ML15293A458
| ML15293A458 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 07/14/2015 |
| From: | Tennessee Valley Authority |
| To: | Japan Lessons-Learned Division |
| Wyman, Stephen, NRR/JLD 415-3041 | |
| References | |
| Download: ML15293A458 (11) | |
Text
Browns Ferry Seismic Risk Insights July 14, 2015
Outline
Background
Seismic Hazard Reevaluation Browns Ferry Improvements High Pressure Injection Seismic Capacity Browns Ferry Seismic Capacity GI-199 Risk Insights Assessment of Group 2 Plants Summary/Conclusions BROWNS FERRY SEISMIC RISK INSIGHTS l 2
=
Background===
BROWNS FERRY SEISMIC RISK INSIGHTS l 3 NTTF R2.3 Seismic Walkdowns
- Walkdown reports submitted on November 27, 2012.
- All findings resolved prior to March 2014
- For inaccessible items reported, subsequent walkdowns resulted in no findings NTTF R2.1 Seismic Hazard
- Expedited Seismic Evaluation Process submitted on December 22, 2014
- No Findings
Seismic Hazard Reevaluation BROWNS FERRY SEISMIC RISK INSIGHTS l 4 0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.1 1
10 100 Acceleration, g Frequency, Hz SSE GMRS IPEEE 0.26g IPEEE 0.30g
Browns Ferry Improvements BROWNS FERRY SEISMIC RISK INSIGHTS l 5 Seismic Capacity Improvements IPEEE outliers resolved (2) diesel auxiliary transformers replaced BFN Site Seismic Capacity > 0.3g IPEEE weakness - no high pressure injection pathway evaluated Evaluated high pressure injection path under ESEP Limiting equipment for RCIC is relays at 0.37g ESEP evaluation completed No modifications required Other Improvements FLEX Additional layer for mitigation FLEX equipment is stored in permanent structure
High Pressure Injection Seismic Capacity BROWNS FERRY SEISMIC RISK INSIGHTS l 6 RCIC Evaluation TVA Evaluated RCIC as part of ESEP-addressing NRC identified weakness in IPEEE Relays are the limiting component for RCIC, HCLPF = 0.37g RCIC is an extremely robust system.
Component (selection)
HCLPF Suction from Torus 0.69g RCIC Pump 0.85g RCIC Vacuum Pump 1.38g RCIC Turbine 0.85g Power Supply RCIC flow controller 0.62g RCIC Local Controls 0.74g RCIC Relays 0.37g
Browns Ferry Seismic Capacity BROWNS FERRY SEISMIC RISK INSIGHTS l 7 0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.1 1
10 100 Acceleration, g Frequency, Hz GMRS IPEEE and ESEP RLE 2 X SSE
GI-199 Risk Insights BROWNS FERRY SEISMIC RISK INSIGHTS l 8 SCDF estimates NRC estimate SCDF 3.5E-6 for 0.26g seismic capacity and USGS hazard (2010 GI-199 risk assessment)
TVA estimate SCDF 3.9E-6 for 0.3g seismic capacity and BFN GMRS 0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.1 1
10 100 Acceleration, g Frequency, Hz GMRS 2008 USGS Hazard (GI-199)
Assessment of Group 2 Plants BROWNS FERRY SEISMIC RISK INSIGHTS l 9 Seismic Hazard Aspect BFN results GMRS/SSE Ratio in 1 to 10 Hz 2.0 2.15 @ 10 Hz GMRS Peak Spectral Acceleration 0.58g @ 25 Hz R2.3 Walkdown reviews and inspections No significant findings; all minor findings promptly resolved IPEEE seismic plant capacity insights Minimum HCLPF > 0.30g Expedited Seismic Evaluation Process No findings GI-199 / Risk Insights for new hazard Low estimated seismic CDF
Summary/Conclusions
- Updated Hazard SCDF Risk 3.9E-6 BROWNS FERRY SEISMIC RISK INSIGHTS l 10
Browns Ferry Seismic Risk Insights July 14, 2015
Outline
Background
Seismic Hazard Reevaluation Browns Ferry Improvements High Pressure Injection Seismic Capacity Browns Ferry Seismic Capacity GI-199 Risk Insights Assessment of Group 2 Plants Summary/Conclusions BROWNS FERRY SEISMIC RISK INSIGHTS l 2
=
Background===
BROWNS FERRY SEISMIC RISK INSIGHTS l 3 NTTF R2.3 Seismic Walkdowns
- Walkdown reports submitted on November 27, 2012.
- All findings resolved prior to March 2014
- For inaccessible items reported, subsequent walkdowns resulted in no findings NTTF R2.1 Seismic Hazard
- Expedited Seismic Evaluation Process submitted on December 22, 2014
- No Findings
Seismic Hazard Reevaluation BROWNS FERRY SEISMIC RISK INSIGHTS l 4 0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.1 1
10 100 Acceleration, g Frequency, Hz SSE GMRS IPEEE 0.26g IPEEE 0.30g
Browns Ferry Improvements BROWNS FERRY SEISMIC RISK INSIGHTS l 5 Seismic Capacity Improvements IPEEE outliers resolved (2) diesel auxiliary transformers replaced BFN Site Seismic Capacity > 0.3g IPEEE weakness - no high pressure injection pathway evaluated Evaluated high pressure injection path under ESEP Limiting equipment for RCIC is relays at 0.37g ESEP evaluation completed No modifications required Other Improvements FLEX Additional layer for mitigation FLEX equipment is stored in permanent structure
High Pressure Injection Seismic Capacity BROWNS FERRY SEISMIC RISK INSIGHTS l 6 RCIC Evaluation TVA Evaluated RCIC as part of ESEP-addressing NRC identified weakness in IPEEE Relays are the limiting component for RCIC, HCLPF = 0.37g RCIC is an extremely robust system.
Component (selection)
HCLPF Suction from Torus 0.69g RCIC Pump 0.85g RCIC Vacuum Pump 1.38g RCIC Turbine 0.85g Power Supply RCIC flow controller 0.62g RCIC Local Controls 0.74g RCIC Relays 0.37g
Browns Ferry Seismic Capacity BROWNS FERRY SEISMIC RISK INSIGHTS l 7 0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.1 1
10 100 Acceleration, g Frequency, Hz GMRS IPEEE and ESEP RLE 2 X SSE
GI-199 Risk Insights BROWNS FERRY SEISMIC RISK INSIGHTS l 8 SCDF estimates NRC estimate SCDF 3.5E-6 for 0.26g seismic capacity and USGS hazard (2010 GI-199 risk assessment)
TVA estimate SCDF 3.9E-6 for 0.3g seismic capacity and BFN GMRS 0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.1 1
10 100 Acceleration, g Frequency, Hz GMRS 2008 USGS Hazard (GI-199)
Assessment of Group 2 Plants BROWNS FERRY SEISMIC RISK INSIGHTS l 9 Seismic Hazard Aspect BFN results GMRS/SSE Ratio in 1 to 10 Hz 2.0 2.15 @ 10 Hz GMRS Peak Spectral Acceleration 0.58g @ 25 Hz R2.3 Walkdown reviews and inspections No significant findings; all minor findings promptly resolved IPEEE seismic plant capacity insights Minimum HCLPF > 0.30g Expedited Seismic Evaluation Process No findings GI-199 / Risk Insights for new hazard Low estimated seismic CDF
Summary/Conclusions
- Updated Hazard SCDF Risk 3.9E-6 BROWNS FERRY SEISMIC RISK INSIGHTS l 10