ML16266A281

Staff Assessment of Response to 10 CFR 50.54(f) Information Request - Flood-Causing Mechanism Reevaluation

ML16266A281
Person / Time
Site:	Hope Creek
Issue date:	10/25/2016
From:	Tekia Govan Japan Lessons-Learned Division
To:	Braun R, Sena P Public Service Enterprise Group
Govan T, NRR/JLD 415-6197
References
CAC MF3789
Download: ML16266A281 (41)

Text

UNITED ST ATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 October 25, 2016 Mr. Peter P. Sena, Ill President PSEG Nuclear LLC-N09 P. 0. Box 236 Hancocks Bridge, NJ 08038

SUBJECT:

HOPE CREEK GENERATING STATION-STAFF ASSESSMENT OF RESPONSE TO 10 CFR 50.54(f) INFORMATION REQUEST- FLOOD-CAUSING MECHANISM REEVALUATION (CAC NO. MF3789)

Dear Mr. Sena:

By letter dated March 12, 2012, the U.S. Nuclear Regulatory Commission (NRC) issued a request for information pursuant to Title 1O of the Code of Federal Regulations, Section 50.54(f)

(hereafter referred to as the 50.54(f) letter). The request was issued as part of implementing lessons learned from the accident at the Fukushima Dai-ichi nuclear power plant. Enclosure 2 to the 50.54(f) letter requested licensees to reevaluate flood-causing mechanisms using present-day methodologies and guidance. By letter dated March 12, 2014 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML14071A511 ), PSEG Nuclear LLC (the licensee) responded to this request for Hope Creek Generating Station (Hope Creek).

By letter dated September 10, 2015 (ADAMS Accession No. ML15238B655), the NRC staff sent the licensee a summary of its review of Hope Creek's reevaluated flood-causing mechanisms.

The enclosed staff assessment provides the documentation supporting the NRC staff's conclusions summarized in the letter. As stated in the letter, because the local intense precipitation (LIP) reevaluated flood hazard mechanism at Hope Creek is not bounded by the plant's current design basis, the NRC staff anticipates that the licensee will perform and document a focused evaluation for LIP and associated site drainage that assesses the impact of the LIP hazard on the site and evaluates and implements any necessary programmatic, procedural, or plant modifications to address this hazard exceedance.

This staff assessment closes out the NRC's efforts associated with CAC No. MF3789.

P.Sena If you have any questions, please contact me at (301) 415-6197 or e-mail at Tekia.Govan@nrc.gov.

Sincerely, Tekia Govan, Project Manager Hazards Management Branch Japan Lessons-Learned Division Office of Nuclear Reactor Regulation Docket No. 50-354

Enclosure:

Staff Assessment of Flood Hazard Reevaluation Report cc w/encl: Distribution via Listserv

STAFF ASSESSMENT BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO FLOODING HAZARD REEVALUATION REPORT NEAR-TERM TASK FORCE RECOMMENDATION 2.1 HOPE CREEK GENERATING STATION DOCKET NO 50-354

1.0 INTRODUCTION

By letter dated March 12, 2012 (NRC, 2012a), the U.S. Nuclear Regulatory Commission (NRC) issued a request for information to all power reactor licensees and holders of construction permits in active or deferred status, pursuant to Title 10 of the Code of Federal Regulations (1 O CFR), Section 50.54(f), "Conditions of Licenses" (hereafter referred to as the "50.54(f) letter"). The request was 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 (NTTF) report (NRC, 2011 b). Recommendation 2.1 in that document recommended that the NRC staff issue orders to all licensees to reevaluate seismic and flooding hazards for their sites against current NRC requirements and guidance. Subsequent staff requirements memoranda associated with SECY-11-0124 (NRC, 2011c) and SECY-11-0137 (NRC, 2011d) directed the NRC staff to issue requests for information to licensees pursuant to 10 CFR 50.54(f) to address this recommendation. to the 50.54(f) letter (NRC, 2012a) requested that licensees reevaluate the flood hazards for their respective sites using present-day methods and regulatory guidance used by the NRC staff when reviewing applications for early site permits (ESPs) and combined licenses (COLs). The required response section of Enclosure 2 specified that NRC staff would provide a prioritization plan indicating the Flooding Hazard Reevaluation Report (FHRR) deadlines for each plant. On May 11, 2012, the NRC staff issued its prioritization of the FHRRs (NRC, 2012c).

