ML14091A005

Seismic Hazard & Screening Report (Central & Eastern United States Sites), Response to Request for Information Pursuant to 1 0 CFR 50.54(f) Re Recommendation 2.1 of Near-Term Task Force Review of Insights from Fukushima Dai-ichi

ML14091A005
Person / Time
Site:	Braidwood
Issue date:	03/31/2014
From:	Kaegi G T Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
Shared Package
ML14091A243	List: ML14091A005 ML14091A006 RS-14-064, Section 2 - Braidwood Station, Units 1 and 2, Selsmic Hazard and Screening Report RS-14-064, Section 5 - Summary of Regulatory Commitments
References
RS-14-064
Download: ML14091A005 (25)

Text

{{#Wiki_filter:Exelon Generation March 31, 2014 U.S. Nuclear Regulatory Commission Attn: Document Control Desk 11555 Rockville Pike, Rockville, MD 20852 Braidwood Station, Units 1 and 2 10 CFR 50.54(f) Facility Operating License Nos. NPF-72 and NPF*77 NBC Pocket Nos. SIN 50-456 and SIN 50-457

References:

Exelon Generation Company, LLC, Seismic Hazard and Screening Report (Central and Eastern United States (CEUS) Sites), Response to NRC Request for Information Pursuant to 1 0 CFR 50.54(f) Regarding Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident 1. NRC Letter, Request for Information Pursuant to Title 1 o of the Code of Federal Regulations 50.54(f) Regarding Recommendations 2.1, 2.3, and 9.3, of the Near* Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, dated March 12, 2012 2. NEI Letter, Proposed Path Forward for NTTF Recommendation 2.1: Seismic Reevaluations, dated April9, 2013 3. NRC Letter, Electric Power Research Institute Final Draft Report XXXXXX, useismic Evaluation Guidance: Augmented Approach for the Resolution of Fukushima Near-Term Task Force Recommendat'bn 2.1: Seismic, 11 as an Acceptable Alternative to the March 12, 2012, Information Request for Seismic Reevaluations, dated May 7, 2013 4. Exelon Generation Company, LLC letter to the NRC, Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding the Seismic Aspects of Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident -1.5 Year Response for CEUS Sites, dated September 12, 2013 5. EPRI Report 1025287, Seismic Evaluation Guidance, Screening, Prioritization and Implementation Details (SPID) for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1: Seismic 6. NRC Letter, Endorsement of Electric Power Research lnstitt.te Fnal Draft Report 1025287, "Seismic Evaluation Guidance," dated February 15, 2013 7. EPRI Technical Report 3002000704, "Seismic Evaluation Guidance: Augmented Approach for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1: Seismic," dated May 2013 U.S. Nuclear Regulatory Commission NTTF 2.1 Seismic Response for CEUS Sites March 31, 2014 Page2 On March 12, 2012, the Nuclear Regulatory Commission (NRC) issued Reference 1 to all power reactor licensees and holders of construction permits in active or deferred status. Enclosure 1 of Reference 1 requested each addressee located in the Central and Eastern United States (CEUS) to submit a Seismic Hazard Evaluation and Screening Report within 1.5 years from the date of Reference 1 . In Reference 2, the Nuclear Energy Institute (NEI) requested NRC agreement to delay submntal of the final CEUS Seismic Hazard Evaluation and Screening Reports so that an update to the Electric Power Research Institute (EPRI) ground motion attenuation model could be completed and used to develop that information. NEI proposed that descriptions of subsurface materials and properties and base case velocity profiles be submitted to the NRC by September 12, 2013, with the remaining seismic hazard and screening information submitted by March 31, 2014. NRC agreed with that proposed path forward in Reference

3. In Reference 4, Exelon Generation Company, LLC (EGC) provided the description of subsurface materials and properties and base case velocity profiles for Braidwood Station, Units 1 and 2. Reference 5 contains industry guidance and detailed information to be included in the Seismic Hazard Evaluation and Screening Report submittals.

NRC endorsed this industry guidance in Reference

6. The enclosed Seismic Hazard Evaluation and Screening Report for Braidwood Station, Units 1 and 2, provides the information described in Section 4 of Reference 5 in accordance with the schedule identified in Reference

2. As described in Enclosure 1, Braidwood Station, Units 1 and 2, meet the requirements of SPID Sections 3.2 and 7 (Reference

5) and therefore screen out and do not need to prepare an Expedited Seismic Evaluation Process (ESEP) Report, in accordance with Reference

7. Additionally, no Seismic Risk Assessment or Spent Fuel Pool evaluation is needed. Braidwood Station, Units 1 and 2, will perform a High Frequency Confirmation evaluation as determined by NRC prioritization following submittal of all nuclear power plant Seismic Hazard per Reference

1. A list of regulatory commitments contained in this letter is provided in Enclosure

2. If you have any questions regarding this report, please contact Ron Gaston at (630) 657-3359.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 31 91 day of March 2014. Respectfully submitted, Glen T. Kaegi Director -Licensing & Regulatory Affairs Exelon Generation Company, LLC U.S. Nuclear Regulatory Commission NTTF 2.1 Seismic Response for CEUS Sites March 31, 2014 Page3

Enclosures:

1. Braidwood Station, Units 1 and 2, Selsmic Hazard and Screening Report 2. Summary of Regulatory Commitments cc: Director, Office of Nuclear Reactor Regulation Regional Administrator-NRC Region Ill NRC Senior Resident Inspector-Braidwood Station NRC Project Manager, NRR-Braidwood Station Ms. Jessica A Kratchman, NRR/JLD/PMB, NRC Mr. Eric E. Bowman, NRR/DPRIPGCB, NRC or Ms. Eileen M. McKenna, NRO/DSRA!BPTS, NRC Illinois Emergency Management Agency -Division of Nuclear Safety Enclosure 1 Braidwood Station, Units 1 and 2 Seismic Hazard and Screening Report (48 pages)

