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| Subsequently, the licensee also found structural deficiencies on supports in the discharge side of the SBGT system and the Control Poom Ventilation (CRV) | | Subsequently, the licensee also found structural deficiencies on supports in the discharge side of the SBGT system and the Control Poom Ventilation (CRV) |
| System. The licensee has since completed support modifications of the SBGT Suction system. The SBGT Discharge and the CRV Systems will be modified during the next refuelino outage beginning in February 1988. | | System. The licensee has since completed support modifications of the SBGT Suction system. The SBGT Discharge and the CRV Systems will be modified during the next refuelino outage beginning in February 1988. |
| In a letter dated December 5, 1986, the staff permitted interim operation of the Cooper Station for the current fuel cycle (Number 11) based on a pre-liminary review of the licensee's submittals of November 25 and December 5, 1986, that provided analyses for the effected systems against interim oper-ability criteria. This Safety Evaluation is a more detailed review of the aforementioned and other additional submittals that the staff has requested. | | In a {{letter dated|date=December 5, 1986|text=letter dated December 5, 1986}}, the staff permitted interim operation of the Cooper Station for the current fuel cycle (Number 11) based on a pre-liminary review of the licensee's submittals of November 25 and December 5, 1986, that provided analyses for the effected systems against interim oper-ability criteria. This Safety Evaluation is a more detailed review of the aforementioned and other additional submittals that the staff has requested. |
| Although the SBGT Discharoe and the CPV Systems have not been modified at this time, the licensee has inspected both Systems to assess their interim oper-ability and is currently analyzing both systems to prepare them for modif-ication in 1988. The focus of the staff review was on: 1) the acceptability of the licensee's methodology and criteria with respect to the Updated Safety Analysis Report (USAR) comitment; and 2) the acceptable criteria for the interim operation of the SBGT Discharge and the CRV Systems. | | Although the SBGT Discharoe and the CPV Systems have not been modified at this time, the licensee has inspected both Systems to assess their interim oper-ability and is currently analyzing both systems to prepare them for modif-ication in 1988. The focus of the staff review was on: 1) the acceptability of the licensee's methodology and criteria with respect to the Updated Safety Analysis Report (USAR) comitment; and 2) the acceptable criteria for the interim operation of the SBGT Discharge and the CRV Systems. |
| EVALUATION i The staff reviewed 1) three sets of stress calculations of the SBGT Suction i | | EVALUATION i The staff reviewed 1) three sets of stress calculations of the SBGT Suction i |
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Category:SAFETY EVALUATION REPORT--LICENSING & RELATED ISSUES
MONTHYEARML20212K9781999-09-30030 September 1999 Safety Evaluation Accepting USI A-46 Implementation Program ML20209H8281999-07-15015 July 1999 Safety Evaluation Accepting GL 95-07, Pressure Locking & Thermal Binding of Safety-Related Power-Operated Gate Valves, for Cooper Nuclear Station ML20206P0481999-05-12012 May 1999 Safety Evaluation Concluding That NPP Established Acceptable Program to Verify Periodically design-basis Capability of safety-related MOVs at CNS & Adequately Addressed Actions Requested in GL 96-05 ML20204B3701999-03-11011 March 1999 SER Accepting Third 