Assessment of Design Info on Piping Restraints for Point Beach Nuclear Plant,Units 1 & 2.Staff Concludes That Licensee Unable to Retrieve Original Analyses That May Have Been Performed to Justify Removal of Shim CollarsML20207D675 |
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Point Beach  |
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02/22/1999 |
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NRC (Affiliation Not Assigned) |
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ML20207D673 |
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NUDOCS 9903100039 |
Download: ML20207D675 (4) |
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Category:SAFETY EVALUATION REPORT--LICENSING & RELATED ISSUES
MONTHYEARML20212D5961999-09-15015 September 1999 Safety Evaluation Supporting Licensee IPEEE Process.Plant Has Met Intent of Suppl 4 to GL 88-20 ML20211A7641999-08-11011 August 1999 Safety Evaluation Supporting Amends 190 & 195 to Licenses DPR-24 & DPR-27,respectively ML20196J4251999-06-30030 June 1999 Safety Evaluation Authorizing Proposed Alternatives Described in Relief Requests VRR-01,ROJ-16,PRR-01 & VRR-02 ML20206A5031999-04-23023 April 1999 Safety Evaluation Supporting Amends 189 & 194 to Licenses DPR-24 & DPR-27,respectively ML20207L3471999-03-0202 March 1999 Safety Evaluation Supporting Amends 187 & 192 to Licenses DPR-24 & DPR-27,respectively ML20207K2751999-03-0202 March 1999 Safety Evaluation Supporting Amends 188 & 193 to Licenses DPR-24 & DPR-27,respectively ML20207D5691999-03-0101 March 1999 Safety Evaluation Supporting Amends 186 & 191 to Licenses DPR-24 & DPR-27,respectively ML20207D6751999-02-22022 February 1999 Assessment of Design Info on Piping Restraints for Point Beach Nuclear Plant,Units 1 & 2.Staff Concludes That Licensee Unable to Retrieve Original Analyses That May Have Been Performed to Justify Removal of Shim Collars ML20206R9001999-01-13013 January 1999 SER Accepting Nuclear Quality Assurance Program Changes for Point Beach Nuclear Plant,Units 1 & 2 ML20198C7671998-12-10010 December 1998 Safety Evaluation Accepting Licensee Proposed Alternative to ASME BPV Code,1986 Edition,Section XI Requirement IWA-2232, to Use Performance Demonstration Initiative Program During RPV Third 10-yr ISI for Plant,Unit 2 ML20236U7201998-07-21021 July 1998 Safety Evaluation Supporting Amend 190 to License DPR-27 ML20236T1761998-07-17017 July 1998 Safety Evaluation Supporting Amends 185 & 189 to Licenses DPR-24 & DPR-27,respectively ML20236S0161998-07-13013 July 1998 Safety Evaluation Supporting Amends 184 & 188 to Licenses DPR-24 & DPR-27,respectively ML20236Q3161998-07-10010 July 1998 Safety Evaluation Accepting Licensee Proposed Alternative to ASME Code Requirements PTP-3-01 & PTP-3-02 ML20236L6061998-07-0808 July 1998 Safety Evaluation Granting Request for Relief RR-2-23,from Performing ASME Code,Section XI Volumetric Coverage Requirements for SG nozzle-to-safe End Welds & Associated Safe end-to-pipe Welds During Third 10-yr ISI Interval ML20236L6771998-07-0707 July 1998 Safety Evaluation Approving Wepco Implementation Program to Resolve USI A-46 at Point Beach NPP Units 1 & 2 ML20217F3131998-04-17017 April 1998 Safety Evaluation Accepting Proposed Alternative to ASME Code for Surface Exam of Nonstructural Seal Welds,For Plant, Unit 1 ML20217K4721998-03-24024 March 1998 Safety Evaluation Supporting Amends 183 & 187 to Licenses DPR-24 & DPR-27,respectively ML20217A8501998-03-19019 March 1998 SER Accepting Proposed Changes Submitted on 980226 by Wiep to Pbnp Final SAR Section 1.8 Which Will Impact Commitments Made in Pbnp QA Program Description.Changes Concern Approval Authority for Procedures & Interviewing Authority ML20216J0101998-03-17017 March 1998 Safety Evaluation Accepting Third 10-yr Inservice Insp Interval Relief Request RR-1-18 