, 8EI8IIC HAZARD AND 8CREEtiNG REPORr IN RIIPDIIIIT01HI-RBOARa*o FUKUII.IAJEAR-ta.-TAM FGRCI! :I'DII.1: -IIIC for .. llnJitiMJtJd ,....,. o.w.-......, llnllltf Md 2 .1tltiSoulll lfoulell Snleew-IL _,....,. Facility ()pending Llclftll Noe. NPF-72 lftd NPF-77 NRC Docket Naa. ITN 10 4. mid 81N II 417 Corti I palid**-No*.: RS-14 G84 ._.. ... c&-012ta. IIIIHr *O ...,,, ... ,., ..... , 1 .. ' Aanllll-Sarge Seismic Hazard and Screening Report-Sraidwood Units 1 and 2 Report No.: SL-012183 Revision 0 -Initial Issue S&L Project No.: 11332-181 Nuclear Related Sections: Cover Page, Executive Summary, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, and Appendix A Prepared by: y Reviewed by: */1. Sectlon: 4.2 Prepared by: Reviewed by: All Sections Approved by*. Ronald Boehm {7 (4-Brent Starks Javad Moslemian RECORD OF REVISIONS \ Revision Affected Pages Description 0 All Braidwood Station Report No : SL-012183, Revision 0 Correspondence No.: RS-14..064 Initial Issue Contents Conten'ts ........................ .............................................................................. ....................... ...............

Tables ............................................... ...........................................................................................

iii Figures ................... -..................................................................................... .................................. iv Executive Summary ................................................................... , ........................... ....................... v 1 Introduction .......... .............................................................................................................. 1-1 2 Seismic Hazard Reevaluation ........................................................................................ 2-1 2.1 Regional and Local Geology ............................. ..................................... ................. 2-1 2.2 Probabilistic Seismic Hazard Analysis ........................................... ......................... 2-2 2.2.1 Probabilistic Seismic Hazard Analysis Results ..................... ......................... 2-2 2.2.2 Base Rock Seismic Hazard Curves ...................... ......................................... 2-3 2.3 Site Response Evaluation ......................................... .............................................. 2.3.1 Description of Subsurface Material. ....................... ................. ....................... 2-3 2.3.2 Development of Base Case Profiles and Nonlinear Material Properties ....... 2-6 2.3.3 Randomization of Base Case Profiles ......................................................... 2-10 2.3.4 Input Spectra ............... ............. .................................. ................................. 2-11 2.3.5 Methodology .................................... .................... ........................................ 2-11 2.3.6 Amplification Functions .............. ............ -............. ........................................ 2-11 2.3.7 Control Point Seismic Hazard Curves .............................. ........................... 2-16 2.4 Control Point Response Spectrum ............... ......................... -............................... 2-.17 3 Plant Design Basis Ground Motion .............................................................................. 3-1 3.1 SSE Description of Spectral Shape ....................... ............ ............ ......................... 3-2 3.2 Control Point Elevation ...................................... ............ ................................... ....... 3-3 4 Screening Evaluation ..................... .......................................... ...................................... 4-1 4.1 Risk Evaluation Screening (1 to 10Hz) ........................ .................. ....................... .4-1 4.2 High Frequency Screening (>1 0 Hz) ..................................... ................................. .4-1 4.3 Spent Fuel Pool Evaluation Screening (1 to 10 Hz) ................ ................................ 4-2 Braidwood Station Report No : SL1l12183. Revision 0 Correspondence No.: RS-14-064 Contents (cont'd.) 5 Interim Actions ............................................................................................................... 5-1 5.1 Expedited Seismic Evaluation Process ................................................................... S-1 5.2 Interim Evaluation of Seismic Hazard ..................................................................... S-1 5.3 Seismic Walkdown Insights ..................................................................................... 5-2 5.4 Beyond-Design-Basis Seismic Insights ......................................................... 5-2 6 Conclusions .................................................................................................................... 6*1 7 References ...................................................................................................................... 7*1 A Additional Tables ........................................................................................................... A*1 Bral:twood Statbn Report No. SL<J12183. R...S.On 0 Corre.sportlsnce No -RS-14-D64 ii Tables Table 2.3.1-1: Summary of geotechnical profile data for Braidwood station ......................... 2-5 Table 2.3.2-1: Layer thicknesses, depths, and shear-wave velocities (Vs) for 3 profiles, Braidwood site ............................................................................................... 2-7 Table 2.3.2-2: Kappa values and weights used for site response analyses ....................... 2-1 0 Table 2.4-1: UHRS and GMRS at the control point for Braidwood (5% of critical damping) .................................................................................................................... 2-17 Table 3.1-1: Horizontal Safe Shutdown Earthquake response spectrum for Braidwood (5% of critical damping) ........................................................................................ 3-2 Table A-1a: Mean and fractile seismic hazard curves for 100 Hz (PGA) at Braidwood, 5% of critical damping ........................................................................................... A-1 Table A-1b: Mean and fractile seismic hazard curves for 25 Hz at Braidwood, 5% of critical damping ......................................................................................................... A-2 Table A-1c: Mean and fractile seismic hazard curves for 10 Hz at Braidwood, 5% of critical damping ......................................................................................................... A-2 Table A-1d*. Mean and fractile seismic hazard curves for 5 Hz at Braidwood, 5% of critical damping ......................................................................................................... A-3 Table A-1e: Mean and fractile seismic hazard curves for 2.5 Hz at Braidwood, 5% of critical damping ......................................................................................................... A-3 TableA-1f: Mean and fractile seismic hazard curves for 1 Hz at Braidwood, 5% of cmtal damping ......................................................................................................... A-4 Table A-1g: Mean and fractile seismic hazard curves for 0.5 Hz at Braidwood, 5% of critical damp'rlg ......................................................................................................... A-4 TableA-2a: Amplification functions for Braidwood, 5% of critical damping ............................ A-5 Table A-2b1*. Median AFs and sigmas for Model1, Profile 1, for 2 PGA levels ................. A-6 Table A-2b2: Median AFs and sigmas for Model2, Profile 1, for 2 PGA levels ................. A-7 Bml:twood statioo Report No. Sl1J121S3. Revision 0 CorrespOndence No-. RS-141)64 iii Figures Figure 2.3.2-1: Shear-wave velocity (Vs) profiles for Braidwood station ............................... 2-6 Figure 2.3.6-1: Example suite of amplification factors (5% of critical damping pseudo absolute acceleration spectra) developed for the mean base-case profile (P1), EPRI rock modulus reduction and hysteretic damping curves (model M1 ), and case kappa (K1) at eleven loading levels of hard rock median peak acceleration values from 0.01g to 1.50g. M 6.5 and single-corner source model .......................................................................................................... 2-12 Figure 2.3.6-2: Example suite of amplification factors (5% of critical damping pseudo absolute acceleration spectra) developed for the mean base-case profile (P1 ), linear site response (model M2), and base-case kappa (K1) at eleven loading levels of hard rock median peak acceleration values from 0.01 g to 1.50g. M 6.5 and single-corner source model. .................................................