By letter dated March 7, 2014 (PSEG, 2014a), PSEG Nuclear, LLC (PSEG, the licensee),

provided its FHRR for Hope Creek Generating Station (Hope Creek). The NRC staff subsequently issued requests for additional information (RAls) to the licensee by letter dated June 28, 2014 (NRC, 2014b). These RAls applied to both Hope Creek and Salem Generating Station, Units 1 and 2 (Salem) sites, and focused on the analysis of three flood hazards: local intense precipitation (LIP), the probable maximum flood (PMF), and storm surge. The licensee responded by letter dated July 28, 2014 (PSEG, 2014b). Additionally, on June 22, 2015, and July 16, 2015, the NRC staff conducted an audit of the licensee's FHRR submittal at which time the RAI responses were discussed (NRC, 2016a). The audit was summarized in the "Nuclear Regulatory Commission Report for the Audit of PSEG Nuclear LLC's Flood Hazard Revaluation Report Submittals Relating to the Near-Term Task Force Recommendation 2.1-Flooding for Hope Creek Generating Station Unit 1" (NRC, 2016a).

By letter dated September 10, 2015, the NRC issued an interim staff response (ISR) letter to the licensee (NRC, 2015b). The purpose of the ISR letter is to provide the flood hazard information

suitable for the assessment of mitigating strategies developed in response to Order EA-12-049 (NRC, 2012b) and the additional assessments associated with Recommendation 2.1: Flooding.

The ISR letter also made reference to this staff assessment, which documents NRC staff's basis and conclusions. The flood hazard mechanism values presented in the letter's enclosures match the values in this staff assessment without change or alteration.

As mentioned in the ISR letter (NRC, 2015b), the reevaluated flood hazard results for the UP flood-causing mechanism is not bounded by the plant's current design-basis (COB). Consistent with the 50.54(f) letter and amended by the process outlined in COMSECY-15-0019 and JLO-ISG-2016-01, Revision O (NRC, 2015a and NRC, 2016c), the NRC staff anticipates that the licensee will perform and document a focused evaluation for UP and associated site drainage that assesses the impact of the UP hazard on the site and evaluates and implements any necessary programmatic, procedural, or plant modifications to address this hazard exceedance.

Additionally, for any reevaluated flood hazards that are not bounded by the plant's COB hazard, the licensee is expected to develop flood event duration (FED) parameters and flood-related associated effects (AE) parameters. These parameters will be used to conduct the mitigating strategies assessment (MSA) and focused evaluations or revised integrated assessments.

2.0 REGULATORY BACKGROUND 2.1 Applicable Regulatory Requirements As stated above, Enclosure 2 to the 50.54(f) letter (NRC, 2012a) requested that licensees reevaluate flood hazards for their sites using present-day methods and regulatory guidance used by the NRC staff when reviewing applications for ESPs and COLs. This section of the staff assessment describes present-day regulatory requirements that are applicable to the FHRR.

Sections 50.34(a)(1 ), (a)(3), (a)(4), (b)(1 ), (b)(2), and (b)(4), of 10 CFR, describe the required content of the preliminary and final safety analysis reports, including a discussion of the facility site with a particular emphasis on the site evaluation factors identified in 10 CFR Part 100. The licensee should provide any pertinent information identified or developed since the submittal of the preliminary safety analysis report in the final safety analysis report.

General Design Criterion 2 in Appendix A of 10 CFR Part 50 states that structures, systems, and components (SSCs) important to safety at nuclear power plants must be designed to withstand the effects of natural phenomena, such as earthquakes, tornados, hurricanes, floods, tsunamis, and seiches without the loss of capability to perform their intended safety functions.

The design bases for these SSCs are to reflect appropriate consideration of the most severe of the natural phenomena that have been historically reported for the site and surrounding area.

The design bases are also to have sufficient margin to account for the limited accuracy, quantity, and period of time in which the historical data have been accumulated.

