RS-14-073, Seismic Hazard and Screening Report (Central and Eastern United States (CEUS) Sites), Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.1 of the Near-Term Task Force Review Of.

Seismic Hazard and Screening Report (Central and Eastern United States (CEUS) Sites), Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.1 of the Near-Term Task Force Review Of.

ML14090A271
Person / Time
Site:	Three Mile Island
Issue date:	03/31/2014
From:	Jim Barstow Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-14-073, TMI-14-026
Download: ML14090A271 (54)

Text

1 ExeLon Generation ~

RS-14-073 TMI-14-026 10 CFR 50.54{f)

March 31, 2014 U.S. Nuclear Regulatory Commission Attn: Document Control Desk 11555 Rockville Pike, Rockville, MD 20852 Three Mile Island Nuclear Station, Unit 1 Renewed Facility Operating License No. DPR-50 NRC Docket No. 50-289

Subject:

Exelon Generation Company, LLC, Seismic Hazard and Screening Report (Central and Eastern United States (CEUS) Sites), Response to 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

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

4. Exelon Generation Company, LLC letter to the NRC, Response to NRC Request for Information Pursuant to 10 CFR 50.54{f) Regarding the Seismic Aspects of Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident - 1.5 Year Response for CEUS Sites, dated September 12, 2013

5. EPRI Report 1025287, Seismic Evaluation Guidance, Screening, Prioritization and Implementation Details (SPID) for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1: Seismic

6. NRC Letter, Endorsement of Electric Power Research Institute Final Draft Report 1025287, "Seismic Evaluation Guidance," dated February 15, 2013

7. EPRI Technical Report 3002000704, "Seismic Evaluation Guidance: Augmented Approach for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1:

Seismic," dated May 2013

u.s. Nuclear Regulatory Commission NTTF 2.1 Seismic Response for CEUS Sites March 31,2014 Page 2 On March 12, 2012, the Nuclear Regulatory Commission (NRC) issued Reference 1 to all power reactor licensees and holders of construction permits in active or deferred status. Enclosure 1 of Reference 1 requested each addressee located in the Central and Eastern United States (CEUS) to submit a Seismic Hazard Evaluation and Screening Report within 1.5 years from the date of Reference 1.

In Reference 2, the Nuclear Energy Institute (NEI) requested NRC agreement to delay 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. In Reference 4, Exelon Generation Company, LLC (EGC) provided the description of subsurface materials and properties and base case velocity profiles for Three Mile Island Nuclear Station, Unit 1 Reference 5 contains industry guidance and detailed information to be included in the Seismic Hazard Evaluation and Screening Report submittals. NRC endorsed this industry guidance in Reference 6.

The enclosed Seismic Hazard Evaluation and Screening Report for Three Mile Island Nuclear Station, Unit 1, provides the information described in Section 4 of Reference 5 in accordance with the schedule identified in Reference 2. As described in Enclosure 1, Three Mile Island Nuclear Station, Unit 1, does not meet the requirements of SPID Sections 3.2 and 7 (Reference

5) and therefore screens in and a Risk Evaluation and Spent Fuel Pool evaluation will be performed as determined by NRC prioritization following submittal of all nuclear power plant Seismic Hazard Re-evaluations per Reference 1. Additionally, Three Mile Island Nuclear Station, Unit 1, will prepare an Expedited Seismic Evaluation Process (ESEP) Report in accordance with Reference 7, by December 31, 2014.

A list of regulatory commitments contained in this letter is provided in Enclosure 2. If you have any questions regarding this report, please contact Ron Gaston at (630) 657-3359.

I declare under penalty of perjury that the foregoing is true and correct. Executed on the 31 st day of March 2014.

Respectfully submitted, d~~

James Barstow Director - Licensing & Regulatory Affairs Exelon Generation Company, LLC

u.s. Nuclear Regulatory Commission NTTF 2.1 Seismic Response for CEUS Sites March 31, 2014 Page 3

Enclosures:

1. Three Mile Island Nuclear Station, Unit 1, Seismic Hazard and Screening Report

2. Summary of Regulatory Commitments cc: Director, Office of Nuclear Reactor Regulation Regional Administrator - NRC Region I NRC Senior Resident Inspector - Three Mile Island Nuclear Station NRC Project Manager, NRR - Three Mile Island Nuclear Station Ms. Jessica A. Kratchman, NRRlJLD/PMB, NRC Mr. Eric E. Bowman, NRR/DPR/PGCB, NRC or Ms. Eileen M. McKenna, NRO/DSRAlBPTS, NRC Director, Bureau of Radiation Protection - Pennsylvania Department of Environmental Resources Chairman, Board of County Commissioners of Dauphin County, PA Chairman, Board of Supervisors of Londonderry Township, PA R. R. Janati, Chief, Division of Nuclear Safety, Pennsylvania Department of Environmental Protection, Bureau of Radiation Protection

Enclosure 1 Three Mile Island Nuclear Station, Unit 1 Seismic Hazard and Screening Report (49 pages)

SEISMIC HAZARD AND SCREENING REPORT IN RESPONSE TO THE 50.54(t) INFORMATION REQUEST REGARDING FUKUSHIMA NEAR-TERM TASK FORCE RECOMMENDATION 2.1: SEISMIC for the THREE MILE ISLAND NUCLEAR STATION UNIT 1 Rout. 441 South, P.O. Box 480, Middletown, PA 17057 Facility Operating License No. DPR*50 NRC Docket No. 50*289 Correspondence No.: RS*14-073, TMI*14-026 Exelon

• Exelon Generation Company. LLC (&elon)

PO Box 806398 Chicago. IL 8088()..5398 Prepared by:

Enercon Servlce8. lno.

500 Townpark Lane. Kennesaw. GA 30144 Report Number. EXLNTM039-PR.(J01. RevI8Ion 1 PrlntodNama SIgoabg QIII Preparar: SIaI8 Gibbs 3l~rf2"'1 RevIewer: MIIcheU McKay

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RECORD OF REVISIONS Revision Affected Pages Description 0 All Initial issue.

1 All Revised text to align with final NEI Seismic Hazard and Screening Report example submittal for CEUS site.

Three Mile Island Nuclear Station Report Number. EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

Contents Contents .....................................................................................................................................i Tables .......................................................................................................................................;;i Figures ...................................................................................................................................*..iv Executive Summary ..................................................................................................................v 1 Introduction ...................................................................................................................1-1 2 Seismic Hazard Reevaluation ......................................................................................2-1 2.1 Regional and Local Geology ........... ... ........ ....... ... .. ...... ................... .... ..... .............. 2-1 2.2 Probabilistic Seismic Hazard Analysis ...................................................................2-2 2.2.1 Probabilistic Seismic Hazard Analysis Results .. ........................................... 2-2 2.2.2 Base Rock Seismic Hazard Curves ...................... ........................................ 2-3 2.3 Site Response Evaluation ......................................................................................2-3 2.3.1 Description of Subsurface Material ...............................................................2-3 2.3.2 Development of Base Case Profiles and Nonlinear Material Properties ........ 2-5 2.3.3 Randomization of Base Case Profiles ........................................................2-11 2.3.4 Input Spectra ..............................................................................................2-11 2.3.5 Methodology ...... .... .... .. ... ... ...... ...................................................................2-11 2.3.6 Amplification Functions ..............................................................................2-11 2.3.7 Control Point Seismic Hazard Curves .......................................... .. ..... ........ 2-17 2.4 Control Point Response Spectra (UHRS & GMRS) ............................................. 2-18 3 Plant Design Basis Ground Motion .............................................................................3-1 3.1 SSE Description of Spectral Shape .. ..................................................................... 3-1 3.2 Control Point Elevation ................. ......................................................................... 3-3 4 Screening Evaluation ...................................................................................................4-1 4.1 Risk Evaluation Screening (1 to 10 Hz) .... .. ... .. ....... ... .. .. ... ..... ...... ... ... .. .. ... ... .. ....... .4-1 4.2 High Frequency Screening (> 10Hz) .................................................................... .4-1 4.3 Spent Fuel Pool Evaluation Screening (1 to 10 Hz) ..... ... ....... .. ... .... ........ .. ... ......... .4-2 Three Mile Island Nuclear Station Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

Contents (cont'd.)

5 Interim Actions..............................................................................................................5-1 5.1 Expedited Seismic Evaluation Process .................................................................. 5-1 5.2 Interim Evaluation of Seismic Hazard .................................................................... 5-1 5.3 Seismic Walkdown Insights ...................................................... '" .......................... 5-2 5.4 Beyond-Design-Basis Seismic Insights ...................... .... ........ .... .... ........................ 5-2 6 Conclusions ..................................................................................................................6-1 7 References .................................................................................................................... 7-1 Appendices A Additional Tables .........................................................................................................A-1 Three Mile Island Nudear Station ii Report Number: EXLNTM039-PR-001. Revision 1 Correspondence No.: RS-14-073. TMI-14-026

Tables Table 2.3.1-1 Summary of site geotechnical profile for TMI (Reference 17) ............ .. ..............2-5 Table 2.3.2-1 (Not used)

Table 2.3.2-2 Layer thicknesses, depths, and shear-wave velocities (Vs) for three profiles, the Three Mile Island site .............. ....................................................................2-7 Table 2.3.2-3 Kappa values and weights used for site response analyses ............................ 2-10 Table 2.4-1 UHRS and GMRS at control point for TMI (5% of critical damping response spectra) ................................................................................... ....................... 2-19 Table 3.1-1 Horizontal SSE for TMI (5% of critical damping response spectrum)................. 3-2 Table A-1a Mean and fractile seismic hazard curves for PGA at TMI, 5% of critical damping ... ................. .............. .............................................................. .... A-1 Table A-1b Mean and fractile seismic hazard curves for 25 Hz at TMI, 5% of critical damping .................................................................................................... A-2 Table A-1c Mean and fractile seismic hazard curves for 10 Hz at TMI, 5% of critical damping ................................................... ........ ............... .......................... A-2 Table A-1d Mean and fractile seismic hazard curves for 5 Hz at TMI, 5% of critical damping ................................................................................................. A-3 Table A-1e Mean and fractile seismic hazard curves for 2.5 Hz at TMI, 5% of critical damping .................................................................................................... A-3 Table A-1f Mean and fractile seismic hazard curves for 1 Hz at TMI, 5% of critical damping ................................................................................................. A-4 Table A-1g Mean and fractile seismic hazard curves for 0.5 Hz at TMI, 5% of critical damping ....................... ........................................... ....... ............................ A-4 Table A-2 Amplification functions for TMI, 5% of critical damping ..................................... A-5 Table A2-b1 Median AFs and sigmas for Model 1, Profile 1, for 2 PGA levels ...................... A-7 Table A2-b2 Median AFs and sigmas for Model 2, Profile 1, for 2 PGA levels ...................... A-a Three Mile Island Nuclear Station iii Report Number: EXLNTM039*PR*001, Revision 1 Correspondence No.: RS*14*073, TMI*14-026

Figures Figure 2.3.2-1 Shear-wave velocity profiles for the Three Mile Island site ... .. ........... .. .............. 2-6 Figure 2.3.6-1 Example suite of amplification factors (5% of critical damping pseudo absolute acceleration spectra) developed for the mean base-case profile (P1), EPRI rock modulus reduction and hysteretic damping curves (model M1), and base-case kappa at eleven loading levels of hard rock median peak acceleration values from 0.01g to 1.50g; M 6.5 and single-corner source model (Reference 3) ..... 2-13 Figure 2.3.6-2 Example suite of amplification factors (5% of critical damping pseudo absolute acceleration spectra) developed for the mean base-case profile (P1), linear analyses (model M2), and base-case kappa at eleven loading levels of hard rock median peak acceleration values from 0.01g to 1.50g; M 6.5 and single-corner source model (Reference 3) ... ... .. ..... ...... ... .. ..... .. ...... ......... ... ........ .. .... .... .... ... ..2-15 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 TMI (5% of critical damping) .... ... ... ....... ..... ........ ....... .... .2-17 Figure 2.4-1 Plots of 1E-4 and 1E-5 UHRS and GMRS at control point for TMI (5% of critical damping response spectra) ........ ..... ....................... ..... ...... ... .. ......................... 2-18 Figure 3.1-1 Horizontal SSE for TMI (5% of critical damping response spectrum) ................. 3-3 Three Mile Island Nudear Station iv Report Number. EXLNTM039*PR*001. Revision 1 Correspondence No.: RS*14*073. TMI-14-026

Executive Summary PURPOSE Following the accident at the Fukushima Dai-ichi nuclear power plant resulting from the March 11, 2011, Great Tohoku Earthquake and subsequent tsunami, the Nuclear Regulatory Commission (NRC) issued a 50.54(f) letter (Reference 1) requesting information in response to NRC Near-Term Task Force (NTTF) recommendations intended to clarify and strengthen the regulatory framework for protection against natural phenomena. The 50.54(f) letter (Reference 1) requests that licensees and holders of construction permits under Title 10 Code of Federal Regulations Part 50 (Reference 2) reevaluate the seismic hazards at their sites using updated seismic hazard information and present-day regulatory guidance and methodologies. This report provides the information requested in items (1) through (7) of the "Requested Information" in Enclosure 1 of the 50.54(f) letter (Reference 1), pertaining to NTTF Recommendation 2.1: Seismic for Three Mile Island Nuclear Station Unit 1 (TMI) in accordance with the documented intention of Exelon Generation Company, LLC transmitted to the NRC via letter dated April 29, 2013 (Reference 15).

