UNITED STATES 

NUCLEAR REGULATORY COMMISSION 

WASHINGTON, D.C. 20555-0001 

Vice President, Operations 

Entergy Nuclear Operations, Inc. 

Palisades Nuclear Plant 

27780 Blue Star Memorial Highway 

Covert, Ml 49043-9530 

April 30, 2015 

SUBJECT: PALISADES NUCLEAR PLANT- STAFF ASSESSMENT OF INFORMATION 

PROVIDED PURSUANT TO TITLE 10 OF THE CODE OF FEDERAL 

REGULATIONS PART 50, SECTION 50.54(f), SEISMIC HAZARD 

REEVALUATIONS RELATING TO RECOMMENDATION 2.1 OF 

THE NEAR-TERM TASK FORCE REVIEW OF INSIGHTS FROM THE 

FUKUSHIMA DAl-ICHI ACCIDENT (TAC NO. MF3786) 

Dear Sir or Madam: 

By letter dated March 12, 2012, the U.S. Nuclear Regulatory Commission (NRC) issued a request 

for information pursuant to Title 10 of the Code of Federal Regulations, Part 50, Section 50.54(f) 

(hereafter referred to as the 50.54(f) letter). The purpose of that request was to gather information 

concerning, in part, seismic hazards at each operating reactor site and to enable the NRC staff, 

using present-day NRC requirements and guidance, to determine whether licenses should be 

modified, suspended, or revoked. 

By letter dated March 31, 2014, Entergy Nuclear Operations, Inc. (Entergy) responded to this 

request for Palisades Nuclear Plant (Palisades). 

The NRC staff has reviewed the information provided related to the reevaluated seismic hazards 

for Palisades and, as documented in the enclosed staff assessment, determined that you 

provided sufficient information in response to Requested Information Items (1) - (3), (5), (7), and 

a partial response to Item (4), identified in Enclosure 1 of the 50.54(f) letter. Further, the staff 

concludes that Entergy's reevaluated seismic hazard for Palisades is suitable for other activities 

associated with the NRC Near-Term Task Force Recommendation 2.1, "Seismic." 

Contingent upon the NRC's review and acceptance of Entergy's expedited seismic evaluation 

process, and seismic risk evaluation including the high frequency and spent fuel pool evaluations 

(i.e., Items (4), (6), (8), and (9)) for Palisades, the sesimc hazard evaluation identified in 

Enclosure 1 of the 50.54(f) letter will be complete. 
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If you have any questions, please contact me at (301) 415-6197 or via e-mail at 

Tekia.Govan@nrc.gov. 

Docket No. 50-255 

Enclosure: 

Staff Assessment of Seismic 

Hazard Evaluation and Screening Report 

cc w/encl: Distribution via Listserv 

Sincerely, 

JL~v>Bw~ Tekia Govan, Project Manager 

Hazards Management Branch 

Japan Lessons-Learned Division 

Office of Nuclear Reactor Regulation 
STAFF ASSESSMENT BY THE OFFICE OF NUCLEAR REACTOR REGULATION 

RELATED TO SEISMIC HAZARD AND SCREENING REPORT 

PALISADES NUCLEAR PLANT 

DOCKET NO. 50-255 

1.0 INTRODUCTION 

By letter dated March 12, 2012 (NRG, 2012a), the U.S. Nuclear Regulatory Commission (NRG or 

Commission) issued a request for information to all power reactor licensees and holders of 

construction permits in active or deferred status, pursuant to Title 1 O of the Code of Federal 

Regulations (10 CFR), Section 50.54(f) "Conditions of license" (hereafter referred to as the 

"50.54(f) letter''). The request and other regulatory actions were issued in connection with 

implementing lessons-learned from the 2011 accident at the Fukushima Dai-ichi nuclear power 

plant, as documented in the "Near-Term Task Force Review of Insights from the Fukushima 

Dai-ichi Accident" (NRG, 2011 b). 1 In particular, the NRG Near-Term Task Force (NTTF) 

Recommendation 2.1, and subsequent Staff Requirements Memoranda (SRM) associated with 

Commission Papers SECY-11-0124 (NRG, 2011c) and SECY-11-0137 (NRG, 2011d), instructed 

the NRG staff to issue requests for information to licensees pursuant to 1 O CFR 50.54(f). 

Enclosure 1 to the 50.54(f) letter requests that addressees perform a reevaluation of the seismic 

hazards at their sites using present-day NRG requirements and guidance to develop a ground 

motion response spectrum (GMRS). 

The required response section of Enclosure 1 requests that each addressee provide the following 

information: 

(1) Site-specific hazard curves (common fractiles and mean) over a range of spectral 

frequencies and annual exceedance frequencies, 

(2) Site-specific, performance-based GMRS developed from the new site-specific seismic 

hazard curves at the control point elevation, 

(3) Safe Shutdown Earthquake (SSE) ground motion values including specification of the 

control point elevation, 

1 Issued as an enclosure to Commission Paper SECY-11-0093 (NRC, 2011 a). 

Enclosure 
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(4) Comparison of the GMRS and SSE (If the GMRS is completely bounded by the SSE, an 

interim action plan or risk evaluation is not necessary. However if the GMRS exceeds the 

SSE only at higher frequencies, information related to the functionality of high-frequency 

sensitive SSCs is requested), 

(5) Additional information such as insights from NTTF Recommendation 2.3 walkdown and 

estimates of plant seismic capacity developed from previous risk assessments to inform 

NRC screening and prioritization, 

(6) 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 (if 

necessary), 

(7) Statement if a seismic risk evaluation is necessary, 

(8) Seismic risk evaluation (if necessary), and 

(9) Spent fuel pool (SFP) evaluation (if necessary). 