• ......................

2-14 Figure 2,3.7-1: Control point mean hazard curves for spectral frequencies of 0.5, 1, 2.5, 5, 10, 25 and 100Hz (PGA) at Braidwood (5% of critical damping) ............... 2-16 Figure 2.4-1: Plot of 1E-4 and 1E-5 UHRS and GMRS at control point for Braidwood (5% of critical damping response spectra) ............................................................. 2-18 Figure 3.1-1: Braidwood Safe Shutdown Earthquake horizontal response spectrum (5% of critical damping) .......................... , ..........................

• ......................................

3-3 Braidwood Statton Repor1 No 5l;)12183. 0 COITllSjlOndence No.' RS-14.064 tv Executive Summary PURPOSE Following the accident at the Fukushima Daiichi nuclear power plant resulting from the March 11, 2011, Great Tohoku Earthquake and subsequent tsunami, the Nuclear Regulatory Commission (NRC) issued a 50.54(f) letter (Reference

1) requesting information in response to NRC Near-Term Task Force (NTTF) recommendations intended to clarify and strengthen the regulatory framework for protection against natural phenomena.

The 50.54(f) letter (Reference

1) requests that licensees and holders of construction permits under Title 10 Code of Federal Regulations Part 50 (Reference

2) reevaluate the seismic hazards at their sites against present-day NRC requirements.

This report provides the information requested in items (1) through (7) of the "Requested Information" section and Attachment 1 of the 50.54(f) letter (Reference

1) pertaining to NTTF Recommendation 2.1 for Braidwood Generating Station Units 1 and 2 in accordance with the documented intention of Exelon Generating Company transmitted to the NRC via letter dated April 29, 2013 (Reference 16). SCOPE In response to the 50.54(f) letter (Reference

1) and following the Screening, Prioritization, and Implementation Details (SPID) industry guidance document (Reference 3), a seismic hazard reevaluation for Braidwood Generating Station was performed to develop a Ground Motion Response Spectrum (GMRS) for screening purposes to compare with the Safe Shutdown Earthquake (SSE). The new GMRS represents a beyond-design-basis seismic demand developed by more modern techniques than were used for plant licensing.

Consistent with NRC letter dated February 20, 2014, (Reference

26) the seismic hazard reevaluations presented herein are distinct from the current design or licensing bases of Braidwood station. Therefore, the results generally do not call into question the operability or functionality of SSCs and are not expected to be reportable pursuant to 10 CFR 50. 72, "Immediate notification requirements for operating nuclear power reactors," and 10 CFR 50.73, "Licensee event report system." Section 2 provides a summary of the Braidwood regional and local geology, seismicity, other major inputs to the seismic hazard reevaluation, and detailed seismic hazard results including definition of the GMRS. Seismic hazard analysis for Braidwood station, including site response evaluation and GMRS development (Sections 2.2. 2.3, and 2-4 of this report) was performed by the Electric Power Research Institute (EPRI) (Reference 11 ). A more in-depth discussion of the calculation methods used in the seismic hazard reevaluation can be found ln References

3. 7, a. 9. and 15. Section 3 describes the characteristics of the appropriate plant-level SSE. Section 4 provides a comparison of the GMRS to the SSE. Sections 5 and 6 discuss interim actions and conclusions, respectively.

Bra Station Report No.: SL-<lt21B3. Revis1on o Correspondence No.: v CONCLUSIONS For Braidwood station, the SSE envelopes the GMRS in the frequency range from 1 Hz to 10 Hz. Therefore, in accordance with the SPID Sections 3.2 and 7 (Reference 3), Braidwood station screens out of further risk assessment and spent fuel pool integrity evaluation in response to NTTF 2.1: Seismic. Additionally, Braidwood station screens out of the Expedited Seismic Evaluation Process (ESEP) interim action per the ESEP guidance, Section 2.2 (Reference 4). Due to the GMRS exceeding the SSE in the frequency range above 10 Hz, high frequency confirmations will be performed for Braidwood station based upon the schedule for central and eastern United States (CEUS) nudear plants provided via letter from the industry to the NRC dated April9, 2013 (Reference 6), as endorsed by the NRC in the May 7, 2013 letter to the industry (Reference 25). Bmid'waOd Station Report No.: SL '()12183. 0 Ccrrespondsnce No : RS-14 -o64 VJ 1 I ntrod uctio n Following the accident at the Fukushima Daiichi nuclear power plant resulting from the March 11, 2011, Great Tohoku Earthquake and subsequent tsunami, the NRC Commission established a Near Term Task Force (NTTF) to conduct a systematic review of NRC processes and regulations and to determine if the agency should make additional improvements to its regulatory system. The NTTF developed a set of recommendations intended to clarify and strengthen the regulatory framework for protection against natural phenomena. Subsequently, the NRC issued a 50.54(1) letter that requests information to assure that these recommendations are addressed by all U. S. nuclear power plants (Reference 1 ). The 50.54(f) letter (Reference