for Plant ML20248L8641998-03-17017 March 1998 Safety Evaluation Supporting Amends 182 & 186 to Licenses DPR-24 & DPR-27,respectively ML20198L1151998-01-0808 January 1998 SER Accepting Licensee Response to GL 95-07, Pressure Locking & Thermal Binding of Safety-Related Power-Operated Gate Valves, for Point Beach Nuclear Plant,Units 1 & 2 ML20198L4671998-01-0202 January 1998 SER Approving Request for Relief VRR-4B to Inservice Testing Program Wisconsin Electric Power Co,Point Beach Nuclear Plant,Units 1 & 2 ML20197J9341997-12-12012 December 1997 Safety Evaluation Accepting Licensee Request for Relief from Performing Inservice Volmetric Exam of Inaccessible Portions of RPV Lower Shell to Lower Head Ring Weld During 10-yr ISI Interval of Plant,Unit 2 ML20217D7111997-09-29029 September 1997 Safety Evaluation Supporting Amends 181 & 185 to Licenses DPR-24 & DPR-27,respectively ML20236R9571997-09-23023 September 1997 Safety Evaluation Supporting Amends 180 & 184 to Licenses DPR-24 & DPR-27,respectively ML20210S9821997-09-0404 September 1997 Safety Evaluation Supporting Amends 179 & 183 to Licenses DPR-24 & DPR-27,respectively ML20216G5781997-09-0303 September 1997 Safety Evaluation Supporting Amends 178 & 182 to Licenses DPR-24 & DPR-27,respectively ML20210Q0231997-08-25025 August 1997 Safety Evaluation Supporting Amends 177 & 181 to Licenses DPR-24 & DPR-27,respectively ML20217H4241997-08-0606 August 1997 Safety Evaluation Supporting Amends 175 & 179 to Licenses DPR-24 & DPR-27,respectively ML20198F0261997-08-0606 August 1997 Safety Evaluation Supporting Amends 176 & 180 to Licenses DPR-24 & DPR-27,respectively ML20149E8331997-07-16016 July 1997 Corrected Pages 9 & 20 to SER for Amends 174 & 178 to Licenses DPR-24 & DPR-27,respectively ML20217N3741997-07-0909 July 1997 Safety Evaluation Supporting Amends 174 & 178 to Licenses DPR-24 & DPR-27,respectively ML20148U4811997-07-0101 July 1997 Safety Evaluation Supporting Amends 173 & 177 to Licenses DPR-24 & DPR-27,respectively ML20137U4991997-04-10010 April 1997 Safety Evaluation Accepting Proposed Alternatives Contained in Requests for Relief RR-1-17 & RR-2-21 ML20138M0571997-02-20020 February 1997 Safety Evaluation Supporting Amends 172 & 176 to Licenses DPR-24 & DPR-27,respectively ML20133G3111997-01-0808 January 1997 Safety Evaluation Supporting Amends 170 & 174 to Licenses DPR-24 & DPR-27,respectively ML20128P4731996-10-0909 October 1996 Safety Evaluation Supporting Amends 169 & 173 to Licenses DPR-24 & DPR-27,respectively ML20129G6901996-10-0303 October 1996 SER Accepting Request for Relief from ASME Code Repair Requirements for ASME Code Class Three Piping at Plant ML20133N4281996-07-16016 July 1996 Safety Evaluation Supporting Amends 171 & 175 to Licenses DPR-24 & DPR-27,respectively ML20101E1851996-03-20020 March 1996 Safety Evaluation Supporting Amends 168 & 172 to Licenses DPR-24 & DPR-27,respectively ML20095K6471995-12-27027 December 1995 Safety Evaluation Supporting Amends 167 & 171 to Licenses DPR-24 & DPR-27,respectively ML20094P3741995-11-22022 November 1995 Safety Evaluation Supporting Amends 166 & 170 to Licenses DPR-24 & DPR-27,respectively ML20094M3101995-11-17017 November 1995 Safety Evaluation Supporting Amends 165 & 169 to Licenses DPR-24 & DPR-27,respectively ML20093E9591995-10-12012 October 1995 Safety Evaluation Supporting Amends 163 & 167 to Licenses DPR-24 & DPR-27,respectively ML20093H7051995-10-12012 October 1995 Safety Evaluation Supporting Amends 164 & 168 to Licenses DPR-24 & DPR-27,respectively ML20086E6271995-07-0505 July 1995 Safety Evaluation Supporting Amends 162 & 166 to Licenses DPR-24 & DPR-27,respectively ML20080R4731995-03-0606 March 1995 Safety Evaluation Supporting Amends 161 & 165 to Licenses DPR-24 & DPR-27,respectively ML20078C2571995-01-18018 January 1995 Safety Evaluation Supporting Amends 160 & 164 to Licenses DPR-24 & DPR-27,respectively ML20079A1071994-12-21021 December 1994 Safety Evaluation Supporting Amends 159 & 163 to Licenses DPR-24 & DPR-27,respectively 1999-09-15