10-year Interval Inservice Insp Plan Requests for Relief for RI-17,Rev 1 and RI-25,Rev 0.Request for Relief RI-13,Rev 2 Involving Snubber Testing & Is Being Evaluated in Separate Report ML20196J9641998-12-0707 December 1998 Safety Evaluation Accepting Licensee Third 10-yr Interval Inservice Insp Plan Request for Relief RI-27,rev 1 ML20196A2861998-11-23023 November 1998 SER Re Core Spray Piping Weld for Cooper Nuclear Station. Staff Concluded That Operation During Cycle 19 Acceptable with Indication re-examined During RFO 18 ML20196A5241998-11-23023 November 1998 Safety Evaluation Accepting Proposed Alternative to Use UT Techniques Qualified to Objectives of App Viil as Implemented by PDI Program in Performing RPV Shell Weld & Shell to Flange Weld Examinations ML20196A5061998-11-23023 November 1998 Safety Evaluation Re Flaw Indication Found in Main Steam Nozzle to Shell Weld NVE-BD-N3A at Cns.Plant Can Be Safely Operated for at Least One Fuel Cycle with Indication in as-is Condition ML20195H1761998-11-17017 November 1998 SER Authorizing Proposed Alternative in Relief Requests RV-06,RV-07,RV-09,RV-11,RV-12 & RV-15 Pursuant to 10CFR50.55a(a)(3)(ii).RV-08 Granted Pursuant to 10CFR50.55a(f)(6)(i) & RV-13 Acceptable Under OM-10 ML20151Z6141998-09-16016 September 1998 SER Accepting Util Responses to NRC Bulletin 95-002 for Cooper Nuclear Station ML20236R9131998-07-20020 July 1998 SER Accepting Rev 13 to Quality Assurance Program for Operation Policy Document for Plant ML20203K0351998-02-26026 February 1998 SER Approving Third ten-year Interval Inservice Inspection Program Plan,Request for Relief PR-10 for Cooper Nuclear Station.Technical Ltr Rept on Request Relief PR-10 Also Encl ML20212E0811997-10-23023 October 1997 SER Accepting Third 10-yr Interval Insp Program Plan & Associated Requests for Relief for Plant ML20217E6141997-09-23023 September 1997 Safety Evaluation Accepting Util Proposed Changes to Licensing Basis for Plant to Reflect Incorporation of Safer/Gestr Methodology for LOCA Analysis ML20199F7411997-08-14014 August 1997 Safety Evaluation Rept Accepting Design of torus-to-reactor Bldg Vacuum Breakers at Plant ML20210J5731997-08-13013 August 1997 Safety Evaluation Denying Relief Request for Plant Third 10-yr Interval Program for Inservice Testing of Pumps. Request Not in Sufficient Detail to Justify Proposed Alternative ML20148H2381997-06-0606 June 1997 Safety Evaluation Granting Licensee Relief Requests for 10-yr Interval Inservice Insp Program Plan for Plant,Unit 1 ML20138K0241997-05-0707 May 1997 Safety Evaluation Supporting Proposed Rev to RPV Surveillance Capsule Withdrawal Schedule ML20134N6911997-02-19019 February 1997 Safety Evaluation Related to Third ten-year Interval Inservice Testing Program Nebraska Public Power District Cooper Nuclear Station ML20198E1091992-11-25025 November 1992 Safety Evaluation Accepting Licensee 920921 120-day Response to GL 87-02, Verification of Seismic Adequacy of Mechanical & Electrical Equipment in Operating Reactors,Usi A-46 ML20127N3741992-11-19019 November 1992 Supplemental SE Accepting Analysis & Results in Response to SBO rule,10CFR50.63 ML20128C2911992-11-19019 November 1992 Safety Evaluation Accepting Revised ACAD Sys Into Nitrogen Containment Atmosphere Dilution,Eliminating Potential post-accident Oxygen Source ML20059E2781990-08-31031 August 1990 Safety Evaluation Granting Licensee 900525 Relief Requests RP-14 & RP-15 from Requirements to Measure Pump Inlet Pressure & Instrument Ranges,Respectively ML20246B2501989-05-31031 May 1989 Safety Evaluation on Generic Ltr 83-28,Item 4.5.3 Re Reactor Trip Sys Reliability for All Domestic Operating Reactors. Intervals