SCOPE In response to the 50.54(f) letter (Reference 1) and following the Screening, Prioritization, and Implementation Details (SPID) industry guidance document (Reference 3), a seismic hazard reevaluation for TMI was performed to develop a Ground Motion Response Spectrum (GMRS) for comparison with the plant-level seismic capacity. The new GMRS represents an alternative seismic demand determined using recently developed techniques. The new GMRS does not constitute a change in the plant design or licensing basis as described in the NRC letter February 20, 2014 (Reference 13). Section 1 provides an introduction. Section 2 provides a summary of the TMI regional and local geology and seismicity, other major inputs to the seismic hazard reevaluation, and detailed seismic hazard results including definition of the GMRS. Seismic hazard analysis for TMI, including site response evaluation and GMRS development (Sections 2.2, 2.3, and 2.4 of this report) was performed by the Electric Power Research Institute (Reference 16). A more in-depth discussion of the calculation methods used in the seismic hazard reevaluation can be found in References 3, 6, 7, 9, and 18. Section 3 describes the characteristics of the plant design basis ground motion for TMI. Section 4 provides a GMRS screening evaluation for TMI. Sections 5 and 6 discuss interim actions and conclusions, respectively, for TMI.

CONCLUSIONS For TMI, the GMRS spectral acceleration exceeds that of the Safe Shutdown Earthquake (SSE) at spectral frequencies above approximately 8.0 Hz. As a result, TMI screens in for a risk evaluation and a Spent Fuel Pool Integrity evaluation in accordance with the SPID, Sections 3 and 7 (Reference 3). Since the GMRS spectral acceleration exceeds that of the SSE in the frequency range above 10Hz, high-frequency Three Mile Island Nudear Station v Report Number: EXLNTM039.PR*001. Revision 1 Correspondence No.: RS*14*073. TMI*14-026

exceedances can be addressed as part of the risk evaluation for TMI. As an interim action/assessment prior to completion of the risk evaluation, an Expedited Seismic Evaluation Process (ESEP) will be performed for TMI in conformance with the "Augmented Approach" guidance document (Reference 4). Actions to address NTTF 2.1: Seismic for central and eastern United States nuclear plants are outlined in the schedule provided in the April 9, 2013 letter from the industry to the NRC (Reference 5),

as agreed to by the NRC in the May 7, 2013 letter to the industry (Reference 20).

Three Mile Island Nuclear Station vi Report Number. EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

1 Introduction Following the accident at the Fukushima Dai-ichi nuclear power plant resulting from the March 11, 2011, Great Tohoku Earthquake and subsequent tsunami, the Nuclear Regulatory Commission (NRC) established a Near Term Task Force (NTTF). The NTTF was tasked with conducting a systematic review of NRC processes and regulations 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 requesting information to assure these recommendations would be addressed by all U.S. nuclear power plants (Reference 1). The 50.54(f) letter (Reference 1) requests that licensees and holders of construction permits under Title 10 Code of Federal Regulations Part 50 (Reference 2) reevaluate the seismic hazards at their sites using updated seismic hazard information and present-day regulatory guidance and methodologies. Depending on the outcome of the comparison between the reevaluated seismic hazard and the current site-specific design basis, performance of a seismic risk assessment may be necessary. Risk assessment approaches acceptable to the NRC 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 to provide additional protection against the updated hazards.

This report provides the information requested in items (1) through (7) of the "Requested Information" in Enclosure 1 of the 50.54(f) letter (Reference 1), pertaining to NTTF Recommendation 2.1: Seismic for Three Mile Island Nuclear Station Unit 1 (TMI),

located in Dauphin County, Pennsylvania in accordance with the documented intention of Exelon Generation Company, LLC (Exelon) transmitted to the NRC via letter dated April 29, 2013 (Reference 15). In providing this information, Exelon followed the Screening, Prioritization, and Implementation Details (SPID) industry guidance document (Reference 3). The "Augmented Approach" guidance document (Reference 4) defines interim actions/evaluations for addressing a higher seismic hazard relative to the plant's current design/licensing basis prior to completion of the risk evaluations to demonstrate additional seismic margin. This short term aspect of the Augmented Approach is referred to as the Expedited Seismic Evaluation Process (ESEP). In response to NTTF Recommendation 2.3, seismic walkdowns for TMI have been completed as initially documented and supplemented in Exelon Correspondence Numbers RS-12-175 and RS-14-032 (References 12 and 25) respectively, to satisfy the 50.54(f) letter (Reference 1).

Geological and seismic investigations for TMI were performed for the original plant construction. TMI structures, systems, and components (SSCs) which are essential to the prevention of accidents which could affect the public health and safety or to the mitigation of accident consequences are designed to withstand the most severe natural phenomena specific to the site, with an appropriate margin to account for uncertainties in the historical data, or upon the most severe conditions which are susceptible to synthetic Three Mile Island Nuclear Station 1-1 Report Number. EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

analyses, including earthquakes, in accordance with the General Design Criteria proposed by the Atomic Energy Commission in July 1967 (Reference 10, Section 1.4).

All Class I SSCs are analyzed under the loading conditions of the Design Earthquake (OBE) and the Maximum Hypothetical Earthquake (MHE), equivalent to the Safe Shutdown Earthquake (SSE) (Reference 10, Section 5.1.2). See Section 3 of this report for further discussion on the development of the TMI SSE.

In response to the 50.54(f) letter (Reference 1) and following the guidance provided in the SPID (Reference 3), a seismic hazard reevaluation for TMI was performed. For screening purposes, a Ground Motion Response Spectrum (GMRS) was developed.

Three Mile Island Nuclear Station 1-2 Report Number: EXLNTM039*PR*001, Revision 1 Correspondence No.: RS*14*073, TMI*14-026

2 Seismic Hazard Reevaluation TMI is located on the northern most section of Three Mile Island near the east shore of the Susquehanna River about 10 miles southeast of Harrisburg in Dauphin County, Pennsylvania (Reference 10, Sections 1.1 and 1.2.1). The site is located in the Triassic lowland of Pennsylvania, within the Gettysburg Basin section of the physiographic division known as the Piedmont Province (Reference 10, Sections 2.7.3.1 and 2.7.3.2).

The island on which the site is located is basically composed of fluvially deposited sand and gravel of adequate density to support moderately heavy loads. The underlying rock is a sedimentary sequence of interbedded sandstone, shaley siltstone, and shaley claystone which belongs to the Gettysburg Formation of Triassic Age. Below the weathered surface, bedrock is capable of safely bearing loads imposed by the heaviest structures. The site is not considered to be deleteriously affected by faulting, and it is concluded that regional tectonic elements are inactive and present no threat to the structural integrity of local geology. (Reference 10, Section 2.7.1)

Historically, earthquakes in Pennsylvania have been infrequent and of low intensity (Reference 10, Section 2.7.1). Earthquakes in the greater Pennsylvania area, which have or might have affected the site, were nearly always felt over very limited areas, and had high attenuation, indicating foci close to the earth's surface (Reference 10, Section 2.8.1). The original investigation of historical seismic activity in the region indicated that a low intensity VI (Modified Mercalli Scale) is an adequately conservative design intensity for the site. TMI determined that a low intensity VI corresponds to a ground acceleration of 0.04g (Reference 10, Section 2.8.1); for conservatism, a peak ground acceleration (PGA) of 0.06g is used for the OBE and a PGA of 0.12g is used for the SSE (Reference 10, Section 5.1.2.1.1).

2.1 REGIONAL AND LOCAL GEOLOGY The site is located in the Triassic lowland of Pennsylvania, within the Gettysburg Basin section of the physiographic division known as the Piedmont Province (Reference 10, Sections 2.7.3.1 and 2.7.3.2). The Triassic lowland of Pennsylvania is one of a series of long narrow basins of Triassic deposits which extend in broken patches from Connecticut to North Carolina (Reference 10, Section 2.7.3.2). The site is underlain by the sedimentary rocks of the Gettysburg shale, a part of the Newark group of Triassic Age (Reference 10, Section 2.7.3.4). The Newark group is believed to have a thickness of approximately 16,000 ft. and tilts toward the northwest due to subsidence and faulting along the northwest border (Reference 10, Section 2.7.3.2).

Three Mile Island is located approximately 2.5 miles south of Middletown, Pennsylvania.

It is one of the largest of a group of several islands in the Susquehanna River and is situated about 900 ft. from the east bank (Reference 10, Section 2.7.1). All Class I structures were founded on bedrock which was excavated to sound rock, with the exception of Storage Tanks and the Diesel Generator Building, which were founded on Three Mile Island Nuclear Station 2-1 Report Number. EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

compacted backfill (Reference 10, Section 2.7.5.2 and Table 2.7-1). At the Reactor Building and other main structures, the top of the rock varies from EI. 275.0 ft. to 279.5 ft. (Reference 10, Section 2.7.5.2). The bedrock underlying the general area is composed of shales, sandstones, and siltstones belonging to the Gettysburg shale of Triassic Age (Reference 10, Section 2.7.4.2). There is a high degree of uniformity of density and of soil types at the plant location, within the upper silty sand layer and the lower sand and gravel layer (Reference 10, Section 2.7.5.1). The tectonic history of the area indicates that the region has been extremely stable for at least the last 10,000 to one million years, and that studies did not establish the existence of minor faults or fractures at the site (Reference 10, Section 2.7.3.2).

2.2 PROBABILISTIC SEISMIC HAZARD ANALYSIS 2.2.1 Probabilistic Seismic Hazard Analysis Results In accordance with the 50.54(f) letter (Reference 1) and following the guidance in the SPID (Reference 3), a probabilistic seismic hazard analysis (PSHA) was completed using the recently developed Central and Eastern United States Seismic Source Characterization (CEUS-SSC) for Nuclear Facilities (Reference 6) together with the updated Electric Power Research Institute (EPRI) Ground-Motion Model (GMM) for the central and eastern United States (CEUS) (Reference 7). For the PSHA, a lower-bound moment magnitude of 5.0 was used, as specified in the 50.54(f) letter (Reference 1).

For the PSHA, the CEUS-SSC background seismic sources out to a distance of 400 miles (640 km) around TMI were included. This distance exceeds the 200 mile (320 km) recommendation contained in NRC Reg. Guide 1.208 (Reference 18) and was chosen for completeness. Background sources included in this site analysis are the following:

1. Atlantic Highly Extended Crust (AHEX)

2. Extended Continental Crust-Atlantic Margin (ECC_AM)

3. Great Meteor Hotspot (GMH)

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

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

6. Midcontinent-Craton alternative A (MIDC_A)

7. Midcontinent-Craton alternative B (MIDC_B)

8. Midcontinent-Craton alternative C (MIDC_C)

9. Midcontinent-Craton alternative D (MIDC_D)

10. Northern Appalachians (NAP) 11 . Non-Mesozoic and younger extended prior - narrow (NMESE-N)

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

13. Paleozoic Extended Crust narrow (PEZ_N)

14. Paleozoic Extended Crust wide (PEZ_W)

15. St. Lawrence Rift, including the Ottawa and Saguenay grabens (SLR)

16. Study region (STUDY_R)

Three Mile Island Nuclear Station 2-2 Report Number. EXLNTM039* PR*001 , Revision 1 Correspondence No.: RS*14*073, TMI*14-026

For sources of large magnitude earthquakes, designated Repeated Large Magnitude Earthquake (RLME) sources in CEUS-SSC (Reference 6) , the following sources lie within 1,000 km of the site and were included in the analysis:

1. Charleston

2. Charlevoix

3. Wabash Valley For each of the above background and RLME sources, the mid-continent version of the updated CEUS EPRI GMM was used.

2.2.2 Base Rock Seismic Hazard Curves Consistent with the SPID, Section 2.5.3 (Reference 3), base rock seismic hazard curves are not provided as the site amplification approach referred to as Method 3 has been used. Seismic hazard curves are shown below in Section 2.3.7 at the SSE control point elevation.

2.3 SITE RESPONSE EVALUATION Following the guidance contained in Enclosure 1 of the 50.54(f) letter (Reference 1) and the SPID, Section 2.4 (Reference 3) for nuclear power plant sites that are not founded on hard rock (considered as having a shear-wave velocity of at least 9285 fps), a site response analysis was performed for TM!.

2.3.1 Description of Subsurface Material TMI is located on Three Mile Island in the Lower Susquehanna River Valley near Harrisburg Pennsylvania. The general site conditions consist of about 25 ft. (8.0 m) of soils (silts, sands, and gravels with some boulders and cobbles) over about 16,000 ft.

(4,877 m) of sound Triassic sedimentary rocks with a basement of hard crystalline rocks (Reference 17). The SSE control point is at an elevation of 280 ft. at the top of the Gettysburg Formation.

The following description of the general geology is taken directly from the SGH Review of Existing Site Response Parameter Data (Reference 17):

"Three Mile Island Nuclear Station is located on Three Mile Island, a low relief land mass situated in the Lower Susquehanna River Valley, upstream from York Haven Dam, approximately 10 miles southeast of Harrisburg in Londonderry Township of Dauphin County, Pennsylvania, about 2.5 miles north of the southern tip of Dauphin County. The island is about 300 yards from the east bank of the river, and over one mile from the western York County shore.

"Three Mile Island formed as a result of fluvial deposition by the Susquehanna River. Boulders carried by the glacial meltwater or transported downstream by ice rafts were first deposited in this wide-channel, low-veloCity section of the river and became the nuclei for subsequent deposition of smaller material. This gradual accretion of river sediment resulted in the growth of most of the islands in this area.