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARNPL-99-0569, Monthly Operating Repts for Sept 1999 for Pbnp,Units 1 & 2. with1999-09-30030 September 1999 Monthly Operating Repts for Sept 1999 for Pbnp,Units 1 & 2. with 05000266/LER-1999-007, :on 990831,cable Tray Fire Stops Do Not Meet App R Exemption Requirements Occurred.Caused by Improper Installation of Approved Plant Mod.New Mod Has Been Initiated to Provide Three H Rated Fire Barrier1999-09-30030 September 1999
- on 990831,cable Tray Fire Stops Do Not Meet App R Exemption Requirements Occurred.Caused by Improper Installation of Approved Plant Mod.New Mod Has Been Initiated to Provide Three H Rated Fire Barrier
ML20212D5961999-09-15015 September 1999 Safety Evaluation Supporting Licensee IPEEE Process.Plant Has Met Intent of Suppl 4 to GL 88-20 05000266/LER-1999-004, :on 990420,fuel Oil Transfer Pump Cable in AFW Pump Room Was Noted Outside App R Design Basis.Caused by Error in Design of New Fuel Oil Transfer Sys.Condition Rept CR 99-1140 Was Initiated1999-09-0202 September 1999
- on 990420,fuel Oil Transfer Pump Cable in AFW Pump Room Was Noted Outside App R Design Basis.Caused by Error in Design of New Fuel Oil Transfer Sys.Condition Rept CR 99-1140 Was Initiated
NPL-99-0051, Monthly Operating Repts for Aug 1999 for Pbnp,Units 1 & 2. with1999-08-31031 August 1999 Monthly Operating Repts for Aug 1999 for Pbnp,Units 1 & 2. with ML20211A7641999-08-11011 August 1999 Safety Evaluation Supporting Amends 190 & 195 to Licenses DPR-24 & DPR-27,respectively NPL-99-0449, Monthly Operating Repts for July 1999 for Pbnp,Units 1 & 2. with1999-07-31031 July 1999 Monthly Operating Repts for July 1999 for Pbnp,Units 1 & 2. with ML20209D2691999-06-30030 June 1999 Monthly Operating Repts for June 1999 for Pbnps,Units 1 & 2 ML20196J4251999-06-30030 June 1999 Safety Evaluation Authorizing Proposed Alternatives Described in Relief Requests VRR-01,ROJ-16,PRR-01 & VRR-02 ML20196F3341999-06-22022 June 1999 Safety Evaluation for Implementation of 422V+ Fuel Assemblies at Pbnp Units 1 & 2 ML20195F9781999-06-10010 June 1999 Unit 2 Refueling 23 Inservice Insp Summary Rept for Form NIS-1 ML20209D2751999-05-31031 May 1999 Revised MORs for May 1999 for Pbnps,Units 1 & 2 NPL-99-0328, Monthly Operating Repts for May 1999 for Pbnp,Units 1 & 2. with1999-05-31031 May 1999 Monthly Operating Repts for May 1999 for Pbnp,Units 1 & 2. with 05000301/LER-1999-003-01, :on 990505,licensee Personnel Discovered That Refueling Interval Surveillance of Emergency Lighting Required by TS 15.4.6.A.3 Was Not Conducted.Cause Unknown. Task Sheet call-ups for Both Procedures Have Been Created1999-05-28028 May 1999
- on 990505,licensee Personnel Discovered That Refueling Interval Surveillance of Emergency Lighting Required by TS 15.4.6.A.3 Was Not Conducted.Cause Unknown. Task Sheet call-ups for Both Procedures Have Been Created
05000266/LER-1999-004, :on 990420,discovered That Fuel Oil Transfer Pump Cable in AFW Pump Room Outside App R Design Basis. Caused by Cable Routing Discrepancy.Fire Rounds Increased & Procedures Being Developed to Facilitate Using G-05 EDG1999-05-20020 May 1999
- on 990420,discovered That Fuel Oil Transfer Pump Cable in AFW Pump Room Outside App R Design Basis. Caused by Cable Routing Discrepancy.Fire Rounds Increased & Procedures Being Developed to Facilitate Using G-05 EDG
05000266/LER-1999-003, :on 990406,TS SR for ECCS & Containment Spray Was Not Fully Implemented.Caused by Conservative Interpretation of Valve Impact.Revised Procedures.With1999-05-0606 May 1999
- on 990406,TS SR for ECCS & Containment Spray Was Not Fully Implemented.Caused by Conservative Interpretation of Valve Impact.Revised Procedures.With