Present-day NRC requirements and guidance with respect to characterizing seismic hazards use 

a probabilistic approach in order to develop a risk-informed performance-based GMRS for the 

site. Regulatory Guide (RG) 1.208, "A Performance-based Approach to Define the Site-Specific 

Earthquake Ground Motion," describes this approach. As described in the 50.54(f) letter, if the 

reevaluated seismic hazard, as characterized by the GMRS, is not bounded by the current plant 

design-basis SSE, further seismic risk evaluation of the plant is merited. 

By letter dated November 27, 2012 (Keithline, 2012), the Nuclear Energy Institute (NEI} submitted 

Electric Power Research Institute (EPRI) report "Seismic Evaluation Guidance: Screening, 

Prioritization, and Implementation Details (SPID) for the Resolution of Fukushima Near-Term 

Task Force Recommendation 2.1 Seismic" (EPRI, 2012), hereafter referred to as the SPID. The 

SPID supplements the 50.54(f) letter with guidance necessary to perform seismic reevaluations 

and report the results to NRC in a manner that will address the Requested Information Items in 

Enclosure 1 of the 50.54(f) letter. By letter dated February 15, 2013 (NRC, 2013b), the staff 

endorsed the SPID. 

The required response section of Enclosure 1 to the 50.54(f) letter specifies that Central and 

Eastern United States (CEUS) licensees provide their Seismic Hazard and Screening Report 

(SHSR) by 1.5 years after issuance of the 50.54(f) letter. However, in order to complete its update 

of the EPRI seismic ground motion models (GMM) for the CEUS (EPRI, 2013), industry proposed 

a six-month extension to March 31, 2014, for submitting the SHSR. Industry also proposed that 

licensees perform an expedited assessment, referred to as the Augmented Approach, for 

addressing the requested interim evaluation (Item 6 above), which would use a simplified 

assessment to demonstrate that certain key pieces of plant equipment for core cooling and 

containment functions, given a loss of all alternating current power, would be able to withstand a 

seismic hazard up to two times the design basis. Attachment 2 to the April 9, 2013, letter 

(Pietrangelo, 2013) provides a revised schedule for plants needing to perform (1) the Augmented 

Approach by implementing the Expedited Seismic Evaluation Process (ESEP) and (2) a seismic 
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risk evaluation. By letter dated May 7, 2013 (NRC, 2013a), the NRC determined that the modified 

schedule was acceptable and by letter dated August 28, 2013 (NRC, 2013c), the NRC 

determined that the updated GMM (EPRI, 2013) is an acceptable GMMfor use by CEUS plants in 

developing a plant-specific GMRS. 

By letter dated April 9, 2013 (Pietrangelo, 2013), industry agreed to follow the SPID to develop the 

SHSR for existing nuclear power plants. By letter dated September 11, 2013 (Vitale, 2013), 

Entergy Nuclear Operations, Inc. (the licensee, Entergy) submitted at least partial site response 

information for Palisades Nuclear Plant (Palisades). By letter dated March 31, 2014 (Vitale, 

2014), the licensee submitted its SHSR. 

2.0 REGULATORY EVALUATION 

The structures, systems, and components (SSCs) important to safety in operating nuclear power 

plants are designed either in accordance with, or meet the intent of Appendix A to 1 O CFR Part 50, 

General Design Criteria (GDC) 2: "Design Bases for Protection Against Natural Phenomena;" and 

Appendix A to 10 CFR Part 100, "Reactor Site Criteria." GDC 2 states that SSCs important to 

safety at nuclear power plants shall be designed to withstand the effects of natural phenomena 

such as earthquakes, tornadoes, hurricanes, floods, tsunami, and seiches without loss of 

capability to perform their safety functions. 

For initial licensing, each licensee was required to develop and maintain design bases that, as 

defined by 10 CFR 50.2, identify the specific functions that an SSC of a facility must perform, and 

the specific values or ranges of values chosen for controlling parameters as reference bounds for 

the design. The design bases for the SSCs reflect appropriate consideration of the most severe 

natural phenomena that had been historically reported for the site and surrounding area. The 

design bases also considered limited accuracy, quantity, and period of time in which the historical 

data have been accumulated. 

The seismic design bases for currently operating nuclear power plants were either developed in 

accordance with, or meet the intent of GDC 2 and 10 CFR Part 100, Appendix A. Although the 

regulatory requirements in Appendix A to 1 O CFR Part 100 are fundamentally deterministic, the 

NRC process for determining the seismic design-basis ground motions for new reactor 

applications after January 10, 1997, as described in 10 CFR 100.23, requires that uncertainties 

be addressed through an appropriate analysis such as a probabilistic seismic hazard analysis 

(PSHA). 

The Palisades design bases was developed in accordance with accepted industry practices that 

existed at the time when their construction permit was issued in 1967. The licensee at that time 

performed an evaluation of their design bases against the draft proposed "General Design Criteria 

for Nuclear Power Plant Construction Permits" issued by the Atomic Energy Commission in July 

1967. The design bases was later evaluated against the final "General Design Criteria for Nuclear 

Power Plants," published as 1 O CFR 50, Appendix A in July 1971. It was determined that the the 

design bases for Palisades meets the intent of GDC 2 and is consistent with 10 CFR Part 100. 

Section 50.54(f) of 10 CFR states that a licensee shall at any time before expiration of its license, 

upon request of the Commission, submit written statements, signed under oath or affirmation, to 
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enable the Commission to determine whether or not the license should be modified, suspended, 

or revoked. On March 12, 2012, the NRC staff issued requests for licensees to reevaluate the 

seismic hazards at their sites using present-day NRC requirements and guidance, and identify 

actions planned to address plant-specific vulnerabilities associated with the updated seismic 

hazards. 