Three Mile Island is made up of two such nuclei which eventually merged. This area between the two nuclei is presently represented by find-grained deposits.

Three Mile Island Nuclear Station 2-3 Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

liThe topography of the area immediately surrounding Three Mile Island is of a slightly undulating nature with maximum relief of about 200 ft and highest elevation seldom above 500 ft. Three Mile Island has very little relief, with elevations ranging from about 280 ft at the water's edge to slightly more than 300 ft in the north central portion.

liThe site is located in the Triassic lowland of Pennsylvania, one of a series of long narrow basins of Triassic deposits which extend in broken patches from Connecticut to North Carolina. The Triassic lowland in the vicinity of the site is referred to as the Gettysburg basin. The site lies within the Gettysburg Basin section of the physiographic division known as the Piedmont Province.

liThe bedrock surface at the site is essentially flat and lies at approximately EI. 277 ft. Lithologic types vary from red to brown, interbedded, fine-to medium-grained sandstone, shaley siltstone, and shaley claystone, which range from medium-hard to hard, possessing compressional wave velocities in a range from 8,500 to 11,500 ftlsec. There is 1 to 3 ft of weathered rock at the overburden-bedrock interface. All Class I structures founded on bedrock were excavated to sound rock. Wherever necessary, concrete fill was placed on top of the rock to the base elevation.

"There is a high degree of uniformity of density and of soil types at the plant location within the upper silty sand layer and the lower sand and gravel layer. The island, as a whole, consists of fluvially stratified subrounded to rounded sand and gravel containing varying amounts of silt, clay, and occasional lenses of clean sand.

Density values range from loose to very dense. Boulders are presented at depth and are mainly confined to the lower portions of the soil zone on the north end of the island. Soil depths vary from approximately 6 ft at the south end of the island to a max of 30 ft near the axial intersection of the island. Depth of soil is relatively constant at about 20 ft in the vicinity of the plant site.

liThe overburden is made up primarily of two units. The top layer is loose to medium dense, fine-grained granular material (alluvial deposits consisting primarily of sands and gravels) which varies from a fine silty sand and gravel to a very stiff (north), clayey silt (south). Directly overlying the sedimentary rocks is a layer of coarse sand and gravel, which at the north end of the island contains numerous boulders and cobbles and ranges from medium dense to very dense (layer of coarse cobbles).

"The bedrock surface at the site is of the Gettysburg shale, a part of the Newark group of the Triassic Age described as reddish-brown shale, and soft, red-brown, medium-to-fine-grained sandstone with minor amounts of yellowish-brown shale and sandstone; it may be metamorphosed by intrusive diabase to dark-purple to black argillite. The Newark Group is believed to have a thickness of approx. 16,000 ft and tilts toward the northwest. II Three Mile Island Nuclear Station 2-4 Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

Table 2.3.1-1 shows the recommended geotechnical properties for TMI (reproduced from Reference 17).

Table 2.3.1-1 Summary of site geotechnical profile for TMI (Reference 17 Elevations of Layer Range in Thickness Shear-Boundaries Compressional Across Soil/Rock Density wave Poisson's Under Reactor Wave Velocity Site Description and Age (pet) Velocity ratio Buildings (fps)

(ft.)

(fps)

(ft., MSL)

Loose to medium dense fine silty sand 125-N/A 3

304 to 298 6 and gravel to very 147 N/A 1000-2300 stiff clayey silt Medium dense to very dense coarse 125-298 to 280 18 sand and gravel with 147 N/A 2300-3800 N/A some boulders and cobbles Triassic Gettysburg Formation, b c sandstone, medium-280 to -15700 16000 hard to hard shaley N/A N/A 8000-12000d N/A siltstone, and shaley claystone

-15700 and N/A Basement rock N/A N/A N/A N/A below a Finish grade elevation is nominally 304 ft. MSL.

b The SSE control point elevation is at the top of bedrock at EI. 280 ft. MSL.

C Bottom of the deepest foundation is at EI. 268 ft. MSL, near the surface of the Gettysburg Formation.

d Gettysburg Formation wave velocities were measured near the surface of the bedrock. The wave velocities are expected to increase with depth, but the degree and rate at which they do so is undetermined.

2.3.2 Development of Base Case Profiles and Nonlinear Material Properties Based on Table 2.3.1-1 and the location of the SSE control point at an elevation of 280 ft. MSL (Reference 17) (see Section 3.2 for further discussion of the control point elevation), the profile consists of about 16,000 ft. (4,877 m) of firm rock overlying hard crystalline basement rock.

Shear-wave velocities for the profile were unspecified with compressional-wave velocities listed between 8,000 and 12,000 fps (2,438 mls and 3,657 mls respectively),

likely based on shallow refraction surveys. To develop a mean base-case shear-wave velocity profile, a shallow velocity of 5,000 fps (1,524 mls), which reflects a reasonable Poisson ratio of 0.35, was assumed for the top of the Triassic Gettysburg Formation.

Provided the materials to basement depth reflect similar sedimentary rocks and age, the shear-wave velocity gradient for sedimentary rock of 0.5 mlslm (Reference 3) was assumed to be appropriate for the site. The shallow shear-wave velocity of 5,000 fps (1,524 m/s) was taken at the surface of the profile with the velocity gradient applied at Three Mile Island Nuclear Station 2-5 Report Number. EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

that point, resulting in a base-case shear-wave velocity of about 8,200 ftls (2,500 m/s) at a depth of 6,562 ft. (2,000 m). The mean or best estimate base-case profile is shown as profile P1 in Figure 2.3.2-1.

Based on the uncertainty in shear-wave velocities due to the lack of measurements, a scale factor of 1.57 was adopted to reflect upper and lower range base-cases. The scale factor of 1.57 reflects a 0llin of about 0.35 based on the SPID (Reference 3) 10th and 90th fractiles which implies a 1.28 scale factor on all. (Reference 16)

Using the best estimate or mean base-case profile (P1), the depth independent scale factor of 1.57 was applied to develop lower and upper range base-cases profiles P2 and P3 respectively with the stiffest profile (P3) reaching reference rock velocities at a depth of about 1,800 ft. (548 m). Base-case profiles P1 and P2 have a mean depth below the SSE control point of 6,562 ft. (2,000 m) to hard reference rock, randomized +/- 1,969 ft. (+/-

600 m). The base-case profiles (P1, P2, and P3) are shown in Figure 2.3.2-1 and listed in Table 2.3.2-2. The depth randomization reflects +/- 30% of the depth to provide a realistic broadening of the fundamental resonance rather than reflect actual random variations to basement shear-wave velocities across a footprint.

Vs profiles for Three Mile Island Site Vs (ft/sec) o 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 o

500 1 \ I\.

1000 1500 2000

\

\

1,

\

\ ,\

\.

'\

I' 2500 - Profile 1 g 3000

.; 3500 CI.

~ 4000

\

'\

\

\

\

\ , r\

Profile 2 Profile 3 4500

\ \

5000 5500 6000

\

\

\ ,

6500 '\

7000 Figure 2.3.2-1 Shear-wave velocity profiles for the Three Mile Island site Three Mile Island Nuclear Station 2-6 Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

Table 2.3.2-2 Layer thicknesses, depths, and shear-wave velocities (Vs) for three proflI es, th e Th ree M'IIe Isan I d sle

't Profile 1 Profile 2 Profile 3 Thickness Depth V. Thickness Depth Vs Thickness Depth Vs (ft. ) (ft.) (fps) (ft.) (ft.) (fps) (ft.) (ft.) (fps) 0 5002 0 3186 0 7854 10.0 10.0 5002 10.0 10.0 3186 10.0 10.0 7854 10.0 20.0 5007 10.0 20.0 3190 10.0 20.0 7861 10.0 30.0 5012 10.0 30.0 3193 10.0 30.0 7869 10.0 40.0 5017 10.0 40.0 3196 10.0 40.0 7877 10.0 50.0 5022 10.0 50.0 3199 10.0 50.0 7885 10.0 60.0 5027 10.0 60.0 3202 10.0 60.0 7893 10.0 70.0 5032 10.0 70.0 3206 10.0 70.0 7901 10.0 80.0 5037 10.0 80.0 3209 10.0 80.0 7908 10.0 90.0 5042 10.0 90.0 3212 10.0 90.0 7916 10.0 100.0 5047 10.0 100.0 3215 10.0 100.0 7924 10.0 110.0 5052 10.0 110.0 3218 10.0 110.0 7932 10.0 120.0 5057 10.0 120.0 3221 10.0 120.0 7940 10.0 130.0 5062 10.0 130.0 3225 10.0 130.0 7948 10.0 140.0 5067 10.0 140.0 3228 10.0 140.0 7956 10.0 150.0 5072 10.0 150.0 3231 10.0 150.0 7963 10.0 160.0 5077 10.0 160.0 3234 10.0 160.0 7971 10.0 170.0 5082 10.0 170.0 3237 10.0 170.0 7979 10.0 180.0 5087 10.0 180.0 3241 10.0 180.0 7987 10.0 190.0 5092 10.0 190.0 3244 10.0 190.0 7995 10.0 200.0 5097 10.0 200.0 3247 10.0 200.0 8003 10.0 210.0 5102 10.0 210.0 3250 10.0 210.0 8011 10.0 220.0 5107 10.0 220.0 3253 10.0 220.0 8018 10.0 230.0 5112 10.0 230.0 3256 10.0 230.0 8026 10.0 240.0 5117 10.0 240.0 3260 10.0 240.0 8034 10.0 250.0 5122 10.0 250.0 3263 10.0 250.0 8042 10.0 260.0 5127 10.0 260.0 3266 10.0 260.0 8050 10.0 270.0 5132 10.0 270.0 3269 10.0 270.0 8058 10.0 280.0 5137 10.0 280.0 3272 10.0 280.0 8065 10.0 290.0 5142 10.0 290.0 3276 10.0 290.0 8073 10.0 300.0 5147 10.0 300.0 3279 10.0 300.0 8081 10.0 310.0 5152 10.0 310.0 3282 10.0 310.0 8089 10.0 320.0 5157 10.0 320.0 3285 10.0 320.0 8097 10.0 330.0 5162 10.0 330.0 3288 10.0 330.0 8105 10.0 340.0 5167 10.0 340.0 3292 10.0 340.0 8113 10.0 350.0 5172 10.0 350.0 3295 10.0 350.0 8120 10.0 360.0 5177 10.0 360.0 3298 10.0 360.0 8128 Three Mile Island Nuclear Station 2-7 Report Number. EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

Profile 1 Profile 2 Profile 3 Thickness Depth Vs Thickness Depth Vs Thickness Depth V.

(ft.) (ft.) (fps) (ft.) (ft.) (fps) (ft.) (ft.) (fps) 10.0 370.0 5182 10.0 370.0 3301 10.0 370.0 8136 10.0 380.0 5187 10.0 380.0 3304 10.0 380.0 8144 10.0 390.0 5192 10.0 390.0 3307 10.0 390.0 8152 10.0 400.0 5197 10.0 400.0 3311 10.0 400.0 8160 10.0 410.0 5202 10.0 410.0 3314 10.0 410.0 8168 10.0 420.0 5207 10.0 420.0 3317 10.0 420.0 8175 10.0 430.0 5212 10.0 430.0 3320 10.0 430.0 8183 10.0 440.0 5217 10.0 440.0 3323 10.0 440.0 8191 10.0 450.0 5222 10.0 450.0 3327 10.0 450.0 8199 10.0 460.0 5227 10.0 460.0 3330 10.0 460.0 8207 10.0 470.0 5232 10.0 470.0 3333 10.0 470.0 8215 10.0 480.0 5237 10.0 480.0 3336 10.0 480.0 8222 10.0 490.0 5242 10.0 490.0 3339 10.0 490.0 8230 10.0 500.0 5247 10.0 500.0 3342 10.0 500.0 8238 100.0 600.0 5274 100.0 600.0 3360 100.0 600.0 8281 100.0 700.0 5324 100.0 700.0 3392 100.0 700.0 8359 100.0 800.0 5374 100.0 800.0 3423 100.0 800.0 8438 100.0 900.0 5424 100.0 900.0 3455 100.0 900.0 8516 100.0 1000.0 5474 100.0 1000.0 3487 100.0 1000.0 8595 100.0 1100.0 5524 100.0 1100.0 3519 100.0 1100.0 8673 100.0 1200.0 5574 100.0 1200.0 3551 100.0 1200.0 8752 100.0 1300.0 5624 100.0 1300.0 3583 100.0 1300.0 8830 100.0 1400.0 5674 100.0 1400.0 3615 100.0 1400.0 8909 100.0 1499.9 5724 100.0 1499.9 3646 100.0 1499.9 8987 100.0 1599.9 5774 100.0 1599.9 3678 100.0 1599.9 9066 100.0 1699.9 5824 100.0 1699.9 3710 100.0 1699.9 9144 100.0 1799.9 5874 100.0 1799.9 3742 100.0 1799.9 9223 100.0 1899.9 5924 100.0 1899.9 3774 100.0 1899.9 9285 100.0 1999.9 5974 100.0 1999.9 3806 100.0 1999.9 9285 100.0 2099.9 6024 100.0 2099.9 3838 100.0 2099.9 9285 100.0 2199.9 6074 100.0 2199.9 3869 100.0 2199.9 9285 100.0 2299.9 6124 100.0 2299.9 3901 100.0 2299.9 9285 100.0 2399.9 6174 100.0 2399.9 3933 100.0 2399.9 9285 100.0 2499.9 6224 100.0 ' 2499.9 3965 100.0 2499.9 9285 100.0 2599.9 6274 100.0 2599.9 3997 100.0 2599.9 9285 100.0 2699.9 6324 100.0 2699.9 4029 100.0 2699.9 9285 100.0 2799.9 6374 100.0 2799.9 4060 100.0 2799.9 9285 100.0 2899.9 6424 100.0 2899.9 4092 100.0 2899.9 9285 100.0 2999.9 6474 100.0 2999.9 4124 100.0 2999.9 9285 Three Mile Island Nuclear Station 2-8 Report Number: EXLNTM039-PR-001. Revision 1 Correspondence No.: RS-14-073. TMI-14-026