ML20196F3521999-04-30030 April 1999 Non-proprietary WCAP-14788, W Revised Thermal Design Procedure Instrument Uncertainty Methodology for Wepc Point Beach Units 1 & 2 (Fuel Upgrade & Uprate to 1656 Mwt - NSSS Power) NPL-99-0273, Monthly Operating Repts for Apr 1999 for Point Beach Nuclear Plant,Units 1 & 2.With1999-04-30030 April 1999 Monthly Operating Repts for Apr 1999 for Point Beach Nuclear Plant,Units 1 & 2.With ML20206A5031999-04-23023 April 1999 Safety Evaluation Supporting Amends 189 & 194 to Licenses DPR-24 & DPR-27,respectively 05000301/LER-1999-002-01, :on 990323,discovered That Red Channel of SG Pressure Indication Passes Through Fire Zone.Caused by 1983 Modification Oversight.Twice Per Shift Fire Round Has Been Established for Fire Zone Pending Cable Routing Correction1999-04-16016 April 1999
- on 990323,discovered That Red Channel of SG Pressure Indication Passes Through Fire Zone.Caused by 1983 Modification Oversight.Twice Per Shift Fire Round Has Been Established for Fire Zone Pending Cable Routing Correction
NPL-99-0193, Monthly Operating Repts for Mar 1999 for Pbnp,Units 1 & 2. with1999-03-31031 March 1999 Monthly Operating Repts for Mar 1999 for Pbnp,Units 1 & 2. with 05000301/LER-1999-001-01, :on 990211,EDG Output Breaker Failed to Remain Closed During Surveillance Testing.Caused by Breaker Control Switch Failing to React Quickly.Modified Closing Circuit for EDG Output1999-03-10010 March 1999
- on 990211,EDG Output Breaker Failed to Remain Closed During Surveillance Testing.Caused by Breaker Control Switch Failing to React Quickly.Modified Closing Circuit for EDG Output
ML20207K2751999-03-0202 March 1999 Safety Evaluation Supporting Amends 188 & 193 to Licenses DPR-24 & DPR-27,respectively ML20207L3471999-03-0202 March 1999 Safety Evaluation Supporting Amends 187 & 192 to Licenses DPR-24 & DPR-27,respectively ML20207D5691999-03-0101 March 1999 Safety Evaluation Supporting Amends 186 & 191 to Licenses DPR-24 & DPR-27,respectively NPL-99-0134, Monthly Operating Repts for Feb 1999 for Pbnp,Units 1 & 2. with1999-02-28028 February 1999 Monthly Operating Repts for Feb 1999 for Pbnp,Units 1 & 2. with ML20207D6751999-02-22022 February 1999 Assessment of Design Info on Piping Restraints for Point Beach Nuclear Plant,Units 1 & 2.Staff Concludes That Licensee Unable to Retrieve Original Analyses That May Have Been Performed to Justify Removal of Shim Collars ML20206R9001999-01-13013 January 1999 SER Accepting Nuclear Quality Assurance Program Changes for Point Beach Nuclear Plant,Units 1 & 2 NPL-99-0091, 1998 Annual Results & Data Rept for Pbnps,Units 1 & 2. with1998-12-31031 December 1998 1998 Annual Results & Data Rept for Pbnps,Units 1 & 2. with NPL-99-0008, Monthly Operating Repts for Dec 1998 for Pbnp,Units 1 & 2. with1998-12-31031 December 1998 Monthly Operating Repts for Dec 1998 for Pbnp,Units 1 & 2. with ML20198C7671998-12-10010 December 1998 Safety Evaluation Accepting Licensee Proposed Alternative to ASME BPV Code,1986 Edition,Section XI Requirement IWA-2232, to Use Performance Demonstration Initiative Program During RPV Third 10-yr ISI for Plant,Unit 2 NPL-98-1006, Monthly Operating Repts for Nov 1998 for Point Beach Nuclear Plant,Units 1 & 2.With1998-11-30030 November 1998 Monthly Operating Repts for Nov 1998 for Point Beach Nuclear Plant,Units 1 & 2.With ML20195J5101998-11-16016 November 1998 Proposed Revs to Section 1.3 of FSAR for Pbnp QA Program ML20198J5941998-11-0303 November 1998 1998 Graded Exercise,Conducted on 981103 ML20154L6751998-10-14014 October 1998 Unit 1 Refueling 24 ISI Summary Rept for Form NIS-1 ML20154M9121998-10-14014 October 1998 Unit 1 Refueling 24 Repair/Replacement Summary Rept for Form NIS-2 NPL-98-0826, Monthly Operating Repts for Sept 1998 for