ML15126A406
| ML15126A406 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 05/12/2015 |
| From: | Doyle G Tennessee Valley Authority |
| To: | Plant Licensing Branch II |
| Saba F DORL/LPL2-2 301-415-1447 | |
| References | |
| Download: ML15126A406 (17) | |
Text
Browns Ferry Nuclear Plant Extended Power Uprate License Amendment Request Containment Accident Pressure Credit Elimination Gerry Doyle Director EPU May 12, 2015
BFN EPU - Agenda Browns Ferry EPU License Amendment Request CAP Credit Elimination
Introductions
OverviewandSchedule ContainmentAccidentPressure(CAP)CreditElimination Questions/Comments G.Doyle G.Doyle D.Green/P.
Donahue G.Doyle l 2
BFN EPU - Overview and Schedule Browns Ferry EPU License Amendment Request CAP Credit Elimination
- New consolidated Browns Ferry Extended Power Uprate (EPU) License Amendment Request (LAR) submittal SupersedespreviousBrownFerryEPUsubmittals AddressescurrentBrownsFerryconditionsandlicensingbasis(e.g.,
AREVAATRIUM10XMfueltype)
UsestheformatofRS001,ReviewStandardforExtendedPower Uprates AddressespreviousapplicableNRCRequestsforAdditional Information(RAIs)
Appliesimprovedsubmittalverificationprocesstoensure completenessandaccuracy l 3
BFN EPU - Overview and Schedule Browns Ferry EPU License Amendment Request CAP Credit Elimination l 4
BFN EPU - Overview and Schedule Browns Ferry EPU License Amendment Request CAP Credit Elimination Weareheretopresentanddiscussourpositionforaddressing EmergencyCoreCoolingSystem(ECCS)pumpNetPositive SuctionHead(NPSH)analysesandCAPcrediteliminationissues inordertoprecludeimpacttotheBrownsFerryEPULARreview
- EPUNPSHanalysesdevelopedconsistentwithexistingguidance IncludesconsiderationoftheguidanceprovidedinSECY110014,Use ofContainmentAccidentPressureinAnalyzingEmergencyCore CoolingSystemandContainmentHeatRemovalSystemPump PerformanceinPostulatedAccidents PreviousBrownsFerryEPULARs(nowwithdrawn)includedCAPcredit CAPwillnotbecreditedinthenewEPULAR l 5
BFN EPU - CAP Credit Elimination
Background
June 2004 TVA submits EPU LARs for BFN Units 2/3 and Unit 1 February 2007 ACRS first raises concerns with BFN crediting Containment Accident Pressure (CAP)
August 2007 -
August 2009 TVA responds to 89 NRC Requests for Additional Information regarding crediting CAP September 2009 NRC letter to TVA indicates additional time is needed to develop additional guidance to address EPU issues with CAP December 2010 During meeting with NRC, TVA discusses actions taken to address CAP issue at BFN Analysis performed using NRC draft guidance to identify and evaluate strategies to address CAP for all events May 2011 NRC letter to TVA indicates that CAP review criteria (SECY-11-0014) was available and that NRC was prepared to resume review of EPU LARs September 2011 During meeting with NRC, TVA discussed plans to eliminate credit for CAP in the EPU LAR NRC recommended that licensees preparing to apply draft guidance should communicate with NRC prior to preparing written documentation so that the most current position on the guidance can be incorporated November 2012 TVA letter to NRC provides status of EPU LARs Includes status of revision to EPU CAP analysis to incorporate criteria in SECY-11-0014 Indicates that prior to submittal of results of the CAP analysis, TVA will request meeting with NRC to discuss the plans for evaluation of CAP February 2013 TVA letter to NRC states plan to revise CAP analysis, complete replacement steam dryer analysis, and revise the BFN EPU LARs, as necessary February 2014 Due to lack of activity associated with BFN EPU LARs, NRC closes BFN EPU LAR TAC numbers June 2014 During drop-in visit with NRC, TVA introduced new EPU Project Team and discussed strategy with BFN Project Manager, EPU PM and Branch Chief Stated new consolidated LAR would include resolution of CAP issues in accordance with SECY-11-0014 September 2014 TVA letter to NRC withdrew previous EPU LARs Stated new consolidated EPU LAR would be submitted in October 2015 and would include revised CAP analysis that incorporates current NRC review criteria Stated upon completion of the revised EPU CAP analysis, TVA will propose meeting with NRC to discuss analysis and results