1) requests that licensees and holders of construction permits under 10 CFR Part 50 (Reference

2) reevaluate the seismic hazards at their sites against present-<lay NRC requirements.

Depending on the comparison between the reevaluated seismic hazard and the current design basis, the result is either no further risk evaluation or the performance of a seismic risk assessment. Risk assessment approaches acceptable to the staff include a seismic probabilistic risk assessment (SPRA), or a seismic margin assessment (SMA). Based upon the risk assessment results, the NRC staff will determine whether additional regulatory actions are necessary. This report provides the information requested in items (1) through (7) of the "Requested Information" section and Attachment 1 of the 50.54(f) letter (Reference

1) pertaining to NTTF Recommendation 2.1 for Braidwood Generating Station Units 1 and 2 (Braidwood station), located in Will County, Illinois in accordance with the documented intention of Exelon Generating Company (Exelon) transmitted to the NRC via letter dated April29, 2013 (Reference 16). In providing this information, Exelon followed the guidance provided in the Seismic Evaluation Guidance:

Screening, Prioritization, and Implementation Details (SPID) for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1: Seismic (Reference 3). The Augmented Approach, Seismic Evaluation Guidance: Augmented Approach for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1: Seismic (Reference 4), has been developed as the process for evaluating critical plant equipment as an interim action to demonstrate additional plant safely margin, prior to performing the complete plant seismic risk evaluations. The SPID (Reference

3) and the Augmented Approach (Reference

4) have been endorsed by the NRC in letters to NEI (Reference 24 and Reference 25). The original geologic and setsm'c siting investigations for Braidwood station were performed in accordance with Appendix A of Title 10 Code of Federal Regulations Part 100 (Reference

5) and meet General Design Criterion 2 in Appendix A of Reference

2. The Safe Shutdown Earthquake (SSE) ground motion was developed in accordance with Appendix A of Reference 5 and is used for the design of seismic Category I systems, structures and components.

See Section 3 of this report for further discussion on the development of the Braidwood station SSE. Braidwood Stalion Report No .. SL./l12183. Revision 0 Co!"respondelce No--RS*1.4*064 In response to the 50.54(f) letter (Reference

1) and following the SPID guidance (Reference 3), a seismic hazard reevaluation for Braidwood station was performed.

For screening purposes, a Ground Motion Response Spectrum (GMRS) was developed. Braidwood Station Report No_; SL-01218:3, Revis en 0 Correspondtmce No-* RS-14-{164 1-2 2 Seismic Hazard Reevaluation Braidwood station is located in Will County, Illinois about 4.5 miles southwest of the Kankakee River. The site is about 1.5 miles southwest of the town of Braidwood, and about 22 miles southwest of Joliet. The station is within the Till Plains Section of the Central Lowland Physiographic province. The site is underlain by a thin veneer of loess and glacial drift, which overlies Pennsylvanian Age bedrock. The plant structures are founded on overconsolidated till, bedrock, or compacted granular fill. The site is located on the north flank of the Illinois Basin Seismogenic Region. An investigation of seismicity within 200 miles of the site was conducted during the plant design phase and it was determined that the largest events were Modified Mercalli Intensity (MMI) VII. Based on the MMI VII intensity, a SSE with a maximum horizontal ground acceleration of 0.13g was originally selected. Subsequently, during the review of the construction permit, the NRC considered a MMI VIII earthquake at the site equally probable. Therefore, a SSE with a 0.2g horizontal peak ground acceleration was considered at the bedrock-till interface.

2.1 REGIONAL

AND LOCAL GEOLOGY The Braidwood site is located in the Kankakee Plain subsection of the Till Plains section of the Central Lowland Physiographic province. This subsection is characterized in the northeastern portion by gently rolling topography formed by glacial deposits, and in the remaining portions by essentially flat-lying topography representing former glacial lakes. Elevations of the natural land surface within the site area range from approximately 580 to 610 feet MSL. Overburden deposits within the plant site area consist of eolian and lacustrine deposits outwash, and glacial till. Borings at the site vicinity encountered soil deposits which ranged in thickness from 26 to 62 feet. The average soil thickness encountered in the site borings was approximately 42 feet. The bedrock deposits in the vicinity of the site range in age from Pennsylvanian to Precambrian, as shown in the regional and stratigraphic columns in UFSAR Figures 2.5-2 and 2.5-19 (Reference 10). The bedrock surface, which is formed in the upper Pennsylvanian deposits ranges from Elevation 552 to 567 feet MSL and averages 558 feet MSL. Braidwood Station Report No.: SL-012183. 0 Correspondence No.: RS-14'()64 2-1

2.2 PROBABILISTIC

SEISMIC HAZARD ANALYSIS 2.2.1 Probabilistic Seismic Hazard Analysis Results In accordance with the 50.54(f) letter (Reference

1) and following the guidance in the SPID (Reference 3), a probabilistic seismic hazard analysis (PSHA) was completed using the recently developed Central and Eastern United States Seismic Source Characterization (CEUS-SSC) for Nuclear Facilities (Reference

7) together with the updated EPRI Ground-Motion Model (GMM) for the CEUS (Reference 8). For the PSHA, a lower-bound moment magnitude of 5.0 was used, as specified in the 50.54(f) letter (Reference 1 ). For the PSHA, the CEUS-SSC background seismic source zones out to a distance of 400 miles around Braidwood were included.