Attachment 1 to Enclosure 1 of the 50.54(f) letter described an acceptable approach for 

performing the seismic hazard reevaluation for plants located in the CEUS. Licensees are 

expected to use the CEUS Seismic Source Characterization (CEUS-SSC) model in 

NUREG-2115 (NRC, 2012b) along with the appropriate EPRI (2004, 2006) GMM. The SPID 

provided further guidance regarding the appropriate use of GMMs for the CEUS. Specifically, 

Section 2.3 of the SPID recommended the use of the updated GMM (EPRI, 2013) and, as such, 

licensees used the NRG-endorsed updated EPRI GMM instead of the older EPRI (2004, 2006) 

GMM to develop PSHA base rock hazard curves. Finally, Attachment 1 requested that licensees 

conduct an evaluation of the local site response in order to develop site-specific hazard curves 

and GMRS for comparison with the plant SSE. 

2.1 Screening Evaluation Results 

By letter dated March 31, 2014 (Vitale, 2014), the licensee provided the SHSR for Palisades. The 

licensee's SHSR indicated that the plant GMRS exceeded the SSE. The licensee stated that a 

seismic risk evaluation will be performed. Also, a SFP evaluation will be performed. Additionally, 

due to exceedances at frequencies above 10 Hertz (Hz), the licensee indicated that a 

high-frequency confirmation will be performed. 

On May 9, 2014 (NRC, 2014), the staff issued a letter providing the outcome of its 30-day 

screening and prioritization evaluation. As indicated in the letter, the staff confirmed the 

licensee's screening results. The GMRS exceeds the SSE in the frequency range of 1 to 1 O Hz. 

Therefore, Palisades screened in for conducting a plant seismic risk evaluation. A SFP 

evaluation is also merited. Additionally, the staff confirmed the licensee's conclusion that a 

high-frequency confirmation for Palisades is merited because the GMRS exceeds the SSE above 

10 Hz. 

3.0 TECHNICAL EVALUATION 

The NRC staff evaluated the licensee's submittal to determine if the provided information 

responded appropriately to Enclosure 1 of the 50.54(f) letter with respect to characterizing the 

reevaluated seismic hazard. 

3.1 Plant Seismic Design-Basis 

Enclosure 1 of the 50.54(f) letter requested the licensee provide the SSE ground motion values, 

as well as the specification of the control point elevation(s) for comparison to the GMRS. For 

operating reactors licensed before 1997, the SSE is the plant licensing basis ground motion and is 

characterized by 1) a peak ground acceleration (PGA) value which anchors the response spectra 

at high frequencies (typically at 33 Hz for the existing fleet of Nuclear Power Plants); 2) a 
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response spectrum shape which depicts the amplified response at all frequencies below the PGA; 

and 3) a control point where the SSE is defined. 

In Section 3.1 of the SHSR, the licensee described its seismic design-basis for Palisades. The 

licensee stated that the design-basis of Palisades was determined by considering the maximum 

earthquake potential for the region surrounding the site. The response spectrum for Palisades is 

anchored at 0.2 g (20 percent the acceleration of earth's gravity) with a spectral shape referred to 

as the Housner spectrum, which represents the average of several observed earthquake spectra 

that have been normalized to the same PGA and enveloped to produce a smooth spectrum. The 

licensee specified that the control point is located at the plant grade elevation which corresponds 

to 589 ft (180 m) above mean sea level at the reactor building. 

Based on the review of the licensee's submittal and the updated final safety analysis report 

(UFSAR), the staff confirms that the licensee's SSE control point elevation determination is 

consistent with information provided in the Palisades UFSAR, as well as guidance in the SPID. 

3.2 Probabilistic Seismic Hazard Analysis 

In Section 2.2 of the SHSR, the licensee stated that, in accordance with the 50.54(f) letter and the 

SPID, it performed a PSHA using the CEUS-SSC model and the updated EPRI GMM for the 

CEUS (EPRI, 2013). The licensee used a minimum magnitude cutoff of M5.0, as specified in the 

50.54(f) letter. The licensee further stated that it included the CEUS-SSC background sources 

out to a distance of 400 mi (640 km) around the site and included the Commerce, Eastern Rift 

Margin-North, Eastern Rift Margin-South, Marianna, New Madrid Fault System, and Wabash 

Valley Repeated Large Magnitude Earthquake (RLME) sources, which lie within 620 mi 

(1,000 km) of Palisades. The RLME sources are those source areas or faults for which more than 

one large magnitude (M ~ 6.5) earthquake has occurred in the historical or paleo-earthquake 

(geologic evidence for prehistoric seismicity) record. The licensee used the mid-continent version 

of the updated EPRI GMM for each of the CEUS-SSC sources. Consistent with the SPID, the 

licensee did not provide its base rock seismic hazard curves since a site response analysis is 

necessary to determine the control point seismic hazard curves. The licensee provided its control 

point seismic hazard curves in Section 2.3.7 of the SHSR. The staff's review of the licensee's 

control point seismic hazard curves is provided in Section 3.3 of this staff assessment. 

As part of its confirmatory analysis of the licensee's GMRS, the staff performed PSHA 

calculations for base rock site conditions at the Palisades site. As input, the staff used the 

CEUS-SSC model as documented in NUREG-2115 (NRC, 2012b) along with the updated EPRI 

GMM (EPRI, 2013). Consistent with the guidance provided in the SPID, and the licensee's 

approach, the staff included all CEUS-SSC background seismic sources within a 310 mi (500 km) 

radius of the Palisades site. In addition, the staff included the Commerce, Eastern Rift 

Margin-North, Eastern Rift Margin-South, New Madrid Fault System, and Wabash Valley RLME 

sources, which lie within 620 km (1,000 mi) of the Palisades site. For each of the CEUS-SSC 

sources used in the PSHA, the staff used the mid-continent version of the updated EPRI GMM. 