Profile 1 Profile 2 Profile 3 Thickness Depth Vs Thickness Depth Vs Thickness Depth Va (ft.) (ft.) (fps) (ft.) (ft.) (fps) (ft.) (ft.) (fps) 100.0 3099.9 6524 100.0 3099.9 4156 100.0 3099.9 9285 100.0 3199.9 6574 100.0 3199.9 4188 100.0 3199.9 9285 100.0 3299.9 6624 100.0 3299.9 4220 100.0 3299.9 9285 100.0 3399.9 6674 100.0 3399.9 4252 100.0 3399.9 9285 100.0 3499.9 6724 100.0 3499.9 4283 100.0 3499.9 9285 100.0 3599.9 6774 100.0 3599.9 4315 100.0 3599.9 9285 100.0 3699.9 6824 100.0 3699.9 4347 100.0 3699.9 9285 100.0 3799.9 6874 100.0 3799.9 4379 100.0 3799.9 9285 100.0 3899.9 6924 100.0 3899.9 4411 100.0 3899.9 9285 100.0 3999.9 6974 100.0 3999.9 4443 100.0 3999.9 9285 100.0 4099.9 7024 100.0 4099.9 4475 100.0 4099.9 9285 100.0 4199.9 7074 100.0 4199.9 4506 100.0 4199.9 9285 100.0 4299.9 7124 100.0 4299.9 4538 100.0 4299.9 9285 100.0 4399.8 7174 100.0 4399.8 4570 100.0 4399.8 9285 100.0 4499.8 7224 100.0 4499.8 4602 100.0 4499.8 9285 100.0 4599.8 7274 100.0 4599.8 4634 100.0 4599.8 9285 100.0 4699.8 7324 100.0 4699.8 4666 100.0 4699.8 9285 100.0 4799.8 7374 100.0 4799.8 4698 100.0 4799.8 9285 100.0 4899.8 7424 100.0 4899.8 4729 100.0 4899.8 9285 100.0 4999.8 7474 100.0 4999.8 4761 100.0 4999.8 9285 100.0 5099.8 7524 100.0 5099.8 4793 100.0 5099.8 9285 100.0 5199.8 7574 100.0 5199.8 4825 100.0 5199.8 9285 100.0 5299.8 7624 100.0 5299.8 4857 100.0 5299.8 9285 100.0 5399.8 7674 100.0 5399.8 4889 100.0 5399.8 9285 100.0 5499.8 7724 100.0 5499.8 4920 100.0 5499.8 9285 100.0 5599.8 7774 100.0 5599.8 4952 100.0 5599.8 9285 100.0 5699.8 7824 100.0 5699.8 4984 100.0 5699.8 9285 100.0 5799.8 7874 100.0 5799.8 5016 100.0 5799.8 9285 100.0 5899.8 7924 100.0 5899.8 5048 100.0 5899.8 9285 100.0 5999.8 7975 100.0 5999.8 5080 100.0 5999.8 9285 100.0 6099.8 8025 100.0 6099.8 5112 100.0 6099.8 9285 100.0 6199.8 8075 100.0 6199.8 5143 100.0 6199.8 9285 100.0 6299.8 8125 100.0 6299.8 5175 100.0 6299.8 9285 100.0 6399.8 8175 100.0 6399.8 5207 100.0 6399.8 9285 100.0 6499.8 8225 100.0 6499.8 5239 100.0 6499.8 9285 61.4 6561 .2 8235 61.4 6561.2 5246 61.4 6561 .2 9285 3280.8 9842.0 9285 3280.8 9842.0 9285 3280.8 9842.0 9285 Three Mile Island Nuclear Station 2-9 Report Number: EXLNTM039*PR*001, Revision 1 Correspondence No.: RS*14*073, TMI*14-026

2.3.2.1 Shear Modulus and Damping Curves No site-specific nonlinear dynamic material properties were determined in the initial siting of TMI for sedimentary rocks. The rock material over the upper 500 ft. (150 m) was assumed to have behavior that could be modeled as either linear or non-linear. To represent this potential for either case in the upper 500 ft. of sedimentary rock at the Three Mile Island site, two sets of shear modulus reduction and hysteretic damping curves were used. Consistent with the SPID (Reference 3), the EPRI rock curves (model M1) were considered to be appropriate to represent the upper range nonlinearity likely in the materials at this site and linear analyses (model M2) was assumed to represent an equally plausible alternative rock response across loading level. For the linear analyses, the low strain damping from the EPRI rock curves were used as the constant damping values in the upper 500 ft. (150 m).

2.3.2.2 Kappa For the Three Mile Island site, kappa estimates were determined using Section 8-5.1.3.1 of the SPID (Reference 3) for a firm CEUS rock site. Kappa for a firm rock site with at least 3,000 ft. (1 km) of sedimentary rock may be estimated from the average S-wave velocity over the upper 100 ft. (VS1OO) of the subsurface profile. For the Three Mile Island site, with about 6,500 ft. (1,969 m) of firm sedimentary rock below the SSE control point elevation, kappa estimates were based on the average shear-wave velocity over the top 100 ft. (30 m) of the three base-case profiles P1, P2, and P3. For the three profiles the corresponding average (100 ft., 30 m) shear-wave velocities were: 5,026 fps (1,532 m/s), 3,201 fps (976 m/s), and 7,980 fps (2,432 m/s) with corresponding kappa estimates of 0.015 s, 0.024 s, and 0.009 s. While profile P3 reached hard reference rock shear-wave velocities at a depth of 1,800 ft. (548 m), significantly less than 3,000 ft. (914 m), the profile reflects very firm sedimentary rock at the surface (about 7,800 fps, 2,393 m/s) and would be expected to increase to hard rock values above a depth of 3,000 ft.

(914 m). For these conditions the kappa estimate based on the average shear-wave velocity over the top 100 ft. (30 m) would be appropriate as assigning a as below 500 ft.

would result in too high a kappa estimate, depending on depth to hard reference rock velocities. The range in kappa about the best estimate base-case value of 0.015 s (profile P1) is roughly 1.6 and is considered to adequately reflect epistemic uncertainty in low strain damping (kappa) for the profile.

Ta bl e 2.3. 2-3 Kappa va ues an d weights used for site response analyses Velocity Profile Kappa (s) Weights P1 0.015 0.4 P2 0.024 0.3 P3 0.009 0.3 G/G max and Hysteretic Damping Curves M1 0.5 M2 0.5 Three Mile Island Nuclear Station 2-10 Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

2.3.3 Randomization of Base Case Profiles To account for the aleatory variability in dynamic material properties that is expected to occur across a site at the scale of a typical nuclear facility, variability in the assumed shear-wave velocity profiles has been incorporated in the site response calculations.

For the Three Mile Island site, random shear-wave velocity profiles were developed from the base case profiles shown in Figure 2.3.2-1. Consistent with the discussion in Appendix B of the SPID (Reference 3), the velocity randomization procedure made use of random field models which describe the statistical correlation between layering and shear-wave velocity. The default randomization parameters developed in Reference 9 for United States Geological Survey (USGS) "A" site conditions were used for this site.

Thirty random velocity profiles were generated for each base case profile. These random velocity profiles were generated using a natural log standard deviation of 0.25 over the upper 50 ft. and a natural log standard deviation of 0.15 below that depth. As specified in the SPID (Reference 3), correlation of shear-wave velocity between layers was modeled using the footprint correlation model. In the correlation model, a limit of +/-

2 standard deviations about the median value in each layer was assumed for the limits on random velocity fluctuations.

2.3.4 Input Spectra Consistent with the guidance in Appendix B of the SPID (Reference 3), input Fourier amplitude spectra were defined for a single representative earthquake magnitude (M 6.5) using two different assumptions regarding the shape of the seismic source spectrum (single-comer and double-comer). A range of 11 different input amplitudes (median PGAs ranging from 0.01g to 1.5g) were used in the site response analyses.

The characteristics of the seismic source and upper crustal attenuation properties assumed for the analysis of the Three Mile Island site were the same as those identified in Tables B-4, B-5, B-6 and B-7 of the SPID (Reference 3) as appropriate for typical CEUS sites.

2.3.5 Methodology To perform the site response analyses for the Three Mile Island site, a random vibration theory (RVT) approach was employed. This process utilizes a simple, efficient approach for computing site-specific amplification functions and is consistent with existing NRC guidance and the SPID (Reference 3). The guidance contained in Appendix B of the SPID (Reference 3) on incorporating epistemic uncertainty in shear-wave velocities, kappa, non-linear dynamic properties and source spectra for plants with limited at-site information was followed for the Three Mile Island site.

2.3.6 Amplification Functions The results of the site response analysis consist of amplification factors (5% of critical damping pseudo absolute response spectra) which describe the amplification (or de-amplification) of hard reference rock motion as a function of frequency and input reference rock amplitude. The amplification factors are represented in terms of a median amplification value and an associated standard deviation (sigma) for each oscillator frequency and input rock amplitude. Consistent with the SPID (Reference 3) a minimum median amplification value of 0.5 was employed in the present analysis.

Figure 2.3.6-1 illustrates the median and +/- 1 standard deviation in the predicted Three Mile Island Nuclear Station 2-11 Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073. TMI-14-026

amplification factors developed for the eleven loading levels parameterized by the median reference (hard rock) peak acceleration (0.01g to 1.50g) for profile P1 and EPRI rock GIG max and hysteretic damping curves. The variability in the amplification factors results from variability in shear-wave velocity, depth to hard rock, and modulus reduction and hysteretic damping curves. To illustrate the effects of nonlinearity at the Three Mile Island site, Figure 2.3.6-2 shows the corresponding amplification factors developed with linear analyses (model M2). Tabulated values of the amplification factors are provided in Appendix A.

Three Mile Island Nudear Station 2-12 Report Number: EXLNTM039. PR*001, Revision 1 Correspondence No.: RS*14*073, TMI*14-026

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AMPLIFICATION} THREE MILE ISLAND, MIPIKl M 6.S} 1 CORNER: P~GE 1 or z Figure 2.3.6-1 Example suite of amplification factors (5% of critical damping pseudo absolute acceleration spectra) developed for the mean base-case profile (P1), EPRI rock modulus reduction and hysteretic damping curves (model M1), and base-case kappa at eleven loading levels of hard rock median peak acceleration values from 0.01g to 1.50g; M 6.5 and single-corner source model (Reference 3)

Three Mile Island Nuclear Station 2-13 Report Number: EXLNTM039-PR-001 . Revision 1 Correspondence No.: RS-14-073. TMI-14-026

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AMPLIFICATION, THREE MILE ISLAND, M1P1Kl M 6.5, 1 CORNER: PRGE Z OF 2 Figure 2.3.6-1 continued Three Mile Island Nuclear Station 2-14 Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

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AMPLIFICATION, THREE MILE ISLAND, M2PIKl M 5.5, 1 CORNER: PRGE 1 Of Z Figure 2.3.6-2 Example suite of amplification factors (5% of critical damping pseudo absolute acceleration spectra) developed for the mean base-case profile (P1), linear analyses (model M2), and base-case kappa at eleven loading levels of hard rock median peak acceleration values from 0.01g to 1.50g; M 6.5 and single-corner source model (Reference 3)

Three Mile Island Nuclear Station 2-15 Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

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AMPLIFICATION, THREE MILE ISLAND, M2PIKl M 6.5, 1 CORNER: PAGE Z OF Z Figure 2.3.6-2 continued Three Mile Island Nudear Station 2-16 Report Number: EXLNTM039-PR-001. Revision 1 Correspondence No.: RS-14-073. TMI-14-026

2.3.7 Control Point Seismic Hazard Curves The procedure to develop probabilistic site-specific control point hazard curves used in the present analysis follows the methodology described in Section 8-6.0 of the SPID (Reference 3). This procedure (referred to as Method 3) computes a site-specific control point hazard curve for a broad range of spectral accelerations given the site-specific bedrock hazard curve and site-specific estimates of soil or soft-rock response and associated uncertainties. This process is repeated for each of the seven spectral frequencies for which ground motion equations are available. The dynamic response of the materials below the control point was represented by the frequency- and amplitude-dependent amplification functions (median values and standard deviations) developed and described in the previous section. The resulting control point mean hazard curves for TMI are shown in Figure 2.3.7-1 for the seven spectral frequencies for which ground motion equations are defined. Tabulated values of mean and fractile seismic hazard curves and site response amplification functions are provided in Appendix A.

Total Mean Soil Hazard by Spectral Frequency at Three Mile Island lE-2

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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 TMI (5% of critical damping)

Three Mile Island Nudear Station 2-17 Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

2.4 CONTROL POINT RESPONSE SPECTRA (UHRS & GMRS)

The control pOint hazard curves described in Section 2.3.7 have been used to develop geometric mean horizontal uniform hazard response spectra (UHRS) and the GMRS.