This distance exceeds the 200 mile recommendation contained in Regulatory Guide 1.208 (Reference

15) and was chosen for completeness.

Background sources included in this site analysis are the following:

1. Illinois Basin Extended Basement (IBEB) 2. Mesozoic and younger extended prior-narrow (MESE-N) 3. Mesozoic and younger extended prior-wide (MESE-W) 4. Midcontinent-Craton alternative A (MIDC...A)

5. Midcontinent-Craton alternative 8 (MIDC_B) 6. Midcontinent-Craton alternative C (MIDC_C) 7. Midcontinent-Craton alternative D (MIDC_D) 8. Non-Mesozoic and younger extended prior-narrow (NMESE-N)

9. Non-Mesozoic and younger extended prior-wide (NMESE-W)

10. Paleozoic Extended Crust narrow (PEZ_N) 11. Paleozoic Extended Crust wide (PEZ_W) 12. Reelfoot Rift (RR) 13. Reelfoot Rift including the Rough Creek Graben (RR-RCG) 14. Study region (STUDY _R) For sources of large magnitude earthqtJakes, designated Repeated Large Magnitude Earthquake (RLME) sources in CEUS-SSC (Reference 7), the following sources lie within 621 miles (1,000 km) of the site and were included in the PSHA: 1. Commerce 2. Eastern Rift Margin Fault northern segment (ERM-N) 3. Eastern Rift Margin Fault southern segment (ERM-S) 4. Marianna 5. New Madrid Fault System (NMFS) 6. Wabash Valley For each of the above background and RLME sources, the mid-continent version of the updated CEUS EPRI GMM was used. Bral1wuod StatOn Report No.: Sl*0121B3, Revislrin 0 Correspondence No.:

2-2 2.2.2 Base Rock Seismic Hazard Curves Consistent with the SPID (Reference 3), base rock seismic hazard curves are not provided as the site amplification approach, referred to as Method 3, has been used. Seismic hazard curves are shown below in Section 2.3.7 at the SSE control point elevation. 2.3 SITE RESPONSE EVALUATION Following the guidance contained in Seismic Enclosure 1 of the 50.54(f) Request for Information (Reference

1) and in the SPID (Reference

3) for nuclear power plant sites that are not founded on hard rock (hard rock is defined as having a shear wave velocity of at least 9285 ftlsec), a site response analysis was performed for Braidwood.

2.3.1 Description

of Subsurface Material Braidwood station is located near Joliet, Illinois within the Central Lowland Physiographic Province. The site consists of about 40 feet of soils overlying about 5,000 feet of firm sedimentary rock. The SSE was specified at elevation 562 feet at the top of the Pennsylvanian limestone (Table 2.3.1-1). Overburden deposits within the plant site area consist of eolian and lacustrine deposits, outwash, and glacial till. Borings at the site vicinity encountered soil deposits which ranged in thickness from 26 to 62 feet. The average soil thickness encountered in the site borings was approximately 42 feet per UFSAR Section 2.5.1.2.4.1. (Reference 1 0) The Pleistocene age soil deposits described in UFSAR Section 2.5.1.2.4.1.1 (Reference 1 0) can be divided into upper and lower units on the basis of origin and distinct sedimentary characteristics. These have been classified as the Equality and Wedron Formations. The Equality Formation consists of lacustrine sands and silts ranging in thickness from approximately 14 to 31 feet and averaging approximately 23 feet. The Wedron Formation frequently consists of three units: an upper till consisting predominantly of clayey silt to silty clay with interspersed sand and dolomitic gravels, underlain by an outwash layer of sandy gravel to gravelly sand with numerous cobbles and some boulders, and a lower till consisting predominantly of a very sandy silt with some interspersed clay and gravel. The Wedron Formation was observed in on-site borings to vary in thickness from 5 to 30 feet, with an average thickness of 18 feet. The top of the formation lies between elevation 569 feet and 584 feet MSL, with an average elevation of 576 feet MSL The bedrock deposits in the vicinity of the site range in age from Pennsylvanian to Precambrian, as shown in the regional and stratigraphic columns in UFSAR Figures 2.5-2 and 2.5-19 (Reference 10}. The bedrock surface, which is formed in the upper Pennsylvanian deposits, ranges from El. 552 feet to 567 feet MSL and averages 558 feet MSL. Braidwood Station Report No-: SL-Q12183. Revision 0 correspondence No.: RS-14-Q64 2-3 The Pennsylvanian bedrock is included within the Kewanee Group, which is subdivided into the Carbondale and Spoon Formations, which are described in detail in UFSAR Section 2.5.1.2.4.2.1.1 (Reference 1 0). The Pennsylvanian deposition in the site area is characterized by rapid vertical changes in rock type and by lateral persistence of the Colchester (No. 2) Coal Member of the Carbondale Formation. Sandstone, and most shale units are also persistent over wide areas when viewed as composite units. However, they show noticeable variation in thickness over relatively short horizontal distances. Below the Pennsylvanian bedrock are Ordovician deposits, which consist of many different layers of shale, limestone, dolomite, and sandstone. The Fort Atkinson, Scales, Wise Lake, and Dunleith formations were encountered in the site geotechnical investigation. Information on deeper layers is obtained from stratigraphic columns produced from nearby deep wells. The thicknesses and composition of the various groups and members are described in more detail in UFSAR Section 2.5.1.2.4.2.3 (Reference 1 0). The Cambrian rocks that underlie the Ordovician deposits consist of dolomites, sandstones, shales, and siltstones. The thicknesses and composition of the various groups and members are described in more detail in UFSAR Section 2.5.1.2.4.2.4 (Reference 1 0). Available data indicate that the Precambrian basement rocks consist largely of to coarse-grained granite. Other rock types reported are quartz monzonite, rhyolite, porphyry, and felsite. Estimated location of the top of the Precambrian basement is (-) 4400 to(-) 4500 feet MSL per UFSAR Section 2.5.1.2.4.2.5 (Reference 1 0). Bra iclwood Station Report No.: SL-012183. Revisbn 0 Correspondence No.: 2-4 Table 2.3.1-1: Summary of geotechnica I profile data for Braidwood station (Reference

