ML14182A099

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July 1, 2014 Public Meeting Slides TVA - NTTF 2.1 - Seismic Reevaluation - GMRS
ML14182A099
Person / Time
Site: Watts Bar  Tennessee Valley Authority icon.png
Issue date: 07/01/2014
From:
Tennessee Valley Authority
To:
Office of Nuclear Reactor Regulation
Balazik M, NRR/JLD, 415-2856
References
Download: ML14182A099 (40)
v • d • e


Text

Information Exchange WBN Seismic Hazard 1

Information Exchange WBN Seismic Hazard

  • NRC May 9 Prioritization Letter

- Seismic Risk Evaluation

  • Prioritization Group 1

- WBN Acknowledges

  • Prioritization Group 1
  • Seismic risk evaluation by June 30, 2017
  • NRC May 21 Support Document

- Preliminary graphical representation

  • NRC staff GMRS differs from Licensee GMRS 2

Information Exchange WBN Seismic Hazard EPRI Maximum:

0.77g @ 15 Hz NRC Maximum:

0.98 @ 30 Hz 3

Information Exchange WBN Seismic Hazard

  • WBN understanding of the causes of the primary differences between the preliminary NRC and licensee results.
  • Elements of NRC staff preliminary assessment
  • FSAR primary source for information on subsurface materials

- narrower velocity profile

>> 4,500 fps lower

>> 6,500 fps upper

- Hard rock at 1,000 ft.

  • Use of EPRI rock curves and low strain damping values
  • Kappa Values and weights 4

Information Exchange WBN Seismic Hazard

  • WBN additional data for subsurface materials
  • Expand site geologic profile due to current understanding of hard rock characteristics - shear wave velocity > 9200 fps.
  • Reduce uncertainty throughout profile to basement >

10,000 ft.

  • Support Development of Seismic Hazard input for SPRA 5

Information Exchange WBN Seismic Hazard

  • Utilized Academic/Industry Expertise

- AMEC - Program Management; regional / local geology

- Dr. Robert Hatcher, Professor of Geology, University of Tennessee -

Knoxville

>> Regional / local geology

- Dr. Ken Stokoe, Professor of Civil Engineering, University of Texas -

Austin

>> Spectra Analysis Surface Wave (SASW) Survey

>> Rock Testing

- Ivan Wong (URS) and

>> Seismic Hazard & Evaluation of SASW / Rock Testing

- Walt Silva (PE&A)

>> Site Modeling/Characterization

- Facility Risk Consultants

>> 3rd party seismic consultant review 6

Information Exchange WBN Seismic Hazard Source: AMEC (2013) 7

Information Exchange WBN Seismic Hazard 8

Information Exchange WBN Seismic Hazard 9

Information Exchange WBN Seismic Hazard 10

Information Exchange WBN Seismic Hazard

  • SASW Survey (8 test sites)

- Sites 6 & 7 profiled depths of approx. 1400 and 1700

- SASW Team believes results from Site 8 would have been similar had sufficient lateral space been available for a longer survey line.

- Achieving profile depths of 14001700 is uncommonly good results for SASW survey!

  • Rock Testing

- 6 Intact Rock Cores (URC freefree unconfined resonant column tests)

- Pumpkin Valley Shale (2), Consauga Middle, Pond Springs Formation, Nolichucky Shale, and Rome Formation 11

Information Exchange WBN Seismic Hazard Source: AMEC (2013) 12

Information Exchange WBN Seismic Hazard

  • Benefits Derived from SASW Survey / Rock Testing

- Provided shearwave velocity data for important geologic formations beneath the site

- Captured the variability in shearwave velocity beneath the site

- Provided sitespecific measurements which reduced the epistemic uncertainty in the profiles (1.25 where appropriate)

- Demonstrates that assumptions of shearwave velocities from the type of rock would have been misleading. For example, it was surprising that the Rome sandstone was as fast as it was and the dolomite slower than was thought. No substitute for real data!

- SASW measurements were performed to a depth up to 1700 ft right next to the reactor, some of the deepest measurements taken in the central and eastern US.

