NOC-AE-14003114, Seismic Hazard and Screening Report (CEUS Sites), Response NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai..

Seismic Hazard and Screening Report (CEUS Sites), Response NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai..

ML14099A235
Person / Time
Site:	South Texas
Issue date:	03/31/2014
From:	Gerry Powell South Texas
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NOC-AE-14003114
Download: ML14099A235 (66)

Text

Nuclear Operating Company South Tcws Pro/ect Ekctdrc GCeneating Station PO Box 28,9 W worth Txas 77483 ,

March 31, 2014 NOC-AE-14003114 10 CFR 54(f)

STI: 33848915 File: G25 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 South Texas Project Units 1 and 2 Docket Nos. STN 50-498, STN 50-499 Seismic Hazard and Screening Report (CEUS Sites),

Response NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident

References:

1. NRC Letter, Request for Information Pursuant to Title 10 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 April 9, 2013, ADAMS Accession No. ML13101A379

3. NRC Letter, Electric Power Research Institute Final Draft Report XXXXXX, "Seismic Evaluation Guidance: Augmented Approach for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1: Seismic," as an Acceptable Alternative to the March 12, 2012, Information Request for Seismic Reevaluations, dated May 7, 2013, ADAMS Accession No. ML13106A331

4. 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, ADAMS Accession No. ML12333A170

5. NRC Letter, Endorsement of EPRI Final Draft Report 1025287, "Seismic Evaluation Guidance," dated February 15, 2013, ADAMS Accession No. ML12319A074 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. 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.

4olO

NOC-AE-14003114 Page 2 of 3 In Reference 2, the Nuclear Energy Institute (NEI) requested NRC agreement to delay submittal 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.

Reference 4 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 5.

The attached Seismic Hazard and Screening Report for the South Texas Project Electric Generating Station, Units 1 and 2 (STPEGS) provides the information described in Section 4 of Reference 4 in accordance with the schedule identified in Reference 2.

This letter contains no new regulatory commitments.

Should you have any questions regarding this letter, please contact Rafael Gonzales, STP Licensing Engineer 361-972-4779 or me at 361-972-7566.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on ate. 4t 1i204 Date G. T. Powell Site Vice President RJG

Attachment:

Seismic Hazard and Screening Report for the South Texas Project Electric Generating Station, Units I and 2 (STPEGS)

NOC-AE-14003114 Page 3 of 3 cc: (electronic copy)

(paper copy)

Regional Administrator, Region IV A. H. Gutterman, Esquire U. S. Nuclear Regulatory Commission Morgan, Lewis & Bockius LLP 1600 East Lamar Boulevard Arlington, TX 76011-4511 Balwant K. Singal U. S. Nuclear Regulatory Commission Balwant K. Singal John Ragan Senior Project Manager Chris O'Hara U.S. Nuclear Regulatory Commission Jim von Suskil One White Flint North (MS 8 B1) NRG South Texas LP 11555 Rockville Pike Rockville, MD 20852 NRC Resident Inspector Kevin Polio U. S. Nuclear Regulatory Commission Cris Eugster P. 0. Box 289, Mail Code: MNl 16 L. D. Blaylock Wadsworth, TX 77483 City Public Service Jim Collins Peter Nemeth City of Austin Crain Caton & James, P.C.

Electric Utility Department 721 Barton Springs Road C. Mele Austin, TX 78704 City of Austin Richard A. Ratliff Robert Free Texas Department of State Health Services 50.54fSeismic.Resource@nrc.gov

NOC-AE-14003114 Page 1 of 63 Seismic Hazard and Screening Report for the South Texas Project Electric Generating Station, Units I and 2 (STPEGS)

Revision 001

NOC-AE-14003114 Page 2 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 1 1.0 Introduction 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(f) letter that requests information to assure that these recommendations are addressed by all U.S. nuclear power plants. The 50.54(f) letter requests that licensees and holders of construction permits under 10 CFR Part 50 reevaluate the seismic hazards at their sites against present-day 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 pertaining to NTTF Recommendation 2.1 for the South Texas Project Electric Generating Station, Units 1 and 2

("STPEGS") nuclear power plants (NPP), located in Matagorda County, Texas. In providing this information, South Texas Project Nuclear Operating Company (STPNOC), licensee for STPEGS, 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 (EPRI 1025287, 2013). The Augmented Approach, Seismic Evaluation Guidance: Augmented Approach for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1: Seismic (EPRI 3002000704, 2013), has been developed as the process for evaluating critical plant equipment as an interim action to demonstrate additional plant safety margin, prior to performing the complete plant seismic risk evaluations.

The original geologic and seismic siting investigations for STPEGS were performed in accordance with Appendix A to 10 CFR Part 100 and meet General Design Criterion 2 in Appendix A to 10 CFR Part 50. The Safe Shutdown Earthquake Ground Motion (SSE) was developed in accordance with Appendix A to 10 CFR Part 100 and used for the design of seismic Category I systems, structures and components.

In response to the 50.54(f) letter and following the guidance provided in the SPID (EPRI 1025287, 2013), a seismic hazard reevaluation was performed for STPEGS.

Since the reevaluation shows that the updated GMRS does not exceed the SSE, based on the results of the screening evaluation, no further evaluations will be performed.

NOC-AE-14003114 Page 3 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Pa e 2 2.0 Seismic Hazard Reevaluation The STPEGS site is located in south-central Matagorda County, Texas, west of the Colorado River, approximately 8 miles north-northwest of the town of Matagorda, and about 89 miles southwest of Houston. The station is located at the north end of the 7,000-Acre Main Cooling Reservoir (MCR), which is the primary cooling source for Units 1 and 2.

STPEGS is in the Gulf Coastal Plain of Texas. The Coastal Plain sediments are underlain by Cretaceous bedrock, followed by the Mesozoic basement rock which occurs at a top depth of approximately 34,500 ft. Stratigraphy at the site is essentially horizontal. As discussed in Section 2.5.1 of the UFSAR, there is no evidence of regional warping which could significantly impact the site, nor deformational zones such as joints, shear zones, fractures, faults or folds.

The reactor containment buildings are founded on dense to very dense fine sand at 60 ft below plant grade. Plant grade is at El. 28 ft (NGVD 29).

Earthquake activity in historic time within 200 miles of the plant site has been low. Sources of major earthquakes in the central and eastern United States (CEUS) are distant, and have not had an appreciable effect at the site. The original investigation of historical seismic activity in the region indicated that a design intensity of VI (Modified Mercalli Scale) is adequately conservative for the site. STPEGS determined that Intensity VI corresponds to a peak ground acceleration of 0.07 g, which was increased to 0.10 g for the SSE (i.e., the minimum Peak Ground Acceleration (PGA) value established in Appendix A of 10 CFR 100).

2.1 Regional and Local Geology STPEGS is located in south-central Matagorda County, Texas in the Gulf Coastal Plain of Texas. The uppermost soils consist of Beaumont Formation (Pleistocene) sediments extending to a minimum depth of approximately 750 ft, underlain by soil and soft rock deposits of Pleistocene, Pliocene, and Miocene ages. These lower deposits extend to a depth of approximately 4,400 ft., at which point they transition to the Oakville Sandstone Formation sediments, with a base depth at approximately 6,200 ft. These sediments are, in turn, underlain by Cretaceous bedrock, followed by the Mesozoic basement rock which occurs at a top depth of approximately 34,500 ft. The basement rock beneath the site is presently believed to be continental crustal material from the Grenville Orogeny.

The principal plant structures are founded on the upper soils of the Beaumont Formation. This formation consists of alternating layers of mostly dense to very dense sands and very stiff to hard clays. Layer thicknesses range from less than 10 ft to over 70 ft. One boring at Units 1 & 2 was extended to a depth of about 2,620 ft, and encountered alternating layers of clays and sands, transitioning to soft sedimentary claystones and siltstones at depths greater than approximately 1,100 ft.

NOC-AE-14003114 Page 4 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 3 2.2 ProbabilisticSeismic Hazard Analysis

-in response to the 50.54(f) letter and following the guidance provided in the SPID (EPRI 1025287, 2013), a seismic hazard reevaluation was performed for STPEGS. Because STPEGS is one of the most recently constructed nuclear power plants (NPPs), the subsurface information and analyses available in the UFSAR were developed using relatively recent techniques, compared with many older plants, and provide a good basis for the seismic reevaluation.

Similar to several other operating units, because of planned construction of the two new nuclear units (STP 3 & 4) adjacent to STP 1 & 2, there is an extensive amount of very recently developed, well-documented site subsurface information, collected and developed with current technologies, together with seismic analyses which have been completed using current state-of-practice methodologies (such as those referred to the SPID, Section B1.0, and NUREG/CR-6728) which can be combined with the UFSAR information to provide very detailed complete geotechnical information for completion of the seismic hazard reevaluation for STPEGS.

These two sets of information have been combined and developed using methodologies consistent with the applicable requirements of the NRC 50.54(f) letter, the EPRI SPID Report and NUREG/CR-6728 to provide a thorough and accurate seismic reevaluation which provides all of the information which has been requested by the NRC for the seismic reevaluation and also maintains a consistent seismic licensing basis for all of the plants on the STP site.

The use of current information and current state-of-practice methodologies available due to the licensing of new plants on the site is endorsed by the SPID in several locations, such as Appendix B, Section B2.0 which indicates "for sites with recent COL and ESP submittals, the co-located operating plants would be expected to utilize any applicable information developed in the ESP and COL site characterizations to the maximum extent possible."

To provide a consistent seismic licensing basis for the site, STPNOC utilized NUREG/CR-6728 Method 2A for the analysis. This methodology is endorsed as an acceptable methodology by the NRC 10 CFR 50.54(f) RFI Letter, Attachment 1 to Seismic Enclosure 1 (which endorses the use of either NUREG/CR-6728 Method 2 or 3) and also the SPID, Section 2.5.3.

EPRI provided hard rock seismic hazard information, developed in accordance with the SPID, for STPNOC to use as the basis for the analysis. STPNOC then utilized this hard rock seismic hazard information and both the new and existing subsurface information to develop updated soil profiles and updated amplification factors.

For screening purposes, an updated Ground Motion Response Spectrum (GMRS) was then developed. Following the development of the new GMRS, the seismic reevaluation was completed in accordance with the SPID and the results documented in this report, which provides all of the information required by the template, developed by the industry and endorsed by the NRC.

NOC-AE-14003114 Page 5 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 4 Since the reevaluation summarized in this report determined that the updated GMRS does not exceed the SSE, based on the results of this screening evaluation, no further evaluations will be performed.

2.2,1 ProbabilisticSeismic HazardAnalysis Results In accordance with the 50.54(f) letter and following the guidance in the SPID (EPRI 1025287, 2013), 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 (CEUS-SSC, 2012 and NUREG-2115, 2012) together with the updated EPRI Ground-Motion Model (GMM) for the CEUS (EPRI 3002000717, 2013). For the PSHA, a minimum moment magnitude cutoff of 5.0 was used, as specified in the 50.54(f) letter.

For the PSHA, the CEUS-SSC background seismic source zones out to a distance of 400 miles (640 km) around STPEGS were included. This distance exceeds the 200 mile (320 km) recommendation contained in NRC (2007) and was chosen for completeness. Background sources included in this site analysis are the following:

1. Extended Continental Crust-Gulf Coast (ECCGC)

2. Gulf Highly Extended Crust (GHEX)

3. Mesozoic and younger extended prior - narrow (MESE-N)

4. Mesozoic and younger extended prior - wide (MESE-W)

5. Midcontinent-Craton alternative A (MIDCA)

6. Midcontinent-Craton alternative B (MIDCB)

7. Midcontinent-Craton alternative C (MIDCC)

8. Midcontinent-Craton alternative D (MIDCD)

9. Non-Mesozoic and younger extended prior - narrow (NMESE-N)

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

11. Oklahoma Aulacogen (OKA)

12. Study region (STUDYR)

For sources of large magnitude earthquakes, designated Repeated Large Magnitude Earthquake (RLME) sources in CEUS-SSC (2012), the following sources lie within 1,000 km of the site and were included in the analysis:

1. Commerce

2. Eastern Rift Margin Fault northern segment (ERM-N)

3. Eastern Rift Margin Fault southern segment (ERM-S)

4. Marianna

5. Meers

6. New Madrid Fault System (NMFS)

For each of the above background and RLME sources, the Gulf version of the updated CEUS EPRI GMM was used.

NOC-AE-14003114 Page 6 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 5 2.2.2 Base Rock Seismic HazardCurves Base rock hazard curves, provided by EPRI in their Project Report 1041, "South Texas Seismic Hazard and Screening Report, Rev. 1'" (EPRI 1041, 2013), are available for STPEGS, as provided in Figure 2.2.2-1, in accordance with the requirement in Section 2.5.3 of the SPID for plants using Method 2A.

The procedure to develop probabilistic seismic hazard curves for hard rock follows standard techniques documented in the technical literature (e.g., McGuire, 2004). Separate seismic hazard calculations are conducted for the 7 spectral frequencies for which ground motion equations are available (100 Hz=peak ground acceleration or PGA, 25 Hz, 10 Hz, 5 Hz, 2.5 Hz, 1 Hz, and 0.5 Hz). As discussed in Section 2.2.1, ground motion equations from the updated EPRI Ground-Motion Model (GMM) for Gulf Coast Region from the CEUS (CEUS-SSC, 2012) were used for the calculation of rock hazard. All spectra accelerations presented herein correspond to 5% of critical damping. Figure 2.2.2-1 shows the mean hard-rock seismic hazard curves for the 7 spectral frequencies. The digital values for the mean and fractile hazard curves are provided in Table 2.2.2-1a through Table 2.2.2-1g.

Total Mean Rock Hazard by Frequency at South Texas 1 E-2 - .... ... ..... . ... ..

1E-3 .i t

.-. . . - 25 Hz

- 10 Hz

-- I~- -t 5 Hz

_-PGA

.2.5 .. -*. Hz

". . .. -- 0.5 Hz r- 1E-6 . . . . ..

..." ......

• I *- * .. . ......

1E-7 1 10 0.01 0.1 1 10 Spectral acceleration (g)

Figure 2.2.2-1. Control point mean hazard curves for oscillator frequencies of 0.5, 1, 2.5, 5, 10, 25 and 100 Hz at STPEGS.