Section 50.2 of 10 CFR defines the design-basis as the information that identifies 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 design which each licensee is required to develop and maintain. These values may be (a) restraints derived from generally accepted "state of the art" practices for achieving functional goals, or (b) requirements derived

from analysis (based on calculation, experiments, or both) of the effects of a postulated accident for which an SSC must meet its functional goals.

Section 54.3 of 10 CFR defines the "current licensing basis" (CLB) as "the set of NRC requirements applicable to a specific plant and a licensee's written commitments for ensuring compliance with and operation within applicable NRC requirements and the plant-specific design basis (including all modifications and additions to such commitments over the life of the license) that are docketed and in effect." This includes 10 CFR Parts 2, 19, 20, 21, 26, 30, 40, 50, 51, 52, 54, 55, 70, 72, 73, 100 and appendices thereto; orders; license conditions; exemptions; and technical specifications, as well as the plant-specific design-basis information as documented in the most recent final safety analysis report. The licensee's commitments made in docketed licensing correspondence, which remain in effect, are also considered part of the CLB.

Present-day regulations for reactor site criteria (Subpart B to 10 CFR Part 100 for site applications on or after January 10, 1997) state, in part, that the physical characteristics of the site must be evaluated and site parameters established such that potential threats from such physical characteristics will pose no undue risk to the type of facility proposed to be located at the site. Factors to be considered when evaluating sites include the nature and proximity of dams and other man-related hazards (10 CFR 100.20(b)) and the physical characteristics of the site, including the hydrology (10 CFR 100.21 (d)).

2.2 Enclosure 2 to the 50.54(f) Letter 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 enable the Commission to determine whether or not the license should be modified, suspended, or revoked. The 50.54(f) letter (NRC, 2012a) requested, in part, that licensees reevaluate the flood-causing mechanisms for their respective sites using present-day methodologies and regulatory guidance used by the NRC for the ESP and COL reviews.

2.2.1 Flood-Causing Mechanisms to Enclosure 2 of the 50.54(f) letter discusses flood-causing mechanisms for the licensee to address in its FHRR (NRC, 2012a). Table 2.2-1 lists the flood-causing mechanisms that the licensee should consider, and the corresponding Standard Review Plan (SAP) (NRC, 2007) sections and applicable ISG documents containing acceptance criteria and review procedures.

2.2.2 Associated Effects In reevaluating the flood-causing mechanisms, the "flood height and associated effects" should be considered. Guidance document JLD-ISG-2012-05 (NRC, 2012e) defines "flood height and associated effects" as the maximum stillwater surface elevation plus:

• Wind waves and run-up effects

• Hydrodynamic loading, including debris

• Effects caused by sediment deposition and erosion

• Concurrent site conditions, including adverse weather conditions

• Groundwater ingress

• Other pertinent factors 2.2.3 Combined Effect Flood The worst flooding at a site that may result from a reasonable combination of individual flooding mechanisms is sometimes referred to as a "combined effects flood." Even if some or all of these individual flood-causing mechanisms are less severe than their worst-case occurrence, their combination may still exceed the most severe flooding effects from the worst-case occurrence of any single mechanism described in the 50.54(f) letter (see SRP Section 2.4.2, "Areas of Review" (NRG, 2007)). Attachment 1 of the 50.54(f) letter describes the "combined effect flood" as defined in American National Standards Institute/American Nuclear Society (ANSI/ANS) 2.8-1992 (ANSI/ANS, 1992), as follows:

For flood hazard associated with combined events, American Nuclear Society (ANS) 2.8-1992 provides guidance for combination of flood causing mechanisms for flood hazard at nuclear power reactor sites. In addition to those listed in the ANS guidance, additional plausible combined events should be considered on a site specific basis and should be based on the impacts of other flood causing mechanisms and the location of the site.

If two less severe mechanisms are plausibly combined per ANSl/ANS-2.8-1992 (ANSI/ANS, 1992), then the NRG staff will document and report the result as part of one of the hazard sections. An example of a situation where this may occur is flooding at a riverine site located where the river enters the ocean. For this site, storm surge and river flooding are plausible combined events and should be considered.

