ML081580553

Summary of 5/22/08 Meeting Regarding Containment Overpressure Portion of the Extended Power Uprate Review - Browns Ferry - Handouts

ML081580553
Person / Time
Site:	Browns Ferry
Issue date:	05/22/2008
From:	Tennessee Valley Authority
To:	Office of Nuclear Reactor Regulation
Brown E, NRR/DLPM 415-2315
Shared Package
ML082040084	List: ML081580553 ML082040065
References
TAC MD5262, TAC MD5263, TAC MD5264
Download: ML081580553 (22)

Text

TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT EXTENDED POWER UPRATE CREDIT FOR CONTAINMENT OVERPRESSURE ACRS CONCERNS Rockville, Maryland May 22, 2008

MEETING PURPOSE

" Review ACRS Concerns - COP

" TVA Approach to ACRS Concerns

" Present BFN Realistic Fire Analysis

" Dry Run ACRS Presentation N-2

ACRS CONCERNS

" Staff ACRS Presentation - COP Satisfactory -

EPU

• February 16, 2007 ACRS Letter COP Concerns

- Too Much - Too Long for Appendix R

- More Defensible Sensitivity Calcs - Long Term LOCA

- Feasibility of Protecting Additional RHR Pump

- Risk-Informed Arguments for Appendix R Should Consider External Initiators

• COP Credit for LOCA, ATWS and SBO Acceptable N-3

APPROACH to ACRS CONCERNS

• Licensing Basis Analysis Complies with Rule

- No Change to Licensing Basis Appendix R

- No Change to EPU Licensing Basis Calculations

" Show Risk of COP is Low

- Use Realistic Deterministic Analysis vs. PRA

- Similar to Information Provided for LOCA, ATWS and SBO N-4

REALISTIC FIRE ANALYSIS Fire Hazards Analysis

- Consistent with Guidance Documents

- NRC Manual Chapter 0609, Appendix F

- NUREG/CR - 6850

- NEI-00-01

- IPEEE FIVE 23 of 39 Fire Areas Screen Out o 16 Areas + Control Room Evaluated Further Available Equipment and Operator Actions o Current EOI Procedures o COP Not Needed in 15 of 17 Fire Areas N-5

REALISTIC FIRE ANALYSIS Containment Response Analysis - Limiting Case

- Applies to 2/39 Fire Areas o Electrical Board Rooms

- Reactor Emergency Depressurization

- 1 RHR Pump Used for Pool Cooling

- BOP Pumps Used for Core Cooling

- RHR Alternate Shutdown Cooling Not Used

- Revised Vendor NPSH Requirement o Constant 17 Ft for Appendix R duration 70 Hours N-6

I I VIA TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT POWER UPRATE ACRS CONTAINMENT OVERPRESSURE Rockville, Maryland Xxxxxx xx, xxxx

IIVAI BFN Licensing History

• Credit for containment overpressure for 105%

OLTP

- LOCA - NRC Bulletin 96-03

- Currently for RHR pumps short-term (< 10 min.)

- Currently for core spray pumps long-term (> 10 min.)

- Credit for COP in Appendix R N-8

BFN ECCS Schematic N-9

NPSH Licensing Basis Analysis EP_.J

• Four events need COP

- LOCA

- ATWS

- SBO

- Appendix R Fire N-10

IM Effect of Power Uprate

• Increase in suppression pool temperature

• LOCA peak suppression pool temperature o 100% OLTP a 177°F o 105% OLTP o 177 to 180°F (dependent on UHS TS limits) o 120% OLTP o3 1870F N-11

NPSH Licensing 1jW Basis Analysis Elements of NPSH analysis:

" Suppression pool temperature profile

" Elevation head

" ECCS pump flows

• Suction path pressure drop

- Suction piping

- Suction strainer blockage and losses

" Required NPSH

" Wetwell pressure N-12

NPSH Licensing Basis Analysis

• LOCA short term (< 10 min.)

4 core spray pumps at maximum system flow 2 RHR pumps at design LPCI flow to intact recirculation loop 2 RHR pumps at maximum system flow to broken loop Debris loading on strainers RHR and core spray pumps need COP

• LOCA long term (> 10 min.)

2 core spray pumps at design flow 2 RHR pumps at containment cooling flow Debris loading on strainers Core spray pumps need COP N-13

COP Available and COP Required Long-Term LOCA Analysis 200 22 190 Containment 20 180Temperature 18 170 160-CS Pump Containment I6 15 Pressure Required Atmospheric Pressure 14 140 13-RHR Pump ContainmentI Pressure Required I

120--

10 0

4 8

12 16 20 24 Time (hours)

N-14

NPSH Licensing Basis Analysis

• Appendix R Fire

- 1 RHR pump injecting to vessel

- No strainer debris

- RHR pump needs COP N-15

COP Available and COP Required Appendix R Fire Analysis 30 220 Suppression Pool Tempe rature 200 25 180 160 Required 140 15 Atmospheric Pressure 120 100 10 0

10 20 30 40 50 60 Time (hours)

N-16

Realistic NPSH Analysis COP Meets Five Principles of Regulatory Guide 1.174

" Meets current regulations

" Consistent with defense-in-depth philosophy

" Maintains sufficient safety margins

" Results in very small risk increase

" Impact is monitored N-17

Realistic NPSH Analysis PSA model for LOCA, ATWS and SBO

• Probability distribution for suppression pool temperature

" River temperature

• Initial suppression pool temperature

" Suppression pool water level

" Initial power level

" Containment failure and containment leakage probability

• Dependence of ECCS on COP vs. No Dependence

• Very Small Risk Increase for LOCA, ATWS and SBO

• ACDF/ALERF 2.4E-8/yr Well within acceptance guidelines for ACDF and ALERF N-18

REALISTIC FIRE ANALYSIS Fire Hazards Analysis 23/39 Fire Areas Screened Out o No Fire Damage o 16 Areas + Control Room Evaluated Further Available Equipment and Operator Actions Identified o Current EOI Procedures o 15/17 Areas Do Not Need COP 2 Areas Require Some COP - Limiting Case o 1 RHR PUMP/Heat Exchanger for Containment Cooling o BOP Pumps for Core Cooling o Significant COP Margin Available N-19

NPSH Licensing Basis Analysis IM 240 40 35 220 200 -

I.

180 160 140 120 100 30 25 20 15 10 5

0 10 20 30 40 50 Time, Hours 60

-Suppression Pool Temperature (realistic)

RHR pump required wetwell pressure (realistic)

-wetwell pressure (realistic)

N-20

Realistic NPSH Analysis

• COP only required for LOCA with specific single failures

° COP not required for ATWS with best estimate code

• Small amount of COP required for Fire Event in warm weather

• COP not required for station blackout for 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> vs.

4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> coping duration N-21

Summary

" Licensing basis NPSH analyses are conservative

" Overpressure credit in-line with industry

" Realistic analyses show reduced or no dependency on COP

" Very low risk following ACRS guidance N-22