NOC-AE-14003114 Page 7 of 63 ISTPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 6 Table 2.2.2-1a. Mean and Fractile Seismic Hazard Curves for PGA at STPEGS AMPS(g) MEAN 0.05 0.16 0.50 0.84 0.95 0.0005 8.50E-03 3.14E-03 5.05E-03 8.OOE-03 1.20E-02 1.55E-02 0.001 5.15E-03 1.64E-03 2.84E-03 4.63E-03 7.55E-03 1.01E-02 0.005 9.36E-04 3.05E-04 4.70E-04 8.OOE-04 1.31E-03 2.19E-03 0.01 3.95E-04 1.16E-04 1.79E-04 3.19E-04 5.35E-04 1.05E-03 0.015 2.30E-04 6.OOE-05 9.51E-05 1.77E-04 3.23E-04 6.83E-04 0.03 8.67E-05 1.51 E-05 2.76E-05 5.75E-05 1.29E-04 3.01E-04 0.05 4.16E-05 4.63E-06 1.08E-05 2.57E-05 6.45E-05 1.49E-04 0.075 2.31E-05 1.82E-06 5.35E-06 1.42E-05 3.63E-05 8.12E-05 0.1 1.52E-05 9.37E-07 3.33E-06 9.24E-06 2.42E-05 5.20E-05 0.15 8.28E-06 3.73E-07 1.74E-06 5.20E-06 1.32E-05 2.76E-05 0.3 2.71E-06 5.75E-08 5.75E-07 1.79E-06 4.43E-06 8.72E-06 0.5 1.07E-06 1.36E-08 2.19E-07 7.23E-07 1.74E-06 3.42E-06 0.75 4.69E-07 3.79E-09 8.35E-08 3.05E-07 7.77E-07 1.51 E-06

1. 2.45E-07 1.55E-09 3.84E-08 1.55E-07 4.01E-07 8.12E-07 1.5 8.87E-08 4.25E-10 1.08E-08 5.20E-08 1.44E-07 3.19E-07

3. 1.13E-08 1.23E-10 8.OOE-10 5.12E-09 1.72E-08 4.83E-08

5. 1.80E-09 1.21E-10 1.55E-10 6.83E-10 2.60E-09 9.11E-09 7.5 3.39E-10 9.79E-11 1.21E-10 1.79E-10 5.42E-10 1.92E-09

10. 9.16E-11 9.11E-1 1 1.01E-10 1.21E-10 2.13E-10 6.17E-10 Table 2.2.2-1b. Mean and Fractile Seismic Hazard Curves for 25 Hz at STPEGS AMPS(g) MEAN 0.05 0.16 0.50 0.84 0.95 0.0005 1.06E-02 4.98E-03 6.83E-03 9.93E-03 1.44E-02 1.84E-02 0.001 7.05E-03 2.80E-03 4.25E-03 6.54E-03 9.93E-03 1.29E-02 0.005 1.74E-03 6.45E-04 9.65E-04 1.51 E-03 2.39E-03 3.73E-03 0.01 8.58E-04 3.14E-04 4.56E-04 7.45E-04 1.16E-03 1.92E-03 0.015 5.53E-04 1.90E-04 2.80E-04 4.77E-04 7.55E-04 1.27E-03 0.03 2.39E-04 7.23E-05 1.1OE-04 1.98E-04 3.33E-04 6.17E-04 0.05 1.19E-04 2.96E-05 4.90E-05 9.51E-05 1.72E-04 3.33E-04 0.075 6.67E-05 1.31 E-05 2.39E-05 5.05E-05 9.93E-05 1.92E-04 0.1 4.38E-05 6.93E-06 1.42E-05 3.19E-05 6.64E-05 1.29E-04 0.15 2.41E-05 2.76E-06 6.93E-06 1.74E-05 3.79E-05 7.03E-05 0.3 8.58E-06 5.35E-07 2.25E-06 6.45E-06 1.38E-05 2.42E-05 0.5 3.85E-06 1.40E-07 1.01E-06 3.01E-06 6.17E-06 1.07E-05 0.75 1.94E-06 4.50E-08 5.12E-07 1.55E-06 3.14E-06 5.12E-06

1. 1.15E-06 1.98E-08 2.92E-07 9.24E-07 1.87E-06 3.05E-06 1.5 5.13E-07 5.75E-09 1.23E-07 4.07E-07 8.60E-07 1.42E-06

3. 1.03E-07 6.26E-10 1.87E-08 7.66E-08 1.74E-07 3.14E-07

5. 2.50E-08 1.82E-10 3.33E-09 1.62E-08 4.19E-08 8.72E-08

NOC-AE-14003114 Page 8 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 7 7.5 6.94E-09 1.21E-10 7.23E-10 3.79E-09 1.16E-08 2.68E-08

10. 2.55E-09 1.21E-10 2.72E-10 1.29E-09 4.31E-09 1.08E-08d

NOC-AE-14003114 Page 9 of 63 I STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 8 Table 2.2.2-1c. Mean and Fractile Seismic Hazard Curves for 10 Hz at STPEGS AMPS(g) MEAN 0.05 0.16 0.50 0.84 0.95 0.0005 1.22E-02 6.45E-03 8.23E-03 1.15E-02 1.64E-02 2.1OE-02 0.001 8.39E-03 3.95E-03 5.27E-03 7.77E-03 1.15E-02 1.49E-02 0.005 2.09E-03 8.72E-04 1.23E-03 1.87E-03 2.88E-03 4.19E-03 0.01 9.95E-04 4.01E-04 5.66E-04 8.98E-04 1.38E-03 1.98E-03 0.015 6.20E-04 2.35E-04 3.37E-04 5.58E-04 8.72E-04 1.27E-03 0.03 2.49E-04 8.23E-05 1.25E-04 2.16E-04 3.52E-04 5.58E-04 0.05 1.17E-04 3.28E-05 5.27E-05 9.93E-05 1.72E-04 2.84E-04 0.075 6.16E-05 1.40E-05 2.46E-05 4.98E-05 9.24E-05 1.57E-04 0.1 3.86E-05 7.23E-06 1.38E-05 3.01E-05 5.91E-05 1.02E-04 0.15 1.99E-05 2.72E-06 6.26E-06 1.51E-05 3.14E-05 5.35E-05 0.3 6.26E-06 4.37E-07 1.67E-06 4.70E-06 1.01 E-05 1.72E-05 0.5 2.56E-06 9.79E-08 6.45E-07 1.95E-06 4.13E-06 7.03E-06 0.75 1.19E-06 2.80E-08 2.92E-07 9.24E-07 1.95E-06 3.28E-06

1. 6.65E-07 1.1OE-08 1.53E-07 5.12E-07 1.1OE-06 1.87E-06 1.5 2.72E-07 2.72E-09 5.75E-08 2.04E-07 4.56E-07 8.OOE-07

3. 4.60E-08 3.28E-10 7.13E-09 3.09E-08 7.77E-08 1.51E-07

5. 9.76E-09 1.29E-10 1.11E-09 5.66E-09 1.64E-08 3.63E-08 7.5 2.42E-09 1.21 E-10 2.68E-10 1.25E-09 4.13E-09 9.93E-09

10. 8.15E-10 1.13E-10 1.42E-10 4.31E-10 1.40E-09 3.63E-09

NOC-AE-14003114 Page 10 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Pa e 9 Table 2.2.2-1d. Mean and Fractile Seismic Hazard Curves for 5 Hz at STPEGS AMPS(g) MEAN 0.05 0.16 0.50 0.84 0.95 0.0005 1.32E-02 6.93E-03 8.72E-03 1.23E-02 1.77E-02 2.25E-02 0.001 9.18E-03 4.25E-03 5.75E-03 8.60E-03 1.25E-02 1.64E-02 0.005 2.05E-03 7.89E-04 1.16E-03 1.84E-03 2.92E-03 4.07E-03 0.01 8.56E-04 3.28E-04 4.70E-04 7.66E-04 1.23E-03 1.69E-03 0.015 4.85E-04 1.82E-04 2.60E-04 4.37E-04 7.03E-04 9.51E-04 0.03 1.65E-04 5.50E-05 8.35E-05 1.46E-04 2.39E-04 3.52E-04 0.05 6.94E-05 1.92E-05 3.14E-05 6.OOE-05 1.02E-04 1.57E-04 0.075 3.38E-05 7.55E-06 1.34E-05 2.84E-05 5.20E-05 8.12E-05 0.1 2.02E-05 3.63E-06 7.23E-06 1.62E-05 3.14E-05 5.05E-05 0.15 9.67E-06 1.23E-06 3.05E-06 7.55E-06 1.55E-05 2.53E-05 0.3 2.67E-06 1.67E-07 7.13E-07 2.07E-06 4.37E-06 7.13E-06 0.5 9.74E-07 3.19E-08 2.39E-07 7.55E-07 1.62E-06 2.68E-06 0.75 4.09E-07 7.77E-09 9.11E-08 3.05E-07 6.93E-07 1.18E-06

1. 2.11E-07 2.84E-09 4.31E-08 1.53E-07 3.63E-07 6.26E-07 1.5 7.68E-08 6.83E-10 1.27E-08 5.12E-08 1.34E-07 2.42E-07

3. 1.06E-08 1.38E-10 1.11E-09 5.58E-09 1.82E-08 3.84E-08

5. 1.92E-09 1.21E-10 2.04E-10 8.47E-10 3.23E-09 8.12E-09 7.5 4.20E-10 1.01E-10 1.21E-10 2.19E-10 7.45E-10 1.95E-09

10. 1.30E-10 9.11E-11 1.04E-10 1.32E-10 2.84E-10 6.93E-10

NOC-AE-14003114 Page 11 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Pa el1 Table 2.2.2-le. Mean and Fractile Seismic Hazard Curves for 2.5 Hz at STPEGS AMPS(g) MEAN 0.05 0.16 0.50 0.84 0.95 0.0005 1.29E-02 6.83E-03 8.60E-03 1.21 E-02 1.72E-02 2.22E-02 0.001 9.05E-03 4.25E-03 5.66E-03 8.47E-03 1.23E-02 1.60E-02 0.005 1.76E-03 6.OOE-04 8.85E-04 1.53E-03 2.57E-03 3.79E-03 0.01 5.79E-04 1.92E-04 2.92E-04 4.90E-04 8.47E-04 1.29E-03 0.015 2.82E-04 9.37E-05 1.40E-04 2.42E-04 4.19E-04 6.17E-04 0.03 7.73E-05 2.29E-05 3.63E-05 6.64E-05 1.15E-04 1.77E-04 0.05 2.83E-05 6.83E-06 1.16E-05 2.35E-05 4.31E-05 6.83E-05 0.075 1.25E-05 2.32E-06 4.50E-06 9.93E-06 1.98E-05 3.14E-05 0.1 6.95E-06 1.04E-06 2.22E-06 5.42E-06 1.13E-05 1.84E-05 0.15 3.03E-06 3.09E-07 8.23E-07 2.25E-06 5.05E-06 8.47E-06 0.3 7.17E-07 3.09E-08 1.46E-07 4.98E-07 1.23E-06 2.16E-06 0.5 2.36E-07 4.83E-09 3.68E-08 1.49E-07 4.19E-07 7.66E-07 0.75 9.20E-08 1.13E-09 1.1OE-08 5.20E-08 1.62E-07 3.14E-07

1. 4.52E-08 4.25E-10 4.25E-09 2.29E-08 8.12E-08 1.62E-07 1.5 1.54E-08 1.60E-10 1.05E-09 6.54E-09 2.72E-08 6.OOE-08

3. 1.86E-09 1.21E-10 1.44E-10 5.91E-10 3.09E-09 8.35E-09

5. 3.03E-10 9.37E-11 1.13E-10 1.51E-10 5.20E-10 1.51E-09 7.5 6.00E-11 9.11E-11 1.01E-10 1.21E-10 1.72E-10 3.84E-10

10. 1.73E-11 9.11E-1 1 1.01E-10 1.21E-10 1.23E-10 1.82E-10

NOC-AE-14003114 Page 12 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Pageli Table 2.2.2-1f. Mean and Fractile Seismic Hazard Curves for 1 Hz at STPEGS AMPS(g) MEAN 0.05 0.16 0.50 0.84 0.95 0.0005 8.94E-03 3.95E-03 5.50E-03 8.47E-03 1.23E-02 1.55E-02 0.001 5.90E-03 2.10E-03 3.28E-03 5.58E-03 8.47E-03 1.08E-02 0.005 1.27E-03 1.95E-04 3.68E-04 9.24E-04 2.22E-03 3.47E-03 0.01 3.69E-04 4.70E-05 8.98E-05 2.25E-04 6.09E-04 1.20E-03 0.015 1.47E-04 1.82E-05 3.47E-05 8.85E-05 2.29E-04 4.98E-04 0.03 2.44E-05 2.92E-06 5.83E-06 1.51 E-05 3.79E-05 8.47E-05 0.05 6.38E-06 6.73E-07 1.44E-06 3.90E-06 1.11 E-05 2.04E-05 0.075 2.33E-06 1.92E-07 4.50E-07 1.36E-06 4.07E-06 7.45E-06 0.1 1.18E-06 7.66E-08 1.98E-07 6.54E-07 2.01E-06 4.01E-06 0.15 4.67E-07 1.98E-08 6.26E-08 2.32E-07 7.66E-07 1.72E-06 0.3 9.84E-08 1.51 E-09 7.55E-09 3.95E-08 1.57E-07 4.07E-07 0.5 3.01E-08 2.60E-10 1.40E-09 9.37E-09 4.70E-08 1.32E-07 0.75 1.1OE-08 1.25E-10 3.73E-10 2.64E-09 1.62E-08 5.05E-08

1. 5.19E-09 1.21E-10 1.82E-10 1.05E-09 7.23E-09 2.42E-08 1.5 1.65E-09 1.01E-10 1.21E-10 2.92E-10 2.01E-09 7.89E-09

3. 1.79E-10 9.11E-11 1.01E-10 1.21E-10 2.46E-10 9.24E-10

5. 2.74E-11 9.11E-11 1.01E-10 1.21E-10 1.21E-10 2.16E-10 7.5 5.26E-12 9.11E-11 1.01E-10 1.21E-10 1.21E-10 1.23E-10

10. 1.48E-12 9.11E-11 1.01E-10 1.21E-10 1.21E-10 1.21E-10

NOC-AE-14003114 Page 13 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 12 Table 2.2.2-1g. Mean and Fractile Seismic Hazard Curves for 0.5 Hz at STPEGS AMPS(g) MEAN 0.05 0.16 0.50 0.84 0.95 0.0005 5.29E-03 1.98E-03 2.96E-03 5.05E-03 7.55E-03 9.51 E-03 0.001 3.51 E-03 8.47E-04 1.49E-03 3.23E-03 5.50E-03 7.34E-03 0.005 7.01E-04 4.56E-05 1.02E-04 3.79E-04 1.36E-03 2.32E-03 0.01 1.87E-04 8.35E-06 2.04E-05 7.45E-05 3.14E-04 7.45E-04 0.015 6.92E-05 2.80E-06 6.73E-06 2.60E-05 1.07E-04 2.88E-04 0.03 9.48E-06 3.42E-07 8.47E-07 3.52E-06 1.40E-05 3.90E-05 0.05 2.05E-06 6.83E-08 1.87E-07 7.23E-07 3.57E-06 8.23E-06 0.075 6.63E-07 1.82E-08 5.42E-08 2.19E-07 1.15E-06 2.76E-06 0.1 3.20E-07 6.36E-09 2.13E-08 9.79E-08 5.12E-07 1.44E-06 0.15 1.23E-07 1.36E-09 5.83E-09 3.28E-08 1.77E-07 6.OOE-07 0.3 2.57E-08 1.62E-10 5.83E-10 4.56E-09 3.05E-08 1.34E-07 0.5 7.83E-09 1.21E-10 1.62E-10 9.65E-10 7.89E-09 4.13E-08 0.75 2.89E-09 1.01E-10 1.21E-10 2.96E-10 2.32E-09 1.51E-08

1. 1.36E-09 9.37E-11 1.18E-10 1.62E-10 9.65E-10 6.73E-09 1.5 4.41E-10 9.11E-11 1.01E-10 1.21E-10 2.92E-10 2.07E-09

3. 5.OOE-11 9.11E-11 1.01E-10 1.21E-10 1.21E-10 2.84E-10

5. 7.95E-12 9.11E-11 1.01E-10 1.21E-10 1.21E-10 1.23E-10 7.5 1.58E-12 9.11E-11 1.01E-10 1.21E-10 1.21E-10 1.21E-10

10. 4.56E-13 9.11E-11 1.01E-10 1.21E-10 1.21E-10 1.21E-10 2.3 Site Response Evaluation Following the guidance contained in Seismic Enclosure 1 of the 3/12/2012 50.54(f) Request for Information and in the SPID (EPRI 1025287, 2013) for nuclear power plant sites that are not sited on hard rock (defined as 2.83 km/sec), a site response analysis was performed for STPEGS.

2.3.1 Descriptionof Subsurface Material Sampling and testing of the site soils was performed in the top approximately 600 ft. Clays in the upper 600 ft comprise about 60 percent of the materials, and the sands about 40 percent.