Browns Ferry EPU License Amendment Request CAP Credit Elimination l 6
Regulatory Alignment Current Licensing Basis Browns Ferry currently credits CAP Regulatory Guide 1.82, Water Sources for Long-Term Recirculation Cooling Following a Loss-of-Coolant Accident For EPU, analyses follow Constant Pressure Power Uprate (CPPU) Licensing Topical Report (NEDC-33004P, Constant Pressure Power Uprate) guidance RS-001 (Section 2.6.5) guidance NRC draft guidance on CAP per SECY-11-0014 NRC communication that 21% uncertainty margin is acceptable in lieu of a plant specific uncertainty evaluation Reference Turkey Point EPU - Containment and Ventilation Branch (SCVB) Request for Additional Information - Round 1.2 (Part 2), SCVB-1.2.4 (ML11119A002)
BFN EPU - CAP Credit Elimination Browns Ferry EPU License Amendment Request CAP Credit Elimination l 7
Methodology In accordance with Regulatory Guide 1.82 Used NRC approved codes SHEX ODYN/STEMP for Anticipated Transients Without Scram (ATWS) analysis Event Type (per SECY-11-0014)
Event Description Pumps Credited in Limiting Analysis RHR CS HPCI RCIC Design Basis Accident (DBA)-
Loss-of-Coolant Accident (LOCA)
Short-term (first 10 minutes)
Yes Yes No No Long-term (beyond 10 minutes)
Yes Yes No No Special Events Fire Event Yes No No No ATWS Yes No Yes Yes Station Blackout (SBO)
Yes No Yes Yes Event-specific Net Positive Suction Head Available (NPSHa) time history developed for each credited pump NPSHa compared to Net Positive Suction Head Required (NPSHr) for each credited pump BFN EPU - CAP Credit Elimination Browns Ferry EPU License Amendment Request CAP Credit Elimination l 8
Key Changes/Modifications Events DBA-LOCA Short-Term (0 - 10 minutes)
Included ECCS pump suction ring header and Residual Heat Removal (RHR) piping volumes NPSHr 3% curves (RHR and CS) + 21% uncertainty ECCS pump flow rates are from safety analysis (ECCS performance - fuel)
DBA-LOCA Long-Term (beyond 10 minutes)
More accurate RHR HX fouling NPSHr 3% curves (RHR and CS) + 21% uncertainty SBO More accurate RHR HX fouling NPSHr 3% curves (RHR)
ATWS (Peak Suppression Pool Temperature)
Increase Standby Liquid Control (SLC) System Boron Enrichment More accurate RHR HX fouling NPSHr 3% curves (RHR)
Fire Event Nominal RHR HX fouling Nominal initial suppression pool volume (level)
NPSHr 3% curves (RHR)
BFN EPU - CAP Credit Elimination Browns Ferry EPU License Amendment Request CAP Credit Elimination l 9
Key Assumptions DBA-LOCA Vendor supplied NPSHr (3%) curves 21% uncertainty included in NPSH margin per SECY-11-0014 Conservative Technical Specification (TS) inputs TS maximum initial suppression pool temperature TS maximum Residual Heat Removal Service Water (RHRSW)
(river water) temperature TS minimum initial suppression pool volume (level)
Modified design RHR Heat Exchanger (HX) Heat Removal Capability BFN EPU - CAP Credit Elimination Browns Ferry EPU License Amendment Request CAP Credit Elimination l 10
Key Assumptions (continued)
Non-LOCA events Vendor supplied NPSHr (3%) curves 0% uncertainty included in NPSH margin per SECY-11-0014 ATWS and SBO Conservative TS inputs TS maximum initial suppression pool temperature TS maximum RHRSW (river water) temperature TS minimum initial suppression pool volume (level)
Modified design RHR HX Heat Removal Capability Fire Event Conservative TS inputs TS maximum initial suppression pool temperature TS maximum RHRSW (river water) temperature Nominal initial suppression pool volume (torus level) per SECY-11-0014 Nominal RHR HX heat removal capability (HX K value) per SECY-11-0014 BFN EPU - CAP Credit Elimination Browns Ferry EPU License Amendment Request CAP Credit Elimination l 11
RHR HX Fouling RHR HX K value used in containment analyses Current Licensed Thermal Power (CLTP) analysis basis: 223 Btu/sec/°F EPU analysis basis:
265 Btu/sec/°F Corresponding RHR HX Fouling Resistance Original Design:
0.002801 hr-ft2-°F/Btu EPU Design:
0.001521 hr-ft2-°F/Btu (preliminary)
Different events may have heat exchanger flow rates different from the base case Where that occurs, the EPU modified design fouling resistance is maintained constant and an event specific K value is calculated A common (EPU design) material condition is thereby the basis for the RHR HX K value used in each event The only event using a nominal RHR HX K value (as allowed by SECY 0014) is the Fire Event All other events were conservatively analyzed using a K value based on the EPU design fouling resistance BFN EPU - CAP Credit Elimination Browns Ferry EPU License Amendment Request CAP Credit Elimination l 12
Lower RHR HX fouling resistance capability maintained by the Generic Letter 89-13 Program Performance tests performed on four RHR HXs support using the lower fouling resistance RHR HXs were selected for testing based on longest time between cleaning and worst case macro fouling observations Industry operating experience Similar plant RHR HX configuration and design incorporated lower fouling factors to support elimination of crediting CAP BFN EPU - CAP Credit Elimination Browns Ferry EPU License Amendment Request CAP Credit Elimination l 13
Preliminary Results Event / Pump RHR HX K value PPT
(°F)
NPSHa (ft)
NPSHreff (ft)1 Margin (ft)
DBA-LOCA Short-Term / RHR N/A 152.0 26.6 21.8 4.8 DBA-LOCA Short-Term / CS 27.0 24.2 2.8 DBA-LOCA Long-Term / RHR 265 178.9 28.8 20.6 8.2 DBA-LOCA Long-Term / CS 26.2 24.2 2.0 SBO / RHR 265 203.7 18.0 17.0 1.0 ATWS / RHR 277 173.3 31.3 17.0 14.3 Fire Event / RHR 307 208.2 16.04 16.0 0.04 SBO, ATWS / High Pressure Coolant Injection (HPCI)
N/A2 N/A2 63.0 18.8 44.2 SBO, ATWS / Reactor Core Isolation Cooling (RCIC)
N/A2 N/A2 75.1 22.7 52.4 Notes:
- 1. NPSHreffective (eff) values consistent with SECY-11-0014 draft guidance (NPSHreff = NPSHr 3% +
uncertainties), includes 21% uncertainty adder for DBA-LOCA Cases and 0% adder for Special Events (per SECY-11-0014)
- 2. Suction for HPCI and RCIC pumps from Condensate Storage Tank BFN EPU - CAP Credit Elimination Browns Ferry EPU License Amendment Request CAP Credit Elimination l 14
Preliminary Results (continued)
Fire Event Sensitivity study being performed to provide defense-in-depth for CAP margin Utilizing new NFPA 805 Emergency High Pressure Makeup Pump to increase Suppression Pool water level and NPSH RHR pump NPSH margin improved BFN EPU - CAP Credit Elimination Browns Ferry EPU License Amendment Request CAP Credit Elimination l 15
BFN EPU - Acronyms Browns Ferry EPU License Amendment Request CAP Credit Elimination l 16 N/A - Not applicable NFPA - National Fire Protection Association NPSH - Net Positive Suction Head NPSHa - Net Positive Suction Head Available NPSHr - Net Positive Suction Head Required PPT - Peak Suppression Pool Temperature RCIC - Reactor Core Isolation Cooling RDLB - Recirculation Discharge Line Break RHR - Residual Heat Removal RHRSW - Residual Heat Removal Service Water RSLB - Recirculation Suction Line Break SCVB - Containment and Ventilation Branch sec - second SLC - Standby Liquid Control TS - Technical Specifications ATWS - Anticipated Transient Without Scram BTU - British Thermal Unit CAP - Containment Accident Pressure CLTP - Current Licensed Thermal Power CPPU - Constant Pressure Power Uprate CS - Core Spray DBA - Design Basis Accident ECCS - Emergency Core Cooling System eff - effective EPU - Extended Power Uprate F - Farenheit ft - feet gpm - gallons per minute HCTL - Heat Capacity Temperature Limit HPCI - High Pressure Coolant Injection hr - hour HX - Heat Exchanger LAR - License Amendment Request LOCA - Loss-of-Coolant Accident LPCI - Low Pressure Coolant Injection LTR - Licensing Topical Report
BFN EPU - Questions/Comments Browns Ferry EPU License Amendment Request CAP Credit Elimination l 17