18) Elevations of Layer Boundaries Under soo* to 579 579 to Range in Thickness 5-15 10-15 10-25 Soli/Rock Deaoriptlon and Age Pleistocene Equality Formation, dry silty sand: medium dense Pleistocene Equaly Formatoo, wet ! samLmeclium.dense.

' Density (pof) 105-110 125-130 13()..145 Shear Wave Veloolty (fps) 330 2400 2400 Comprvsslonal Wave (fps) 1000 5500-5500 6400 Poiaeon's Ratio 0.41-0.44 . 0.41-0.42 0.38-0.42 I Pleistocene Vl/edron Formation, clayey I sift to silty clay with sand, gravel, cobbles, and boulders, hard, stiff ----r------t------+-------1 Pennsylvanian limestone, sandstone, siltstone and coa I 562 to 462c 70-105 462 to 425 37-45 425 to 338 85-90 338 to 133 165-245 Ordovician Fort Atlcinson Formation, limestone and dolomite Ordovician Scales Formation, shale, limestone Ordovician Wise Lake and Dunleith dolomite 113-162 3200 7800-10000 0.38..().41 164 6800 12000-17000 0.32-0.37 155-158 3400 8800-17000 0.32-0.44 162 8700 18400 0.30.0.32 133to 118 10-20 Ordovician Guttenburg Formation, N/A NIA N/A NIA 118 to -37 124-186 Ordovicjan Platteville Group, dolomite NIA N/A NIA N/A and limestone -37 to -3&4 157-540 -384to-694 285-334 -694 to -4234 3300-3800 -4234 and below N/A Ordovician Ancell Group, dolomitic sandstone and sandstone Ordovician Canadian Series, dolomite and sandstone Cambrian dolomite, shale, and sandstone Precambrian granite, quartz monzonite, . myolite porphyry, felsite NIA N/A NfA N/A N/A N/A NIA NIA N!A N/A N/A NIA N/A N/A NIA NfA

• Surface of finish grade Is nominally Ill El. eoo feet MSL, at the top of the Pleittocene Equality Formation.

b The centro! points for the sse and IPEEE HCLPF are at El. 562 It MSL, wl'tidl is the e1nabon or the Reactor Building and lhe elevation or the roc61.-llll interface. o Bottom of the deepest foundation is 8l El. 523 t MSL, withll the Pennsylvamim bedrock* Braidwood Station Report No.: SL-012183 Re111siono Corraepondence No.: RS* ,4-064 2-5

2.3.2 Development

of Base Case Profiles and Nonlinear Material Properties Table 2.3.1-1 shows the recommended shear-wave velocities and unit weights along with elevations and corresponding stratigraphy. From Table 2.3.1-1 the SSE control point is at elevation 562 feet within the Pennsylvanian limestone, sandstone, and shales. Velocities listed in Table 2.3.1-1 reflect refraction, uphole, and downhole surveys along with unspecified information from the ISFSI at an unreported distance from the site (Reference 14). The location of the SSE at elevation 562 feet is at the top of the Pennsylvanian limestone, sandstone, siltstone, and coal beds with firm sedimentary rocks to Precambrian basement at a depth of about 5,000 feet. Velocity measurement extends to a depth below the SSE of about 700 feet. The mean base-case profile (P1) was based on the specified shear-wave velocities in Table 2.3.2-1 with the deepest velocity of 8, 700 ft/s extended to Precambrian basement. Lower (P2)-and upper range profiles were developed with scale factors of 1.25 reflecting uncertainty in measured velocities to a depth of 695 feet and 1.57 below to reflect increased epistemic uncertainty for assumed 1 shear-wave velocities. The scale factors of 1.25 and 1.57 reflect a a 11 1n of about 0.2 and about 0.35 respectively based on the SPID (Reference

3) 1 0 111 and 90 111 fractiles which implies a scale factor of 1.28 on a.,. Depth to Precambrian basement was taken at 5,062 feet randomized

+/- 1,519 feet. The depth randomization reflects +/-30% of the depth and was included to provide a realistic broadening of the fundamental resonance at deep rock sites rather than reflect actual random variations to basement shear-wave velocities across a footprint. Profile P3, the stiffest profile, encountered hard rock shear-wave velocities (9,285 ft/s) at a depth below the SSE of about 224 feet. The three shear-wave velocity profiles are shown in Figure 2.3.2-1 and listed in Table 2.3.2-1. --**-***-**** Vs profiles for Braidwood Site Vs (ft/sec) 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 500 *---+---r-- +---r-_,-;-+---r--+--r++--1500 . ---+---t----t---1----t-t-+---1----t- -+-H--' 2000 g 2500 *--+----t--- -+--+---1f --ll-+---+---+---+-+.c i 3000 Q 3500 4000 4500 5000 5500 ---+--r---1--r-_,-;-+--r--t--r-H-*--Profile 1 -Profile2 -Proflle3 ,. ___ 1 Figure 2.3.2-1: Shear-wave velocity (Vs) profiles for Braidwood station (Reference

18) 1 Assumptions discussed in Section 2 are provided by EPRI engineers (Reference

11) in accordance with implementation of the SPID (Reference

3) methodology.