There are 12 distinct clay interbeds which range from stiff to hard, and are predominantly high plasticity materials. There are 11 distinct sand interbeds which range from medium dense to very dense, and are predominantly silty sand materials. There is one silt interbed. The Beaumont formation encountered in the top 600 ft extends to about 750 ft depth and is underlain by similar deposits of Pleistocene, Pliocene and Miocene age to about 1,100 ft depth.

The soils then grade into soft claystone and siltstone to about 4,400 ft depth. The Oakville Sandstone extends from about 4,400 to 6,000 ft depth and is underlain by Cretaceous rock to about 34,500 ft depth. Mezozoic basement rock extends below about 34,500 ft depth.

Table 2.3.1-1 provides a brief description of the subsurface material in terms of the geologic units and layer thicknesses. This table includes best estimate values of shear wave velocity (Vs), compressive wave velocity (Vp), unit weight and Poisson's ratio. Note that the stratigraphy

NOC-AE-14003114 Page 14 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 13 in Table 2.3.1-1 for the upper 341 ft (the limit of detailed exploration for Units 1 & 2) is the average stratigraphy for Units 1 & 2.

The Unit 1 & 2 stratigraphy is very similar to the Units 3 & 4 stratigraphy, with layer thicknesses exhibiting variation that would be expected to typically occur for measurements taken over a large site in this area of the US. From 341 to 603 ft depth, the stratigraphy is the average Units 3 & 4 stratigraphy, since there is no detailed stratigraphy available for Units 1 & 2 below 341 ft depth. As described in Section 2.3.2, two base case profiles are used for the upper 341 ft, since there was some difference in the measured Vs values for Units 1 & 2 and Units 3 & 4. The Values given in Table 2.3.1-1 are the Base Case 2 values (Units 3 & 4) since they have a higher weighting than the Base Case 1 values.

NOC-AE-140031 14 Page 15 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 14 Table 2.3.1-1 Geologic profile and estimated layer thicknesses for STPEGS Depth Range Stratum Soil/Rock Density Vsp8 ) Vp(b)

(ft) Description (pcf) (ft/sec) - (ft/sec) PR(c) 0 SSE control point (at surface) --........ .

0-22 A Medium Stiff to Very Stiff Clay 125 575 1905 0.45 22- 36.5 B Loose to Dense Sandy Silt 125 725 3695 0.48 36.5 -44 C Dense to Very Dense Silty Sand 125 785 5605 0.49 44-59.5 D Very Stiff to Hard Silty Clay 126 925 4715 0.48 59.5-81.5 E Dense to Very Dense Slightly Silty Fine Sand 126 1080 5505 0.48 81.5-119.5 F Very Stiff to Hard Silty Clay 129 945 4820 0.48 119.5-132 H Very Dense Silty Sand 128 1075 5480 0.48 132- 172 J clay Hard Silty Clay 126 1180 5705 0.48 172-212 J sand Very Dense Silty Sand 126 1040 5255 0.48 212-222 K clay Stiff to Hard Sandy Clay 130 1170 5965 0.48 222-232 K sand Dense to Very Dense Silty Sand 130 1370 5760 0.47 232 -281 L Very Stiff to Hard Silty Clay 128 975 4970 0.48 281 -291 M Dense to Very Dense Silty Sand 125 1165 4895 0.47 291 -331 N clayl Very Stiff to Hard Silty Clay 127 1230 5170 0.47 331 -352 N sand1 Dense to Very Dense Silty Sand 125 1645 6045 0.46 352-360 N clay2 Very Stiff to Hard Silty Clay 123 1535 5640 0.46 360-393 N sand2 Dense to Very Dense Silty Sand 128 1665 5520 0.45 393-401 N clay3 Very Stiff to Hard Silty Clay 123 1850 6135 0.45 401 -420 N sand3 Dense to Very Dense Silty Sand 128 1570 5770 0.46 420-450 N clay4 Very Stiff to Hard Silty Clay 123 1205 5065 0.47 450-458 N sand4 Dense to Very Dense Silty Sand 128 1355 5695 0.47 458-512 N clay5 Very Stiff to Hard Silty Clay 123 1220 6220 0.48 512-530 N sand5 Dense to Very Dense Silty Sand 128 1845 6120 0.45 530-603 N ciay6 Very Stiff to Hard Silty Clay 123 1345 5655 0.47 603- 750 - Beaumont Formation (Pleistocene) 128 1645 6045 0.46 750- 1100 - Pleistocene, Pliocene & Miocene Deposits 129 1785 6170 0.45 130-140 2005- 6560- 0.45-1100 - 4400 Soft Claystone & Siltstone 4230 9045 0.34 4400 -6200 - Oakville Sandstone 140 4045- 8190- 0.34-5285 9890 0.30 6200 - 34,500 - Cretaeous Rock 140 3470- 6495- 0.30 6200 -_34,500_CretaceousRock 6 4 4 0 (d) 12,050 34,500+ Mesozoic Basement Rock 165 9200+ 15,900+ 0.25

NOC-AE-14003114 Page 16 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 15 Notes for Table 2.3.1-1 (a) Vs from Base Case 2, measured by P-S Suspension Logging to 603 ft depth, computed from Vp below 603 ft depth. Values tabulated are best estimate values; upper and lower bound values are presented in Section 2.3.2.

(b) Vp from Base Case 2, measured by P-S Suspension Logging to 603 ft depth, obtained from well logs below 603 ft depth.

(C) Poisson's ratio computed from Vs and Vp to 603 ft depth, extrapolated below 603 ft depth.

(d) Measurements only computed to approximately 20,000 ft depth.

(e) Various modulus and damping curves are used for the soils; these are described in Section 2.3.2.1.

2.3.2 Development of Base Case Profiles and NonlinearMaterial Properties Vs and Vp measurements were obtained for Units 1 & 2 and Units 3 & 4. Vp measurements were obtained to a depth of approximately 20,000 ft in oil-field borings.

Units 1 & 2 Shear and Compression Wave Velocity Seismic cross-hole measurements were used to determine Vs and Vp. Measurements were taken in two receiver boreholes, 15 ft apart. In the initial series of tests, readings were taken to 280 and 298 ft depth in Unit 1 and Unit 2 locations, respectively. A final series of tests was run to 315 ft depth at a location between Units 1 and 2. Tests were made at 5-ft depth intervals.

Four to 10 readings were taken at each depth interval, and individual readings were generally within 6 percent of the average reading. STP UFSAR indicates that Vs values between 305 and 341 ft were derived based on the soil stratigraphy and extrapolation of the Vs data in the upper 305 ft.

Units 3 & 4 Shear and Compression Wave Velocity Suspension P-S logging was performed in 11 boreholes, 6 at the proposed Unit 3 location and 5 at the proposed Unit 4 location. P-S measurements were taken to about 200 ft depth in 8 of the borings and to about 470 ft in one boring. In one boring in the Unit 3 area and one boring in the Unit 4 area P-S measurements were taken to about 600 ft depth. Readings were taken at either 0.5-meter (1.6-ft) or 1-meter (3.2-ft) intervals.

NOC-AE-14003114 Page 17 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Pa e 16 Oil Well Loaq Data The oil wells are located about 11, 13 and 19 miles from the STP site. Readings extend from a depth of approximately 600 ft to depths of about 16,000 ft in two of the wells, and 20,000 ft in the third well. Vp was measured at 0.5-ft intervals in each well. For analysis, the readings were averaged over 200-ft intervals in each well. These averaged Vp measurements were converted to Vs using typical values of Poisson's ratio.

Design Shear and Compression Wave Velocity Profiles Comparison of the Vs values in the upper 341 ft showed that the Units 1 & 2 values were typically somewhat higher than those measured in the top 341 ft for Units 3 & 4. The technique used to measure Vs for Units 1&2 (seismic cross-hole) is well established and is still commonly used today (ASTM D4428). We examined the Unit 1&2 Vs results in detail and could find no reason to doubt their credibility. Since these results were part of the input to the Units 1 &2 seismic analysis, we did not want to dismiss them. In addition, the Suspension P-S logging used for proposed Units 3&4 is the accepted state-of-the-art technique and has been used for all of the COL investigations. As a result, two base cases are developed.

Base Case 1 uses the average Vs values from Units 1 & 2 to 341 ft depth. Base Case 2 uses the Vs values from Units 3 & 4 to 341 ft depth, but uses the stratigraphy from Units 1 & 2.

Below 341 ft depth, both base cases use the Units 3 & 4 Vs values to 603 ft depth, and the sonic log values from 603 to 20,000 ft depth. The values for Base Cases 1 and 2 to 341 ft depth are given in Tables 2.3.2-1 and 2.3.2-2, respectively. The values below 341 ft depth are the same for both base cases and are given in Table 2.3.2-3.

The best estimate and upper and lower bound Vs values are provided along with the best estimate Vp values in Tables 2.3.2-1, 2.3.2-2 and 2.3.2-3. The upper and lower bound Vs values to 341 ft depth in Table 2.3.2-1 are taken directly from STP UFSAR. Coefficients of variation range from about 0.21 to 0.25. The upper and lower bound Vs values from 341 to 530 ft depth in Table 2.3.2-1 and from zero to 530 ft depth in Table 2.3.2-2 have a logarithmic standard deviation of 0.20; from 530 to 603 ft depth the logarithmic standard deviation is 0.19. Below 603 ft, the upper and lower bound Vs values are based on the standard deviation of all of the data within the 200 ft depth interval.

For analysis using the Vs and Vp data in Tables 2.3.2-1 and 2.3.2-2, weighting of 40% should be given to Base Case 1 (Table 2.3.2-1) and weighting of 60% should be given to Base Case 2 (Table 2.3.2-2).

The Base Case 1 and 2 Vs values to 341 ft depth are plotted on Figure 2.3.2-1. The Vs values below 341 ft (same for both base cases) are plotted on Figure 2.3.2-2.

The depth to hard rock for both base cases is defined as the depth where the Vs reaches a value of 9300 ft/sec (2830 m/s). As noted above, this depth is approximately 34,500 ft.

Consistent with the guidance in the SPID (EPRI 1025287, 2013), the depth to hard rock can be

NOC-AE-14003114 Page 18 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Pa e17 modeled at a shallower depth provided reasonable site amplification values can be obtained for spectral frequencies of 0.5 Hz and higher. Soil column analysis for Units 3 & 4 showed that the column could be truncated at less than 10,000 ft (3050 m) depth with no change in the site response at frequencies above 0.5 Hz at the STPEGS site. Because the depth to hard rock is very large (34,500 ft) at this site, no epistemic uncertainty in this parameter was incorporated in the analyses.

Table 2.3.2-1 Geologic profile and estimated layer thicknesses for top 341 ft, Base Case 1, STPEGS Shear Wave Velocity, Soil Below Grade (El 28 ft) Vs (ft/sec)

Stratum Top Thickness Depth Best Lower Upper (ft) (ft) Estimate Bound Bound 6.0 0 610 460 760 5.0 6.0 610 460 760 A

5.0 11.0 625 475 775 6.0 16.0 790 600 980 7.5 22.0 900 685 1115 B

7.0 29.5 910 700 1120 C 7.5 36.5 910 700 1120 6.0 44.0 840 645 1035 D

9.5 50.0 1150 880 1420 11.0 59.5 1150 880 1420 E

11.0 70.5 1160 890 1430 9.5 81.5 1280 990 1570 F 9.0 91.0 1280 990 1570 9.0 100.0 1220 930 1510 10.5 109.0 1460 1130 1790 H 12.5 119.5 1560 1210 1910 40.0 132.0 1229 950 1508 40.0 172.0 1173 900 1446 K 20.0 212.0 1541 1190 1892 L 49.0 232.0 1271 990 1552 M 10.0 281.0 1520 1190 1850 N clayl 40.0 291.0 1324 1040 1608 N sandl 10.0 331.0 1585 1268 1902

NOC-AE-14003114 Page 19 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 18 Table 2.3.2-2 Geologic profile and estimated layer thicknesses for top 341 ft, Base Case 2, STPEGS Shear Wave Velocity, SoilTo Below Grade (El 28 ft) Vs (ft/sec)

Stratum Top Thickness Depth Best Lower Upper (ft) (ft) Estimate Bound Bound 6.0 0 A 5.0 6.0 575 460 690 5.0 11.0 6.0 16.0 B 7.5 22.0 725 580 870 7.0 29.5 C 7.5 36.5 785 628 942 D6.0 44.0 925 740 1110 9.5 50.0 E 11.0 1080 864 1296 11.0 70.5 9.5 81.5 F 9.0 91.0 945 756 1134 9.0 100.0 10.5 109.0 H 12.5 119.5 1075 860 1290 40.0 132.0 1180 945 1415 40.0 172.0 1040 835 1250 K 8.0 212.0 1170 936 1404 12.0 220.0 1370 1096 1644 L 49.0 232.0 975 780 1170 M 10.0 281.0 1165 932 1398 N clayl 40.0 291.0 1230 984 1476 N sandl 10.0 331.0 1645 1316 1974

NOC-AE-14003114 Page 20 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 19 Table 2.3.2-3 Geologic profile and estimated layer thicknesses below 341 ft, Base Cases 1 & 2, STPEGS Below Grade (El 28 f) Shear Wave Velocity, Bs (ft/sec)

Soil Stratum Thickness Top Depth Best Estimate Lower Upper (ft) (ft) Bound Bound N sand1 11.0 341 1645 1316 1974 N clay2 8.0 352 1535 1228 1842 N sand2 33.0 360 1665 1332 1998 N clay3 8.0 393 1850 1480 2220 N sand3 19.0 401 1570 1256 1884 N clay4 30.0 420 1205 964 1446 N sand4 8.0 450 1355 1084 1626 N clay5 54.0 458 1220 976 1464 N sand5 18.0 512 1845 1476 2214 N clay6 73.0 530 1345 1089 1601

- 91.0 603 1625 1427 1824

- 200 694 1677 1524 1830

- 200 894 1862 1703 2022

- 200 1094 2006 1794 2218

- 200 1294 2147 1913 2381

- 200 1494 2311 1993 2629

- 200 1694 2336 1986 2686

- 200 1894 2510 2175 2844

- 200 2094 2700 2351 3048

- 200 2294 2965 2666 3263

- 200 2494 2980 2577 3383

- 200 2694 3234 2841 3628

- 200 2894 2901 2484 3319

- 200 3094 3305 2823 3788

- 200 3294 3663 3130 4197 200 3494 3887 3198 4577

- 200 3694 4231 3599 4863

- 200 3894 3932 3133 4730

- 200 4094 3860 3137 4583

_ 200 4294 4046 3380 4712

- 200 4494 4166 3647 4684

_ 200 4694 4126 3664 4588

_ 200 4894 4393 4045 4742

- 200 5094 4607 4237 4976 200 5294 4773 4216 5330 200 5494 5008 4229 5787

NOC-AE-14003114 Page 21 of 63 STPEGS Seismic Hazard and Screening Repor Revision 001, March 27, 2014 Pa e20 Below Grade (El 28 ft) Shear Wave Velocity, Belw GVs (ft/sec)

SoilfT Stratum Thickness Top Depth Best Estimate Lower Upper (ft) (ft) Bound Bound 200 5694 4889 4323 5454 200 5894 4976 4526 5426 200 6094 5287 4740 5833

- 200 6294 5045 4520 5570

- 200 6494 4607 3776 5438 200 6694 3928 3160 4697 200 6894 3741 3257 4225 200 7094 3644 3352 3937 200 7294 3610 3477 3744

- 200 7494 3575 3447 3703 200 7694 3472 3318 3626 200 7894 3511 3354 3668 200 8094 3576 3475 3677 200 8294 3619 3433 3805

