ML15293A458

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Slides for July 14, 2015 Public Meeting on Browns Ferry Seismic Risk Evaluations (MF3764 Through MF3766)
ML15293A458
Person / Time
Site: Browns Ferry  Tennessee Valley Authority icon.png
Issue date: 07/14/2015
From:
Tennessee Valley Authority
To:
Japan Lessons-Learned Division
Wyman, Stephen, NRR/JLD 415-3041
References
Download: ML15293A458 (11)
v • d • e


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

  • Walkdown reports submitted on November 27, 2012.

NTTF R2.3

  • All findings resolved prior to March 2014 Seismic
  • For inaccessible items reported, subsequent Walkdowns walkdowns resulted in no findings NTTF R2.1
  • Hazard Reevaluation submitted on March 31, Seismic 2014 Hazard
  • Expedited Seismic Evaluation NTTF R2.1 Process submitted on ESEP December 22, 2014
  • No Findings BROWNS FERRY SEISMIC RISK INSIGHTS l 3

Seismic Hazard Reevaluation 0.7 0.6 0.5 Acceleration, g 0.4 SSE GMRS 0.3 IPEEE 0.26g IPEEE 0.30g 0.2 0.1 0

0.1 1 10 100 Frequency, Hz BROWNS FERRY SEISMIC RISK INSIGHTS l 4

Browns Ferry Improvements 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 BROWNS FERRY SEISMIC RISK INSIGHTS l 5

High Pressure Injection Seismic Capacity RCIC Evaluation Component (selection) HCLPF

  • TVA Evaluated RCIC as part of ESEP- addressing Suction from Torus 0.69g NRC identified weakness in IPEEE RCIC Pump 0.85g
  • Relays are the limiting RCIC Vacuum Pump 1.38g component for RCIC, RCIC Turbine 0.85g HCLPF = 0.37g Power Supply RCIC flow 0.62g
  • RCIC is an extremely controller robust system.

RCIC Local Controls 0.74g RCIC Relays 0.37g BROWNS FERRY SEISMIC RISK INSIGHTS l 6

Browns Ferry Seismic Capacity 0.7 0.6 0.5 Acceleration, g 0.4 GMRS 0.3 IPEEE and ESEP RLE 2 X SSE 0.2 0.1 0

0.1 1 10 100 Frequency, Hz BROWNS FERRY SEISMIC RISK INSIGHTS l 7

GI-199 Risk Insights 0.7 SCDF estimates 0.6 NRC estimate SCDF 3.5E-6 for 0.26g 0.5 seismic capacity and Acceleration, g 0.4 USGS hazard (2010 GMRS GI-199 risk 0.3 assessment) 2008 USGS Hazard (GI-199) 0.2 TVA estimate SCDF 3.9E-6 for 0.3g 0.1 seismic capacity and 0

BFN GMRS 0.1 1 10 100 Frequency, Hz BROWNS FERRY SEISMIC RISK INSIGHTS l 8

Assessment of Group 2 Plants 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 BROWNS FERRY SEISMIC RISK INSIGHTS l 9

Summary/Conclusions

  • Seismic Capacity Improvements

- IPEEE outliers and weakness resolved

- HCLPF = 0.3g

  • 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

  • Walkdown reports submitted on November 27, 2012.

NTTF R2.3

  • All findings resolved prior to March 2014 Seismic
  • For inaccessible items reported, subsequent Walkdowns walkdowns resulted in no findings NTTF R2.1
  • Hazard Reevaluation submitted on March 31, Seismic 2014 Hazard
  • Expedited Seismic Evaluation NTTF R2.1 Process submitted on ESEP December 22, 2014
  • No Findings BROWNS FERRY SEISMIC RISK INSIGHTS l 3

Seismic Hazard Reevaluation 0.7 0.6 0.5 Acceleration, g 0.4 SSE GMRS 0.3 IPEEE 0.26g IPEEE 0.30g 0.2 0.1 0

0.1 1 10 100 Frequency, Hz BROWNS FERRY SEISMIC RISK INSIGHTS l 4

Browns Ferry Improvements 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 BROWNS FERRY SEISMIC RISK INSIGHTS l 5

High Pressure Injection Seismic Capacity RCIC Evaluation Component (selection) HCLPF

  • TVA Evaluated RCIC as part of ESEP- addressing Suction from Torus 0.69g NRC identified weakness in IPEEE RCIC Pump 0.85g
  • Relays are the limiting RCIC Vacuum Pump 1.38g component for RCIC, RCIC Turbine 0.85g HCLPF = 0.37g Power Supply RCIC flow 0.62g
  • RCIC is an extremely controller robust system.

RCIC Local Controls 0.74g RCIC Relays 0.37g BROWNS FERRY SEISMIC RISK INSIGHTS l 6

Browns Ferry Seismic Capacity 0.7 0.6 0.5 Acceleration, g 0.4 GMRS 0.3 IPEEE and ESEP RLE 2 X SSE 0.2 0.1 0

0.1 1 10 100 Frequency, Hz BROWNS FERRY SEISMIC RISK INSIGHTS l 7

GI-199 Risk Insights 0.7 SCDF estimates 0.6 NRC estimate SCDF 3.5E-6 for 0.26g 0.5 seismic capacity and Acceleration, g 0.4 USGS hazard (2010 GMRS GI-199 risk 0.3 assessment) 2008 USGS Hazard (GI-199) 0.2 TVA estimate SCDF 3.9E-6 for 0.3g 0.1 seismic capacity and 0

BFN GMRS 0.1 1 10 100 Frequency, Hz BROWNS FERRY SEISMIC RISK INSIGHTS l 8

Assessment of Group 2 Plants 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 BROWNS FERRY SEISMIC RISK INSIGHTS l 9

Summary/Conclusions

  • Seismic Capacity Improvements

- IPEEE outliers and weakness resolved

- HCLPF = 0.3g

  • Updated Hazard SCDF Risk

- 3.9E-6 BROWNS FERRY SEISMIC RISK INSIGHTS l 10

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