Based on its review of the SHSR, the staff concludes that the licensee appropriately followed the 

guidance provided in the SPID for selecting the PSHA input models and parameters for the site. 
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This includes the licensee's use and implementation of the CEUS-SSC model and the updated 

EPRI GMM. 

3.3 Site Response Evaluation 

After completing PSHA calculations for reference rock conditions, Attachment 1 to Enclosure 1 of 

the 50.54(f) letter requests that licensees provide a GMRS developed from the site-specific 

seismic hazard curves at the control point elevation. In addition, the 50.54(f) letter specifies that 

the subsurface site response model, for both soil and rock sites, should extend to sufficient depth 

to reach the generic or base rock conditions as defined in the GMMs used in the PSHA. To 

develop site-specific hazard curves at the control point elevation, Attachment 1 requests that 

licensees perform a site response analysis. 

Detailed site response analyses were not typically performed for many of the older operating 

plants; therefore, Appendix B of the SPID provides detailed guidance on the development of 

site-specific amplification factors (including the treatment of uncertainty) for sites that do not have 

detailed, measured soil and rock parameters to extensive depths. 

The purpose of the site response analysis is to determine the site amplification that would occur 

as a result of bedrock ground motions propagating upwards through the soil/rock column to the 

surface. The critical parameters that determine what frequencies of ground motion are affected 

by the upward propagation of bedrock motions are the layering of soil and/or soft rock, the 

thicknesses of these layers, the shear-wave velocities and low-strain damping of these layers, 

and the degree to which the shear modulus and damping change with increasing input bedrock 

amplitude. To develop site-specific hazard curves at the control point, the licensee performed a 

site response analysis. 

3.3.1 Site Base Case Profiles 

In its SHSR, the licensee indicated that it performed a site response analysis for Palisades. 

According to the licensee, the current site grade exists at approximately elevation 589 ft (180 m) 

and rests on dense to very dense dune sand which extends approximately 25 ft ( m) deep. Below 

this is approximately 23 ft (7 m) of grey, fine-grained silty sand and 22 ft (7 m) of grey, stiff clay 

overlying 78 ft (24 m) of glacial till. Below these surficial deposits is the Mississippian Age (359 -

318 Ma) Coldwater Shale. According to the licensee, Precambrian crystalline rock lies at an 

approximate depth of 3,238 ft (987 m). 

The licensee provided site profile descriptions in Sections 2.3.1 and 2.3.2 of its SHSR based on 

information in the Palisades UFSAR (Entergy, 2012). The licensee stated that the site is 

underlain by approximately 25 ft (8 m) of very dense dune sand overlying 23 ft (7 m) of silty sand, 

22 ft (7 m) of gray, stiff clay and 78 ft (24 m) of glacial till. Bedrock at the site, which underlies 

these surficial soils, is the Mississippian Age (359 - 318 Ma) Coldwater Shale. According to the 

licensee, Precambrian crystalline rock lies at an approximate depth of 3,238 ft (987 m) below the 

surface. 

Due to the limited geophysical data that was collected at the site during initial construction, the 

licensee used compressional-wave measurements and an assumed Poisson ratio (a measure of 
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compressional- to shear-wave velocity ratio) to estimate the shear-wave velocities of the site. 

The licensee used the shear-wave velocity estimates, along with guidance provided in the SPID, 

to develop two best-estimate profiles. For the first best-estimate profile, the licensee assumed 

that reference rock, defined by a shear-wave velocity of 9,285 ft/s (2,830 m/s), occurs at a depth 

of 148 ft (45 m) below the control point, at the top of the sedimentary rock section. The licensee 

based the second best-estimate profile on the assumption that the entire sedimentary section 

could be modeled with a shear wave velocity of 5,000 ft/s (1,424 m/s) with reference rock 

occurring at the top of the Precambrian crystalline rock. For both best-estimate profiles, the 

licensee developed upper and lower base case profiles using a natural log standard deviation of 

0.35, following guidance in the SPID. This approach to developing base case profiles results in 

six profiles, rather than the three recommended in the SPID. The licensee justified this approach 

by stating that the lack of geophysical data from the sedimentary rocks beneath the site meant 

that additional epistemic uncertainty in the depth to reference rock was necessary. 

Because the seismic velocities of the site are different from the generic reference rock velocity 

used in the PSHA, a site-specific model of shear modulus degradation and damping is required. 

However, the licensee stated that no site-specific dynamic material properties were determined 

during the initial investigations of the Palisades site. Therefore, the licensee selected two 

alternative characterizations of dynamic material behavior following guidance provided in the 

SPID for each best-estimate profile and associated upper and lower base case models. 

For the best-estimate shear wave velocity model in which reference rock conditions occur at the 

top of the sedimentary rock section, the licensee considered two alternatives for non-linear 

dynamic material properties. The licensee used the EPRI model for cohesionless soils for one 

model and the Peninsular Range dynamic material curves for the other model. The licensee 

weighted these alternatives equally, assigning 50 percent to each case. For the best-estimate 

profile with reference rock conditions at greater depth, the licensee used the same dynamic 

material properties for the soil portion of the site. For the upper 352 ft (107 m) of rock, the licensee 

assumed that the rock material could be modeled as either behaving linearly or non-linearly. To 

model the potential non-linear dynamic material properties, the licensee used the EPRI rock 

dynamic material curves. To model the linear behavior over the upper 352 ft (107 m) of rock, the 

licensee used the low strain damping values (approximately 3 percent) from the EPRI rock curves 

for each of the rock layers. The licensee weighted these alternatives material behaviors equally, 

assigning 50 percent to each case. 

The licensee also considered the impact of kappa, or small strain damping, on site response. 