The UHRS were obtained through linear interpolation in log-log space to estimate the spectral acceleration at each spectral frequency for the 1E-4 and 1E-5 per year hazard levels. The 1E-4 and 1E-5 UHRS, along with a design factor (DF) are used to compute the GMRS at the control point using the criteria in NRC Reg. Guide 1.208 (Reference 18). The GMRS developed herein represents an alternative seismic demand for TMI determined using recently developed techniques. Table 2.4-1 shows the UHRS and GMRS accelerations for a range of spectral frequencies. Figure 2.4-1 shows the UHRS and GMRS at the control point.

Mean Soil UHRS and GMRS at Three Mile Island 0.8 II.D - lE-S UHRS

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0.1 1 10 100 Spectral frequency, Hz Figure 2.4-1 Plots of 1E-4 and 1E-5 UHRS and GMRS at control point for TMI (5% of critical damping response spectra)

Three Mile Island Nudear Station 2-18 Report Number. EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

Table 2.4-1 UHRS and GMRS at control point for TMI (5% of critical damping response spectra)

Freq (Hz) 1E-4 UHRS (g) 1E-5 UHRS (g) GMRS (g) 100 1.41E-01 4.85E-01 2.27E-01 90 1.41E-01 4.87E-01 2.28E-01 80 1.41E-01 4.92E-01 2.30E-01 70 1.42E-01 5.02E-01 2.34E-01 SO 1.48E-01 5.30E-01 2.4SE-01 50 1.64E-01 S.02E-01 2.79E-01 40 1.88E-01 7.02E-01 3.24E-01 35 2.01 E-01 7.5SE-01 3.48E-01 30 2.18E-01 8.21E-01 3.78E-01 25 2.32E-01 8.79E-01 4.04E-01 20 2.53E-01 9.31 E-01 4.30E-01 15 2.75E-01 9.83E-01 4.57E-01 12.5 2.B4E-01 9.9SE-01 4.S5E-01 10 2.88E-01 9.87E-01 4.S3E-01 9 2.80E-01 9.58E-01 4.49E-01 8 2.S9E-01 9.17E-01 4.30E-01 7 2.53E-01 8.S3E-01 4.05E-01 S 2.33E-01 7.95E-01 3.73E-01 5 2.10E-01 7. 14E-01 3.35E-01 4 1.74E-01 5.87E-01 2.7SE-01 3.5 1.52E-01 5.13E-01 2.42E-01 3 1.28E-01 4.28E-01 2.02E-01 2.5 1.0SE-01 3.50E-01 1.S5E-01 2 9.42E-02 3.0SE-01 1.45E-01 1.5 7.S9E-02 2.43E-01 1.1SE-01 1.25 S.5SE-02 2.03E-01 9.73E-02 1 5.44E-02 1.S4E-01 7.89E-02 0.9 5.14E-02 1.53E-01 7.39E-02 0.8 4.S5E-02 1.37E-01 S.S2E-02 0.7 4.14E-02 1.20E-01 5. 82E-02 O.S 3.53E-02 1.01E-01 4.90E-02 0.5 2.94E-02 8.23E-02 4.02E-02 0.4 2.3SE-02 S.58E-02 3.21E-02 0.35 2.0SE-02 5.7SE-02 2.81E-02 0.3 1.77E-02 4.94E-02 2.41E-02 0.25 1.47E-02 4.11E-02 2.01E-02 0.2 1.18E-02 3.29E-02 1.S1E-02 0.15 8.83E-03 2.47E-02 1.21E-02 0.125 7.3SE-03 2.0SE-02 1.00E-02 0.1 5.89E-03 1.S5E-02 8.04E-03 Three Mile Island Nudear Station 2-19 Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

3 Plant Design Basis Ground Motion The design basis for TMI is identified in the TMI Updated Final Safety Analysis Report (UFSAR) (Reference 10). The current licensing basis maximum hypothetical earthquake (MHE), equivalent to the SSE, is based on an evaluation of the maximum earthquake potential considering regional and local geology, seismology, tectonic history, and specific characteristics of local subsurface material. An estimate of the maximum expected intensity of an earthquake is predicted on the assumption that the activity which would affect the site would originate along the border fault of the Triassic Lowland, five to six miles north of the site. The highest recorded intensity within a 50 mile radius of the site was modified Mercalli VI, which would attenuate to an intensity of V at the site if the earthquake originated at the assumed location. Due to the uncertainty associated with epicenter focal depth and ground motion attenuation, the maximum earthquake intensity is conservatively equated to a low intensity VI. The SSE acceleration response spectrum is based on data recorded from the March 1957 San Francisco and 1940 EI Centro earthquakes. (Reference 10, Section 2.7.1) 3.1 SSE DESCRIPTION OF SPECTRAL SHAPE The SSE is defined in terms of a PGA and a design response spectrum. Considering a site design intensity of VI, the maximum horizontal ground acceleration is defined with 12% of gravity (0.12g) as the anchor point for the SSE (Reference 10, Section 5.1.2.1.1).

The site design response spectrum, shown in Figure 2.7-1, is derived from the ground motions of the 1957 Golden Gate Park, San Francisco earthquake together with the revised acceleration spectra reflecting the greater response at lower frequencies based upon the 1940 EI Centro spectra (Reference 10, Section 2.8.2).

Table 3.1-1 shows the spectral acceleration values as a function of frequency for horizontal SSE (5% of critical damping). The SSE acceleration values are based on digitized data from UFSAR Figure 2.7-1 (Reference 10) normalized to the SSE PGA of 0.12g. The horizontal SSE (5% of critical damping) for TMI is shown in Figure 3.1-1.

Three Mile Island Nuclear Station 3-1 Report Number. EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

Table 3.1-1 Horizontal SSE for TMI 5% of critical dam:>ing response spectrum)

Spectral Frequency (Hz)

Acceleration (g) 1 0.17 1.25 0.18 1.5 0.23 2 0.27 2.5 0.30 3 0.32 4 0.36 5 0.40 6 0.42 7 0.43 8 0.43 9 0.42 10 0.41 12.5 0.36 15 0.29 20 0.21 25 0.18 30 0.17 35 0.15 40 0.15 50 0.14 60 0.14 70 0.13 80 0.13 90 0.12 100/PGA 0.12 Three Mile Island Nuclear Station 3-2 Report Number. EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

Horizontal SSE for Three Mile Island 0.50 0.45 I I I I I

,",~I 0.40 I I I ~~ Iil. I I II.D 035 c*

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III 0.15 0.10 I I I I ,"-- - iT 0.05 I I I 0.00 I / I 0.1 1 10 100 Spectral frequency, Hz Figure 3.1-1 Horizontal SSE for TMI (5% of critical damping response spectrum) 3.2 CONTROL POINT ELEVATION The TMI UFSAR (Reference 10) does not define an SSE control point. The site is layered with approximately 20 ft. of soil (Reference 10, Section 2.7.3.6) over underlying rock composed of a sedimentary sequence of interbedded sandstone, shaley siltstone, and shaley claystone which belongs to the Gettysburg Formation of the Triassic Age (Reference 10, Section 2.7.1). TMI is identified as a rock site (Reference 17) with the top of rock varying from EI. 275.0 to 279.5 ft. (Reference 10, Section 2.7.5.2) directly underlying the main power block building foundations. Based on estimation from subsurface sections and seismic refraction survey results (Reference 10, Figures 2.7-3 and 2.7-4), the SSE control point elevation is taken to be at the approximate top of the rock surface at EI. 280 ft. MSL. This definition of the control point is consistent with the approach described in the SPID (Reference 3, Section 2.4.2).

Three Mile Island Nuclear Station 3-3 Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

4 Screening Evaluation Following completion of the seismic hazard reevaluation, as requested in the SO.S4(f) letter (Reference 1), a screening evaluation is performed in accordance with the SPID, Section 3 (Reference 3). The horizontal GMRS determined from the hazard reevaluation is used to characterize the amplitude of the alternative seismic hazard at each of the nuclear power plant sites. The screening evaluation is based upon a comparison of the GMRS with the established plant-level seismic capacity (either the SSE or IPEEE HCLPF Spectrum (IHS), where IPEEE is defined as Individual Plant Examination of External Events and HCLPF is defined as high-confidence-of-Iow-probability-of-failure), in accordance with the SPID (Reference 3). For TMI, the plant-level seismic capacity is based on the SSE.

4.1 RISK EVALUATION SCREENING (1 TO 10 Hz)

In the frequency range of 1 to 10Hz, the TMI GMRS spectral acceleration exceeds that of the SSE at spectral frequencies above approximately 8.0 Hz. As a result, TMI screens in for a risk evaluation in accordance with the SPID, Section 3.2 (Reference 3).

Section 6.2 of the SPID (Reference 3) provides guidance as to whether an NRC SMA, as described in NRC Interim Staff Guidance JLD-ISG-2012-04 (Reference 8), or an SPRA is the appropriate approach for the risk evaluation. As the re-evaluated seismic hazard is not considerably higher than the design basis seismic hazard, since the GMRS is less than 1.3 times the SSE, an SMA and an SPRA are both acceptable risk evaluation approaches for TMI.

Further, in accordance with the screening requirements in Section 2.2 of the "Augmented Approach" guidance document (Reference 4), TMI will perform an ESEP as an interim action/assessment.

4.2 HIGH FREQUENCY SCREENING (> 10Hz)

In the frequency range above 10Hz, the GMRS spectral acceleration exceeds that of the SSE. The high frequency exceedances can be addressed in the risk evaluation discussed in Section 4.1 Section 3.4 of the SPID (Reference 3) discusses the impact of high-frequency ground motion on plant components and identifies the component groups that are sensitive to high-frequency vibration. As summarized in the SPID (Reference 3), EPRI Report NP-7498 (Reference 21) concludes that high-frequency vibration is not damaging, in general, to components with strain- or stress-based failure modes. However, components, such as relays, subject to electrical functionality failure modes have unknown acceleration sensitivity for frequencies above 16 Hz.

Three Mile Island Nuclear Station 4-1 Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

EPRI Report 1015108 (Reference 22) provides evidence that supports the conclusion that high-frequency motions are not damaging to the majority of nuclear plant components, excluding relays and other electrical devices whose output signals may be affected by high-frequency vibration. EPRI Report 1015109 (Reference 23) provides guidance for identifying and evaluating potentially high-frequency sensitive components.

Guidance from these documents is considered in the SPID (Reference 3) for identifying components that are sensitive to high-frequency vibration. Component types listed in Table 3-3 of the SPID (Reference 3) provide examples of components that are potentially sensitive to high-frequency vibrations. Those component types are:

• Electro-mechanical relays

• Circuit breakers

• Control switches

• Process switches and sensors

• Electro-mechanical contactors

• Auxiliary contacts

• Transfer switches

• Potentiometers 4.3 SPENT FUEL POOL EVALUATION SCREENING (1 TO 10 Hz)

As the GMRS spectral acceleration exceeds that of the SSE in the frequency range of 1 to 10 HZ, a Spent Fuel Pool Integrity evaluation is needed for TMI in accordance with the SPID, Section 7 (Reference 3).

Three Mile Island Nuclear Station 4-2 Report Number. EXLNTM039-PR-001 . Revision 1 Correspondence No.: RS-14-073, TMI-14-026

5 Interim Actions Based on the screening results described in Section 4 of this report, the GMRS spectral acceleration exceeds that of the SSE at all spectral frequencies above approximately B.O Hz at TMI. Therefore, TMI screens in for a risk evaluation in response to the SO.54(f) letter (Reference 1). Additionally, the "Augmented Approach" guidance document (Reference 4) prescribes expedited seismic evaluations of key components be performed.

5.1 EXPEDITED SEISMIC EVALUATION PROCESS Based on the screening results, the ESEP will be performed for TMI as proposed in the April 9, 2013 letter from the industry to the NRC (Reference S) and agreed to by the NRC in a letter dated May 7,2013 (Reference 20).

Exelon has committed to follow the "Augmented Approach" guidance document (Reference 4), which introduces the ESEP as an interim action to augment the response to the NRC request for information. The ESEP addresses the part of the SO.S4(f) letter (Reference 1) that requests "interim evaluation and actions taken or planned to address the higher seismic hazard relative to the design basis, as appropriate, prior to completion of the risk evaluation." Specifically, the ESEP focuses initial industry efforts on short term evaluations that will lead to prompt modifications to some of the most important components that could improve plant seismic safety.

5.2 INTERIM EVALUATION OF SEISMIC HAZARD Consistent with the NRC letter dated February 20, 2014 (Reference 13), the seismic hazard reevaluations presented herein are distinct from the current design and licensing bases of TMI. Therefore, the results do not call into question the operability or functionality of SSCs and are not reportable pursuant to 10CFRSO. 72, "Immediate notification requirements for operating nuclear power reactors" (Reference 2, Section SO.72) and 10CFRSO. 73, "Licensee event report system" (Reference 2, Section SO.73).

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, the Nuclear Energy Institute (NEI) letter dated March 12, 2014 (Reference 24) provides seismic core damage risk estimates using the updated seismic hazards for the operating nuclear plants in the CEUS. These risk estimates continue to support the following conclusions ofthe NRC GI-199 Safety/Risk Assessment (Reference 19):

"Overall seismic core damage risk estimates are consistent with the Commission's Safety Goal Policy Statement because they are within the subsidiary objective of 10-4/year for core damage frequency. The GI-199 Safety/Risk Assessment, based in Three Mile Island Nuclear Station S-1 Report Number: EXLNTM039-PR-001. Revision 1 Correspondence No.: RS-14-073, TMI-14-026

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."