Point Beach Nuclear Plant,Units 1 & 2.With1998-09-30030 September 1998 Monthly Operating Repts for Sept 1998 for Point Beach Nuclear Plant,Units 1 & 2.With ML20151W3851998-08-31031 August 1998 Monthly Operating Repts for Aug 1998 for Pbnp Units 1 & 2 ML20151W4541998-07-31031 July 1998 Corrected Page to MOR for July 1998 for Pbnp Unit 1 ML20151W4471998-07-31031 July 1998 Corrected Page to MOR for July 1998 for Pbnp Unit 2 ML20236U7201998-07-21021 July 1998 Safety Evaluation Supporting Amend 190 to License DPR-27 ML20236T1761998-07-17017 July 1998 Safety Evaluation Supporting Amends 185 & 189 to Licenses DPR-24 & DPR-27,respectively 05000266/LER-1998-015, :on 980420,containment Fan Cooler Test Results Were Noted Outside Acceptance Criteria.Cause Is Under Evaluation.Pressure Washing of Air Side of Cooling Coils for All Four Unit 1 CFCs Has Been Completed1998-07-17017 July 1998
- on 980420,containment Fan Cooler Test Results Were Noted Outside Acceptance Criteria.Cause Is Under Evaluation.Pressure Washing of Air Side of Cooling Coils for All Four Unit 1 CFCs Has Been Completed
05000266/LER-1998-019, :on 980615,discovered That Containment Hydrogen Monitors Lacked Environmentally Qualified Coating on Terminal Strips.Caused by Terminal Strips Being Disturbed W/O Subsequent Reapplication of Coating.Replaced Coating1998-07-14014 July 1998
- on 980615,discovered That Containment Hydrogen Monitors Lacked Environmentally Qualified Coating on Terminal Strips.Caused by Terminal Strips Being Disturbed W/O Subsequent Reapplication of Coating.Replaced Coating
ML20236S0161998-07-13013 July 1998 Safety Evaluation Supporting Amends 184 & 188 to Licenses DPR-24 & DPR-27,respectively ML20236Q3161998-07-10010 July 1998 Safety Evaluation Accepting Licensee Proposed Alternative to ASME Code Requirements PTP-3-01 & PTP-3-02 ML20236L6061998-07-0808 July 1998 Safety Evaluation Granting Request for Relief RR-2-23,from Performing ASME Code,Section XI Volumetric Coverage Requirements for SG nozzle-to-safe End Welds & Associated Safe end-to-pipe Welds During Third 10-yr ISI Interval ML20236L6771998-07-0707 July 1998 Safety Evaluation Approving Wepco Implementation Program to Resolve USI A-46 at Point Beach NPP Units 1 & 2 NPL-98-0558, Monthly Operating Repts for June 1998 for Pbnp,Units 1 & 21998-06-30030 June 1998 Monthly Operating Repts for June 1998 for Pbnp,Units 1 & 2 ML20151W4261998-06-30030 June 1998 Corrected Page to MOR for June 1998 for Pbnp Unit 2 1999-09-30
[Table view] |
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[""'%k UNITED STATES y
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- r NUCLEAR REGULATORY COMMISSION L
WASHINGTON, D.C. 30000 4001 ASSESSMENT OF THE DESIGN INFORMATION ON PIPING RESTRAINTS WISCONSIN ELECTRIC POWER COMPANY l
POINT BEACH NUCLEAR PLANT. UNITS 1 AND 2 l
DOCKET NOS.60-266 AND 50-301
1.0 INTRODUCTION
i By letter dated April 16,1998, the staff informed Wisconsin Electric (WE or licensee) that it wan l
performing a review of records related to the design of restraints on the main steam (MS) piping and primary loop auxiliary piping systems at the Point Beach Nuclear Plant (PBNP). ' Specific i
requests for information were included in an enclosure to that letter. On June 15,1998, the licensee responded to the request for information based on availab!e records and the licensee i
staff's recollection of original design aspects requested in the NRC staff's inquiry. As a follow-j up to this assessment activity, the staff visited WE corporate offices on October 15 and 16, 1998, to review relevant design records and interview licensee representatives. Duke Engineering and Services (DE&S) was recently contracted by WE to perform an independent j
evaluation of the existing MS piping at PBNP to confirm the adequacy of restraint design in the MS piping system.