for on-line Functional Testing Consistent W/ Achieving High Reactor Trip Sys Availability at Reactors ML20247A4241989-03-20020 March 1989 Safety Evaluation Accepting Revised Process Control Program Re General Methods of Sampling,Processing,Analysis & Waste Formulation During Solidification of Radwaste ML20205S2031988-11-0303 November 1988 Safety Evaluation Supporting Interim Operability of Piping Sys ML20147B5161988-02-23023 February 1988 Safety Evaluation Supporting Amend 117 to License DPR-46 ML20148C9591988-01-13013 January 1988 Safety Evaluation Concluding That Inservice Testing Program Submitted w/860730 Ltr as Modified in Subj Safety Evaluation Will Provide Reasonable Assurance of Operational Readiness of safety-related Pumps & Valves ML20238C4001987-12-23023 December 1987 Safety Evaluation Supporting Proposed Mod to 10CFR50.62, ATWS Rule ML20237E3261987-12-21021 December 1987 Safety Evalution Supporting Amend 113 to License DPR-46 ML20236B8901987-10-20020 October 1987 Sser Re Alternate Rod Insertion (ARI) Sys.Util Plans for Relocating ARI Position Indication Out of Control Room to Another Location in Control Bldg Acceptable ML20235H0351987-09-23023 September 1987 Safety Evaluation Re Alternate Rod Injection & Recirculating Pump Trip Sys ML20235N4581987-07-10010 July 1987 Safety Evaluation Supporting Util 810707,820623,0730 & 831215 Submittals Re Valve Operability Info for 24-inch Isolation Valves in Purge & Vent Sys.Nrc Conclusion Subj to Valves Being Modified to Have Torque Readjustments ML20214S8741987-05-21021 May 1987 Supplemental Safety Evaluation Re Dcrdr.Listed Activities Must Be Finished in Order to Satisfy Dcrdr Requirements in Suppl 1 to NUREG-0737 ML20212Q9721987-04-16016 April 1987 Safety Evaluation Accepting Util 831104 & 870121 Responses to Generic Ltr 83-28,Items 3.2.1 & 3.2.2, Post-Maint Verification Testing ML20212L1751987-03-0606 March 1987 Safety Evaluation Supporting Util Methodology in Standby Gas Treatment Suction Analysis & Interim Operation for Fuel Cycle 11 Only ML20209A7001987-01-30030 January 1987 Safety Evaluation Accepting Util Response to Vendor Recommended Reliability Verification Testing Per Generic Ltr 83-28,Item 4.5.1 Re Reactor Trip Sys Reliability (Sys Functional Testing) ML20215M5021986-10-27027 October 1986 Safety Evaluation Accepting Util Response to Generic Ltr 82-33 Re Conformance to Rev 2 to Reg Guide 1.97,except for Instrumentation Associated W/Neutron Flux Variable ML20210K2491986-09-25025 September 1986 Safety Evaluation Supporting Analytical Method Used by Licensee to Evaluate Critical Stresses ML20141E9291986-04-10010 April 1986 Safety Evaluation Supporting Amend 98 to License DPR-46 ML20151Y2541986-01-27027 January 1986 Safety Evaluation Re Requests for Relief from Inservice Insp Requirements.Relief Not Granted for Surface & Volumetric Exam of Drywell Piping Spray Welds Since Requirements Not Impractical ML20140C5761986-01-17017 January 1986 Safety Evaluation Supporting 831104 Response to Generic Ltr 83-28,Items 3.1.1 & 3.1.2 Concerning post-maint Testing Verification of Reactor Trip Sys Components ML20134J6301985-08-21021 August 1985 Safety Evaluation Accepting Proposed Mods as Ensuring Safe Shutdown Capability in Event of Fire in Areas of Concern in Accordance W/Requirements of 10CFR50,App R ML20127E7281985-06-10010 June 1985 Safety Evaluation Supporting Response to Generic Ltr 83-28, Item 1.2 Re post-trip Review Data & Info Capability ML20127E1051985-05-0606 May 1985 Safety Evaluation Re Util 831104 Response to Generic Ltr 83-28,Item 1.1 Concerning post-trip Review Program & Procedure ML20148N2351978-11-0101 November 1978 Safety Eval Rept of Main Stream Isolation Valve Test Results. Util Request for Continuing CNS in Present Fuel Cycle for Addl mid-cycle Msltv Leak Test Is Approved ML20147D3101978-09-29029 September 1978 Safety Evaluation Rept Supporting Amend 52 to Facil Oper Lic DPR-46 Concludes That Installation & Use of New Fuel Racks Can Be Accomplished Safety & Health & Safety of Pub Will Not Be Endangered ML20235F1591968-04-0404 April 1968 Safety Evaluation Re Facility 1999-09-30