Kappa is measured in units of seconds (sec), and is the damping contributed by both intrinsic 

hysteretic damping as well as scattering due to wave propagation in heterogeneous material. The 

licensee calculated kappa for each profile independently, resulting in six kappa estimates. For the 

set of profiles with reference rock located at the top of the sedimentary rock section, the licensee 

used the low strain damping values from the EPRI soil damping curves (approximately 3 percent) 

over the 148 ft (45 m) of the soil profile. The licensee also added an additional kappa of 0.006 sec 

to account for the damping in the underlying reference rock material. For the best-estimate profile 

in which reference rock conditions located at the base of the sedimentary rock section, the 

licensee used the low strain damping values from the EPRI cohesionless soil damping curves 

over the upper 148 ft (45 m) to calculate the kappa contribution from the soil. The licensee used 

the low strain damping values from the EPRI rock curves (approximately 3 percent) over the 
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upper 352 ft (107 m) of rock material and assumed a damping value of 1.25 percent over the 

remainder of the profile. In addition to considering the kappa contribution from the soil and 

sedimentary rocks underlying the site, the licensee added an additional 0.006 sec to account for 

damping in the reference rock material. Kappa values for the profiles with reference rock located 

at the top of the sedimentary section were 0.009, 0.008, and 0.010 for the best-estimate, upper 

and lower base case profiles respectively. For the profiles with reference rock located at the base 

of the sedimentary section, kappa values were 0.013, 0.019, and 0.038 sec for the best-estimate, 

upper, and lower base cases, respectively. 

To account for aleatory variability in material properties across the plant site in its site response 

calculations, the licensee stated that it randomized its base case profiles in accordance with 

Appendix B of the SPID. For the profiles with reference rock at a depth of 3,238 ft (987 m), the 

licensee stated that it also randomized the depth to reference rock ±971 ft (296 m), which 

corresponds to 30 percent of the total thickness. The licensee stated that this randomization did 

not represent actual uncertainty in the depth to reference rock, but was used to broaden the 

spectral peak. For the base case profiles with reference rock located at the top of rock, the 

licensee did not randomize the depth to reference rock. 

3.3.2 Site Response Method and Results 

In Section 2.3.4 of its SHSR, the licensee stated that it followed the guidance in Appendix B of the 

SPID to develop input ground motions for the site response analysis, and in Section 2.3.5, the 

licensee described its implementation of the random vibration theory (RVT) approach to perform 

its site response calculations. Finally, Section 2.3.6 of the SHSR shows the resulting 

amplification functions and associate uncertainties for two of the eleven input loading levels for 

the each base case profile. The shallow base case profile is shown with both EPRI cohesionless 

soil damping Peninsular Range damping shear modulus and damping curves. 

In order to develop probabilistic site-specific control point hazard curves, as requested in 

Requested Information Item (1) of the 50.54(f) letter, the licensee used Method 3, described in 

Section B-6.0 of the SPID. The licensee's use of Method 3 involved computing the site-specific 

control point elevation hazard curves for a broad range of spectral accelerations by combining the 

site-specific reference rock hazard curves, determined from the initial PSHA (Section 3.2 of this 

assessment), and the amplification function and their associated uncertainties, determined from 

the site response analysis. 

3.3.3 Staff Confirmatory Analysis 

To confirm the licensee's site response analysis, the staff performed site response calculations 

for the Palisades site. The staff independently developed a shear-wave velocity profile, damping 

values, and modeled the potential nonlinear behavior of the site using measurements and 

geologic information provided in the Palisades UFSAR (Entergy, 2011 ), the nearby Donald C. 

Cook Nuclear Plant UFSAR (Indiana Michigan Power, 2010), and Appendix B of the SPID. For its 

site response calculations, the staff employed the RVT approach and developed input ground 

motions in accordance with Appendix B of the SPID. 
- 9 -

Following guidance provided in the SPID for sites with little at-site information, the staff 

independently determined a best-estimate and upper and lower base case profiles using 

guidance provided in the SPID and information provided in the Palisades UFSAR, the Donald C. 

Cook UFSAR, and literature sources. The staff modeled the upper 45 ft (14 m) of the profile as 

very dense dune sands and silty sands with a best-estimate shear-wave velocity of 1,360 ft/s 

(415 mis). Below the sand layers, the staff modeled 90 ft (27 m) of glacial till with a best-estimate 

shear-wave velocity of 2,728 ft/s (831 mis) overlying the sedimentary rocks, which have a 

best-estimate shear-wave velocity of 5,620 ftls (1,713 mis). Due to the lack of detailed 

stratigraphy and geophysical data, the staff assumed a shear-wave velocity gradient of 0.7 ft/sift 

for the sedimentary rock section and based its best-estimate shear-wave velocities on the 

General Atomic Site Parameter Study (Leeds, 1974). The staff used a natural log standard 

deviation of 0.35 to calculate upper and lower base-case profiles in the soil layers and a natural 

log standard deviation of 0.25 to calculate upper and lower base-case profiles in the rock layers. 

Staff used information provided in Fisher, et al. (1988) to determine a best-estimate depth to 

reference rock of 4,295 ft (1,309 m). Figure 3.3-1 of this staff assessment shows a comparison of 

the six velocity profiles developed by the licensee with the three developed by the staff. The 

profiles developed by the licensee are more heavily weighted towards higher velocities because 

three of the six profiles have shallow depths to reference rock. With the exception of the sand 

layers, the velocity profiles developed by the staff are higher than those developed by the licensee 

for reference rock located at the base of the sedimentary section. The staff randomized the depth 

to reference rock by ±15 percent to account for additional uncertainty. 

Similar to the approach used by the licensee, the staff assumed both linear and non-linear 

behavior for the materials beneath the Palisades site in response to the range of input ground 

motions. The staff developed two damping profiles that incorporate different degrees of 

non-linearity. The staff used the same damping curves as the licensee when developing the soil 

profile. However, for the rock layers, the staff assumed that the rock would behave linearly under 

all loading levels and assumed a constant damping value of 1.25 percent. The staff weighted 

each of these alternatives equally in the site response analysis. 