- 200 8494 3703 3499 3906 200 8694 3690 3502 3878 200 8894 3840 3592 4088 200 9094 3827 3560 4094 200 9294 3849 3531 4167 200 9494 3897 3585 4208

- 200 9694 3966 3666 4266

- 200 9894 3924 3691 4158 200 10094 3880 3697 4063

- 200 10294 3943 3714 4172 200 10494 4047 3804 4291 200 10694 4080 3826 4334

- 200 10894 4117 3856 4377 200 11094 4163 3913 4412

- 200 11294 4299 4065 4532 200 11494 4291 4015 4566 200 11694 4260 4001 4518 200 11894 4328 4072 4583 200 12094 4473 4157 4789 200 12294 4568 4280 4857

_ 200 12494 4621 4356 4886 200 12694 4619 4335 4903 200 12894 4610 4453 4767 200 13094 4674 4479 4869

NOC-AE-14003114 Page 22 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 21 Shear Wave Velocity, Soil ~Below Soil Grade (El 28 if) V (ft/sec)

Vs (tec Stratum Thickness Top Depth Best Estimate Lower Upper (ft) (ft) Bound Bound

- 200 13294 4873 4584 5162

- 200 13494 4679 4487 4870

- 200 13694 4749 4498 4999

- 200 13894 4879 4571 5188

- 200 14094 4942 4423 5461

- 200 14294 5054 4622 5487 200 14494 5000 4672 5328

- 200 14694 5361 4896 5825

- 200 14894 5195 4767 5623

- 200 15094 5219 4869 5570

- 200 15294 5083 4596 5570

- 200 15494 4910 4565 5255

- 200 15694 4864 4406 5322

- 200 15894 5084 4742 5426

- 200 16094 5369 5070 5668

- 200 16294 5490 5136 5845 200 16494 5527 5157 5897 200 16694 5405 5159 5651

- 200 16894 5424 5118 5730

- 200 17094 5405 5152 5659

- 200 17294 5268 5109 5427 200 17494 5321 5074 5567

- 200 17694 5565 5327 5803

- 200 17894 5664 5398 5929

- 200 18094 6442 5911 6974

- 200 18294 6376 5941 6810 200 18494 5767 5593 5941 200 18694 5720 5594 5847

_ 200 18894 5447 5223 5671

_ 200 19094 5635 5462 5808

_ 200 19294 5817 5288 6345 200 19494 5320 5006 5634

_ 200 19694 4898 4688 5107 200 19894 4803 4724 4881

NOC-AE-14003114 Page 23 of 63 ISTPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 22 Shear Wave Velocity, Vs (ftls) 0 500 1000 1500 2000 2500 1

0 I

50

-i I-,

-S 100 L

-Case 1 Best Estimate It

- - - Case I Upper Bound

0) 150

- - Case 1 Lower Bound

- Case 2 Best Estimate 0-1K 0 - - Case 2 Lower Bound 200

- - - Case 2 Upper Bound LI a

250 16-.

300 II 350 Figure 2.3.2-1. Shear wave velocity profiles, Base Cases 1 & 2, used in site response calculations for STPEGS above 341 ft depth

NOC-AE-14003114 Page 24 of 63 ISTPEGS Seismic Hazard and Screening Report I Revision 001, March 27, 2014 Page 23 Shear Wave Velocity, Vs (ftls) 0 2000 4000 6000 8000 0

2000 4000 6000 (U

8000

.02

-Best Estimate 0

10000

-- - Upper Bound M-

- - - Lower Bond 12000 14000 -

16000 -

18000 -

20000 -

Figure 2.3.2-2. Shear wave velocity profiles, Base Cases 1 & 2, used in site response calculations for STPEGS below 341 ft depth

NOC-AE-14003114 Page 25 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 24 2.3.2.1 Shear Modulus and Damping Curves Shear Modulus The shear modulus reduction (G/GMAx) versus cyclic shear strain curves from Units 1 & 2 (STP UFSAR) were digitized and compared against the curves from Units 3 & 4 (STP FSAR) for each stratum. The curves for Units 1 & 2 were generated based on laboratory cyclic triaxial test results while the curves for Units 3 & 4 were generated based on laboratory resonant column torsional shear (RCTS) tests. The comparison indicated that values from Units 1 & 2 decrease much more rapidly with increasing strain (more strain dependent). Considering the improved technology used in RCTS tests, the corresponding test results from Units 3 & 4 are expected to more accurately reflect the actual soil characteristics. They are adopted here for both base case profiles down to 603 ft depth.

Based on the comparison between the RCTS test results and published curves, the following shear modulus reduction curves for sand, clay and silt are adopted. The EPRI curves are from EPRI 102293 (1993) and the Vucetic & Dobry curves are from Vucetic & Dobry (1991).

• For sands located at depths greater than or equal to 100 ft, use the EPRI curve for depths of 500 to 1000 ft

• For sands located at depths less than 100 ft, use the EPRI curve for depths of 250 to 500 ft

• For clays with PI greater than or equal to 30, use the Vucetic & Dobry curve for PI = 100

• For silt, use the EPRI curve for PI = 50.

Based on the soil type and the corresponding plasticity index, the recommended modulus reduction curves are provided in Table 2.3.2-4 for each stratum. The G/GMAx values with increasing cyclic shear strain are given in Table 2.3.2-5 for each material. Note that the RCTS tests gave very consistent G/GMAx results for each material tested. This is reflected in the small variation given in Table 2.3.2-5. The curves are plotted in Figure 2.3.2-3 without showing the variation (for clarity).

Linear properties (implying G/GMAx = 1 in the strain range of the response analysis) are used for soils below 603 ft depth.

Damping Ratio Like the shear modulus reduction curves, the damping ratio (D) versus cyclic shear strain curves from Units 1 & 2 were generated based on laboratory cyclic triaxial test results while the curves for Units 3 & 4 were generated based on laboratory RCTS tests. Comparison between the two sets of curves indicated that values from Units 1 & 2 increase much more rapidly with increasing strain and constantly stay higher. As with the shear modulus reduction curves, the corresponding test results from Units 3 & 4 are expected to more accurately reflect the actual soil characteristics, because of the improved testing technology. They are adopted here for both base case profiles down to 603 ft depth.

NOC-AE-14003114 Page 26 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 25 Based on the comparison between the RCTS test results and published curves, the following damping ratio curves for sand, clay and silt are adopted. The EPRI curves are from EPRI 102293 (1993) and the Vucetic & Dobry curves are from Vucetic & Dobry (1991).

• For all sands, use EPRI curve for depths of 500 to 1000 ft

• For clays with PI greater than or equal to 30, use the Vucetic & Dobry curve for PI = 200.

• For low PI clay and silt samples, use the Vucetic & Dobry (1991) curve for PI = 200 up to strains of 0.005% and use the EPRI interpolated PI = 60 curve for strains above 0.05%.

Based on the soil type and the corresponding plasticity index, the recommended damping ratio curves are provided in Table 2.3.2-4 for each stratum. The values of D with increasing cyclic shear strain are given in Table 2.3.2-6 for each material. Note that the RCTS tests gave consistent results of D for each material tested. This is reflected in the relatively small variation (about 10 percent) given in Table 2.3.2-6. The curves are plotted in Figure 2.3.2-4 without showing the variation (for clarity).

Linear behavior is used for soils below a depth of 603 ft. and kappa estimates are used to account for the strain-independent damping ratios, see Section 2.3.2.2

NOC-AE-14003114 Page 27 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 26 Table 2.3.2-4 Modulus reduction and damping curves assigned for each stratum for STPEGS Stratum PI (%) G/Gmax J Damping A-fill N/A None Given None Given A 40 CLAY (V&D PI = 100) CLAY (V&D, PI=200)

B 20 SILT (EPRI PI = 50) Low PI CLAY and SILT (Hybrid)

C N/A SAND at < 100 ft depth (EPRI 250 ft - 500 ft) SAND (EPRI 500 ft - 1000 ft)

D 40 CLAY (V&D PI = 100) CLAY (V&D, PI=200)

E N/A SAND at < 100 ft depth (EPRI 250 ft - 500 ft) SAND (EPRI 500 ft - 1000 ft)

F 40 CLAY (V&D PI = 100) CLAY (V&D, PI=200)

H N/A SAND at > 100 ft depth (EPRI 500 ft - 1000 ft) SAND (EPRI 500 ft - 1000 ft)

J Clay 35 CLAY (V&D PI = 100) CLAY (V&D, PI=200)

J Sand N/A SAND at > 100 ft depth (EPRI 500 ft - 1000 ft) SAND (EPRI 500 ft - 1000 ft)

K Clay 35 CLAY (V&D PI = 100) CLAY (V&D, PI=200)

KSand N/A SAND at Ž 100 ft depth (EPRI 500 ft - 1000 ft) SAND (EPRI 500 ft - 1000 ft)

L 50 CLAY (V&D PI = 100) CLAY (V&D, PI=200)

M N/A SAND at > 100 ft depth (EPRI 500 ft - 1000 ft) SAND (EPRI 500 ft - 1000 ft)

N Clay 45 CLAY (V&D PI = 100) CLAY (V&D, PI=200)

N Sand N/A SAND at > 100 ft depth (EPRI 500 ft - 1000 ft) SAND (EPRI 500 ft - 1000 ft)

Table 2.3.2-5 Modulus reduction curves for profiles for Base Cases 1 & 2 for STPEGS Sand at Sand at Clay

< 100 ft depth (V&D PC Silt Strain 100 ft depth N (EPRI 500 ft-1000 (EPRI 250 ft - =100) (EPRI PI = 50) ft) 500 ft)

G/Grmax 1.0 0.20 +/- 0.05 0.15 +/- 0.05 0.36 +/- 0.05 0.14 +/- 0.05 0.316 0.40 +/- 0.05 0.33 +/- 0.05 0.62 +/- 0.04 0.32 +/- 0.05 0.1 0.65 +/- 0.04 0.57 +/- 0.04 0.82 +/- 0.03 0.58 +/- 0.04 0.0316 0.86 +/- 0.03 0.80 +/- 0.03 0.93 +/- 0.02 0.81 +/- 0.03 0.01 0.95 +/- 0.02 0.94 +/- 0.02 0.98 +/- 0.01 0.95 +/- 0.02 0.00316 1.00 0.99 +/- 0.01 1.00 1.00 0.001 1.00 1.00 1.00 1.00 0.000316 1.00 1.00 1.00 1.00 0.0001 1.00 1.00 1.00 1.00

NOC-AE-14003114 Page 28 of 63 ISTPEGS Seismic Hazard and Screening Report I Revision 001, March 27, 2014 Page 27 Table 2.3.2-6 Damping curves for profiles for Base Cases 1 & 2 for STPEGS

_Low PI Silt Clay and Sand Clay (V&D, PI =

Strain (EPRI 500 ft-1 000 ft) 200) Silt

(%) (Hybrid)

Damping Ratio (%)

1.0 16.66 +/- 1.7 8.08 +/- 0.8 15.72 +/- 1.6 0.316 10.70 +/- 1.1 4.86 +/- 0.5 10.96 +/- 1.1 0.1 5.64 +/- 0.6 3.09 +/- 0.3 6.61 +/- 0.7 0.0316 2.67 +/- 0.3 2.22 +/- 0.2 3.54 +/- 0.4 0.01 1.30 +/- 0.1 1.65 +/- 0.2 2.03 +/- 0.2 0.00316 0.83 +/- 0.08 1.33 +/- 0.1 1.33 +/- 0.1 0.001 0.67 +/- 0.07 1.09 +/- 0.1 1.09 +/- 0.1 0.000316 0.60 +/- 0.06 1.09 +/- 0.1 1.09 +/- 0.1 0.0001 0.60 +/- 0.06 1.09 +/- 0.1 1.09 +/- 0.1

NOC-AE-14003114 Page 29 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 28 1.00 0.90 0.80 0.70 0.60 w 0.50 0.40 0.30 0.20 0.10 0.00 4-0.0001 0.001 0.01 0.1 Strain (%)

Figure 2.3.2-3. Shear modulus reduction curves for STPEGS

NOC-AE-14003114 Page 30 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 29 18 16 k 14 12 SAND (EPRI 500 ft - 1000 ft) 10 -U-CLAY with PI > 30 (V&D, PI=200)

-*-Low PI CLAY and SILT (Hybrid) I 8

6 4

2 0

0.0001 0.001 0.01 0.1 1 Shear Strain, y Figure 2.3.2-4. Damping ratio curves for STPEGS

NOC-AE-14003114 Page 31 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 30 2.3.2.2 Kappa In site response analysis, the material above the depth of 603 ft is modeled as nonlinear with strain-dependent shear modulus reduction and material damping curves as discussed above in Section 2.3.2.1. Below the depth of 603 ft, the material is considered to be linear for all analyses with damping ratio calibrated to provide the prescribed kappa for the soil column at the surface of the site.

Based on the guidance in the Section B-5.1.3.1 of the SPID (EPRI 1025287, 2013), the STPEGS site is considered a deep soil site. Thus, a median value of kappa of 0.04 sec is considered for the soil column. As specified in Section B-5.1.3.2 of the SPID (EPRI 1025287, 2013), a natural log standard deviation of 0.4 was used to estimate the upper and lower range values of kappa. Table 2.3.2-7 summarizes the soil column kappa values used for site response analysis, where BCl and BC2 refer to the two alternative Vs profiles, presented in Section 2.3.2.

The range of kappa values in the table encompasses the values listed in the SPID (EPRI 1025287, 2013) for deep soil sites (e.g., 0.060, 0.054, and 0.052 sec).

Table 2.3.2-7. Soil Column Kappa Values Used for Site Response Analyses Velocity Profile Lower (sec) Median (sec) Upper (sec)

BCl 0.024 0.040 0.067 BC2 0.024 0.040 0.067 Because two base case Vs profiles were considered, a total of six alternative soil columns (2 base cases for Vs x 3 for kappa) are used for randomization and site response analysis. These soil columns, as well as their associated weights for the purpose of site response analysis, are summarized in Table 2.3.2-8.

Table 2.3.2-8. Alternative Base Case Soil Columns and Associated Weights Base Soil Shear Wave Velocity Kappa Soil Column Column Profile Weight Profile Weight Weight Name (wVs) (wk) (wVs x wk)

BC1-kL Base Case 1 Lower range (kL) 0.3 0.12 BC1-kM (BC1) 0.4 Median (kM) 0.4 0.16 BC1-kU Upper range(kU) 0.3 0.12 BC2-kL Base Case 2 Lower range (kL) 0.3 0.18 BC2-kM (BC2) 0.6 Median (kM) 0.4 0.24 BC2-kU Upper range (kU) 0.3 0.18 Total 1.0

NOC-AE-14003114 Page 32 of 63 I STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 31 2.3.3 Randomization of Base Case Profiles To account for the aleatory variability in material properties and soil profile data that is expected to occur across a site at the scale of a typical nuclear facility, variability in the assumed Vs profiles has been incorporated in the site response calculations. For the STPEGS site, random Vs profiles were developed from the base case profiles, presented in Section 2.3.2. The simulation procedure generates a set of site-specific simulated soil profiles which include uncertainty associated with the dynamic property and soil profile configuration, and correlations between different parameters.