13

Information Exchange WBN Seismic Hazard Base Case 600 Lower Bound 600 Upper Bound 592 Base Case 936 Lower Bound 936 Upper Bound 936 Figure 2.3.21 Shearwave velocity profiles for Watts Bar Nuclear Plant (EPRI, 2014) 14

Information Exchange WBN Seismic Hazard

  • Development Of Total Effective Kappa

- Following SPID Guidelines For Firm Rock Profile <

3,000 ft Deep

- Total Effective Kappa Based on Firm Rock Damping of 1.25% (QS = 40)

- Plus Hard Rock Contribution 0.006s

  • Uncertainty In Depth To Hard Rock Accommodated With Two Mean Depths 600 ft, 900 ft

- Results In Six Kappa Estimates For BaseCase, Upper Range, LowerRange Profiles and Two Depths to Hard Rock 15

Information Exchange WBN Seismic Hazard

  • Epistemic Uncertainty In BaseCase VS Profiles Of 1.25 Results In Narrow Range Of Kappa

- Following SPID Guidelines, Epistemic Uncertainty In Kappa Taken as ln 0.4 About Mean Estimate

- Shallow Profile 0.012s +/- , range 0.007s to 0.020s

- Deep Profile 0.013s +/- , range 0.008s to 0.022s 16

Information Exchange WBN Seismic Hazard

  • Summary

- Watts Bar developed a significantly enhanced site geological profile to support site characterization

- Supplemented by SASW survey to provide additional clarity for strata above Top of Hard Rock

- Accounts for variation in the top of the Rome Formation underlying WBN

- Rock testing of 6 intact cores to determine parameters for site characterization

- Site characterization and EPRI GMRS performed in conformance with SPID and is appropriate characterization of seismic hazard for Watts Bar site.

17

Information Exchange SQN Seismic Hazard 1

Information Exchange SQN Seismic Hazard

  • NRC May 9 Prioritization Letter

- Seismic Risk Evaluation

  • Prioritization Group 2

- SQN Acknowledges

  • Prioritization Group 2
  • Seismic risk evaluation by December 31, 2019
  • NRC May 21 Support Document

- Preliminary graphical representation

  • NRC staff GMRS differs from Licensee GMRS 2

Information Exchange SQN Seismic Hazard EPRI Maximum SA:

0.76g @ 20 Hz NRC Maximum SA:

0.84g @ 40 Hz 3

Information Exchange SQN Seismic Hazard

  • SQN understanding of the causes of the primary differences between the preliminary NRC and licensee results.
  • Elements of NRC staff preliminary assessment
  • Velocity profile
  • Use of EPRI rock curves and low strain damping values
  • Kappa Values and weights 4

Information Exchange SQN Seismic Hazard

  • SQN additional data for subsurface materials
  • Expand site geologic profile due to current understanding of hard rock characteristics - shear wave velocity > 9200 fps.
  • FSAR had limited rock characteristics data available at depth (> 103 ft)
  • Definition of rock profile to basement 12,000 ft.

Information Exchange SQN Seismic Hazard

  • Utilized Academic/Industry Expertise

- AMEC - Program Management; regional / local geology

- Dr. Robert Hatcher, Professor of Geology, University of Tennessee

- Knoxville

>> Regional / local geology

- Dr. Ken Stokoe, Professor of Civil Engineering, University of Texas

- Austin

>> Spectra Analysis Surface Wave (SASW) Survey @ WBN

>> Rock Testing

- Ivan Wong (URS)

>> Site Modeling/Characterization 6

Information Exchange SQN Seismic Hazard Source: AMEC (2013) 7

Information Exchange SQN Seismic Hazard Vs profiles for Sequoyah Site Vs (ft/sec) 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 0

500 1000 1500 2000 Base Case Profile 1 2500 Profile 2 Lower Bound Depth (ft) 3000 3500 Profile 3 Upper Bound 4000 4500 5000 5500 6000 6500 Figure 2.3.21 Shearwave velocity profiles for Sequoyah Nuclear Plant (EPRI, 2014) 8

Information Exchange SQN Seismic Hazard

  • Development of Total Effective Kappa
  • Following SPID Guidelines For Firm Rock Profile > 3,000 ft Deep

- Total Effective Kappa Based on Avg. VS over Top 100 ft, Surface Outcrop

- P1 6,000 ft/s, 0.012s

- P2 3,821 ft/s, 0.020s

- P3 9,285 ft/s, 0.006s Hard Rock

- Likely Conservative (low), 0 to 40 ft Soil, No Weathered Zone

  • Range 0.006s to 0.020s Considered Sufficient Expression Of Epistemic Uncertainty 9

Information Exchange SQN Seismic Hazard

  • Summary

- Sequoyah developed an enhanced site geological profile

  • Supplemented by regional geology maps, industry experts, and nearby SASW surveys

- EPRI GMRS and site characterization performed in conformance with SPID and is appropriate characterization of seismic hazard for Sequoyah site.