Braidwood Station Report No-: SL *012183, Revision 0 Correspondence No* RS-14iJS4 2-6 Table 2.3.2*1: Layer thicknesses, depths, and shear-wave velocities (Vs) for 3 profiles , Braidwood site (Reference

18) Profile 1 (P1) Thickness(ft)

LJepth {ft) Vs(fUs) 0 3200 10.0 10.0 3200 10.0 20.0 3200 10.0 3(.:.0 32C:C: 10.0 40.0 3200 10.0 50.0 32('(1 10.0 60.0 3200 10.0 70.0 3200 10.0 8o.o 3200 10.0 90.0 320(. 10.0 100.0 3200 10.0 110.0 6800 1 (.:,0 120.0 6800 7.0 127.0 6800 1 (l.O 137.0 6800 7.0 144.0 34(.:0 10.0 154.0 10.0 164.0 3400 10.0 174.0 3400 10.0 184.0 3400 10.0 194.0 3400 10.0 204.0 341Xi 10.0 214.0 3400 10.0 224.0 3400 6.0 230.0 8700 10.0 240.0 8700 10.0 250.0 8700 25.0 275.0 8700 25.0 300.0 8700 25.0 325.0 8700 25.0 350.0 8700 25.0 375.0 8700 25.0 400.0 8700 25.0 425.0 8700 25.0 450.0 8700 Bra tlwootl Station Repon No-: SL-012163, Revisbn 0 Correspondence No-.' RS-14 -Q64 2 (P2) lllickness(ft) Depth (ft) 0 ---* 10.0 10.0 10.0 20.0 10.0 30.0 10.0 40.0 10.0 50.0 10.0 60.0 10.0 70.0 10.0 8(..0 10.0 90.0 10.0 100.0 10.0 110.0 10.0 120.0 7.Ci 127.0 10.0 137.0 7.0 144.0 10.0 154.0 10.0 164.() 10.0 174.0 10.0 184.0 10.0 194.0 10.0 204.0 10.(.: 214.0 10.0 224.0 6.(1 230.0 10.0 240-0 10.0 250.0 25.0 275.0 25.0 300.0 25.0 325.0 25.0 350.0 25.0 375.0 25.0 400.0 25.0 425.0 25.0 450.0 Pl\lfile 3 (P3) ----* Vs(ft/s) Thickness(tt) Depth {ft) Vs(fUs) 2560 0 400U ----2560 10.0 10.0 4000 2560 10.0 20.0 4000 ------*---2560 10.0 30.0 400U 2560 10.0 40.0 4000 2560 10.U 50.0 4000 --2560 1U.O 60.0 4000 --2560 10.0 70.0 40UO --2560 10.0 80.0 4000 2560 1 l\.C: 90.0 4000 2560 1 t.r 1W.O 4000 5440 10.0 110.0 8500 ------5440 me: 120.0 8500 5440 7.C 127.0 8500 5440 1fo.C 137.0 8500 2690 7.C: 144.0 4250 2690 1N' 154.0 4250 2690 mr 164.0 4250 2690 1 C:.l\ 174.0 4250 2690 1(\.C:. 184.0 4250 2690 1C.l\ 194.0 4250 2690 1('1.t 204.0 4250 2690 10.0 21 4.0 4250 2690 10.0 224.0 4250 6960 6.0 230.0 9285 6960 10.0 240.0 9285 6960 10.0 250.0 9285 *--6960 25.0 275.0 9285 6960 25.0 300.0 9265 6960 25.0 325.0 9285 6960 25.0 350.0 9285 6960 25.0 375.0 9285 6960 25.0 400.0 9285 6960 25.0 425.0 9285 6960 25.0 450.0 9285 --* -----* 2-7 Table 2.3.2-1: (Continued) Profile 1 (P1) Thickness(ft) Depth {ft) Vs(ft/s) 25.0 475.0 8700 25.0 500.0 8700 24.4 524.4 8700 24.4 548.7 8700 24.4 573.1 8700 24.4 597.5 8700 24.4 621.8 8700 24.4 646.2 8700 24.4 670.6 8700 24.4 695.0 8700 218.3 913.3 8700 218.3 1131.6 8700 218.3 1350.0 8700 218.3 1568.3 8700 218.3 1786.7 8700 218.3 2005.0 8700 218.3 2223.3 8700 218.3 2441.7 8700 218.3 2660.0 8700 218.3 2878.4 8700 218.3 3096.7 8700 218.3 3315.0 8700 218.3 3533.4 8700 218.3 3751.7 8700 218.3 3970.0 8700 218.3 4188.4 8700 218.3 4406.7 8700 218.3 4625.1 8700 218.3 4843.4 8700 218.3 5061.7 8700 3280.8 8342.6 9285 Bra'tlwood Report No.: SL -()12183. Revisbn 0 Correspondence No.: RS-14-004 Profile 2 (P2) Thickness(ft) Depth (ft) 25.0 475.0 25.0 500.0 24.4 524.4 24.4 548.7 24.4 573.1 24.4 597.5 24.4 621.8 24.4 646.2 24.4 670;6 24.4 695.0 218.3 913.3 218.3 1131.6 218.3 1350.0 218.3 1568.3 218.3 1786.7 218.3 2005.0 218.3 2223.3 218.3 2441.7 218.3 2660.0 218.3 2878.4 218.3 3096.7 218.3 3315.0 218.3 3533.4 218.3 3751.7 218.3 3970.0 218.3 4188.4 218.3 4406.7 218.3 4625.1 218.3 4843.4 218.3 5061.7 3280.8 8342.6 Profile 3 (P3) Vs(ft/s) Thickness(ft) Depth (ft) Vs(fVs) 6960 25.0 475.0 9285 6960 25.0 500.0 9285 6960 24.4 524.4 9285 6960 24.4 548.7 9285 6960 24.4 573.1 9285 6960 24.4 597.5 9285 6960 24.4 621.8 9285 6960 24.4 646.2 9285 6960 24.4 9285 6960 24.4 695.0 9285 5541 218.3 913.3 9285 5541 218.3 1131.6 9285 5541 218.3 1350.0 9285 5541 218.3 1568.3 9285 5541 218.3 1786.7 9285 5541 218.3 2005.0 9285 5541 218.3 2223.3 9285 5541 218.3 2441.7 9285 5541 218.3 2660.0 9285 5541 218.3 2878.4 9285 5541 218.3 3096.7 9285 5541 218.3 3315.0 9285 5541 218.3 3533.4 9285 5541 218.3 3751.7 9285 5541 218.3 3970.0 9285 5541 218.3 4188.4 9285 5541 218.3 4406.7 9285 5541 218.3 4625.1 9285 5541 218.3 4843.4 9285 5541 218.3 5061.7 9285 9285 3280.8 8342.6 9285 2-8 2.3.2.1 Shear Modulus and Damping Curves Recent nonlinear dynamic material properties were not available for Braidwood station for sedimentary rocks. The rock material over the upper 500 feet was assumed' to have behavior that could be modeled as either linear or non-linear. To represent this potential for either case in the upper 500 feet of sedimentary rock at Braidwood station, two sets of shear modulus reduction and hysteretic damping curves were used. Consistent with the SPID (Reference 3), the EPRI rock curves (model M1) were considered to be appropriate to represent the upper range nonlinearity likely in the materials at this site; and, linear analyses (model M2) was assumed' to represent an equally plausible alternative rock response across loading level. For the linear analyses, the low strain damping from the EPRI rock curves were used as the constant damping values in the upper 500 feet. 2.3.2.2 Kappa Base-case kappa estimates were determined using Section B-5.1.3.1 of the SPID (Reference