Note that epistemic uncertainty at the STPEGS site is limited given the level of geotechnical investigation conducted at the site, refer to Section 2.3.2. Six profiles (2 base cases for Vs x 3 for kappa) are adopted, as described in Section 2.3.2.2 (see Table 2.3.2-8), and a set of sixty random profiles was generated for each. The random Vs profiles, presented in Figure 2.3.3-1 and Figure 2.3.3-2 for two of the six soil columns, were generated using a natural log standard deviation ranging from 0.19 to 0.25 over the upper 603 ft, and ranging from 0.1 to 0.2 below that depth (see Section 2.3.2 and Tables 2.3.2-1, 2.3.2-2 and 2.3.2-3). Note that some values of the measured natural log standard deviation below 603 ft depth were less than 0.1; these were set at 0.1 for the analysis. As specified in the SPID (EPRI 1025287, 2013), correlation of Vs between layers was modeled using the USGS C correlation model. In profile simulation, a limit of +/- 2 standard deviations about the median value in each layer was assumed for the limits on random velocity fluctuations, as well as on strain-dependent shear modulus reduction and damping ratios. All random velocities were limited to be less than or equal to 9,200 ft/sec.

Bedrock at the STPEGS site is found at a very large depth (about 34,500 ft deep). For the purpose of soil profile simulation and seismic site response analysis, the soil column is truncated at a best estimate depth of 8094 ft. The truncation depth is determined such that the soil column frequency at that depth is less than 0.1 Hz, where bedrock with a Vs of 9200 ft/sec is placed. Since the soil hazard and GMRS calculation only needs to consider frequencies higher than about 0.5 Hz (EPRI 1025287, 2013), appropriately truncated soil profiles can be used to produce accurate results for the site response in the range of frequencies of interest. A 10% uniform variation on the best estimate (BE) total depth of the soil column is applied. The thicknesses of individual soil/rock formations were also simulated, where the maximum and minimum thicknesses for each soil/rock formation were estimated by a 20% increase and decrease from the BE value, respectively.

NOC-AE-14003114 Page 33 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 32 STP - BC1-kM - Low-Strain Shear-Wave Velocity [fi/sec]

0 2000 4000 6000 8000 10000 0

1000 2000 3000 4000 5000 6000 7000 8000 9000 Figure 2.3.3-1. Simulated shear wave velocity profiles for the BC1-kM base soil column (Individual profiles plotted in gray, and median profile plotted in red)

NOC-AE-14003114 Page 34 of 63 ISTPEGS Seismic Hazard and Screening Report I Revision 001, March 27, 2014 Page 33 STP - BC2-kM - Low-Strain Shear-Wave Velocity [ft/sec]

0 2000 4000 6000 8000 10000 0

1000 2000 3000 4000 5000 6000 7000 8000 9000 Figure 2.3.3-2. Simulated shear wave velocity profiles for the BC2-kM base soil column (Individual profiles plotted in gray, and median profile plotted in red)

NOC-AE-14003114 Page 35 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 34 2.3.4 Input Spectra For the calculation of the control point motions, Method 2A (McGuire et al., 2001) was used, which is endorsed as an acceptable methodology by both the NRC 10 CFR 50.54(f) RFI Letter, to Seismic Enclosure 1 (which endorses the use of either NUREG/CR-6728 Method 2 or 3) and also the SPID, Section 2.5.3. Consistent with Method 2A, the input spectra used for the site response analysis are based on the base rock hazard results for both high frequency (HF) and low frequency (LF) cases. Given the hazard curves presented in Section 2.2.2, the deaggregation results for annual frequency of exceedance (AFE) levels of 1 0 4, 105, and 10-6 from a previous probabilistic seismic hazard analysis for the STP Units 3&4 (STPNOC, 2012) were adopted to be acceptable in the Method 2A approach for STP Units 1&2.

This assumption is acceptable based on the expectation that the mean magnitude and mean distance values would not change between the PSHA studies in a way to significantly change the resulting HF and LF spectra. The adopted controlling mean magnitude and distances are listed in Table 2.3.4-1. The 10-4 AFE level values were assumed to be equal to the 10-3 AFE level values. Similarly, the AFE level values less than 10-6 were assumed to be equal to the 106 AFE level values. These deaggregation magnitude and distance values were also adopted for the fractile cases.

Table 2.3.4-1 Mean magnitude and distance values for the high frequency (HF) and low frequency (LF) cases. For the LF cases the values are computed based on the contribution from sources greater than 100 km following the guidance provided in NRC (2007).

High Frequency (HF) Low Frequency (LF)

AFE Mean Magnitude Mean Distance (kin) Mean Magnitude Mean Distance (kin) 10-3 6.7 230 7.6 880 10-4 6.7 230 7.6 880 10-5 6.1 46 7.7 890 10.6 5.6 10 7.8 890 10-7 5.6 10 7.8 890 Separate input spectra were developed for HF and LF cases. For the HF cases the spectral shape is anchored to the uniform hazard response spectra (UHRS) values at PGA (100 Hz), 25 Hz, 10 Hz, and 5 Hz in order to reflect accurately the UHRS values. In between these frequencies, the spectrum is logarithmically smoothed using shapes anchored to the next higher and next lower frequencies. This technique provides a reasonable spectral shape at these intermediate frequencies. Below 5 Hz, the spectral amplitudes were scaled using the HF spectral shape given the appropriate magnitude and distance values anchored to the 5 Hz spectral amplitude.

For the LF cases a similar procedure was used except that the LF spectral shape was anchored to the UHRS values at all seven ground motion frequencies (PGA(100 Hz), 25 Hz, 10 Hz, 5 Hz, 2.5 Hz, 1 Hz, and 0.5 Hz). Anchoring the LF spectral shape to all frequencies was adopted to prevent the high frequency ground motions values associated with the LF case to exceed the high frequency ground motion values associated with the HF case. With this constraint, the HF and LF input spectra were constrained to be equal at the PGA (100 Hz), 25 Hz, 10 Hz, and 5 Hz

NOC-AE-14003114 Page 36 of 63 ISTPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 35 spectral frequencies and were similar for frequencies between these reference spectra frequencies based on the interpolated spectral shapes given the appropriate magnitude and distance values.

As an example the HF, LF and Broadband input spectra are plotted in Figure 2.3.4-1 for the mean hazard curve case for 1 0 4 AFE level. The Broadband spectrum is the envelope of the HF and LF spectra and is not used in the site amplification analysis. The UHS ground motion values for the seven reference frequencies are shown in the figure as the red open circles. Similar results for the 10s AFE level are plotted in Figure 2.3.4-2. The digital values for the HF and LF spectra for the mean hazard curve case are provided in Table 2.3.4-2 at a suite of 38 spectral frequencies. These resulting HF and LF spectra for the suite of AFE level (i.e., 10-3 to 10-8) for the mean and five fractile levels are used as the input spectra for the site response analysis.

104 spectra 0.07 M MEAN

,- O.O6 I 0 0.05 1 - I K 0.04 ........ l 2 0.03 0O.02 I 0.01 - - 1 4 0 1 10 0.1 1 1010 100 Frequency, Hz Figure 2.3.4-1 Mean, LF, HF, and Broadband 104 spectra for STP Units 1 & 2.

NOC-AE-14003114 Page 37 of 63 STPEGS Seismic Hazard and Screening Report I Revision 001, March 27, 2014 Page 36 10-5 spectra 0.3 0.2 0.2 .....

MEAN MAO2_

...".. j

-'Broadband-10-5

-igh HiLowgFrequency Frequency 00H 0.15 i . .i f -,

0.15 (U

0.05 .  !..... . . ..

0 ... 100..

0.1 1 10 100 Frequency, Hz Figure 2.3.4-2 Mean, LF, HF, and Broadband 10-5 spectra for STP Units 1 & 2.

NOC-AE-14003114 Page 38 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 37 Table 2.3.4-2 Input HF and LF spectra for the 10-4 and 10-5 AFE level associated with the mean hazard curves at a suite of 38 spectral frequencies.

Frequency (Hz) HF 10-4 (g) LF 10-4 (g) HF 10-5 (g) LF 10-5 (g) 100 2.711 E-02 2.711 E-02 1.322E-01 1.322E-01 90 2.928E-02 2.926E-02 1.428E-01 1.425E-01 80 3.311E-02 3.305E-02 1.615E-01 1.608E-01 70 3.896E-02 3.884E-02 1.899E-01 1.887E-01 60 4.620E-02 4.600E-02 2.251E-01 2.230E-01 50 5.281E-02 5.251E-02 2.571E-01 2.540E-01 45 5.519E-02 5.485E-02 2.684E-01 2.649E-01 40 5.675E-02 5.638E-02 2.757E-01 2.719E-01 35 5.749E-02 5.713E-02 2.787E-01 2.750E-01 30 5.741E-02 5.715E-02 2.773E-01 2.746E-01 25 5.648E-02 5.648E-02 2.707E-01 2.707E-01 20 5.780E-02 5.694E-02 2.696E-01 2.628E-01 15 5.793E-02 5.677E-02 2.581 E-01 2.495E-01 12.5 5.709E-02 5.625E-02 2.457E-01 2.397E-01 10 5.522E-02 5.522E-02 2.266E-01 2.266E-01 9 5.303E-02 5.304E-02 2.138E-01 2.144E-01 8 5.051E-02 5.056E-02 1.996E-01 2.008E-01 7 4.761E-02 4.770E-02 1.838E-01 1.854E-01 6 4.425E-02 4.434E-02 1.665E-01 1.678E-01 5 4.031E-02 4.031 E-02 1.473E-01 1.473E-01 4 3.563E-02 3.498E-02 1.255E-01 1.232E-01 3 2.975E-02 2.910E-02 1.003E-01 9.690E-02 2.5 2.605E-02 2.614E-02 8.543E-02 8.367E-02 2 2.154E-02 2.358E-02 6.828E-02 7.001E-02 1.5 1.599E-02 2.069E-02 4.866E-02 5.575E-02 1.25 1.287E-02 1.881 E-02 3.832E-02 4.806E-02 1 9.686E-03 1.740E-02 2.813E-02 4.214E-02 0.9 8.434E-03 1.672E-02 2.421 E-02 3.993E-02 0.8 7.212E-03 1.584E-02 2.041E-02 3.732E-02 0.7 6.031 E-03 1.472E-02 1.677E-02 3.428E-02 0.6 4.899E-03 1.394E-02 1.332E-02 3.210E-02 0.5 3.821E-03 1.291 E-02 1.007E-02 2.945E-02 0.4 2.803E-03 9.363E-03 7.085E-03 2.142E-02 0.3 1.854E-03 5.934E-03 4.403E-03 1.364E-02 0.2 9.953E-04 2.795E-03 2.129E-03 6.457E-03 0.167 7.402E-04 1.898E-03 1.500E-03 4.391 E-03 0.125 4.457E-04 9.387E-04 8.185E-04 2.171E-03 0.1 2.922E-04 5.044E-04 4.917E-04 1.162E-03

NOC-AE-14003114 Page 39 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 38 2.3.5 Methodology This section defines the random vibration theory (RVT) methodology which was used to perform the site response analyses for the STPEGS site. This process utilizes a simple, efficient approach for computing site-specific amplification functions and is consistent with existing NRC guidance and the SPID (EPRI 1025287, 2013).

Using the input spectra developed for STPEGS, as defined in Section 2.3.4, as well as the significant amount of initial and newly developed information which is now available for the STPEGS site,, the 5% damped acceleration response spectra at the ground surface (SSE control point) are computed, and the amplification functions are calculated as the ratio of the surface response spectra to the hard rock spectra, both at 5% spectral damping. Arithmetic mean (mean) and natural log-mean (median) amplification functions and associated natural log-standard deviations are calculated for each of the six sets of 60 profiles. The analysis is carried out at 301 frequency points ranging from 0.1 to 100 Hz and equally spaced in logarithmic space.

The total (weighted average) arithmetic mean and log-mean amplification as a function of frequency, at each hard rock motion level, are calculated as:

PT = I wi/

In this equation, p/ is the total arithmetic mean (or log-mean) amplification at each spectral frequency, A, is the arithmetic mean (or log-mean) amplification function for soil column i at the same spectral frequency, and wi is the weight assigned to soil column i. In the case of the STPEGS site, six soil columns are used and their associated weights are provided in Table 2.3.2-4. Similarly, the total natural log-standard deviation o-T of the amplification as a function of spectral frequency, is calculated by the equation below, where a, is the natural log-standard deviation of soil column i.

CrT = wj (21 -r) + O' The site amplification function is inherently probabilistic in nature and the SPID Report (Section B2.1) provides definitions of aleatory variability and epistemic uncertainties (Appendix A, Section B2.1) and requires that they be addressed in the Seismic Reevaluation. However, it also acknowledges that, for a site like STPEGS, with extensive seismic data and analyses, "For well-characterized sites, with abundant high-quality data, this uncertainty would be reduced, possibly eliminating the need to vary some of the site parameters such as the site profile."

Development of the GMRS and hazard curves involves establishment of frequency-dependent spectral amplification factors that define how the input rock motion corresponding to a defined return period is amplified because of the site response, and convolution of the rock hazard with site amplification function (since magnitude of site amplification depends on the input rock amplitude, which itself has a range of values).

NOC-AE-140031 14 Page 40 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 39 Even for a 'Well characterized" site, such as STP 1&2, with an exhaustive recent subsurface investigation that supplements the existing UFSAR seismic information, there will be random variability of soil properties within each soil layer, for parameters such as Vs, non-linear dynamic material properties, the overall thickness of soil/soft rock above firm rock, and inherent near surface site damping (kappa value, which represents damping of soil layers below the depth of subsurface investigation). In addition, the soil layer thickness itself will randomly vary.

Additional random variability could occur with the kappa value. As explained below, although the depth to bedrock may vary, it is not expected to impact results for frequencies greater than or equal to 0.5 Hz.

Aleatory variability is addressed through the randomization process. The potential Vs variability for each soil layer and potential variability for each soil layer thickness is captured by considering random perturbations to the "base case" soil column mode. Sixty randomizations are used to address the aleatory variability (60 being a large enough number to help provide stable statistical mean and standard deviation values for the amp function for each profile).

Perturbations relative to the kappa value are considered to address its aleatory variability.

For STP 1&2, the soil amplification function is essentially insensitive to the as-modeled soil column height for the frequency range of interest (i.e., 1 Hz to 100 Hz). The epistemic uncertainty primarily impacts the base case soil column model and is accounted for by employing alternative base case models. Based on the SPID recommendations, in addition to the base case model, upper and lower-range alternative base case models are developed. Soil properties for upper-range and lower-range models are assigned using a "profile epistemic uncertainty factor".

For well characterized sites such as STP, due to the availability of good subsurface data from Units 3 and 4, the epistemic uncertainty is relatively small. The SPID states that "For well-characterized sites, with abundant high-quality data, this uncertainty would be reduced, possibly eliminating the need to vary some of the site parameters such as the site profile" (the term "site profile" is used here to refer to the base case soil model).

The Vs measurement data for Units 1 and 2 considered two alternative base cases to account for the modeling ("epistemic") uncertainty of Vs. For both base cases, the local soil layering under Units 1 and 2 is based on the lithology reported in the UFSAR for Units 1 and 2.

The soil dynamic properties for depths be:ow 341-ft are based on the new data used for Units 3 and 4 since no such data are available for Units 1 and 2. Also, for both base cases, the strain-dependent properties for each layer (e.g., soil damping and modulus) were wholly based on the data from Units 3 and 4 since the recent RCTS-based test data are considered highly reliable compared to the older testing methods. So, the only difference between the two base cases is that one base case considers the Vs values entirely based on Units 3 and 4 data, whereas the other base case considers the reported Vs values for Units I and 2 (down to the reported depth). Kappa estimates are used to calculate strain-independent damping rations for layers below 603 ft. depth, and three alternative values (lower range, median and upper range are adopted. This results in a total of 6 alternative soil columns (2 base cases for Vs C3 for kappa).

NOC-AE-14003114 Page 41 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 40 The approach for STP Units 1 and 2 thus employs an appropriate basis for developing the alternative base case profiles and the associated weighting factors, and will result in more accurate estimation of the GMRS and hazard curves. A higher weighting was assigned to the base case model that is based on velocity measurements from Units 3 and 4, since the data were developed by more recent techniques. Each base case is then randomized to address aleatory variability concerning soil properties and layer thickness. The final GMRS results are obtained using a weighted average approach to the corresponding results for the individual alternative base cases.