10

Information Exchange BFN Seismic Hazard 11

Information Exchange BFN Seismic Hazard

  • NRC May 9 Prioritization Letter

- Seismic Risk Evaluation

  • Prioritization Group 2
  • NRC May 21 Support Document

- Preliminary graphical representation

  • NRC staff GMRS differs from Licensee GMRS 12

Information Exchange BFN Seismic Hazard Licensee Maximum SA:

0.58g @ 25 Hz NRC Maximum SA:

0.68g @ 40 Hz 13

Information Exchange BFN Seismic Hazard

  • BFN understanding of the causes of the primary differences between the preliminary NRC and licensee results.
  • Elements of NRC staff preliminary assessment
  • Narrower velocity profile

- 7,000 fps lower bound

- 9,285 fps upper bound (hard rock)

  • Use of EPRI rock curves and low strain damping values
  • Kappa Values and weights 14

Information Exchange BFN Seismic Hazard

  • BFN additional data for subsurface materials
  • Expand site geologic profile due to current understanding of hard rock characteristics - shear wave velocity > 9200 fps.
  • FSAR had limited rock characteristics data available at depth (> 200 ft)
  • Definition of rock profile to basement 5,000 ft.

Information Exchange BFN Seismic Hazard

  • Utilized Academic/Industry Expertise

- AMEC - Program Management; regional / local geology

- Dr. Robert Hatcher, Professor of Geology, University of Tennessee

- Knoxville

>> Regional / local geology

- Dr. Ken Stokoe, Professor of Civil Engineering, University of Texas

- Austin

>> Spectra Analysis Surface Wave (SASW) Survey @ WBN

>> Rock Testing

- Ivan Wong (URS)

>> Site Modeling/Characterization 16

Information Exchange BFN Seismic Hazard Source: AMEC (2013) 17

Information Exchange BFN Seismic Hazard Vs profiles for Browns Ferry Site Base Case Lower Bound Upper Bound Figure 2.3.21 Shearwave velocity profiles for Browns Ferry Nuclear Plant (EPRI, 2014) 18

Information Exchange BFN Seismic Hazard

  • Development of Total Effective Kappa
  • Following SPID Guidelines For Firm Rock Profile > 3,000 ft Deep

- Total Effective Kappa Based on Avg. Vs Over Top 100 ft, surface outcrop

- Profiles P1, P3 Hard Rock Near Surface, = 0.006s

- Profile P2 Vs(100 ft) 5,914 ft/s, = 0.012s

- Likely Conservative (low), 0 to 50 ft Soil, No Weathered Zone

  • Range 0.006s to 0.012s Considered Sufficient Expression of Epistemic Uncertainty 19

Information Exchange BFN Seismic Hazard

  • Summary

- Browns Ferry developed an enhanced site geological profile

  • Supplemented by regional geology maps and industry experts

- EPRI GMRS and site characterization performed in conformance with SPID and is appropriate characterization of seismic hazard for Browns Ferry site.

20

BFN Seismic Risk Evaluation Screening Results 21

  • BFN understands the IPEEE evaluation did not meet NRC staffs expectation for screening purposes

- Prerequisite #3

- Adequacy Demonstration #3

  • BFN adequacy review acknowledged the SER identified weakness and provided justification for addressing the weakness as part of the ESEP
  • BFN has subsequently completed seismic capacity evaluations for the additional RCIC components

- Minimum HCLPF > 0.50g

Information Exchange BFN Seismic Hazard

  • Additional information

- BFN reevaluated minimum HCLPF SSC (Auxiliary Diesel Generator Transformers)

  • HCLPF > 0.30g in current configuration and replacement configuration
  • BFN commitment to complete transformer replacement by Sept 30, 2014 to resolve PCB/IPEEE screening capacity
  • TVA requests that the NRC staff reconsider the May 9, 2014 screening result that BFN screens in for seismic risk evaluation
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