3) for a firm CEUS rock site. Kappa for a firm rock site with at least 3,000 feet of sedimentary rock may be estimated from the average S-wave velocity over the upper 100 feet (V, 10 a) of the subsurface profile while for a site with less than 3,000 feet of firm rock, kappa may be estimated with a Q, of 40 below 500 feet combined with the low strain damping from the EPRI rock curves and an additional kappa of 0.006s for the underlying hard rock. For Braidwood station, with at least 3,000 feet of firm rock, the corresponding average shear-wave velocities (equivalent travel time averaging procedure) over the top 100 feet were 3,200 fils (P1), 2,560ft.ls (P2), and 4,000 ftfs (P3). The corresponding kappa estimates were 0.024s, 0.031s, and 0.019s respectively.

The range in kappa was considered insufficient and a scale factor of 1.68 (Reference

3) about the mean base-case profile estimate was applied resulting in corresponding low-range estimates of 0.014s, D.018s, and 0.011s respectively.

For the upper-range kappa estimates the values for profiles P1, P2, and P3 were 0.040s, 0.040s, and 0.032s, where 0.040s reflected the maximum considered estimate (Reference 3). As a result each base-case profile was associated with three, mid-, low-, and high-range estimates of kappa as summarized in Table 2.3.2-2. 1 Assumptions discussed in Section 2 are provided by EPRI engineers (Reference

11) in accordance with implementation of the SPID (Reference

3) methodology.

Braidwood Station Report No.' Sl-0121B3. Rev1sLOO 0 Correspondence No,. RS-14-Q54 2-9 Table 2.3.2-2: Kappa values and weights used for site response analyses (Reference

11) Kappa(s) Velocity Profile Lower Range (k3) Base-Case (k1) Upper Range {k2) P1 0.014 0.024 0.040 P2 0.018 0.031 0.040 P3 0.011 0.019 0.032 Weights P1 0.4 P2 0.3 P3 0.3 k1 0.40 k2 0.30 k3 0.30 G/Gm 1 x and Hysteretic Damping Curves M1 0.5 M2 0.5 2.3.3 Randomization of Base Case Profiles To account for the aleatory variabmty in dynamic material properties that is expected to occur across a site at the scale of a typical nuclear facility, variability in the assumed 1 shear-wave velocity profiles has been incorporated in the site response calculations.

For Braidwood station, random shear wave velocity profiles were developed from the base case profiles shown in Figure 2.3.2-1. Consistent with the discussion in Appendix B of the SPID (Reference 3), the velocity randomization procedure made use of random field models which describe the statistical correlation between layering and shear wave velocity. The default randomization parameters developed in Taro (Reference

9) for USGS "A" site conditions were used for this site. Thirty random velocity profiles were generated for each base case profile. These random velocity profiles were generated using a natural log standard deviation of 0.25 over the upper 50 feet and 0.15 below that depth. As specified in the SPID (Reference 3), correlation of shear wave velocity between layers was modeled using the footprint correlation model. In the correlation model, a limit of +1-2 standard deviations about the median value in each layer was assumed 1 for the limits on random velocity fluctuations.

1 * .

• Assumptions discussed 1n Section 2 are provrded by EPRI engineers (Reference

11) in accordance with implementation of the SPID (Reference

3) methodology.

Braidwood Station Report No.: SL-012183. Revision 0 COIT'espondence No.: 2-10}}