Thus, for STP 1&2, the epistemic uncertainty has been fully considered by: (a) proper selection of the base case models and (b) judicious assignment of the "profile epistemic uncertainty factors".

2.3.6 Amplification Functions The results of site response analysis consist of amplification functions which describe the amplification (or de-amplification) of hard rock motion as a function of frequency and input reference rock amplitude. The amplification factors are represented in terms of a mean (and median) amplification value and an associated standard deviation (sigma) as a function of spectral frequency for the hard rock spectra presented in Section 2.3.4 (mean High Frequency (HF) and Low Frequency (LF) at various annual frequencies of exceedance (AFE), from 1 E-3 to 1E-7, as well at different fractile levels).

As an example, Figure 2.3.6-1a illustrates the mean amplification functions developed for the BC1-kM soil column (see Table 2.3.2-8 for a definition of alternative base soil columns). The variability in the amplification factors results from variability in Vs, depth to hard rock, and modulus reduction and hysteretic damping curves, and is represented by the natural log-standard deviations illustrated in Figure 2.3.6-1b. Figure 2.3.6-2a and Figure 2.3.6-2b show similar results for the BC2-kM soil column. Similarly, amplification functions are developed for all six alternative base soil columns.

The total (weighted average) mean amplification functions and corresponding standard deviations are presented in Figure 2.3.6-3a and Figure 2.3.6-3b, respectively. Note that while the illustrated amplification functions are computed using the mean bedrock input motions, amplification functions are also developed for 5 th, 1 6th, 5 0 th 8 4 th, and 9 5 th percentile rock motions at the 1E-3 through 1 E-7 AFE.

Tabulated values of the amplification factors for the presented figures, at the 1 E-4 and 1E-5 AFE, are provided in Tables 2.3.6-1, 2.3.6-2 and 2.3.6-3. Additionally, the weighted average amplification and total standard deviation is reported at the seven frequencies, for which the GMM is defined, in Table A-2 in the Appendix for the 1 E-3 through 1 E-7 AFE.

NOC-AE-14003114 Page 42 of 63 ISTPEGS Seismic Hazard and Screening Report I Revision 001, March 27, 2014 Page41 4.5

- BCIkM HF7 - - BCI_kM LF7

- BC1IkM HF6 - - BCIkM LF6 4.0 A - BC1_kM HF5 -- BCIkM LF5 3.5 - BCIlkM HF4 - - BCIlkM LF4

- _kM HF3 - - BC1_kM LF3 3.0 2.5 C

7& 2.0 E

1.5

/0 1.0 IV 0oo 0.

0.5 0.0 0.1 1 10 100 Frequency [Hz]

Figure 2.3.6-1a. Example suite of mean site amplification functions for the BC1 -kM soil column for the 1 E-3 through 1 E-7 AFE input motions.

NOC-AE-14003114 Page 43 of 63 ISTPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 42 0.35 0.3 0.25 0.2 2F 0.15 0.1 A 0.05 0

0.1 1 10 100 Frequency [Hz]

Figure 2.3.6-1b. Example suite of natural logarithmic standard deviations of the amplification functions for the BC1-kM soil column.

NOC-AE-14003114 Page 44 of 63 I STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 43 4.5

- BC2_kM HF7 - - BC2_kM LF7 4.0 S- BC2kM HF6 - - BC2_kM LF6

- BC2_kM HF5 - - BC2_kM LF5 C 3.5 - -- BC2_kM HF4 - - BC2_kM LF4 C0 -BC2_kM HF3 - - BC:2_kM LF3 3.0 2.5 AlI C

2.0 E

1.5 1.0 0.5 0.0 0.1 1 10 100 Frequency (Hz]

Figure 2.3.6-2a. Example suite of mean site amplification functions for the BC2-kM soil column for the 1 E-3 through 1E-7 AFE input motions.

NOC-AE-14003114 Page 45 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page44 0.3 0.25 0.2 IF 0.15 0.1 0.05 n

0.1 1 10 100 Frequency [HzJ Figure 2.3.6-2b. Example suite of natural logarithmic standard deviations of the amplification functions for the BC2-kM soil column.

NOC-AE-14003114 Page 46 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page45 4.5 4.0 0

C 3.5 3.0 2.5

'C 7& 2.0

.5 1.5 1.0 0.5 0.0 0.1 10 100 Frequency [Hz]

Figure 2.3.6-3a. Total (weighted average) mean site amplification functions for the STPEGS site for the 1E-3 through 1E-7 AFE input motions.

NOC-AE-14003114 Page 47 of 63 ISTPEGS Seismic Hazard and Screening Report I Revision 001, March 27, 2014 Page46 0.6 0.5 0.4 12 0.3 0

0.2 - - - - -- -Wegte-vrae---- WihedAeag F L* *-Weighted Average HF6 - - Weighted Average LF7 V * -Weighted Average HF5 -- -- Weighted Average LF5 0.1

-Weighted Average HF - - Weighted Average LF4

- Weighted Average HF3 - - Weighted Average LF3 0

0.1 10 100 Frequency [Hz]

Figure 2.3.6-3b. Total (weighted average) natural logarithmic standard deviations of the amplification functions for the STPEGS site.

NOC-AE-14003114 Page 48 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page47 Table 2.3.6-1. Arithmetic mean and log-standard deviation of the 5% damped amplification function (AF) for the BC 1-kM soil column and the HF4, LF4, HF5, and LF5 motions Frequency HF 1E-4 LF 1E-4 HF 1E-5 LF 1E-5

[Hz] Mean AF Ln (AF) Mean AF Ln (AF) Mean AF Ln (AF) Mean AF Ln (AF) 0.1 2.97E+00 1.46E-01 3.08E+00 1.12E-01 3.01E+00 1.38E-01 3.06E+00 1.11E-01 0.125 3.29E+00 8.45E-02 3.31E+00 8.18E-02 3.28E+00 8.89E-02 3.30E+00 8.19E-02 0.167 2.77E+00 9.58E-02 2.81E+00 9.12E-02 2.74E+00 8.99E-02 2.80E+00 9.16E-02 0.2 2.77E+00 8.18E-02 2.83E+00 8.43E-02 2.75E+00 7.68E-02 2.82E+00 8.52E-02 0.3 3.24E+00 1.83E-01 3.25E+00 1.81E-01 3.13E+00 1.76E-01 3.23E+00 1.82E-01 0.4 3.04E+00 1.66E-01 3.05E+00 1.60E-01 2.97E+00 1.47E-01 3.05E+00 1.61E-01 0.5 2.94E+00 1.62E-01 2.92E+00 1.69E-01 2.86E+00 1.54E-01 2.89E+00 1.70E-01 0.6 2.85E+00 1.38E-01 2.86E+00 1.29E-01 2.77E+00 1.29E-01 2.82E+00 1.31E-01 0.7 2.61E+00 1.53E-01 2.65E+00 1.45E-01 2.55E+00 1.49E-01 2.59E+00 1.51E-01 0.8 2.55E+00 1.39E-01 2.57E+00 1.37E-01 2.50E+00 1.34E-01 2.51E+00 1.40E-01 0.9 2.54E+00 1.48E-01 2.55E+00 1.45E-01 2.49E+00 1.44E-01 2.49E+00 1.51E-01 1 2.62E+00 1.33E-01 2.62E+00 1.32E-01 2.56E+00 1.28E-01 2.56E+00 1.35E-01 1.25 2.72E+00 1.57E-01 2.72E+00 1.52E-01 2.66E+00 1.52E-01 2.68E+00 1.56E-01 1.5 2.84E+00 1.65E-01 2.84E+00 1.55E-01 2.75E+00 1.64E-01 2.78E+00 1.68E-01 2 2.53E+00 1.94E-01 2.54E+00 1.83E-01 2.46E+00 1.91E-01 2.46E+00 1.94E-01 2.5 2.65E+00 1.89E-01 2.64E+00 1.79E-01 2.57E+00 1.85E-01 2.57E+00 1.88E-01 3 2.87E+00 2.03E-01 2.84E+00 1.97E-01 2.73E+00 1.98E-01 2.71E+00 2.04E-01 4 2.59E+00 2.21E-01 2.54E+00 2.18E-01 2.42E+00 2.20E-01 2.35E+00 2.33E-01 5 2.14E+00 2.66E-01 2.09E+00 2.60E-01 1.99E+00 2.66E-01 1.90E+00 2.72E-01 6 1.97E+00 2.41E-01 1.91E+00 2.37E-01 1.81E+00 2.43E-01 1.70E+00 2.51E-01 7 1.76E+00 2.32E-01 1.71E+00 2.26E-01 1.62E+00 2.38E-01 1.52E+00 2.46E-01 8 1.64E+00 2.33E-01 1.59E+00 2.28E-01 1.51E+00 2.40E-01 1.40E+00 2.50E-01 9 1.52E+00 2.42E-01 1.47E+00 2.35E-01 1.38E+00 2.48E-01 1.27E+00 2.56E-01 10 1.37E+00 2.54E-01 1.32E+00 2.45E-01 1.23E+00 2.62E-01 1.12E+00 2.68E-01 12.5 1.05E+00 2.22E-01 1.03E+00 2.07E-01 9.15E-01 2.34E-01 8.36E-01 2.37E-01 15 8.85E-01 2.20E-01 8.81E-01 1.99E-01 7.45E-01 2.35E-01 6.81E-01 2.32E-01 20 7.39E-01 2.10E-01 7.52E-01 1.85E-01 5.86E-01 2.29E-01 5.37E-01 2.21E-01 25 6.80E-01 1.93E-01 6.96E-01 1.66E-01 5.15E-01 2.10E-01 4.68E-01 1.99E-01 30 6.32E-01 1.81E-01 6.57E-01 1.55E-01 4.70E-01 1.95E-01 4.35E-01 1.84E-01 35 6.12E-01 1.75E-01 6.42E-01 1.49E-01 4.50E-01 1.87E-01 4.22E-01 1.76E-01 40 6.10E-01 1.71E-01 6.42E-01 1.45E-01 4.46E-01 1.82E-01 4.20E-01 1.72E-01 60 7.31E-01 45 6.21E-01 1.65E-01 1.69E-01 6.56E-01 7.74E-01 1.43E-01 4.52E-01 1.80E-01 4.28E-01 1.70E-01 1.40E-01 5.31E-01 50 6.44E-01 1.67E-01 6.81E-01 1.42E-01 4.68E-01 1.77E-01 1.76E-01 4.43E-01 1.68E-01 5.02E-01 1.67E-01 70 8.63E-01 1.65E-01 9.13E-01 1.40E-01 6.26E-01 1.75E-01 5.91E-01 1.66E-01 80 1.01E+00 1.64E-01 1.07E+00 1.40E-01 7.33E-01 1.74E-01 6.91E-01 1.65E-01 90 1.14E+00 1.64E-01 1.21E+00 1.39E-01 8.27E-01 1.74E-01 7.77E-01 1.65E-01 100 1.23E+00 1.64E-01 1.30E+00 1.39E-01 8.93E-01 1.74E-01 8.39E-01 1.65E-01

NOC-AE-14003114 Page 49 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 48 Table 2.3.6-2. Arithmetic mean and log-standard deviation of the 5% damped amplification function (AF) for the BC2-kM soil column and the HF4, LF4, HF5, and LF5 motions Frequency HF 1E-4 LF 1E-4 HF 1E-5 LF 1E-5

[Hz] Mean AF Ln (AF) Mean AF Ln (AF) Mean AF Ln (AF) Mean AF Ln (AF) 0.1 2.93E+00 1.57E-01 3.08E+00 1.11E-01 2.99E+00 1.37E-01 3.07E+00 1.10E-01 0.125 3.26E+00 7.33E-02 3.31E+00 6.70E-02 3.25E+00 7.06E-02 3.29E+00 6.72E-02 0.167 2.91E+00 1.21E-01 2.97E+00 1.16E-01 2.88E+00 1.11E-01 2.95E+00 1.16E-01 0.2 2.90E+00 9.83E-02 2.97E+00 9.91E-02 2.89E+00 9.11E-02 2.96E+00 1.OOE-01 0.3 3.49E+00 1.86E-01 3.52E+00 1.86E-01 3.38E+00 1.78E-01 3.51E+00 1.87E-01 0.4 3.17E+00 1.48E-01 3.19E+00 1.42E-01 3.10E+00 1.27E-01 3.19E+00 1.41E-01 0.5 3.43E+00 1.91E-01 3.42E+00 1.98E-01 3.32E+00 1.81E-01 3.39E+00 2.OOE-01 0.6 3.17E+00 1.55E-01 3.19E+00 1.50E-01 3.08E+00 1.47E-01 3.14E+00 1.55E-01 0.7 3.14E+00 1.84E-01 3.17E+00 1.77E-01 3.05E+00 1.77E-01 3.11E+00 1.81E-01 0.8 3.01E+00 1.46E-01 3.04E+00 1.47E-01 2.94E+00 1.42E-01 2.98E+00 1.52E-01 0.9 3.14E+00 1.53E-01 3.15E+00 1.51E-01 3.04E+00 1.48E-01 3.07E+00 1.54E-01 1 3.08E+00 1.27E-01 3.10E+00 1.27E-01 2.99E+00 1.24E-01 3.03E+00 1.31E-01 1.25 3.12E+00 1.36E-01 3.14E+00 1.31E-01 3.01E+00 1.33E-01 3.06E+00 1.38E-01 1.5 2.91E+00 1.54E-01 2.93E+00 1.49E-01 2.80E+00 1.52E-01 2.82E+00 1.58E-01 2 2.85E+00 1.91E-01 2.87E+00 1.87E-01 2.77E+00 1.87E-01 2.81E+00 1.95E-01 2.5 3.11E+00 1.96E-01 3.08E+00 1.90E-01 2.92E+00 1.97E-01 2.89E+00 2.11E-01 3 2.69E+00 2.16E-01 2.68E+00 2.06E-01 2.56E+00 2.12E-01 2.53E+00 2.18E-01 4 2.69E+00 1.65E-01 2.64E+00 1.63E-01 2.49E+00 1.62E-01 2.39E+00 1.69E-01 5 2.31E+00 1.74E-01 2.24E+00 1.71E-01 2.10E+00 1.73E-01 1.97E+00 1.80E-01 6 1.88E+00 1.86E-01 1.83E+00 1.83E-01 1.72E+00 1.92E-01 1.60E+00 2.01E-01 7 1.69E+00 2.14E-01 1.64E+00 2.07E-01 1.55E+00 2.12E-01 1.42E+00 2.13E-01 8 1.57E+00 2.13E-01 1.52E+00 2.07E-01 1.42E+00 2.16E-01 1.30E+00 2.20E-01 9 1.40E+00 2.18E-01 1.36E+00 2.09E-01 1.25E+00 2.22E-01 1.14E+00 2.26E-01 10 1.27E+00 2.23E-01 1.23E+00 2.13E-01 1.12E+00 2.28E-01 1.OOE+00 2.32E-01 12.5 9.86E-01 2.24E-01 9.77E-01 2.04E-01 8.41E-01 2.36E-01 7.58E-01 2.30E-01 15 8.58E-01 2.27E-01 8.65E-01 2.01E-01 7.04E-01 2.42E-01 6.36E-01 2.30E-01 20 7.23E-01 1.96E-01 7.49E-01 1.70E-01 5.57E-01 2.10E-01 5.08E-01 1.93E-01 25 6.69E-01 1.76E-01 6.99E-01 1.51E-01 4.93E-01 1.88E-01 4.49E-01 1.73E-01 30 6.29E-01 1.66E-01 6.68E-01 1.42E-01 4.56E-01 1.77E-01 4.24E-01 1.61E-01 35 6.12E-01 1.60E-01 6.56E-01 1.37E-01 4.39E-01 1.69E-01 4.13E-01 1.55E-01 40 6.11E-01 1.56E-01 6.58E-01 1.34E-01 4.37E-01 1.64E-01 4.13E-01 1.51E-01 45 6.23E-01 1.54E-01 6.73E-01 1.33E-01 4.44E-01 1.62E-01 4.21E-01 1.50E-01 50 6.47E-01 1.53E-01 7.OOE-01 1.32E-01 4.61E-01 1.60E-01 4.37E-01 1.48E-01 60 7.36E-01 1.51E-01 7.96E-01 1.31E-01 5.23E-01 1.59E-01 4.96E-01 1.47E-01 70 8.69E-01 1.51E-01 9.40E-01 1.30E-01 6.17E-01 1.58E-01 5.84E-01 1.47E-01 80 1.02E+00 1.50E-01 1.10E+00 1.30E-01 7.23E-01 1.58E-01 6.83E-01 1.46E-01 90 1.15E+00 1.50E-01 1.24E+00 1.30E-01 8.15E-01 1.57E-01 7.69E-01 1.46E-01 100 1.24E+00I 1.50E-01 1.34E+00 1.30E-01 8.81E-01 1.57E-01 8.30E-01 1.46E-01