[Table view] Category:TEXT-SAFETY REPORT
MONTHYEARML20212K9781999-09-30030 September 1999 Safety Evaluation Accepting USI A-46 Implementation Program ML20217A9931999-09-30030 September 1999 NRC Regulatory Assessment & Oversight Pilot Program, Performance Indicator Data ML20217G7461999-09-30030 September 1999 Monthly Operating Rept for Sept 1999 for Cooper Nuclear Station ML20217A1691999-09-22022 September 1999 Part 21 Rept Re Engine Sys,Inc Controllers,Manufactured Between Dec 1997 & May 1999,that May Have Questionable Soldering Workmanship.Caused by Inadequate Personnel Training.Sent Rept to All Nuclear Customers ML20212C5001999-08-31031 August 1999 Monthly Operating Rept for Aug 1999 for Cooper Nuclear Station ML20211D6491999-08-25025 August 1999 Part 21 Rept Re Nonconformance within LCR-25 safety-related Lead Acid Battery Cells Manufactured by C&D.Analysis of Cells Completed.Analysis of Positive Grid Matl Shows Nonconforming Levels of Calcium within Positive Grid Alloy ML20210R0381999-07-31031 July 1999 Monthly Operating Rept for July 1999 for Cooper Nuclear Station ML20210J2921999-07-29029 July 1999 Special Rept:On 990406,OG TS & Associated Charcoal Absorbers Were Removed from Svc.Caused by Scheduled Maint on Hpci. Evaluation of Offsite Effluent Release Dose Effects Was Performed to Ensure Plant Remained in Compliance ML20209H8281999-07-15015 July 1999 Safety Evaluation Accepting GL 95-07, Pressure Locking & Thermal Binding of Safety-Related Power-Operated Gate Valves, for Cooper Nuclear Station ML20211A9981999-07-12012 July 1999 Draft,Probabilistic Safety Assessment, Risk Info Matrix, Risk Ranking of Systems by Importance Measure ML20196H8621999-06-30030 June 1999 NRC Regulatory Assessment & Oversight Pilot Program, Performance Indicator Data, June 1999 Rept ML20209E1061999-06-30030 June 1999 Monthly Operating Rept for June 1999 for Cns.With ML20196B3851999-06-17017 June 1999 Summary Rept of Facility Changes,Test & Experiments,Per 10CFR50.59 for Period 970901-990331.Summary of Commitment Changes Made During Same Time Period Also Encl ML20195K2851999-05-31031 May 1999 Monthly Operating Rept for May 1999 for Cooper Nuclear Station.With ML20206P0481999-05-12012 May 1999 Safety Evaluation Concluding That NPP Established Acceptable Program to Verify Periodically design-basis Capability of safety-related MOVs at CNS & Adequately Addressed Actions Requested in GL 96-05 ML20206J0811999-05-0404 May 1999 Rev 14 to CNS QA Program for Operation ML20206P9751999-04-30030 April 1999 Monthly Operating Rept for Apr 1999 for Cooper Nuclear Station ML20205Q0891999-03-31031 March 1999 Monthly Operating Rept for Mar 1999 for Cooper Nuclear Station.With ML20204G8951999-03-15015 March 1999 CNS Inservice Insp Summary Rept Fall 1998 Refueling Outage (RFO-18) 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 ML20204B3701999-03-11011 March 1999 SER Accepting Third 10-year Interval Inservice Insp Plan Requests for Relief for RI-17,Rev 1 and RI-25,Rev 0.Request for Relief RI-13,Rev 2 Involving Snubber Testing & Is Being Evaluated in Separate Report ML20204C9751999-02-28028 February 1999 Monthly Operating Rept for Feb 1999 for Cooper Nuclear Station ML20199E6751999-01-14014 January 1999 