To determine kappa for its three profiles, the staff used the low strain damping values, shear wave 

velocities, and layer thicknesses for each geologic layer to arrive at a value of 0.022, 0.028, and 

0.012 sec, for the best-estimate, lower, and upper base case velocity profiles, respectively. 

These values include the 0.006 sec contribution from the reference rock. To model the 

uncertainty in the kappa values determined in the staff's analysis, the staff used a natural log 

standard deviation of 0.15 to calculate lower and upper values of kappa for each profile. This 

approach resulted in nine kappa values for use in the site response analysis, which range from 

0.01 to 0.034 sec. Based on staff's confirmatory calculations of the licensee's inputs, kappa 

values for the profile with reference rock located at the base of the sedimentary section should be 

0.026, 0.019, and 0.038 for the best-estimate, upper, and lower base case profile respectively 

rather than the reported 0.013, 0.019, and 0.038 sec. Staff's confirmatory analysis found that the 

licensee used the correct values and the reported value of 0.013 sec for this for the best-estimate 

profile was a typographical error. 

Figure 3.3-2 of this assessment shows a comparison on the staff's and the licensee's median site 

amplification functions and associated uncertainties (±1 standard deviation) for two of the eleven 

input loading levels. Peaks in amplification functions occur between approximately 1 and 5 Hz in 
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both staff and licensee curves. Differences in the amplification functions developed by the staff 

and licensee are due to the licensee's use of six profiles, as described above, with three of the six 

profiles having reference rock directly beneath the soil layers. 

The licensee's approach to modeling the subsurface rock properties and their uncertainty results 

in higher amplification factors at low and high frequencies compared to those developed by the 

staff. As shown in Figure 3.3-3 of this assessment, these differences in site response analysis 

have a moderate impact on the control point seismic hazard curves and the resulting GMRS as 

discussed below. Specifically, hazard curves developed by the licensee are higher than those 

developed by the staff at 1.0 Hz, but consistent at other frequencies. These differences are the 

result of differences in site response analysis. Appendix B of the SPID provides guidance for 

performing site response analyses, including capturing the uncertainty for sites with less 

subsurface data; however, the guidance is neither entirely prescriptive nor comprehensive. As 

such, alternative approaches in performing site response analyses, including the modeling of 

uncertainty, are acceptable for this application. 

In summary, the staff concludes that the licensee's site response was conducted using 

present-day guidance and methodology, including the NRG-endorsed SPID. The staff performed 

independent calculations to confirm that the licensee's amplification factors and control point 

hazard curves adequately characterize the site response, including the uncertainty associated 

with the subsurface material properties, for the Palisades site. 

3.4 Ground Motion Response Spectra 

In section 2.4 of the SHSR, the licensee stated that it used the control point hazard curves, 

described in SHSR Section 2.3.7, to develop the 10-4 and 10-5 (mean annual frequency of 

exceedance) uniform hazard response spectra (UHRS) an then computed the GMRS using the 

criteria in RG 1 .208. 

The staff independently calculated the 10-4 and 10-5 UHRS using the results of its confirmatory 

PSHA and site response analysis, as described in Sections 3.2 and 3.3 of this staff assessment, 

respectively. Figure 3.4-1 of this assessment shows a comparison of the GMRS determined by 

the licensee to that determined by the staff. 

As shown in Figure 3.4-1 of this assessment, the licensee's GMRS shape is generally similar to 

that calculated by the staff. At frequencies where the amplitude of the GMRS determined by the 

licensee is different from that determined by the staff, the licensee's generally exceeds that of the 

staff. These differences in GMRS are the result of differences in the site response analyses 

performed by the licensee and staff, as discussed in Section 3.3 above. The staff concludes that 

these differences are acceptable for this application because the licensee followed the guidance 

provided in the SPID with respect to both the PSHA and site response analysis for the Palisades 

site. 

The staff confirms that the licensee used the present-day guidance and methodology outlined in 

RG 1.208 and the SPID to calculate the horizontal GMRS, as requested in the 50.54(f) letter. The 

staff performed both a PSHA and site response confirmatory analysis and achieved results 

consistent with the licensee's horizontal GMRS. As such, the staff concludes that the GMRS 
- 11 -

determined by the licensee adequately characterizes the reevaluated hazard for the Palisades 

site. Therefore, this GMRS is suitable for use in subsequent evaluations and confirmations, as 

needed, for the licensee's response to the 50.54(f) letter, dated March 12, 2012. 

4.0 CONCLUSION 

The NRC staff reviewed the information provided by the licensee for the reevaluated seismic 

hazard for the Palisades site. Based on its review, the staff concludes that the licensee 

conducted the seismic hazard reevaluation using present-day methodologies and regulatory 

guidance, appropriately characterized the site given the information available, and met the intent 

of the guidance for determining the reevaluated seismic hazard. Based on the preceding 

analysis, the NRC staff concludes that the licensee provided an acceptable response to 

Requested Information Items (1) - (3), (5), and (7) and a partial response to Item (4), identified in 

Enclosure 1 of the 50.54(f) letter. Further, the licensee's reevaluated seismic hazard is 

acceptable to address other actions associated with NTTF Recommendation 2.1, "Seismic." 