2.0 DISCUSSION 2.1 Main Steam Pioina i
j The licensee analyzed the MS piping for high energy line break (HELB) scenarios inside the Unit 1 and Unit 2 containments at PBNP. This evaluation was performed to assess the impact of removing various shim collars from the original Unit 2 pipe whip restraint design. The evaluation utilized criteria contained in Generic Letter (GL) 87-11 (" Relaxation in Arbitrary 4
l Intermediate Pipe Rupture Requirements") to determine postulated break Irt.ations on the piping. In accordance with GL 87-11, licensees may eliminate intermediate.o re breaks when i
pipe stresses are within specified acceptance limits. Review of the pipin'a @ ass analysis 4
reports for the MS piping inside containment indicates that the stresses in affected piping are j
below the limits established in GL 87-11, and consequently, only the terminal endpoints required evaluation for HELBs in the MS piping inside containment.
The methodology utilized to evaluate the consequences of an HELB in the MS piping in this analysis is consistent with the criteria established by Bechtel for the original plant design. This method employs a concentrated blowdown force (originally developed by Westinghouse) equal i
to the pressure multiplied by the intemal area of the pipe that is applied statically at the break ~
location. The piping system is then evaluated for plastic hinge formation as well as for the 4
effects on the piping system.-
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i 9903100039 990222 PDR ADOCK 05000266 P
pop e
ENCLOSURE'
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1 1
2 1
DE&S utilized the "AutoPIPE" computer program to perform an elastic analysis of the MS piping for a guillotine failure at the SG MS nozzle and the containment penetration anchor. This computer program has been adequately benchmarked and has been accepted by the NRC for I
similar applications. The analytical results were reviewed to determine whether plastic moments are developed in the system. If no plastic hinges are formed, then the system is stable and the piping is acceptable. If a plastic hinge is formed, then a moment-less hinge connection is modeled at that point, and the analysis is repeated based on the modified geometry and boundary conditions. The force applied to the terminal end for the second run is l
equal to the original blowdown load minus the load required to form the initial plastic hinge. The l
results of the second run are superimposed upon the results of the initial analysis, and then reviewed for development of additional plastic hinges. If no additional hinges are formed, the piping model is considered stable and deemed acceptable. If an additional hinge forms, further reanalysis would be required.
In the evaluation of the MS piping for a guillotine break at the containment penetration, the Unit 2 Loop B MS piping system was used as an enveloping case. A plastic hinge developed near one whip restraint due to a load less than the Bechtel tJowdown force. The result from the second run (including the plastic hhge in the model) was superimposed onto the results from the initial analyses. The combined results indicate that no additional plastic hinges will form in the piping. Therefore, the piping system was determined to be acceptable for the containment penetration guillotine break scenario.
Evaluation of the MS piping for a guillotine break at the SG MS nozzle addressed the deleted shim collars in the Unit 2 failure restraints. The Loop B MS piping system was again used as an enveloping case. A plastic hinge developed at an elbow as a result of a load less than the Bechtel blowdown force. Further evaluation identified that an additional plastic hinge will form at the snubber support upstream of the first hinge. This condition required additional analyses to be performed, as described below.
The jet loads required to develop the initial hinge on each MS piping loop (Unit 1 A/B and Unit 2 A/B) were also determined. These loads were used to perform a nonlinear inelastic analysis to determine the rotation of the plastic hinge using an energy balance method. An energy balance of the plastic moment capacity of the hinge is equated to the energy in the system due to the fore applied to the overhung segment of piping from the break location at the SG nozzle to the location near the snubber supports where the initial plastic hinge formed.