Monthly Operating Rept for Dec 1998 for Cooper Nuclear Station ML20195B9191998-12-31031 December 1998 1998 NPPD Annual Rept. with ML20196J9641998-12-0707 December 1998 Safety Evaluation Accepting Licensee Third 10-yr Interval Inservice Insp Plan Request for Relief RI-27,rev 1 ML20198D2471998-11-30030 November 1998 Monthly Operating Rept for Nov 1998 for Cooper Nuclear Station.With ML20196A2861998-11-23023 November 1998 SER Re Core Spray Piping Weld for Cooper Nuclear Station. Staff Concluded That Operation During Cycle 19 Acceptable with Indication re-examined During RFO 18 ML20196A5241998-11-23023 November 1998 Safety Evaluation Accepting Proposed Alternative to Use UT Techniques Qualified to Objectives of App Viil as Implemented by PDI Program in Performing RPV Shell Weld & Shell to Flange Weld Examinations ML20196A5061998-11-23023 November 1998 Safety Evaluation Re Flaw Indication Found in Main Steam Nozzle to Shell Weld NVE-BD-N3A at Cns.Plant Can Be Safely Operated for at Least One Fuel Cycle with Indication in as-is Condition ML20196C4241998-11-20020 November 1998 Rev 1 to Cooper Nuclear Station COLR Cycle 19 ML20195H1761998-11-17017 November 1998 SER Authorizing Proposed Alternative in Relief Requests RV-06,RV-07,RV-09,RV-11,RV-12 & RV-15 Pursuant to 10CFR50.55a(a)(3)(ii).RV-08 Granted Pursuant to 10CFR50.55a(f)(6)(i) & RV-13 Acceptable Under OM-10 ML20195F8601998-10-31031 October 1998 Monthly Operating Rept for Oct 1998 for Cooper Nuclear Station.With ML20155D9961998-10-31031 October 1998 Rev 0 to GE-NE-B13-01980-24, Fracture Mechanics Evaluation on Observed Indication at N3A Steam Outlet Nozzle to Shell Weld at Cooper Nuclear Station ML20154Q5661998-10-0505 October 1998 Rev 0 to CNS COLR Cycle 19 ML20154L5381998-09-30030 September 1998 Monthly Operating Rept for Sept 1998 for Cooper Nuclear Station.With ML20151Z6141998-09-16016 September 1998 SER Accepting Util Responses to NRC Bulletin 95-002 for Cooper Nuclear Station ML20154F7931998-08-31031 August 1998 Rev 0 to J11-03354-10, Supplemental Reload Licensing Rept for CNS Reload 18,Cycle 19 ML20153B1101998-08-31031 August 1998 Monthly Operating Rept for Aug 1998 for Cooper Nuclear Station ML20237E7771998-08-20020 August 1998 Revised COLR Cycle 18 for Cooper Nuclear Station ML20151Q1211998-08-14014 August 1998 Rev 0 to Control of Hazard Barriers ML20237C0591998-07-31031 July 1998 Monthly Operating Rept for Jul 1998 for Cooper Nuclear Station ML20236R9131998-07-20020 July 1998 SER Accepting Rev 13 to Quality Assurance Program for Operation Policy Document for Plant ML20236P2971998-07-0707 July 1998 Rev 2 to NPPD CNS Strategy for Achieving Engineering Excellence ML20236R0931998-06-30030 June 1998 Monthly Operating Rept for June 1998 for Cooper Nuclear Station ML20249A7701998-05-31031 May 1998 Monthly Operating Rept for May 1998 for Cooper Nuclear Station ML20247G6131998-05-13013 May 1998 Part 21 Rept Re Defect Contained in Automatic Switch Co, Solenoid Valves,Purchased Under Purchase Order (Po) 970161. Caused by Presence of Brass Strands.Replaced Defective Valves ML20247G0951998-04-30030 April 1998 Monthly Operating Rept for Apr 1998 for Cooper Nuclear Station ML20237B6861998-04-24024 April 1998 Vols I & II to CNS 1998 Biennial Emergency Exercise Scenario, Scheduled for 980609 ML20217A1531998-04-16016 April 1998 Closure to Interim Part 21 Rept Submitted to NRC on 970929. New Date Established for Completion of Level I & 2 Setpoint Project Committed to in .Final Approval of Setpoint Calculations Will Be Completed by 980531 ML20216G5331998-03-31031 March 1998 Monthly Operating Rept for Mar 1998 for Cooper Nuclear Station 1999-09-30
[Table view] |
Text
.
