-0808 November 1997 1997 Evaluated Exercise BECO-LTR-97-111, Monthly Operating Rept for Oct 1997 for Pilgrim Nuclear Power Station1997-10-31031 October 1997 Monthly Operating Rept for Oct 1997 for Pilgrim Nuclear Power Station ML20217D6431997-10-0101 October 1997 Safety Evaluation Granting Request for Approval to Repair Flaws in Accordance W/Gl 90-05 for ASME Class 3 SSW Piping for Pilgrim ML20217H5621997-09-30030 September 1997 Monthly Operating Rept for Sept 1997 for Pilgrim Nuclear Power Station ML20216J4131997-08-31031 August 1997 Monthly Operating Rept for Aug 1997 for Pilgrim Nuclear Power Station ML20210J3321997-07-31031 July 1997 Monthly Operating Rept for Jul 1997 for Pilgrim Nuclear Power Station 1999-09-08
[Table view] |
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., 1 UNITED STATE 8
- ! J,.i ,j . NUCLEAR REGULATORY COMMISSION i *, ,
WASHINGTON, D.C. 20066-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION l
l i
REQUEST FOR APPROVAL TO REPAIR FLAWS IN
' ASME CODE CLASS 3 SALT SERVICE WATER PIPING BOSTON EDISON COMPANY PILGRIM NUCLEAR POWER STATION J l
DOCKET NO 50-293 l
1.0 INTRODUCTION
Title 10 of the Code of Federal Reaulations (10 CFR) Part 50.55a(g) requires nuclear power facility piping and components to meet the applicable requirements of Section XI of the i American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (the j 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 l the structuralintegrity 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 licensees since the repairs normally -
require an isolation of the system requiring the repair, and often a shutdown of the nuclear power plant.
Alternatives to Code requirements may be used by licensees when authorized by the Commission if the proposed alternatives to the requirements 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 compliance with the Code requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety (10 CFR 50.55a(a)(3)(ii));
A licensee may also submit requests for relief from certain Code requirements when it has I determined that conformance with certain Code requirements is impractical for its facility (10 CFR 50.55a(g)(5)(iii)). Pursuant to 10 CFR 50.55a(g'(6)(i), the Commission will evaluate determinations of impracticality and may grant relief and may impose attemative requirements as it determines is authorized by law. .
l 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. The staff uses the guidance in GL 90-05 as its criteria for making its safety evaluation of relief requests for temporary non Code repairs of Code Class 3 piping.
9905140215 99051123 DR ADOCK 0 Enclosure
2-
2.0 BACKGROUND
I in a letter dated August 26,1998, Boston Edison Company (the licensee) reported to the NRC 1 that through-wall leaks have been identified on piping in the salt service water (SSW) system l to the reactor building closed cooling water system (RBCCW) at the Pilgrim Nuclear Power )
Station (Filgrim). There are two discrete through-wall pits. The leak location is in an elbow downstream of the RBCCW heat exchanger. The SSW system is a moderate energy system
- and provides the ultimate heat sink for containment heat removal. The licensee requested under the provisions of 10 CFR 50.55a(g)(6)(i) relief from the ASME Code,Section XI requirements to perform Code repair or replace the degraded piping. The relief was sought until the next refueling outage which is scheduled to take place in May 1999. At that time, the licensee is planning to make a permanent ASME code repair. The licensee based its request for relief on the results of a "through-wall flaw" evaluation that was performed in accordance with the guidelines and acceptance criteria contained in GL 90-05.
3.0 LICENSEE'S RELIEF REQUEST 3.1 Component for Which Relief is Requested The piping in the SSW system to the RBCCW heat exchanger has through-wall leaks due to localized delamination of the rubber lining and subsequent erosion and corrosion of the carbon steel pipe. The leak location is in an elbow downstream of the RBCCW heat exchanger, There are two discrete through-wall pits. The 18-inch elbow is 300 series stainless steel having nominal thickness of 0.375 inches. The line is designed to take 100 psi pressure.
However, the line is open-ended; and, there is usually a small vacuum in the pipe at this location depending on the changing tides.
3.2 ' Section Xi Edition for the Pilgrim Plant The applicable Edition of Section XI of the ASME Code for Pilgrim is the 1980 Edition including the Winter 1980 Addenda.
-3.3 ASME Section XI Code Requirement 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 serves to provide an acceptable means of restoring the structuralintegrity of a degraded Code Class system back to the original design requirements.
3.4 Content of the Relief Request Relief is sought from performing a Code repair or replacement of the SSW system piping per the requirements of Article IWA-4000 or IWA-7000, respectively. Relief is being sought until the next refueling outage which is scheduled to take place in May of 1999. The relief is being sought because performing a Code repair during plant operation was determined to be impracticable.- The licensee will perform a Permanent Code repair for the affected piping during the next scheduled refueling outage (RF012).