NOC-AE-14003114 Page 50 of 63 ISTPEGS Seismic Hazard and Screening Report I Revision 001, March 27, 2014 Page49 Table 2.3.6-3. Total (weighted Average) arithmetic mean and log-standard deviation of the 5%

damped amplification function (AF) for the HF4, LF4, HF5, and LF5 motions Frequency HF 1E-4 LF 1E-4 HF 1E-5 LF 1E-5

[Hz] Mean AF Ln (AF) Mean AF Ln (AF) Mean AF Ln (AF) Mean AF Ln (AF) 0.1 2.93E+00 1.54E-01 3.07E+00 1.13E-01 2.99E+00 1.40E-01 3.06E+00 1.12E-01 0.125 3.26E+00 8.36E-02 3.30E+00 7.67E-02 3.26E+00 8.24E-02 3.28E+00 7.73E-02 0.167 2.84E+00 1.17E-01 2.89E+00 1.12E-01 2.82E+00 1.13E-01 2.88E+00 1.13E-01 0.2 2.83E+00 9.86E-02 2.90E+00 9.85E-02 2.83E+00 9.67E-02 2.89E+00 9.99E-02 0.3 3.37E+00 1.93E-01 3.39E+00 1.91E-01 3.27E+00 1.88E-01 3.38E+00 1.92E-01 0.4 3.10E+00 1.63E-01 3.12E+00 1.56E-01 3.03E+00 1.48E-01 3.11E+00 1.57E-01 0.5 3.21E+00 2.02E-01 3.20E+00 2.07E-01 3.11E+00 1.96E-01 3.17E+00 2.09E-01 0.6 3.02E+00 1.69E-01 3.04E+00 1.60E-01 2.93E+00 1.65E-01 2.99E+00 1.65E-01 0.7 2.91E+00 2.06E-01 2.94E+00 1.96E-01 2.83E+00 2.02E-01 2.88E+00 2.OOE-01 0.8 2.81E+00 1.81E-01 2.83E+00 1.77E-01 2.74E+00 1.79E-01 2.77E+00 1.81E-01 0.9 2.87E+00 2.OOE-01 2.89E+00 1.95E-01 2.79E+00 1.97E-01 2.82E+00 1.98E-01 1 2.87E+00 1.76E-01 2.88E+00 1.71E-01 2.79E+00 1.74E-01 2.82E+00 1.75E-01 1.25 2.93E+00 1.87E-01 2.94E+00 1.79E-01 2.84E+00 1.86E-01 2.88E+00 1.83E-01 1.5 2.85E+00 1.93E-01 2.86E+00 1.81E-01 2.75E+00 1.94E-01 2.77E+00 1.91E-01 2 2.69E+00 2.42E-01 2.71E+00 2.30E-01 2.62E+00 2.42E-01 2.64E+00 2.41E-01 2.5 2.89E+00 2.59E-01 2.87E+00 2.45E-01 2.74E+00 2.55E-01 2.73E+00 2.55E-01 3 2.72E+00 2.76E-01 2.71E+00 2.61E-01 2.59E+00 2.72E-01 2.57E+00 2.71E-01 4 2.62E+00 2.87E-01 2.57E+00 2.77E-01 2.43E+00 2.82E-01 2.34E+00 2.83E-01 5 2.21E+00 3.36E-01 2.15E+00 3.21E-01 2.03E+00 3.29E-01 1.91E+00 3.28E-01 6 1.90E+00 3.57E-01 1.85E+00 3.40E-01 1.74E+00 3.56E-01 1.62E+00 3.55E-01 7 1.71E+00 3.93E-01 1.66E+00 3.71E-01 1.57E+00 3.92E-01 1.45E+00 3.88E-01 8 1.60E+00 4.22E-01 1.55E+00 3.95E-01 1.46E+00 4.23E-01 1.34E+00 4.19E-01 9 1.46E+00 4.46E-01 1.41E+00 4.14E-01 1.31E+00 4.50E-01 1.19E+00 4.43E-01 10 1.33E+00 4.65E-01 1.29E+00 4.26E-01 1.18E+00 4.72E-01 1.07E+00 4.60E-01 12.5 1.05E+00 4.65E-01 1.03E+00 4.08E-01 8.99E-01 4.84E-01 8.14E-01 4.55E-01 15 9.13E-01 4.62E-01 9.10E-01 3.94E-01 7.56E-01 4.88E-01 6.84E-01 4.45E-01 20 7.75E-01 4.29E-01 7.87E-01 3.55E-01 6.06E-01 4.58E-01 5.48E-01 4.05E-01 25 7.08E-01 3.86E-01 7.25E-01 3.16E-01 5.30E-01 4.13E-01 4.77E-01 3.61E-01 30 6.55E-01 3.58E-01 6.83E-01 2.90E-01 4.81E-01 3.81E-01 4.41E-01 3.30E-01 35 6.31E-01 3.39E-01 6.64E-01 2.75E-01 4.59E-01 3.60E-01 4.26E-01 3.11E-01 40 6.25E-01 3.28E-01 6.62E-01 2.65E-01 4.52E-01 3.47E-01 4.23E-01 3.01E-01 45 6.35E-01 3.21E-01 6.74E-01 2.60E-01 4.57E-01 3.38E-01 4.29E-01 2.95E-01 50 6.57E-01 3.15E-01 7.OOE-01 2.56E-01 4.72E-01 3.33E-01 4.44E-01 2.91E-01 60 7.43E-01 3.09E-01 7.93E-01 2.51E-01 5.33E-01 3.26E-01 5.02E-01 2.86E-01 70 8.75E-01 3.07E-01 9.35E-01 2.49E-01 6.27E-01 3.23E-01 5.91E-01 2.84E-01 80 1.03E+00 3.05E-01 1.10E+00 2.48E-01 7.34E-01 3.22E-01 6.90E-01 2.83E-01 90 1.16E+00 3.04E-01 1.23E+00 2.48E-01 8.28E-01 3.21E-01 7.77E-01 2.83E-01 100 1.25E+00 3.04E-01 1.33E+00 2.47E-01 8.94E-01 3.20E-01 8.38E-01 2.82E-01

NOC-AE-14003114 Page 51 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 50 2.3.7 Control Point Seismic Hazard Curves The SSE control point for STPEGS is defined as the site ground surface. The dynamic response of the materials below the control point was represented by the frequency and amplitude-dependent amplification functions (mean values and standard deviations) developed and described in the previous section. The procedure to develop probabilistic site-specific control point hazard curves used in the present analysis follows Method 2A (McGuire et al.,

2001) which is endorsed as an acceptable methodology by both the NRC 10 CFR 50.54(f) RFI Letter, Attachment 1 to Seismic Enclosure i (which endorses the use of either NUREG/CR-6728 Method 2 or 3) and also the SPID, Section 2.5.3.

This method computes a site-specific control point hazard curve for a broad range of spectral accelerations (corresponding to the input bedrock motions at a range of AFE) given the site-specific bedrock hazard curve and associated uncertainties and site-specific estimates of soil or soft-rock response.

As an example, the mean 5 Hz hazard curve point at 1E-3 AFE is the product of the total (weighted average) arithmetic mean amplification function of the 1 E-3 motion multiplied by the mean 1 E-3 bedrock motion (envelope of LF and HF mean 1E-3 bedrock motions). Similarly the 16th percentile 5 Hz hazard curve at 1E-3 AFE is the product of the total (weighted average) arithmetic mean amplification function of the 1E-3 motion multiplied by the 16 th percentile 1E-3 bedrock motion (envelope of LF and HF 1 6 th percentile 1 E-3 bedrock motions).

The resulting control point mean hazard curves for the STPEGS site are shown in Figure 2.3.7-1 for the seven oscillator frequencies for which the GMM is defined. Tabulated values of the site response amplification functions and control point hazard curves are provided in Tables A-la through AI-g in Appendix A.

NOC-AE-14003114 Page 52 of 63 STPEGS Seismic Hazard and Screening Report I Revision 001, March 27, 2014 Page 51 I 1.E-03

-0.5 Hz

-1 Hz

-2.5 Hz 1.E-04

• 1

-5 Hz

-10 Hz

-25 Hz 1.E-05 +

-100 Hz 0

1.E-06 1.E-07 I 0.0001 0.01 0.1 10 5% Damped Spectral Acceleration [g]

Figure 2.3.7-1. Control point mean hazard curves for spectral frequencies of 0.5, 1, 2.5, 5, 10, 25 and 100 Hz (PGA) at the STPEGS site.

NOC-AE-14003114 Page 53 of 63 ISTPEGS Seismic Hazard and Screening Report I Revision 001, March 27, 2014 Page 52 2.4 Control PointResponse Spectra The control point hazard curves described above have been used to develop UHRS and the ground motion response spectrum (GMRS).

The I E-4 and 1 E-5 UHRS, along with a design factor (DF) are used to compute the GMRS at the control point using the criteria in Regulatory Guide 1.208. Figure 2.4-1 shows the control point UHRS and GMRS. Table 2.4-1 shows the UHRS and GMRS spectral accelerations. Note that the UHRS are computed at 301 frequency points ranging from 0.1 to 100 Hz and equally spaced in logarithmic space. These values were interpolated at the 38 frequency points presented in Table 2.4-1.

1.E+00 C

1.E-02 _,__,_

,I "i *UHRS 1E-5

-UHRS 1E-4

-GMRS Frequency [Hz]

Figure 2.4-1. UHRS for 1E-4 and 1E-5 and GMRS at control point for STPEGS.

NOC-AE-14003114 Page 54 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 53 Table 2.4-1. UHRS for 1 E-4 and 1E-5 and GMRS at control point for STPEGS.

Frequency UHRS 1E-4 UHRS 1E-5 GMRS

[Hz] [g] [g] [g]

0.1 1.55E-03 3.55E-03 1.81E-03 0.125 3.09E-03 7.12E-03 3.61E-03 0.167 5.49E-03 1.26E-02 6.42E-03 0.2 8.10E-03 1.87E-02 9.47E-03 0.3 2.01E-02 4.60E-02 2.34E-02 0.4 2.92E-02 6.66E-02 3.39E-02 0.5 4.12E-02 9.32E-02 4.75E-02 0.6 4.24E-02 9.60E-02 4.89E-02 0.7 4.34E-02 9.87E-02 5.02E-02 0.8 4.48E-02 1.03E-01 5.25E-02 0.9 4.82E-02 1.12E-01 5.70E-02 1 5.01E-02 1.19E-01 5.99E-02 1.25 5.54E-02 1.39E-01 6.92E-02 1.5 5.92E-02 1.55E-01 7.66E-02 2 6.39E-02 1.85E-01 8.98E-02 2.5 7.53E-02 2.34E-01 1.12E-01 3 8.10E-02 2.60E-01 1.23E-01 4 9.32E-02 3.05E-01 1.44E-01 5 8.92E-02 2.99E-01 1.41E-01 6 8.40E-02 2.90E-01 1.36E-01 7 8.15E-02 2.88E-01 1.34E-01 8 8.1OE-02 2.90E-01 1.35E-01 9 7.73E-02 2.80E-01 1.30E-01 10 7.33E-02 2.67E-01 1.24E-01 12.5 5.97E-02 2.21E-01 1.02E-01 15 5.28E-02 1.95E-01 9.01E-02 20 4.48E-02 1.63E-01 7.57E-02 25 4.1OE-02 1.44E-01 6.70E-02 30 3.90E-02 1.33E-01 6.26E-02 35 3.79E-02 1.28E-01 6.01E-02 40 3.73E-02 1.24E-01 5.87E-02 45 3.70E-02 1.23E-01 5.78E-02 50 3.67E-02 1.21E-01 5.73E-02 60 3.64E-02 1.20E-01 5.66E-02 70 3.63E-02 1.19E-01 5.63E-02 80 3.62E-02 1.19E-01 5.62E-02 90 3.62E-02 1.18E-01 5.60E-02 100 3.61E-02 1.18E-01 5.60E-02

NOC-AE-14003114 Page 55 of 63 ISTPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 54 3.0 Plant Design Basis [and Beyond Design Basis Evaluation Ground Motion]

The design basis for STPEGS is identified in the STPEGS Updated Final Safely Evaluation Report (UFSAR), and other pertinent documents.

3.1 SSE Descriptionof Spectral Shape The SSE was developed in accordance with 10 CFR Part 100, Appendix A through an evaluation of the maximum earthquake potential for the region surrounding the site. The maximum earthquake is about an intensity VI (modified Mercalli Scale), produced by either an intensity VII (modified Mercalli Scale) earthquake 70 miles away in basement rocks in the Ouachita Seismotectonic Province or by an intensity VI (modified Mercalli Scale) adjacent to the STPEGS site produced by an earthquake in the pre-Cretaceous basement rocks at least 34,000 ft below the surface.

The SSE is defined in terms of a PGA and a design response spectrum. Considering a site intensity of VI (modified Mercalli Scale), a PGA of 0.07 g was estimated. Because this acceleration value is below the minimum established in Appendix A of 10 CFR 100, the selected SSE acceleration is 0.10 g in accordance with the 10 CFR Part 100, Appendix A criteria. The spectral shape is defined by NRC Regulatory Guide 1.60 (NRC, 1973). The 5% damped horizontal SSE spectrum is shown in Table 3.1-1.

Table 3.1-1. SSE for STPEGS Freq (Hz) SSE (g) 0.1 0.00754 0.25 0.0471 2.5 0.313 9.00 0.261 33.00 0.100 100.00 0.100 3.2 ControlPoint Elevation The SSE control point elevation is defined at the ground surface.

3.3 IPEEE Descriptionand Capacity Response Spectrum The IPEEE is not required for screening, since the SSE envelopes the GMRS throughout the required spectra.

NOC-AE-14003114 Page 56 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 55 4.0 Screening Evaluation In accordance with SPID Section 3, a screening evaluation was performed as described below.

4.1 Risk EvaluationScreening (1 to 10 Hz)

In the 1 to 10 Hz part of the response spectrum, the SSE exceeds the GMRS. Therefore, a risk evaluation will not be performed.

4.2 High Frequency Screening (> 10 Hz)

Above 10 Hz, the SSE exceeds the GMRS. Therefore, the high frequency confirmation will not be performed.