[pu cs o UNITED STATES
- {. sq 'T,j NUCLE AR REGULATORY COMMISSION
.p , W4SHINGTON, D. C. 20555 k ....
j' SAFETY EVALUATION BY THE 0FFICE OF NUCLEAR REACTOP PEGULATION RELATING TO INTERIP OPERATION FOR FUEL CYCLE 11 COOPER NUCLEAR STATION NEBRASKA PUBLIC POWER DISTRICT DOCKET NO.52-298 INTRODUCTION In October 1986 Nebraska Public Power District identified 58 out of 88 supports on the suction side of the Standby Gas Treatment (SBGT) System that were structurally inadequate for seismic class I loads at the Cooper Nuclear Station.
Subsequently, the licensee also found structural deficiencies on supports in the discharge side of the SBGT system and the Control Poom Ventilation (CRV)
System. The licensee has since completed support modifications of the SBGT Suction system. The SBGT Discharge and the CRV Systems will be modified during the next refuelino outage beginning in February 1988.
In a letter dated December 5, 1986, the staff permitted interim operation of the Cooper Station for the current fuel cycle (Number 11) based on a pre-liminary review of the licensee's submittals of November 25 and December 5, 1986, that provided analyses for the effected systems against interim oper-ability criteria. This Safety Evaluation is a more detailed review of the aforementioned and other additional submittals that the staff has requested.
Although the SBGT Discharoe and the CPV Systems have not been modified at this time, the licensee has inspected both Systems to assess their interim oper-ability and is currently analyzing both systems to prepare them for modif-ication in 1988. The focus of the staff review was on: 1) the acceptability of the licensee's methodology and criteria with respect to the Updated Safety Analysis Report (USAR) comitment; and 2) the acceptable criteria for the interim operation of the SBGT Discharge and the CRV Systems.
EVALUATION i The staff reviewed 1) three sets of stress calculations of the SBGT Suction i
side for modified ductwork and supports, 2) the interim operability of the SBGT Discharge System and CRV Systems; and 3) the discussion of the seismic margin from a viewpoint of probability risk assessment.
The first set of the three calculations, Report 86140/2/F (Ref 4), provides the stress analysis for the ductwork at elevation 976'-0". The ductwork at this elevation consists of regular 12" schedule 105 piping which is within the generally accepted diameter to thickness ratio for the standard piping computer code. The ADLPIPE code was used to perform the deadweight and seismic analyses.
l The forces and moments from the deadweight and seismic analyses were combined to evaluate the supports, and the stresses were combined to determine if these
' 8703100202 070306 PDR ADOCK 05000298 P PDR
t were within the ASME cede allowables. After the support modificatinnt were completed, as-built recenciliation_ analyses were performed to determine whether the self-weicht of the modified supports affected the stresses of the ductwork..
The staff reviewed both anclyses, concentrating er 1) modeling of pipe sections compared to the ductwork isometrics, 2) modeling of concentrated weights'such .
as motors and valves, 3) seismic acceleration input, 4) pipe material proper-ties, 5) forces and moments at pipe nodal points, 6) load combinations for pire support design, and 7) stress intensificttion factors.
The second Report. 86140/2/F, set B (Ref. 5), generated the support loads for the sheetmetal fabricated ductwork sizes 36", 24", and 12" sec.tions which connect the torus and drywell penetrations to the aforementioned 12" pipe section at elevation 976'-0". The third Report. 86140/2/F (Ref. 3), calculated stresses due to deadweight, internal pressure, and seismic loads on sheetmetal ductwork. The stresses were evaluated using equivalent static beam theory.
. Because of the laroe diameter-to-thickness ratio of the sheetmetal fabriceted duct (12" to 36") and the inherent limitation of-beam theory which does not consider cross sectionel deformation, thin shell finite element models were also developed to calculate the stresses as a comparison. The staff reviewed the static beam analysis, stress calculations and the finite element analysis.
Based on the review of these three reports, the staff finds that the licensee's stress analysis methodology and stress levels in.the SBGT suction ductwork are acceptable.