Two cases were considered for the energy balance evaluation:
I Case 1 assumed no singla active failures occur and a limited fluid reservoir is available in the system; j
Case 2 assumed a single active failure of the MS check valves,in the SG foop. This scenario provided an essentia!!y unlimited fluid reservoir from the opposite SG which j
caused a sustained jet force to exist.
The energy balance evaluation used a 3-step time history considering an " initial" blowdown force, a " transitional" blowdown force, and a
- steady state" blowdown force. The blowdown forces developed in the time history were based on theoretical and testing data available with DE&S, as well as in supplemental technical procedures used for pipe rupture analysis and design in the 1978
I 3
through 1983 time period. This data has been previously reviewed and found to be acceptable by the NRC staff. The initial and transitional blowdown forces were dependent on the pipe dimensions, and the pipe configuration from the break location to the fluid reservoir or an intermediate flow restriction. The steady-state blowdown force is dependent on the system frictional flow losses from the break location to the flow reservoir or an intermediate flow restriction.
The time history was used as a basis for the development of a single blowdown thrust force to be used for the two phases of pipe whip motion: (1) the fluid accelerating the pipe from zero to a maximum velocity, and (2) the hinge decelerating the piping from a maximum velocity back to
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zero. These pipe movements determined the input inelastic energy and this energy was compared j
1 to the energy needed for hinge rotation where all energy is conservatively absorbed. The overhung beam model was used to determine the rotation of the plastic hinge.
'l The snubber loads generated in Case 1 were determined to be less than the design loads provided by Bechtel. The system is therefore considered stable and the piping is acceptable. The rotational path of the plastic hinge was reviewed to verify that the jet loads do not impact critical systems / equipment. However, the energy developed as a result of the initial blowdown force in l
Case 2 is suffacient to rotate the plastic hinge in the piping system. This second case also includes a steady-state load remaining in the system after rotation of the hinge. Hence, a supplemental analysis was performed to determine additional formation of hinges. The results from this i
1 supplementary analysis determined that no further plastic hinges will form in the system.
Therefore, the system was considered stable and the piping was determined to be acceptable for the guillotine break at the SG nozzle.
i Based on its review of the licensee's summary of reanalysis of the MS piping and interviews with licensee staff, the staff concludes that the licensee provided adequate justification that the existing l
MS piping system and restraints inside containment at PBNP Units 1 and 2 are structurally j
adequate and meet current licensing and design-basis requirements. On the basis of its assessment as discussed above, the staff believes the licensee provided a reasonable justification regarding the deletion of shim collars in the MS piping.
2.2 Auxiliary Pioina The staff examined records relating to the licensee's implementation of IE Bulletin 79-14 (" Seismic Analyses for As Built Safety-Related Piping Systems") for the auxiliary piping system. The records indicate that the licensee has completed the piping reverification program to satisfy the requirements of IE Bulletin 79-14 for safety-related piping at PBNP. The purpose of this program was to compare and reconcile the as-built pipo routing and support configurations against the l
design records. A total of 139 subsystems have been evaluated since the program was initiated in 1991, comprising almost 3000 piping supports and more than 36,000 feet of pipe. Fourteen subsystems in the original scope were dropped from the analysis effort in 1996 when the piping was identified as nonsafety-related, independent contractors performed the piping reverification programs related to IE Bulletin 79-14 for the licensee. As-built walkdowns of selected relrod piping were completed by the licensee in 1996, with the exception of some of the RHR (residual heat removal) subsystems, which were added to the scope and completed in 1997. The majority of piping analyses were completed by the first half of 1998. The NRC regional staff followed the licensee's implementation program for IE Bulletin 79-14 and found it acceptable as discussed in a number of reports issued during the
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-4 period between 1991 and 1998. The overall modification rate for the program, which includes support upgrades, was approximately 8 percent.
The staff believes the implementation of thic program provides reasonable assurance to conclude that the as built auxiliary piping and support installation are structurally adequate.
3.0 CONCLUSION
in summary, the staff concludes that the licensee was unable to retrieve the original analyses that may have been performed to justify the removal of the shim collars in the early 1970s, and hence, the staff cannot conclude whether or not their removal was justified in consideration of the licensing basis requirements at that time. However, based on the recent evaluations of the MS piping examined by the staff, the licensee has provided adequate technical justification for the removal of certain shim collars in the MS piping restraints. The staff also finds that the licensee has provided reasonable basis to confirm the structural adequacy of the current as built configuration of the MS and auxiliary piping systems.
Principal contributor: Jai Rajan Date: February 22, 1999 i
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