In reaching this determination, the staff confirmed the licensee's conclusion that the licensee's 

GMRS exceeds the SSE for the Palisades site in the frequency range of 1 to 10 Hz. As such, a 

seismic risk evaluation is merited for Palisades. A SFP evaluation is also merited. The staff also 

confirms the licensee's conclusion that because the GMRS exceeds the SSEs above 1 O Hz, 

Palisades will perform a high-frequency confirmation (i.e., Item (4) of the Seismic Hazard 

Evaluation), which the licensee indicated would be performed as part of its seismic risk 

evaluation. NRC review and acceptance of the Entergy's plant seismic risk evaluation which 

includes the high frequency confirmation, an ESEP interim evaluation and a SFP evaluation (i.e., 

Items (4), (6), (8), and (9)) for Palisades will complete Seismic Hazard Evaluation identified in 

Enclosure 1 of the 50.54(f) letter. 
- 12 -

REFERENCES 

Note: ADAMS Accession Nos. refer to documents available through NRC's Agencywide 

Documents Access and Management System (ADAMS). Publicly-available ADAMS 

documents may be accessed through http://www.nrc.gov/readinq-rm/adams.html. 

U.S. Nuclear Regulatory Commission Documents and Publications 

NRC (U.S. Nuclear Regulatory Commission), 2011a, "Near-Term Report and Recommendations 

for Agency Actions Following the Events in Japan," Commission Paper SECY-11-0093, 

July 12, 2011, ADAMS Accession No. ML 11186A950. 

NRC (U.S. Nuclear Regulatory Commission), 2011 b, "Recommendations for Enhancing Reactor 

Safety in the 21 51 Century: The Near-Term Task Force Review of Insights from the 

Fukushima Dai-lchi Accident," Enclosure to SECY-11-0093, July 12, 2011, ADAMS 

Accession No. ML 11186A950. 

NRC (U.S. Nuclear Regulatory Commission), 2011 c, "Recommended Actions to be Taken 

Without Delay from the Near-Term Task Force Report," Commission Paper 

SECY-11-0124, September 9, 2011, ADAMS Accession No. ML 11245A 158. 

NRC (U.S. Nuclear Regulatory Commission), 2011d, "Prioritization of Recommended Actions to 

be Taken in Response to Fukushima Lessons Learned," Commission Paper 

SECY-11-0137, October 3, 2011, ADAMS Accession No. ML 11272A 111. 

NRC (U.S. Nuclear Regulatory Commission), Regulatory Guide 1.208 "A Performance-Based 

Approach to Define the Site-Specific Earthquake Ground Motion", March, 2007. 

NRC (U.S. Nuclear Regulatory Commission), 2012a, letter from Eric J. Leeds, Director, Office of 

Nuclear Reactor Regulation and Michael R. Johnson, Director, Office of New Reactors, to 

All Power Reactor Licensees and Holders of Construction Permits in Active or Deferred 

Status, March 12, 2012, ADAMS Accession No. ML 12053A340. 

NRC (U.S. Nuclear Regulatory Commission), 2012b, "Central and Eastern United States Seismic 

Source Characterization for Nuclear Facilities", NUREG-2115, ADAMS stores the 

NU REG as multiple ADAMS documents, which are most easily accessed through the web 

page http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr2115/. 

NRC (U.S. Nuclear Regulatory Commission), 2013a. Letter From Eric J. Leeds, to Joseph 

Pollock, Executive Director NEI, Acceptance Letter for NEI Submittal of Augmented 

Approach, Ground Motion Model Update Project, and 1 O CFR 50.54(f) Schedule 

Modifications Related to the NTTF Recommendation 2.1, Seismic Reevaluations, May 7, 

2013, ADAMS Accession No. ML 13106A331. 

NRC (U.S. Nuclear Regulatory Commission), 2013b, letter from David L. Skeen, Director, Japan 

Lessons-Learned Directorate, to Joseph E. Pollock, Executive Director, Nuclear Energy 

Institute, Endorsement of Electric Power Research Institute Draft Report 1025287, 
- 13 -

"Seismic Evaluation Guidance," February 15, 2013, ADAMS Accession No. 

ML 12319A074. 

NRC (U.S. Nuclear Regulatory Commission), 2013c. Letter from David L. Skeen, Director, Japan 

Lessons-Learned Directorate to Kimberly A. Keithline (NEI), Approval of Electric Power 

Research Institute Ground Motion Model Review Project Final Report for Use by Central 

and Eastern United States Nuclear Power Plants, August 28, 2013 ADAMS Accession No. 

ML 13233A102. 

NRC (U.S. Nuclear Regulatory Commission), 2014. Letter from Eric J. Leeds, Director, Office of 

Nuclear Reactor Regulation to All Power Reactor Licensees and holders of Construction 

Permits in Active or Deferred Status, Seismic Screening and Prioritization Results 

Regarding Information Pursuant to Title 1 O of the Code of Federal Regulations 50.54(f) 

Regarding Seismic Hazard Reevaluations for Recommendations 2.1 of the Near-Term 

Task Force Review of Insights, May 9, 2014, ADAMS Accession No. ML 14111A147. 

Other References 

Leeds, 1974, Letter from D. J. Leeds to George Loh (General Atomic Company), Transmittal of 

"Site Parameter Study GASSAR Seismic Design for General Atomic Company". 

Fisher, J. H., M. W. Barrat, J. B. Droste, and R. H. Shaver, 1988, "Michigan Basin", The Geology 

of North America, 2, p. 361-382. 

Entergy Nuclear Operations, Inc. (Entergy), 2011, Palisades Nuclear Plant Final Safety Analysis 

Report (Updated) (UFSAR), Revision 29. 

Indiana Michigan Power, 2010, Donald C Cook Nuclear Plant Units 1 and 2 Final Safety Analysis 

Report (Updated) (UFSAR), Revision, 23. 

McGuire, R. K., W. J. Silva, and C. J. Constantino, 2001, "Technical Basis for Revision of 

Regulatory Guidance on Design Ground Motions: Hazard- and Risk- Consistent Ground 

Motion Spectra Guidelines", NUREG/CR-6728, ADAMS stores the NUREG as multiple 

ADAMS documents, which are most easily accessed through the web page 

http://www.nrc.gov/docs/ML0131/ML013100232.html 

Electric Power Research Institute (EPRI), 2004. EPRI Report 1009684, "CEUS Ground Motion 

Project Final Report." Palo Alto, CA, 2004. 