At the time of the November 1986 submittals, the licensee had not performed duct or support calculations for the SBGT Discharge and CRV Systems. The licensee, however, had inspected the duct and supports to determine their structural integrity for interim operability and to compare them with that of the SBGT Suction System. The primary requirement for the operability are that
- 1) a minimum factor of safety of 2.0 must be maintained; 2) the slenderress ratio of the support steel must satisfy AISC limits; and 3) the span between vertical supports be acceptable. For the ducts, the licensee observed that the support span (about 8 feet apart) among the three systems are similar, j The SBGT Suction System analysis showed that its duct is not overstressed; i therefore, the ducts of the SBGT Discharge and CRV Systems will most likely I
not be overstressed. The stresses in the ductwork under normal conditions is due to deadweight. Under upset conditions the stresses are due to deadweight and earthquake; the pressure and thermal stresses are insignificant. Even if i the ducts are defomed in an DBE, their complete collapse or rupture would be unlikely because of the flexibility and non-linear behavior of the sheetmetal.
All three systems have similar support design; trapeze type for the vertical supports and angle beams for the lateral supports. For the SBGT Discharge t Supports, the licensee observed that 1) the Discharge Supports are of a short trapeze type with an average height less than 4 feet, hence, their slenderness l
j ratios will be acceptable; 2) the Discharge duct contributes less deadweicht i to the supports due to the smaller diameter; 3) the Discharge System has no concentrated weights such as motors or valves; and 4) a section of the duct is
! embedded in the concrete which provides additiorel three directional restraints for the system.
- The CRV ductwork is larger and heavier; therefore, to assure the structural integrity of the supports, the licensee analyzed three typical supports (Ref. ,
- 2) using the guidelines of I&E Bulletin 7c-02. The support calculations showed r
t that the stress levels are below the norraal allowables and a minicum factor cf safety cf 2.0 is most likely meintained for the Phillips Red Head (shell type) anchor bolts in teth systems. The trapere supports in the CRV System are also short; hence, their slenderness ratios are also within the AISC limits.
' Although a safety factor of 5.01s reouired for shell type anchors, the staff has pennitted interim creration of the plants of several licensees by the use of a factor of 2.0 in response to IAE bulletin 79-02. Therefore, the lictosee's interim criteria for the aforementioned anchor bolts are acceptable for the current operating cycle.
The licensee used the results of a probabilistic risk assessment argument tu show that both systems have enough seismic margin to be operable in a DBE. The measure of seismic margin is represented by the high confidence, low probab-ility of failure (HCLPF) capacity (Ref. 7). This is an esticate of seismic capacity, expressed by the fragility curves, that corresponds to a 95% con-fidence level of not exceeding a 57 chance of failure. Based on Reference 7 the HVAC systems have HCLPF capacity of at least 0.39 peek ground acceleratier (PGA). The licensee reasoned that since the ductwork at the Cooper Station is qualified for 0.29 PGA there is sufficiert margin in the seismic capacity in the SBGT and CRV systems.
CONCLUSIONS The staff concludes that the litersee's methodology in the SBGT suction analysis is based on generally acceptable engineering practice and the acceptance criteria satisfy the commitment in the Ccoper Station's USAR. The licensee has shown that for fuel cycle 11 the ductwork and supports of the existing SBGT Discharge System and CRV System satisfy the interim operability criteria and; therefore, there is reasonable assurance that system functions would not be lost should a desion basis earthquake occur. This Safety Evaluation finds interim operation is acceptable for fuel cycle 11 only. The remaining Systems should be completely modified prior to the startup of fuel cycle 12.
Principal Contributor: John Tsao Dated: March 6, 1987
N G
\' REFERENCES.
- 1. Letter, Villiam 0. Long from J. M. Pilant of Nebraska Public Power-District, November 2S, 1985 s
,'e E. .Cygna Erergy Services, " Preliminary Structural Evalbation of Main Contro.
Rocr. HVAC supports for Cooper Nuclear Station," 66140/5/F, Set B, Revisier 0,
- 3. Cygna Energy Services. " Stress Analysis", 86140/4/F set A, Revision D.
4 Cyana Energy Services, "Strucutral Evaluation of the SBGT System" 86140/2/F, set A, Revision'0.
- 5. Cygna Energy Services, " Support Evaluation," 86140/2/F, Set B, Revision 0.
- 6. Cygna Energy Services, " Seismic Evaluation Criteria and Pethodoloay,"
86140/DC-1, Revision 2.
- 7. Budnitz, R.J., et al., " An Approach to the Ouantification of Seismic Margins in Nuclear Plants," NURFC/CR-4334, Nuclear Regulatory Commission, August 1985. ,
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