TMI is included in the March 12, 2014 NEI letter risk estimates (Reference 24). Using the methodology described in the NEI letter, the seismic core damage risk estimates for all plants were shown to be below 1E-4/year; thus, the above conclusions apply.

5.3 SEISMIC WALKDOWN INSIGHTS In response to NTTF 2.3, the 50.54(f) letter (Reference 1) also requested licensees to perform seismic walkdowns in order to, in the context of seismic response: 1) verify that the current plant configuration is consistent with the licensing basis; 2) verify the adequacy of current strategies, monitoring, and maintenance programs; and 3) identify degraded, nonconforming, or unanalyzed conditions. Exelon committed to and performed seismic walkdowns in accordance with the seismic walkdown guidance (Reference 14) as initially documented and supplemented in Exelon Correspondence Numbers RS-12-175 and RS-14-032 (References 12 and 25) respectively.

Based on the successful completion of seismic walkdowns in response to NTTF 2.3, and the lack of identified adverse seismic conditions resulting in an operability concern, Exelon has directly concluded that the TMI current plant configuration is consistent with the plant licensing basis and can safely shut down the reactor and maintain containment integrity following the design basis SSE event. Additionally, the findings of the seismic walkdown program indirectly verify that the current TMI strategies, monitoring, and maintenance programs are adequate for ensuring seismic safety consistent with the licensing basis.

Plant vulnerabilities and commitments identified in the TMI IPEEE (Reference 11) were reviewed as part of the NTTF 2.3 seismic walkdowns (References 12 and 25). The TMI seismic walkdown reports verified the IPEEE report did not identify any vulnerabilities and confirmed all previously identified IPEEE commitments have been resolved (References 12 and 25).

5.4 BEYOND-DESIGN-BASIS SEISMIC INSIGHTS An evaluation of beyond-design-basis ground motions was performed for TMI as part of the IPEEE program. The TMI IPEEE (Reference 11) analyzed seismic risk quantitatively via an SPRA. The IPEEE seismic evaluation included plant walkdowns, earthquake induced soil liquefaction analysis, review of relay chatter effects, evaluation of containment performance, and examination of seismic core damage frequency (SCDF) sensitivity to changes in input assumptions and model characteristics. The results of the TMI IPEEE showed there were no vulnerabilities to severe accident risk from external events, including seismic events (Reference 11). The final SCDF for TMI was found to be 3.21 E-5/year (Reference 11), which is less than the Commission's Safety Goal subsidiary objective of 1E-4/year (Reference 19). Based on the SCDF value, it may be qualitatively concluded that the plant has adequate seismic margin beyond the design basis. Additionally, improvements were made to TMI based on the TMI IPEEE seismic Three Mile Island Nuclear Station 5-2 Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

evaluation, as confirmed in the NTTF 2.3 seismic walkdown reports (References 12 and 25), to further enhance the TMI seismic margin.

Three Mile Island Nuclear Station 5-3 Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

6 Conclusions In accordance with the 50.54(f) letter (Reference 1), a seismic hazard and screening evaluation was performed for TMI. This evaluation followed the SPID guidance (Reference 3) in order to develop a site GMRS for the purpose of screening the plant in accordance with the SPID. The new GMRS does not constitute a change in the plant design or licensing basis as described in the NRC letter dated February 20, 2014 (Reference 13).

The screening evaluation comparison demonstrates that the GMRS spectral acceleration exceeds that of the SSE at spectral frequencies above approximately 8.0 Hz. Based on the screening evaluation, TMI screens in for a risk evaluation and a Spent Fuel Pool Integrity evaluation in accordance with the SPID, Sections 3 and 7 (Reference 3). Since the GMRS spectral acceleration exceeds that of the SSE in the frequency range above 10Hz, high-frequency exceedances can be addressed as part of the risk evaluation for TMI. As an interim action/assessment, an ESEP will be performed for TMI in conformance with the "Augmented Approach" guidance document (Reference 4).

This is an interim action to establish beyond-design-basis safety margin prior to completion of the risk evaluation. Actions to address NTTF 2.1: Seismic for CEUS nuclear plants are outlined in the schedule provided in the April 9, 2013 letter from the industry to the NRC (Reference 5), as agreed to by the NRC in the May 7, 2013 letter to the industry (Reference 20).

Three Mile Island Nudear Station 6-1 Report Number. EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

7 References

1. NRC (E. Leeds and M. Johnson) Letter to All Power Reactor Licensees et aI.,

Request for Information Pursuant to Title 10 of the Code of Federal Regulations SO.S4(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. Title 10 Code of Federal Regulations Part SO, Domestic Licensing of Production and Utilization Facilities.

3. EPRI 102S287, Seismic Evaluation Guidance: Screening, Prioritization and Implementation Details (SPID) for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1: Seismic, Palo Alto, CA, February 2013.

4. EPRI 3002000704, Seismic Evaluation Guidance: Augmented Approach for the Resolution of Fukushima Near-Term Task Force Recommendation 2.1: Seismic, Palo Alto, CA, May 2013.

5. NEI Letter (A. R. Pietrangelo) to the NRC, Proposed Path Forward for NTTF Recommendation 2.1: Seismic Reevaluations, dated April 9, 2013.

6. EPRI 1021097 (NUREG-2115), Central and Eastern United States Seismic Source Characterization for Nuclear Facilities, Palo Alto, CA, January 2012.

7. EPRI 3002000717, EPRI (2004, 2006) Ground-Motion Model (GMM) Review Project, Palo Alto, CA, June 2013.

8. NRC Japan Lessons-Learned Project Directorate Interim Staff Guidance JLD-ISG-2012-04, Revision 0, Guidance on Performing a Seismic Margin Assessment in Response to the March 2012 Request for Information Letter, November 2012.

9. Silva, W.J., N. Abrahamson, G. Toro and C. Costantino, Description and validation of the stochastic ground motion model, Report Submitted to Brookhaven National Laboratory, Associated Universities, Inc. Upton, New York 11973, Contract No.

770573, 1997.

10. Exelon Generation Company, Three Mile Island Nuclear Station, Unit 1, Updated Final Safety Analysis Report (UFSAR), Revision 22.

11. GPU Nuclear Corporation, Three Mile Island Nuclear Station, Unit 1, Individual Plant Examination for External Events (IPEEE), December 1994.

Three Mile Island Nuclear Station 7-1 Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

12. Exelon Generation Company Letter to the NRC, Exelon Generation Company, LLC's 1BO-day Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding the Seismic Aspects of Recommendation 2.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, RS-12-175, dated November 19,2012.

13. NRC (E. Leeds) Letter to All Power Reactor Licensees et aI., ML14030A046, Supplemental Information Related to Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(f) Regarding Seismic Hazard Reevaluations for Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, dated February 20,2014.

14. EPRI 1025286, Seismic Walkdown Guidance for Resolution of Fukushima Near-Term Task Force Recommendation 2.3: Seismic, Palo Alto, CA, June 2012.

15. Exelon Generation Company Letter to the NRC, Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding the Seismic Aspects of Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, RS-13-102, dated April 29, 2013.

16. EPRI RSM-112013-027, Three Mile Island Seismic Hazard and Screening Report, dated November 27, 2013.

17. SGH Report No. 128018-R-01, Revision 1, Review of Existing Site Response Parameter Data for the Exelon Nuclear Fleet, dated July 17, 2012.

18. NRC Regulatory Guide 1.208, A performance-based approach to define the site-specific earthquake ground motion, 2007.

19. NRC Memorandum (from P. Hiland to B. Sheron), ML100270582, "Safety/Risk Assessment Results for Generic Issue 199, Implications of Updated Probabilistic Seismic Hazard Estimates in Central and Eastern United States on Existing Plants,"

dated September 2, 2010.

20. NRC (E. Leeds) Letter to NEI (J. Pollock), ML13106A331, 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 Altemative to the March 12, 2012, Information Request for Seismic Reevaluations, dated May 7, 2013.

21. EPRI NP-7498, Industry Approach to Seismic Severe Accident Policy Implementation, Palo Alto, CA, November 1991.

22. EPRI 1015108, Program on Technology Innovation: The Effects of High-Frequency Ground Motion on Structures, Components, and Equipment in Nuclear Power Plants, Palo Alto, CA, June 2007.

23. EPRI 1015109, Program on Technology Innovation: Seismic Screening of Components Sensitive to High-Frequency Vibratory Motions, Palo Alto, CA, October 2007.

Three Mile Island Nuclear Station 7-2 Report Number. EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

24. NEI Letter (A. R. Pietrangelo) to the NRC, Seismic Risk Evaluations for Plants in the Central and Eastern United States, dated March 12, 2014.

25. Exelon Generation Company, Seismic Walkdown Report In Response to the 50.54(t) Information Request Regarding Fukushima Near-Term Task Force Recommendation 2.3: Seismic, Updated Transmittal #1 (Annex A) for the Three Mile Island Generating Station Unit 1, RS-14-032, February 2014.

Three Mile Island Nuclear Station 7-3 Report Number. EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

A Additional Tables Table A-1a Mean and fractile seismic hazard curves for PGA at TMI, 5% of critical damping AMPS(g) MEAN 0.05 0.1S 0.50 0.84 0.95 0.0005 3.B7E-02 1.S7E-02 3.0SE-02 3.9SE-02 4.77E-02 S.3SE-02 0.001 2.7SE-02 1.0SE-02 2.04E-02 2.72E-02 3.S3E-02 4. 19E-02 0.005 7.43E-03 3.0SE-03 4.70E-03 S.73E-03 9.S1E-03 1.S7E-02 0.01 3.S0E-03 1.S1E-03 2. 1OE-03 3.19E-03 4.S0E-03 B.72E-03 0.015 2.24E-03 B.72E-04 1.23E-03 1.92E-03 2.BBE-03 S.B3E-03 0.03 9.20E-04 2.72E-04 4.01E-04 7.34E-04 1.32E-03 2.64E-03 0.05 4.S0E-04 1.02E-04 1.S7E-04 3.47E-04 7. 13E-04 1.3SE-03 0.075 2.S0E-04 4.9BE-OS B.47E-OS 1.90E-04 4. 19E-04 7.SSE-04 0.1 1.71E-04 3.0SE-OS S.3SE-OS 1.23E-04 2.7SE-04 4. 90 E-04 0.15 9.09E-OS 1.49E-OS 2.72E-OS S.4SE-OS 1.49E-04 2.S0E-04 0.3 2.S9E-OS 3.47E-OS 7.03E-OS 1.B2E-OS 4.43E-OS 7.77E-OS 0.5 9.40E-OS B.SOE-07 2.01E-OS S.91E-OS 1.S0E-OS 2.92E-OS 0.75 3.S7E-OS 2.19E-07 S.00E-07 2.13E-OS S.4SE-OS 1.23E-OS

1. 1.77E-OS S.93E-OB 2.19E-07 9.11E-07 3.09E-OS S.2SE-OS 1.5 S.7SE-07 1.0SE-OB 4.31E-OB 2.42E-07 9.93E-07 2.22E-OS

3. S.2SE-OB 2.3SE-10 1.4SE-09 1.S3E-OB 9.SSE-OB 2.64E-07

5. 9.03E-09 7.4SE-11 1.40E-10 1.3BE-09 1.1BE-OB 4.01E-OB 7.5 1.S7E-09 S.OSE-11 9.93E-11 2.04E-10 1.79E-09 7.23E-09

10. 4.00E-10 S.OSE-11 S.09E-11 1.11 E-10 4.S3E-10 1.90E-09 Three Mile Island Nuclear Station A-1 Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

Table A-1b Mean and fractile seismic hazard curves for 25 Hz at TMI , 5% of critical damping AMPS(g) MEAN 0.05 0.1S 0.50 0.B4 0.95 0.0005 4.19E-02 2.19E-02 3.S2E-02 4.19E-02 4.9BE-02 S.SBE-02 0.001 3.17E-02 1.4SE-02 2.49E-02 3.14E-02 3.9SE-02 4.S3E-02 0.005 1.0SE-02 4.77E-03 7.13E-03 9.SSE-03 1.31 E-02 2.13E-02 0.01 S.73E-03 2.S4E-03 3.SBE-03 S.20E-03 7.03E-03 1.27E-02 0.015 3.B3E-03 1.77E-03 2.39E-03 3.47E-03 4.77E-03 B.SOE-03 0.03 1.72E-03 S.B3E-04 9.SSE-04 1.S1E-03 2.29E-03 3.90E-03 0.05 B.B4E-04 2.BOE-04 4.2SE-04 7.SSE-04 1.27E-03 2.04E-03 0.075 S.OBE-04 1.31E-04 2. 13E-04 4. 19E-04 7. 77E-04 1.20E-03 0.1 3.41E-04 7.SSE-OS 1.31 E-04 2.7SE-04 S.3SE-04 B.3SE-04 0.15 1.92E-04 3.79E-OS S.73E-OS 1.S1E-04 3. 14E-04 4.90E-04 0.3 S.B3E-OS 1.1SE-OS 2.19E-OS S.20E-OS 1.1SE-04 1.79E-04 0.5 2.92E-OS 4.37E-OS B.72E-OS 2.1SE-OS 4.9BE-OS B.OOE-OS 0.75 1.3BE-OS 1.77E-OS 3.73E-OS 9.93E-OS 2.3SE-OS 3.90E-OS