Electric Power Research Institute (EPRI), 2006. EPRI Report 1014381, "Truncation of the 

Lognormal Distribution and Value of the Standard Deviation for Ground Motion Models in 

the Central and Eastern United States." Palo Alto, CA, 2006. 

Electric Power Research Institute (EPRI), 2012. 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" November 27, 

2012, ADAMS Accession No. ML 12333A 170. 
- 14 -

Electric Power Research Institute (EPRI), 2013. EPRI Report 3002000717 "EPRI (2004, 2006) 

Ground-Motion Model Review Project Final Report," Palo Alto, CA, 2013. 

Keithline, 2012, Letter from Kimberly Keithline, Senior Project Manager, NEI, to David L. Skeen, 

Director, Japan Lessons Learned Project Directorate, NRC, Final Draft of Industry 

Seismic Evaluation Guidance (EPRI 1025287), November 27, 2012, ADAMS Accession 

No. ML12333A168. 

Keithline, 2013, Submittal of EPRI (2004, 2006) Ground Motion Model Review Final Report, June 

3, 2013, ADAMS Accession No. ML13170A378. 

Pietrangelo, 2013. Letter from A. R. Pietrangelo (NEI) to D. L. Skeen (NRC), Proposed Path 

Forward for NTTF Recommendation 2.1: Seismic Reevaluations, April 9, 2013, ADAMS 

Accession No. ML 13101 A379. 

Vitale, A. J. 2013, Letter from A. J. Vitale (Entergy Nuclear Operations, Inc.) to NRC, Palisades 

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, September 

11, 2013, ADAMS Accession No. ML 13255A052. 

Vitale, A. J. 2013, Letter from A. J. Vitale (Entergy Nuclear Operations, Inc.) to NRC, Palisades 

Nuclear Plant Seismic Hazard and Screening Report (CEUS Sites), Response to NRC 

Request for Information Pursuant to 1 O CFR 50.54(f) Regarding Recommendation 2.1 of 

the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident, 

March 31, 2014, ADAMS Accession No. ML 14090A069. 
- 15 -

Figure 3.3-1 Plot of Staff's and Licensee's Base Case Shear-Wave Velocity Profiles. 

Shallow and Deep Refer to Reference rock Depths of 148 ft (45 m) and 3,238 ft (987 m), 

Respective! , for the Palisades Site 

0 

0 

500 

1000 

g 

.. 1500 c 

·a 

Q. 

0 

... 2000 .. 

c 

0 

u 

~ 2500 

Qi 

ca 

..c 

~ 3000 Cll 

c 

3500 

4000 

4500 

Shear-Wave Velocity (ft/s) 

1000 2000 3000 4000 5000 6000 7000 

--- • • • • • • • • • • • • • ••• • • • • • • • 

8000 

• 

~, 

• 

• 

9000 

• • • • ••• • • • • 

• 

• •-, • • • • • • • • • • •• • , 

• , • , • • ••••• • • - Licensee {Shallow) Bese Case : 

- Licensee {Shallow) LQwer Base Case : 

• 

• 

•• 

• 

• 

• 

• 

• 

• 

• 

• 

• • 

• - 1censee • • • 

•••• Licensee {Deep) Bas( Case • :. • 

·-

10000 

· (n ) 1 • 'h~ • • • • •••••••• , •••••••• -.. ensee __ eep __ ower_ ~~~~~~~~~~~~--1--~~--~~ 

•••• Licensee {Deep) Upper Base Case • 

•• 

• -NRC Base Case 

• • • • NRC Lower Base Case 

- - NRC Upper Base Case 

I 

• 

~ ................ ~ 
- 16 -

Figure 3.3- 1 Plot Comparing the Staff's and the Licensee's Median Amplification 

Functions and Uncertainties for the Palisades site. 

4.5 - NRC A=0.1 

4 

3.5 - ... 

0 3 - .... - . u 

ra 

L&. 

c 2.5 

0 

~ 

ra 

u 2 ~ 

a. 

E 1.5 

<t 

1 

0.5 

___ __ .,, .... -..-:.. .... ::::.. -- .... -------=-

0.1 1 10 

Frequency (Hz) 

100 
- 17 -

Figure 3.3-2 Plot Comparing the Staff's and the Licensee's Mean Control Point Hazard 

Curves at a Variet of Fre uencies for the Palisades site 

iii 

:I 

c 

1.E-01 -c:---------.---------,---------~--------. 

:f 1.E-05 

c 

I'll 

Cll 

:? - Licensee 1 H 

- Licensee 10 z 

1.E-06 +------•biteA-See-¥~---------11--------....--: -+-',.._ o------1 

1.E-07 

0.001 

-- NRClHz 

-- NRC 10 Hz 

-- NRCPGA 

0.01 0.1 1 10 

Spectral Acceleration (g) 
- 18 -

Figure 3.4-1 Comparison of the Staff's GMRS with Licensee's GMRS and the SSE for the 

Palisades site 

1.4 

1.2 

1 

-

~0 8 

ct 

"' 0.6 

0.4 

0.2 

0 

0.1 1 10 100 

Frequency {Hz) 

- Palisades SSE - Licensee GMRS - NRC GMRS 
- 2 -

If you have any questions, please contact me at (301) 415-6197 or via e-mail at 

Tekia.Govan@nrc.gov. 

Docket No. 50-255 

Enclosure: 

Staff Assessment of Seismic 

Sincerely, 

IRA/ 

Tekia Govan, Project Manager 

Hazards Management Branch 

Japan Lessons-Learned Division 

Office of Nuclear Reactor Regulation 

Hazard Evaluation and Screening Report 

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