4.3 Spent Fuel Pool Evaluation Screening (I to 10 Hz)

In the 1 to 10 Hz part of the response spectrum, the SSE exceeds the GMRS. Therefore, a spent fuel pool evaluation will not be performed.

5.0 Interim Actions Since the screening evaluation results summarized in Section 4.0, confirm that the SSE exceeds the updated GMRS across the total spectrum required, based on the methodology in the SPID, STPEGS screens out and no further evaluations are required.

Consistent with NRC letter dated February 20, 2014, [ML14030A046] the seismic hazard reevaluations presented herein are distinct from the current design and licensing bases of STPEGS. Therefore, the results do not call into question the operability or functionality of SSCs and are not reportable pursuant to10 CFR 50.72, "Immediate notification requirements for operating nuclear power reactors," and10 CFR 50.73, "Licensee event report system.

The NRC letter also requests that licensees provide an interim evaluation or actions to demonstrate that the plant can cope with the reevaluated hazard while the expedited approach and risk evaluations are conducted. In response to that request, NEI letter dated March 12, 2014, provides seismic core damage risk estimates using the updated seismic hazards for the operating nuclear plants in the Central and Eastern United States. These risk estimates continue to support the following conclusions of the NRC GI-199 Safety/Risk Assessment:

Overall seismic core damage risk estimates are consistent with the Commission's Safety Goal Policy Statement because they are within the subsidiary objective of 104/year for core damage frequency. The GI-199 Safety/Risk Assessment, based in part on information from the U.S. Nuclear Regulatory Commission's (NRC's) Individual Plant Examination of External Events (IPEEE) program, indicates that no concern exists regarding adequate protection and that the current seismic design of operating reactors provides a safety margin to withstand potential earthquakes exceeding the original design basis.

NOC-AE-14003114 Page 57 of 63 ISTPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 56 STPEGS is included in the March 12, 2014 risk estimates. Using the methodology described in the NEI letter, all plants were shown to be below 104/year; thus, the above conclusions apply.

6.0 Conclusions In accordance with the 50.54(f) request for information, a seismic hazard and screening evaluation was performed for STPEGS. A GMRS was developed solely for purpose of screening for additional evaluations in accordance with the SPID.

Based on the results of the screening evaluation, no further evaluations will be performed.

NOC-AE-14003114 Page 58 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 57 7.0 References

1. CEUS-SSC (2012). Central and Eastern United States Seismic Source Characterization for Nuclear Facilities, U.S. Nuclear Regulatory Commission Report, NUREG-2115; EPRI Report No. 1021097, 6 Volumes, DOE Report No. DOE/NE-0140.

2. Electric Power Research Institute (EPRI), "Guidelines for Determining Design Basis Ground Motions", Vols. 1-5, Report No. TR-102293, Palo Alto, CA, 1993.

3. Electric Power Research Institute (EPRI), "Seismic Evaluation Guidance, Screening, Prioritization and Implementation Details (SPID) for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1: Seismic," Report No. 1025287, Palo Alto, CA, February 28, 2013.

4. Electric Power Research Institute (EPRI), "Seismic Evaluation Guidance: Augmented Approach for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1

- Seismic," Report No. 3002000704, Palo Alto, CA, May 31, 2013.

5. Electric Power Research Institute (EPRI), "EPRI (2004, 2006) Ground-Motion Model (GMM) Review Project," Report No. 3002000717, 2 volumes, Palo Alto, CA, June, 2013.

6. Electric Power Research Institute (EPRI), "South Texas Seismic Hazard and Screening Report," Project Number 1041, Rev. 1, Palo Alto, CA, October 30, 2013.

7. McGuire, R.K., W. J. Silva, and C. J. Costantino (2001). "Technical Basis for Revision of Regulatory Guidance on Design Ground Motions: Hazard- and Risk-Consistent Ground Motion Spectra Guidelines", NUREG/CR-6728, (Nonproprietary), U.S. Nuclear Regulatory Commission, Washington, D.C., 2001.

8. McGuire, R.K. (2004). Seismic Hazard and Risk Analysis, Earthquake Engineering Research Institute, Monograph MNO-10.

9. STP FSAR, South Texas Project Electric Generating Station Final Safety Analysis Report (FSAR), Rev. 010, for Units 3 & 4 Project.

10. STP UFSAR, South Texas Project Electric Generating Station (STPEGS) Updated Final Safety Analysis Report (UFSAR), Rev. 015, for Units 1 & 2 Project.

11. U.S. NRC (2007). "A performance-based approach to define the site-specific earthquake ground motion," U.S. Nuclear Regulatory Commission Reg. Guide 1.208.

12. Vucetic, M. and R. Dobry (1991). "Effect of Soil Plasticity on Cyclic Response," Journal of Geotechnical Engineering, ASCE, Vol. 117, No. 1.

NOC-AE-14003114 Page 59 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 58 Appendix A Table A-la. PGA Seismic Hazard Curves at STPEGS (Mean and Fractiles).

84h 9 5 th Mean 5 th 1 6 'h 5 0th PGA (g) AFE PGA (g) AFE PGA (g) AFE PGA (g) AFE PGA (g) AFE PGA (g) AFE 0.0094 1E-03 0.0038 1E-03 0.0053 1E-03 0.0082 1E-03 0.0126 1E-03 0.0169 1E-03 0.0361 1E-04 0.0181 1E-04 0.0230 1E-04 0.0321 1E-04 0.0443 1E-04 0.0584 1E-04 0.1182 1E-05 0.0536 1E-05 0.0693 1E-05 0.1037 1E-05 0.1508 1E-05 0.1937 1E-05 0.3538 1E-06 0.1238 1E-06 0.1958 1E-06 0.3174 1E-06 0.4336 1E-06 0.5308 1E-06 0.7794 1E-07 0.2534 1E-07 0.4841 1E-07 0.7051 1E-07 0.8994 1E-07 1.0443 1E-07 Table A-I b. 0.5 Hz Seismic Hazard Curves at STPEGS (Mean and Fractiles).

h 9 5 th Mean 5 th 1 6 th 50 th PSA (g) AFE PSA (g) AFE PSA (g) AFE PSA (g) AFE PSA (g) AFE PSA (g) AFE 0.0113 1E-03 0.0028 1E-03 0.0041 1E-03 0.0078 1E-03 0.0186 1E-03 0.0268 1E-03 0.0412 1E-04 0.0105 1E-04 0.0162 1E-04 0.0282 1E-04 0.0490 1E-04 0.0689 1E-04 0.0932 1E-05 0.0297 1E-05 0.0414 1E-05 0.0663 IE-05 0.1075 1E-05 0.1476 1E-05 0.2027 1E-06 0.0672 1E-06 0.0898 1E-06 0.1414 1E-06 0.2465 1E-06 0.3688 1E-06 0.5090 1E-07 0.1407 1E-07 0.1921 1E-07 0.3093 1E-07 0.5826 1E-07 1.0417 1E-07 Table A-Ic. 1 Hz Seismic Hazard Curves at STPEGS (Mean and Fractiles).

Mean 1 6 th 501h 84 th 95_th 5 th PSA (g) AFE PSA (g) AFE PSA (g) AFE PSA (g) AFE PSA (g) AFE PSA (g) AFE 0.0167 1E-03 0.0048 1E-03 0.0070 1E-03 0.0135 1E-03 0.0224 1E-03 0.0317 1E-03 0.0501 1E-04 0.0199 1E-04 0.0272 1E-04 0.0408 1E-04 0.0593 1E-04 0.0803 1E-04 0.1187 1E-05 0.0535 1E-05 0.0690 1E-05 0.0988 1E-05 0.1460 1E-05 0.1857 1E-05 0.2956 1E-06 0.1224 1E-06 0.1580 1E-06 0.2333 1E-06 0.3675 1E-06 0.5298 1E-06 0.8078 1E-07 0.2554 1E-07 0.3483 1E-07 0.5697 1E-07 0.9903 1E-07 1.4355 1E-07

NOC-AE-14003114 Page 60 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 59 Table A-ld. 2.5 Hz Seismic Hazard Curves at STPEGS (Mean and Fractiles).

Mean 16 t1 5 0 th 84th 95 th 5 th PSA (g) AFE PSA (g) AFE PSA (g) AFE PSA (g) AFE PSA (g) AFE PSA (g) AFE 0.0212 1E-03 0.0098 1E-03 0.0134 1E-03 0.0194 1E-03 0.0268 1E-03 0.0340 1E-03 0.0753 1E-04 0.0423 1E-04 0.0519 1E-04 0.0698 1E-04 0.0938 1E-04 0.1211 1E-04 0.2342 1E-05 0.1207 1E-05 0.1497 1E-05 0.2068 1E-05 0.3002 1E-05 0.3873 1E-05 0.6534 1E-06 0.2777 1E-06 0.3709 1E-06 0.5784 1E-06 0.8208 1E-06 1.0339 1E-06 1.6280 1E-07 0.5510 1E-07 0.9309 1E-07 1.4389 1E-07 1.9362 1E-07 2.3116 1E-07 Table A-le. 5 Hz Seismic Hazard Curves at STPEGS (Mean and Fractiles).

Mean 5 th 16' 50th 84 9 5 th PSA (g) AFE PSA (g) AFE PSA (g) AFE PSA (g) AFE PSA (g) AFE PSA (g) AFE 0.0208 1E-03 0.0094 1E-03 0.0132 1E-03 0.0191 1E-03 0.0271 1E-03 0.0336 1E-03 0.0892 1E-04 0.0483 1E-04 0.0607 1E-04 0.0830 1E-04 0.1106 1E-04 0.1414 1E-04 0.2990 1E-05 0.1438 1E-05 0.1829 IE-05 0.2659 1E-05 0.3771 1E-05 0.4772 1E-05 0.8744 1E-06 0.3299 1E-06 0.4954 1E-06 0.7835 1E-06 1.0699 1E-06 1.3070 1E-06 1.9135 1E-07 0.6624 1E-07 1.1939 1E-07 1.7279 1E-07 2.1995 1E-07 2.5189 1E-07 Table A-If. 10 Hz Seismic Hazard Curves at STPEGS (Mean and Fractiles).

Mean 5 th 1 6 th 50th 84_th 95 th PSA (g) AFE PSA (g) AFE PSA (g) AFE PSA (g) AFE PSA (g) AFE PSA (g) AFE 0.0155 1E-03 0.0067 1E-03 0.0093 1E-03 0.0140 1E-03 0.0205 1E-03 0.0274 1E-03 0.0733 1E-04 0.0372 1E-04 0.0474 1E-04 0.0668 1E-04 0.0924 1E-04 0.1260 1E-04 0.2666 IE-05 0.1145 1E-05 0.1506 1E-05 0.2308 1E-05 0.3415 1E-05 0.4406 1E-05 0.8066 IE-06 0.2702 1E-06 0.4453 1E-06 0.7282 1E-06 0.9724 1E-06 1.1694 1E-06 1.6003 1E-07 0.5463 1E-07 1.0706 1E-07 1.4858 1E-07 1.7856 1E-07 1.9985 1E-07

NOC-AE-14003114 Page 61 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 60 Table A-lg. 25 Hz Seismic Hazard Curves at STPEGS (Mean and Fractiles).

Mean 5 th 1 6 th 5 0 th 84th 9 5 th PSA (g) AFE PSA (g) AFE PSA (g) AFE PSA (g) AFE PSA (g) AFE PSA (g) AFE 0.0102 1E-03 0.0041 1E-03 0.0058 1E-03 0.0089 1E-03 0.0136 1E-03 0.0185 1E-03 0.0410 1E-04 0.0206 1E-04 0.0262 1E-04 0.0365 1E-04 0.0505 1E-04 0.0680 1E-04 0.1435 1E-05 0.0628 1E-05 0.0820 1E-05 0.1250 1E-05 0.1826 1E-05 0.2342 1E-05 0.4249 1E-06 0.1469 1E-06 0.2407 1E-06 0.3856 1E-06 0.5130 1E-06 0.6156 1E-06 0.8727 1E-07 0.2971 1E-07 0.5688 1E-07 0.7999 1E-07 0.9897 1E-07 1.1318 1E-07

NOC-AE-14003114 Page 62 of 63 STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 61 Table A-2. Mean and logarithmic standard deviation of amplification factors for STPEGS Motion 0.5 Hz 1.0 Hz 2.5 Hz 5.0 Hz Input [g] AF Ln(AF) Input [g] AF Ln(AF) Input [g] AF Ln(AF) Input [g] AF Ln(AF)

HF 1E-3 0.0008 3.242 0.203 0.0021 2.905 0.177 0.0057 2.964 0.262 0.0088 2.316 0.343 LF 1E-3 0.0035 3.236 0.206 0.0057 2.912 0.174 0.0071 2.985 0.244 0.0088 2.356 0.308 HF 1E-4 0.0038 3.214 0.202 0.0097 2.867 0.176 0.0260 2.889 0.259 0.0403 2.214 0.336 LF 1E-4 0.0129 3.202 0.207 0.0174 2.879 0.171 0.0261 2.871 0.245 0.0403 2.155 0.321 HF 1E-5 0.0101 3.113 0.196 0.0281 2.790 0.174 0.0854 2.743 0.255 0.1472 2.031 0.329 LF 1E-5 0.0294 3.171 0.209 0.0421 2.818 0.175 0.0837 2.728 0.255 0.1472 1.913 0.328 HF 1E-6 0.0231 3.161 0.213 0.0721 2.701 0.175 0.2553 2.560 0.251 0.4933 1.773 0.320 LF 1E-6 0.0646 3.138 0.210 0.1075 2.749 0.184 0.2556 2.526 0.261 0.4933 1.572 0.325 HF 1E-7 0.0632 3.171 0.217 0.1971 2.670 0.184 0.6982 2.332 0.240 1.3490 1.418 0.310 LF 1E-7 0.1642 3.101 0.211 0.2979 2.712 0.215 0.7233 2.072 0.276 1.3491 1.077 0.333 Motion 10.0 Hz 25.0 Hz 100.0 Hz (PGA)

Input [g] AF Ln(AF) Input [g] AF Ln(AF) Input [g] AF Ln(AF)

HF 1E-3 0.0100 1.471 0.446 0.0086 0.970 0.355 0.0047 1.566 0.295 LF 1E-3 0.0100 1.558 0.363 0.0086 1.182 0.256 0.0047 2.001 0.214 HF 1E-4 0.0552 1.327 0.465 0.0565 0.708 0.386 0.0271 1.250 0.304 LF 1E-4 0.0552 1.285 0.426 0.0565 0.725 0.316 0.0271 1.333 0.247 HF 1E-5 0.2266 1.177 0.472 0.2708 0.530 0.413 0.1322 0.894 0.320 LF 1E-5 0.2266 1.066 0.460 0.2706 0.477 0.361 0.1322 0.838 0.282 HF 1E-6 0.8174 0.987 0.461 1.0729 0.396 0.402 0.5169 0.685 0.320 LF 1E-6 0.8174 0.804 0.453 1.0721 0.318 0.342 0.5169 0.584 0.282 HF 1E-7 2.2161 0.722 0.414 3.0321 0.288 0.324 1.4299 0.545 0.276 LF 1E-7 2.2161 0.481 0.397 3.0297 0.212 0.261 1.4299 0.427 0.236

NOC-AE-14003114 Page 63 of 63 I STPEGS Seismic Hazard and Screening Report Revision 001, March 27, 2014 Page 62 Appendix A Note:

Although tabular versions of the typical amplification factors included in Section 2.3.6 were provided in Appendix A in the NEI Template, for STPEGS, these tabular values are provided in Tables 2.3.6.1, 2.3.6.2 and 2.3.6.3, which are provided in the body of this Report, following the amplification factor curves, Figures 2.3.6-1 a and b, Figures 2.3.6-2 a and b and Figures 2.3.6-3 a and b.