1. 7.70E-OS B.SOE-07 1.90E-OS S.27E-OS 1.32E-OS 2.2SE-OS 1.5 3.12E-OS 2.72E-07 S.4SE-07 1.9BE-OS S.SOE-OS 9.SSE-OS

3. S.13E-07 2.3SE-OB S.73E-OB 2.S4E-07 B.9BE-07 1.B2E-OS

5. 1.07E-07 2.S3E-09 B.SOE-09 4.31E-OB 1.84E-07 4. 13E-07 7.5 2.S1E-OB 3.73E-10 1.3BE-09 8.00E-09 4.37E-OB 1.0BE-07

10. B.7BE-09 1.32E-10 3.S7E-10 2.1SE-09 1.40E-OB 3.73E-OB Table A-1c Mean and fractile seismic hazard curves for 10 Hz at TMI, 5% of critical damping AMPS(g) MEAN 0.05 0.1S 0.50 0.84 0.95 0.0005 4.7BE-02 3.S7E-02 4.13E-02 4.77E-02 S.SOE-02 S.00E-02 0.001 3.91E-02 2.49E-02 3.23E-02 3.90E-02 4.S3E-02 S.20E-02 0.005 1.42E-02 7.03E-03 1.01 E-02 1.3SE-02 1.82E-02 2.3SE-02 0.01 7.S3E-03 3.SBE-03 S.OSE-03 7.13E-03 9.SSE-03 1.3SE-02 0.015 4.98E-03 2.42E-03 3.2BE-03 4.70E-03 S.3SE-03 9.37E-03 0.03 2.29E-03 1.07E-03 1.44E-03 2.13E-03 2.9SE-03 4.S0E-03 0.05 1.22E-03 4.9BE-04 7.03E-04 1.11E-03 1.S7E-03 2.42E-03 0.075 7.14E-04 2.S3E-04 3. 73E-04 S.3SE-04 1.04E-03 1.4SE-03 0.1 4.B2E-04 1.51 E-04 2. 32E-04 4.19E-04 7.23E-04 1.01 E-03 0.15 2.72E-04 7.13E-OS 1.1SE-04 2.32E-04 4.2SE-04 S.00E-04 0.3 9.39E-OS 1.9BE-OS 3.S2E-OS 7.SSE-OS 1.SSE-04 2.2SE-04 0.5 3.90E-OS 7.03E-OS 1.32E-OS 3.0SE-OS S.54E-OS 9.79E-OS 0.75 1.7BE-OS 2.7SE-OS S.SOE-OS 1.3SE-OS 3.0SE-OS 4.70E-OS

1. 9.73E-OS 1.27E-OS 2.SBE-OS 7.13E-OS 1.S9E-OS 2.S8E-OS 1.5 3.82E-OS 3.S7E-07 B.47E-07 2.S7E-OS S.B3E-OS 1.1SE-OS

3. S.1SE-07 2. 1OE-OB S.B3E-OB 3.14E-07 1.10E-OS 2.22E-OS

5. 1.31 E-07 1.44E-09 S.S4E-09 S.OSE-OB 2.29E-07 S.20E-07 7.5 3.32E-08 1.74E-10 8.47E-10 9.SSE-09 S.SSE-OB 1.42E-07

10. 1.1SE-OB 1.01 E-10 2.13E-10 2.S4E-09 1.B7E-OB S.12E-OB Three Mile Island Nuclear Station A-2 Report Number. EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

Table A-1d Mean and fractile seismic hazard curves for S Hz at TMI , S% of critical damping AMPS(a) MEAN O.OS 0.16 O.SO 0.84 0.9S O.OOOS 4.94E-02 3.79E-02 4.2SE-02 4.90E-02 S.66E-02 6. 17E-02 0.001 4.1BE-02 2.72E-02 3.37E-02 4 .19E-02 4.9BE-02 S.SOE-02 O.OOS 1.S6E-02 7.13E-03 1.07E-02 1.S1 E-02 2.10E-02 2.49E-02 0.01 7.70E-03 3.42E-03 4.9BE-03 7.23E-03 1.07E-02 1.29E-02 0.01S 4.77E-03 2.16E-03 3.0SE-03 4.S0E-03 6.64E-03 B.23E-03 0.03 1.93E-03 B.72E-04 1.21E-03 1.B2E-03 2.64E-03 3.42E-03 O.OS 9.37E-04 3.B4E-04 S.SOE-04 B.72E-04 1.31 E-03 1.74E-03 0.07S S.1SE-04 1.B2E-04 2.72E-04 4.70E-04 7.SSE-04 1.01 E-03 0.1 3.33E-04 1.04E-04 1.62E-04 2.96E-04 S.OSE-04 6.B3E-04 0.1S 1.76E-04 4.63E-OS 7.66E-OS 1.S3E-04 2.BOE-04 3.B4E-04 0.3 S.47E-OS 1.13E-OS 2.04E-OS 4 .S0E-OS B.9BE-OS 1.31 E-04 O.S 2.09E-OS 3.6BE-06 7.03E-06 1.64E-OS 3.S2E-OS S.27E-OS 0.7S 9.02E-06 1.32E-06 2.6BE-06 6 .73E-06 1.S3E-OS 2.46E-OS

1. 4.71E-06 S.91E-07 1.27E-06 3.37E-06 B.00E-06 1.34E-OS 1.S 1.74E-06 1.64E-07 3.90E-07 1.16E-06 3.01E-06 S.3SE-06

3. 2.49E-07 1.10E-OB 3.2BE-OB 1.32E-07 4.37E-07 B.BSE-07 S. 4.7BE-OB 9.79E-10 3.42E-09 1.90E-OB B.23E-OB 1.90E-07 7.S 1.11E-OB 1.62E-10 4.90E-10 3.23E-09 1.79E-OB 4.77E-OB

10. 3.63E-09 9.37E-11 1.SSE-10 B.60E-10 S.SOE-09 1.62E-OB Table A-1e Mean and fractile seismic hazard curves for 2.S Hz at TMI, S% of critical damping AMPS{g) MEAN O.OS 0.16 O.SO 0.84 0.9S O.OOOS 4.6SE-02 3.42E-02 3.90E-02 4.63E-02 S.42E-02 S.91E-02 0.001 3.71E-02 2.32E-02 2.B4E-02 3.6BE-02 4.63E-02 S.20E-02 O.OOS 1.14E-02 S.OSE-03 7.13E-03 1.0BE-02 1.60E-02 1.9SE-02 0.01 4 .90E-03 2.04E-03 2.BBE-03 4.S0E-03 7.03E-03 9.11E-03 0.01S 2.73E-03 1.10E-03 1.SSE-03 2.49E-03 3.90E-03 S.27E-03 0.03 B.9BE-04 3.33E-04 4.B3E-04 B.12E-04 1.31E-03 1.79E-03 O.OS 3. 76E-04 1.20E-04 1.84E-04 3. 33E-04 S.66E-04 7.B9E-04 0.07S 1.B4E-04 4.9BE-OS B.12E-OS 1.S7E-04 2.BBE-04 4.13E-04 0.1 1.10E-04 2.60E-OS 4.43E-OS 9.11E-OS 1.74E-04 2.60E-04 0.1S S.26E-OS 1.04E-OS 1.B7E-OS 4. 13E-OS B.60E-OS 1.34E-04 0.3 1.3BE-OS 1.90E-06 3.90E-06 9.93E-06 2.32E-OS 3.9SE-OS O.S 4.7SE-06 4.70E-07 1.0BE-06 3.14E-06 B.12E-06 1.49E-OS 0.7S 1.90E-06 1.34E-07 3.42E-07 1.1SE-06 3. 33E-06 6.36E-06

1. 9.49E-07 S.OSE-OB 1.42E-07 S.27E-07 1.67E-06 3. 33E-06 1.S 3.30E-07 1.10E-OB 3.S7E-OB 1.60E-07 S.B3E-07 1.23E-06

3. 4 .22E-OB S.SOE-10 2. 16E-09 1.3BE-OB 7. 13E-OB 1.79E-07 S. 7.2SE-09 1.11 E-1 0 2.42E-10 1.60E-09 1.0BE-OB 3.2BE-OB 7.S 1.S2E-09 6.09E-11 1.11 E-10 2.B4E-10 1.9BE-09 6.93E-09

10. 4.S4E-10 S.OSE-11 6.64E-11 1.23E-10 S.66E-10 2.07E-09 Three Mile Island Nudear Station A-3 Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

Table A-1f Mean and fractile seismic hazard curves for 1 Hz at TMI 5% of critical damping I

AMPS(g) MEAN 0.05 0.1S 0.50 0.B4 0.95 0.0005 3.45E-02 1.B4E-02 2.4SE-02 3.47E-02 4.37E-02 4.9BE-02 0.001 2.37E-02 1.0BE-02 1.57E-02 2.35E-02 3.14E-02 3.73E-02 0.005 5.B1E-03 1.B4E-03 3.05E-03 5.35E-03 B.SOE-03 1.13E-02 0.01 2.35E-03 S.00E-04 1.04E-03 2.01E-03 3.S3E-03 5.35E-03 0.015 1.23E-03 2.B4E-04 4.9BE-04 1.01 E-03 1.92E-03 3.05E-03 0.03 3.41E-04 S.45E-05 1.1BE-04 2.S0E-04 5.50E-04 9.24E-04 0.05 1.19E-04 1.92E-05 3.S3E-05 B.SOE-05 1.9BE-04 3.37E-04 0.075 S.07E-05 7.03E-OS 1.3SE-05 3.47E-05 B.SOE-05 1.S1E-04 0.1 2.7BE-05 3.33E-OS S.73E-OS 1.79E-05 4.70E-05 B.SOE-05 0.15 1.20E-05 1.13E-OS 2.4SE-OS 7.13E-OS 2.04E-05 3.95E-05 0.3 2.BBE-OS 1.57E-07 4.07E-07 1.44E-OS 4.B3E-OS 1.07E-05 0.5 9.71E-07 3.01E-OB 9.24E-OB 4.07E-07 1.S2E-OS 3.90E-OS 0.75 3.90E-07 S.93E-09 2.49E-OB 1.34E-07 S.45E-07 1.S7E-OS

1. 1.97E-07 2.22E-09 B.9BE-09 5.SSE-OB 3.14E-07 B.72E-07 1.5 7.02E-OB 4.37E-10 1.B4E-09 1.49E-OB 1.04E-07 3.23E-07

3. 9.S1E-09 9.24E-11 1.51E-10 1.11E-09 1.10E-OB 4.43E-OB

5. 1.79E-09 5.0SE-11 8.98E-11 1.72E-10 1.57E-09 7. 77E-09 7.5 4.05E-10 5.05E-11 S.09E-11 1.11 E-10 3.2BE-10 1.64E-09

10. 1.30E-10 5.05E-11 5.12E-11 1.11E-10 1.42E-10 5.27E-10 Table A -Ig 1 Mean an dfracfII e . . hazard curves seismic ~or 0 5 Hza t TMI I 5'*00f cnI lcaI da mping AMPS(g) MEAN 0.05 0.1S 0.50 0.B4 0.95 0.0005 1.B4E-02 9.24E-03 1.29E-02 1.79E-02 2.39E-02 2.BBE-02 0.001 1.12E-02 4.B3E-03 7.13E-03 1.07E-02 1.51 E-02 1.90E-02 0.005 2.29E-03 4.70E-04 B.B5E-04 1.92E-03 3.SBE-03 5.42E-03 0.01 B.27E-04 1.13E-04 2.35E-04 S.09E-04 1.40E-03 2.35E-03 0.015 4.02E-04 4.43E-05 9.51E-05 2.SBE-04 S.93E-04 1.25E-03 0.03 9.S2E-05 7.77E-OS 1.74E-05 5.50E-05 1.S9E-04 3.2BE-04 0.05 3.05E-05 1.9BE-OS 4.5SE-OS 1.53E-05 5.50E-05 1.11E-04 0.075 1.22E-05 S.45E-07 1.55E-OS 5.5BE-OS 2.1SE-05 4.70E-05 0.1 S.52E-OS 2.BOE-07 7.13E-07 2.72E-OS 1.11E-05 2.64E-05 0.15 2.7SE-OS B.12E-OB 2.35E-07 9.93E-07 4.50E-OS 1.21 E-05 0.3 S.55E-07 7.B9E-09 2.9SE-OB 1.S7E-07 9.37E-07 3.19E-OS 0.5 2.20E-07 1.15E-09 5.27E-09 3.B4E-OB 2.BOE-07 1.13E-OS 0.75 B.B2E-OB 2.57E-10 1.1BE-09 1.04E-OB 9.S5E-OB 4.S3E-07

1. 4.45E-OB 1.23E-10 3.95E-10 3.79E-09 4.25E-OB 2.32E-07 1.5 1.S0E-OB 7.45E-11 1.27E-10 B.35E-10 1.1SE-OB 7.B9E-OB

3. 2.24E-09 5.05E-11 S.09E-11 1.1SE-10 9.93E-10 9.37E-09

5. 4.29E-10 5.05E-11 5.35E-11 1.11E-10 1.77E-10 1.49E-09 7.5 1.00E-10 5.05E-11 5.05E-11 1.01E-10 1.11 E-10 3.2BE-10

10. 3.2BE-11 5.05E-11 5.05E-11 1.01 E-10 1.11 E-10 1.51 E-1 0 Three Mile Island Nudear Station A-4 Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

Table A-2 Amolification functions for TMI. S% of critical d ---- ---

Median Sigma Median Sigma Median Sigma Median Sigma PGA 2S Hz 10 Hz SHz AF In(AF) AF In (AF) AF In(AF) AF In(AF) 1.00E-02 1.1BE+00 4.0BE-02 1.30E-02 1.02E+00 4.B1E-02 1.90E-02 1.13E+00 B.B4E-02 2.09E-02 1.2BE+00 9.44E-02 4.9SE-02 9.B3E-01 S.22E-02 1.02E-01 7.S9E-01 9.S4E-02 9.99E-02 1.0BE+00 1.0SE-01 B.24E-02 1.26E+00 9.BBE-02 9.64E-02 9.13E-01 S.6SE-02 2.13E-01 7.13E-01 1.07E-01 1.BSE-01 1.07E+00 1.0BE-01 1.44E-01 1.2SE+00 9.99E-02 1.94E-01 B.S6E-01 6.0BE-02 4.43E-01 6.77E-01 1.1SE-01 3.S6E-01 1.04E+00 1.11E-01 2.6SE-01 1.23E+00 1.02E-01 2.92E-01 B.26E-01 6.33E-02 6.76E-01 6.S7E-01 1.19E-01 S.23E-01 1.03E+00 1.13E-01 3.B4E-01 1.22E+00 1.03E-01 3.91E-01 B.OSE-01 6.S1E-02 9.09E-01 6.41E-01 1.21E-01 6.90E-01 1.01E+00 1.1SE-01 5.02E-01 1.21E+00 1.D4E-01  !