e 3.5 Basis for Relief Request for relief has been submitted and attematives to the Code requirements have been proposed by the licensee. The licensee has evaluated the piping in accordance with the guidance provided in GL 90-05. Based upon the evaluation, it was established that the piping is degraded, but it is operable. The piping also satisfies the criteria for non-code repair as
' described in GL 90-05 and performing permanent repairs in accordance with the ASME Code l during plant operation would constitute an undue burden (create undue hardship) upon the licensee since the repairs would have necessitated a plant shutdown. ;
3.6 Licensee's Alternative Program
)
. The licensee has proposed a temporary Code repair to maintain the structural integrity of the i
. piping until the piping is replaced during an outage of sufficient duration. The temporary repair will consist of stainless steel cover plates that encapsulate the 18-inch elbow. The plates (elbow pieces) will be welded to the pipe at the leak location. The welding procedures and the welders will be qualified using the guidance provided in ASME Code Case N-562. Although ASME Code Case N-562 was written as guidance for the weld overlay repair method, it will be used as a technical guide to attach the cover plate. The cover plate method was selected as ,
the preferred temporary repair instead of the overlay method for the following reasons:
. The cover plate repair method will stop the leak with less risk of enlarging the pitting than the overlay method. All other guidance of N 562 will be followed as applicable, j For example, the cover plate will be UT examined periodically for erosion until the pipe !
is replaced in RF012.
l
. The cover plates are acceptable for up to 100 psi, although the pressure at the leak's location ranges from a slight vacuum to a slight positive pressure, it is dependent on 1 tide level because the line discharges to the sea. The line's 100 psi design j specification was selected at Pilgrim's construction to make it uniform with other parts j of the system that are subjected to higher pressures; therefore,100 psiis a conservative value for this application.
. The cover plate method has less potential impact on the existing rubber lining of the pipe because it exposes the pipe to less heat from the welding process. Existing procedures for welding the cover plate to a water-backed pipe are qualified.
- The cover plate method will not affect plant operations I
4.0 STAFF EVALUATION AND CONCLUSIONS !
4.1 Operability Determination, Root Cause Analysis and StructuralIntegrity Evaluation l
The piping elbow condition was analyzed by the licensee and found to be within the allowable stress limit of 35 ksi. The licensee performed an operability determination of the SSW system in the "as found" condition and the system was determined to be operable. The l
i.
4 system was constructed in accordance with the requirements of ASME Code, Class 3.
The root cause of the piping degradation was attributed to delamination of aging rubber pipe lining. Rubber lined piping flaws experience accelerated erosion and corrosion where the rubber lining has delaminated. Where the lining remains intact, the pipe remains at its nominal full-wall thickness. Hence, the wall erosion is local to the areas where lining has delaminated.
This conclusion'was also confirmed by the results of the u:trasonic examination of nine additional pipe locations which identified no other type of operationally caused defects. The licensee evaluated the structuralintegrity of the piping using the guidance of GL 90-05. Based upon the evaluation it was determined that the two through wall pits are within the stress criteria allowable pit size and the integrity of the piping will be maintained and that the degraded piping satisfied the criteria of GL 90-05.
4.2 Augmented inspection To assess the overall degradation of the SSW system, augmented ultrasonic examinations were performed on nine additionallocations as described in the August 26,1998 letter. The ,
l locations that were examined are similar locations to the SSW system piping location where the leaks occurred. All augmented inspection results at these locations found values greater than the manufacturer's minimum pipe-wall thickness.
4.3 Proposed Temporary Non-code Repair and Monitoring Provisions The licensee has proposed a temporary Code repair to maintain the structural integrity of the piping until the piping is replaced during an outage of sufficient duration. The licensee will install stainless steel cover plates to the pipe at the degraded locations as a temporary repair.
After completion of the repair, the cover plate will be ultrasonically examined periodically until the pipe is replaced in the next refueling outage. This is acceptable because the pressure at the repair location is low. It ranges from a slight vacuum to a slight positive pressure. In addition, plant operators will visually monitor any changes to the pipe once per shift during operator tours until permanent ASME Code repair is completed. Further, bi-weekly monitoring (ultrasonic testing) of the carbon steel material adjacent to the cover plate, and quarterly monitoring of the stainless cover plate material, will continue until test results show the test frequencies can be changed.
4.4 Staff Evaluation No safety-related components are within the proximity of the piping pitting location that would be directly affected by this leakage. The leakage is accommodated by the design of the auxiliary bay Airin-leakage has a negligible effect on the flow rate through the heat exchangers. . The staff has determined that the licensee's flaw evaluation is consistent with the guidelines and acceptance criteria of GL 90-05. Therefore, based on the preceding, the staff finds the licensee's structuralintegrity and operability assessments to be acceptable.
The licensee will weld stainless steel plates to encapsulate the degraded piping elbow as a temporary repair. During the period of plant operation and until a permanent Code repair is accomplished, the repair area will be monitored by plant personnel. The licensee has evaluated the temporary repair and determined that the SSW is operable.
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5.0 CONCLUSION
The staff finds that performance of an immediate Code repair during plant operation would have constituted an undue burden (create undue hardship) upon the licensee since the repair would have necessitated a plant shutdown. Shutting the plant down is not in the best interest of plant safety, given the magnitude of the flaw and the licensee's altemative program. The staff, therefore, grants the licensee's request for relief from performing the Code repair, pursuant to 10 CFR 50.55a(g)(6)(i), and finds .that implementation of the licensee's attemative progrism is authonzod 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 the licensee and facility that could have resulted if the Code requirements were imposed on the facility. The attemative program is authorized.
PrincipalContributor: A. Wang Date: May 11, 1999 1
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