4.93E-01 7.B9E-01 6.64E-02 1.1SE+00 6.29E-01 1.23E-01 B.61E-01 1.00E+00 1.16E-01 6.22E-01 1.20E+00 1.0SE-01 7.41E-01 7.61E-01 6.B2E-02 1.73E+00 6.0SE-01 1.26E-01 1.27E+00 9.74E-01 1.17E-01 9.13E-01 1.19E+00 1.07E-01 1.01E+00 7.40E-01 6.96E-02 2.36E+00 S.B6E-01 1.29E-01 1.72E+00 9.S2E-01 1.1BE-01 1.22E+00 1.17E+00 1.0BE-01 1.2BE+00 7.24E-01 7.03E-02 3.01E+00 S.70E-01 1.31E-01 2.17E+00 9.31E-01 1.1BE-01 1.54E+00 1.16E+00 1.10E-01 1.SSE+00 7.10E-01 7.0BE-02 3.63E+00 S.S7E-01 1.32E-01 2.61E+00 9.14E-01 1.19E-01 1.BSE+00 1.14E+00 1.11 E-01 Median Sigma Median Sigma Median Sigma 2.S Hz 1 Hz O.S Hz AF In(AF) AF In(AF) AF In(AF) 2.1BE-02 1.20E+00 B.27E-02 1.27E-02 1.4BE+00 9.94E-02 B.2SE-03 1.41E+00 9.S1E-02 7.0SE-02 1.19E+00 B.34E-02 3.43E-02 1.47E+00 9.67E-02 1.96E-02 1.40E+00 9.1BE-02 1.1BE-01 1.1BE+00 B.39E-02 S.S1E-02 1.46E+00 9.S6E-02 3.02E-02 1.40E+00 9.07E-02 2.12E-01 1.1BE+00 B.49E-02 9.63E-02 1.46E+00 9.47E-02 S.11E-02 1.40E+00 9.00E-02 3.04E-01 1.17E+00 B.S7E-02 1.36E-01 1.46E+00 9.4SE-02 7.10E-02 1.40E+00 B.97E-02 3.94E-01 1.17E+00 B.62E-02 1.7SE-01 1.47E+00 9.4SE-02 9.06E-02 1.40E+00 B.97E-02 4.B6E-01 1.17E+00 B.67E-02 2.14E-01 1.47E+00 9.46E-02 1.10E-01 1.40E+00 B.97E-02 7.09E-01 1.16E+00 B.73E-02 3.10E-01 1.47E+00 9.S1E-02 1.5BE-01 1.41E+00 B.9BE-02 9.47E-01 1.16E+00 B.B1E-02 4.12E-01 1.4BE+00 9.S4E-02 2.09E-01 1.41E+00 9.01E-02 1.19E+00 1.1SE+00 B.90E-02 S.1BE-01 1.4BE+00 9.SBE-02 2.62E-01 1.41E+00 9.0SE-02 1.43E+00 1.1SE+00 9.0SE-02 6.19E-01 1.4BE+00 9.S9E-02 3.12E-01 1.41E+00 9.14E-02 Three Mile Island Nuclear Station A-S Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

Tables A2-b1 and A2-b2 are tabular versions of the typical amplification factors provided in Figures 2.3.6-1 and 2.3.6-2. Values are provided for two input motion levels at approximately 1E-4 and 1E-5 mean annual frequency of exceedance. These tables concentrate on the frequency range of 0.5 Hz to 25 Hz, with values up to 100 Hz included, and a single value at 0.1 Hz included for completeness. These factors are unverified and are provided for information only. The figures should be considered the governing information.

Three Mile Island Nuclear Station A-6 Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

Ta bl e A2 b1 Melan d* AF san d* sigmas for Mode I 1 ProfilIe 1 f or 2 PGA Ieves I I M1P1K1 Rock PGA=0.194 M1P1K1 PGA=0.741 Freq Median Sigma Freq Median Sigma Soil SA Soil SA (Hz) AF In(AF) (Hz) AF In(AFJ 100.0 0.169 0.869 0.066 100.0 0.532 0.719 0.082 87.1 0.170 0.853 0.067 87.1 0.535 0.700 0.083 75.9 0.171 0.824 0.068 75.9 0.539 0.666 0.084 66.1 0.174 0.769 0.069 66.1 0.546 0.605 0.087 57.5 0.181 0.681 0.074 57.5 0.560 0.515 0.093 50.1 0.192 0.601 0.085 50.1 0.587 0.442 0.105 43.7 0.208 0.551 0.101 43.7 0.624 0.397 0.122 38.0 0.228 0.549 0.105 38.0 0.673 0.395 0.133 33.1 0.248 0.564 0.105 33.1 0.728 0.411 0.132 28.8 0.269 0.611 0.121 28.8 0.791 0.453 0.145 25.1 0.289 0.652 0.136 25.1 0.856 0.493 0.158 21.9 0.307 0.727 0.137 21.9 0.912 0.561 0.161 19.1 0.329 0.788 0.132 19.1 0.978 0.619 0.162 16.6 0.350 0.874 0.131 16.6 1.051 0.702 0.158 14.5 0.361 0.943 0.124 14.5 1.110 0.785 0.151 12.6 0.371 0.994 0.110 12.6 1.145 0.842 0.130 11 .0 0.374 1.026 0.112 11.0 1.170 0.891 0.124 9.5 0.371 1.066 0.125 9.5 1.164 0.937 0.132 8.3 0.369 1.151 0.126 8.3 1.157 1.019 0.138 7.2 0.368 1.223 0.109 7.2 1.164 1.103 0.120 6.3 0.362 1.282 0.090 6.3 1.173 1.192 0.106 5.5 0.349 1.291 0.095 5.5 1.135 1.217 0.100 4.8 0.331 1.252 0.101 4.8 1.069 1.179 0.111 4 .2 0.315 1.228 0.082 4.2 1.025 1.173 0.093 3.6 0.299 1.199 0.073 3.6 0.980 1.160 0.080 3.2 0.282 1.199 0.090 3.2 0.927 1.171 0.083 2.8 0.265 1.188 0.098 2.8 0.885 1.184 0.100 2.4 0.252 1.224 0.068 2.4 0.845 1.231 0.076 2.1 0.233 1.246 0.079 2.1 0.787 1.266 0.088 1.8 0.221 1.319 0.077 1.8 0.744 1.345 0.072 1.6 0.198 1.361 0.098 1.6 0.663 1.389 0.099 1.4 0.185 1.478 0.074 1.4 0.615 1.505 0.070 1.2 0.163 1.481 0.081 1.2 0.539 1.506 0.080 1.0 0.146 1.469 0.100 1.0 0.478 1.489 0.100 0.91 0.135 1.492 0.076 0.91 0.437 1.507 0.074 0.79 0.120 1.471 0.095 0.79 0.386 1.483 0.092 0.69 0.103 1.416 0.076 0.69 0.328 1.426 0.076 0.60 0.091 *1.431 0.071 0.60 0.286 1.438 0.071 0.52 0.078 1.449 0.075 0.52 0.245 1.455 0.075 0.46 0.065 1.429 0.058 0.46 0.200 1.433 0.059 0.10 0.003 1.346 0.037 0.10 0.008 1.337 0.039 Three Mile Island Nuclear Station A-7 Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073. TMI-14-026

Ta bl e A2 b2 Melan d' AF san d'sigmas f or Mode I 2, ProfilIe 1, for 2 PGA Ieves M2P1K1 PGA=0.194 M2P1K1 PGA=0.741 Freq Median Sigma Freq Median Sigma Soil SA Soil SA (Hz) AF In(AF) (Hz) AF In(AF) 100.0 0.179 0.925 0.050 100.0 0.646 0.872 0.053 87.1 0.181 0.909 0.050 87.1 0.652 0.853 0.053 75.9 0.183 0.880 0.050 75.9 0.662 0.818 0.053 66.1 0.187 0.825 0.050 66.1 0.681 0.754 0.053 57.5 0.195 0.737 0.050 57.5 0.720 0.661 0.054 50.1 0.210 0.659 0.054 50.1 0.789 0.594 0.061 43.7 0.232 0.615 0.067 43.7 0.886 0.564 0.077 38.0 0.257 0.620 0.070 38.0 0.995 0.584 0.079 33.1 0.281 0.640 0.081 33.1 1.087 0.613 0.089 28.8 0.303 0.690 0.110 28.8 1.168 0.669 0.119 25.1 0.325 0.733 0.131 25.1 1.241 0.716 0.139 21.9 0.342 0.811 0.126 21.9 1.295 0.797 0.132 19.1 0.365 0.875 0.111 19.1 1.367 0.865 0.115 16.6 0.385 0.961 0.119 16.6 1.429 0.955 0.122 14.5 0.393 1.024 0.113 14.5 1.440 1.019 0.116 12.6 0.399 1.070 0.103 12.6 1.448 1.065 0.104 11 .0 0.400 1.100 0.109 11 .0 1.439 1.096 0.110 9.5 0.395 1.135 0.120 9.5 1.406 1.131 0.121 8.3 0.391 1.218 0.114 8.3 1.379 1.214 0.115 7.2 0.386 1.283 0.101 7.2 1.350 1.280 0.101 6.3 0.376 1.331 0.081 6.3 1.306 1.328 0.081 5.5 0.360 1.334 0.092 5.5 1.242 1.332 0.092 4.8 0.342 1.293 0.100 4.8 1.170 1.290 0.100 4.2 0.323 1.258 0.078 4.2 1.098 1.256 0.078 3.6 0.305 1.222 0.075 3.6 1.031 1.220 0.075 3.2 0.285 1.214 0.089 3.2 0.960 1.212 0.088 2.8 0.267 1.196 0.096 2.8 0.893 1.194 0.095 2.4 0.253 1.228 0.062 2.4 0.842 1.226 0.062 2.1 0.233 1.245 0.073 2.1 0.773 1.243 0.072 1.8 0.221 1.318 0.078 1.8 0.728 1.315 0.078 1.6 0.197 1.357 0.096 1.6 0.647 1.355 0.095 1.4 0.184 1.474 0.076 1.4 0.601 1.470 0.075 1.2 0.163 1.477 0.081 1.2 0.527 1.473 0.080 1.0 0.146 1.466 0.100 1.0 0.469 1.462 0.099 0.91 0.135 1.490 0.077 0.91 0.431 1.485 0.076 0.79 0.120 1.469 0.095 0.79 0.382 1.465 0.094 0.69 0.103 1.415 0.076 0.69 0.325 1.412 0.075 0.60 0.091 1.430 0.071 0.60 0.284 1.427 0.070 0.52 0.078 1.448 0.075 0.52 0.243 1.445 0.074 0.46 0.065 1.428 0.058 0.46 0.199 1.426 0.058 0.10 0.003 1.347 0.037 0.10 0.008 1.334 0.040 Three Mile Island Nudear Station A-8 Report Number: EXLNTM039-PR-001, Revision 1 Correspondence No.: RS-14-073, TMI-14-026

Enclosure 2

SUMMARY

OF REGULATORY COMMITMENTS The following table identifies commitments made in this document. (Any other actions discussed in the submittal represent intended or planned actions. They are described to the NRC for the NRC's information and are not regulatory commitments.)

COMMITMENT TYPE COMMITTED COMMITMENT DATE OR ONE-TIME ACTION PROGRAMMATIC "OUTAGE" (Yes/No) (Yes/No)

1. Three Mile Island Nuclear Station, Unit 1, will As determined by Yes No perform a Risk Evaluation including a High NRC prioritization Frequency Confirmation evaluation. following submittal of all nuclear power plant Seismic Hazard Re-evaluations, but no later than December 31 ,

2019.

2. Three Mile Island Nuclear Station, Unit 1, will As determined by Yes No perform a Spent Fuel Pool evaluation in NRC prioritization accordance with EPRI Report 1025287, following submittal Section 7. of all nuclear power plant Seismic Hazard Re-evaluations, but no later than December 31, 2019.

3. Three Mile Island Nuclear Station, Unit 1, will December 31 , Yes No prepare an Expedited Seismic Evaluation 2014 Process (ESEP) Report in accordance with EPRI Report 3002000704.