2.2.4 Flood Event Duration Flood event duration was defined in JLD-ISG-2012-05 (NRG, 2012e) as the length of time during which the flood event affects the site. It begins when conditions are met for entry into a flood procedure, or with notification of an impending flood {e.g., a flood forecast or notification of dam failure), and includes preparation for the flood. It continues during the period of inundation, and ends when water recedes from the site and the plant reaches a safe and stable state that can be maintained indefinitely. Figure 2.2-1 illustrates flood event duration.

2.2.5 Actions Following the FHRR For the sites where the reevaluated flood hazard is not bounded by the COB flood hazard elevation for any flood-causing mechanisms, the 50.54(f) letter {NRG, 2012a) requests licensees and construction permit holders to:

• Submit an interim action plan with the FHRR documenting actions planned or already taken to address the reevaluated hazard.

• Perform an integrated assessment to (a) evaluate the effectiveness of the COB {i.e., flood protection and mitigation systems); (b) identify plant-

specific vulnerabilities; and (c) assess the effectiveness of existing or planned systems and procedures for protecting against and mitigating consequences of flooding for the flood event duration.

If the reevaluated flood hazard is bounded by the COB flood hazard for all f load-causing mechanisms at the site, licensees were not required to perform an integrated assessment.

COMSECY-15-0019 (NRG, 2015a) outlines a revised process for addressing cases in which the reevaluated flood hazard is not bounded by the plant's COB. The revised process describes an approach in which licensees with LIP hazards exceeding their COB flood will not be required to complete an integrated assessment, but instead will perform a focused evaluation. As part of the focused evaluation, licensee will assess the impact of the LIP hazard on their sites and then evaluate and implement any necessary programmatic, procedural, or plant modifications to address the hazard exceedance. For other flood hazard mechanisms that exceed the COB, licensees can assess the impact of these reevaluated hazards on their site by performing either a focused evaluation or a revised integrated assessment (NRG, 2015a).

3.0 TECHNICAL EVALUATION

The NRG staff reviewed the information provided for the reevaluation of the Hope Creek site (PSEG, 2014a and 2014b). The licensee conducted the hazard reevaluation using present-day methodologies and regulatory guidance used by the NRG staff in connection with ESP and COL reviews.

To provide additional information in support of the summaries and conclusions in the Hope Creek FHRR, the licensee made certain calculation packages available to the NRG staff via an electronic reading room. The NRG staff did not rely directly on this calculation package in its review; they were found only to expand upon and clarify the information provided in the Hope Creek FHRR, and so those calculation packages were not docketed or cited.

In connection with the NRG staff's FHRR review, electronic copies of the computer input/output (1/0) files used in the numerical modeling were provided to the NRG staff and cited as part of the "Nuclear Regulatory Commission Report for the Audit of PSEG Nuclear LLC's Flood Hazard Revaluation Report Submittals Relating to the Near-Term Task Force Recommendation 2.1-Flooding for Hope Creek Generating Station Unit 1" (NRG, 2016a).

Unless otherwise stated, all elevations in this staff assessment are given with respect the North American Vertical Datum of 1988 (NAVD88). Table 3.0-1 provides the summary of controlling reevaluated flood-causing mechanisms, including associated effects, the licensee computed to be higher than the powerblock elevation.

3.1 Site Information The 50.54(f) letter (NRG, 2012a) includes the SSCs important to safety in the scope of the hazard reevaluation. The licensee included pertinent data concerning these SSCs in the Hope Creek FHRR. The NRG staff reviewed and summarized this information as follows in the sections below.

3.1.1 Detailed Site Information The Hope Creek FHRR (PSEG, 2014a) states that the site is located on the east bank of the Delaware River, on the southern portion of an artificial island. This artificial island was constructed by the U.S. Army Corps of Engineers (USAGE) on behalf of PSEG to site both the Hope Creek and the Salem reactor complexes; the two reactor complexes are contiguous to each other and are located on the western (river-facing) portion of the island. The PSEG property extends over an area of approximately 741 acres (299 hectares) in an estuarine setting of which 153 acres (62 hectares) are dedicated to the Hope Creek reactor complex containing two power units (See Figure 3.2-1 ). By way of comparison, the Salem site property consists of 220 acres (89 hectacres) or about 30 percent of the PSEG site. The topography of the artificial island is generally flat; elevations rise gently from sea level and throughout most of the Atlantic Coastal Plain. Natural elevations in the vicinity of the Hope Creek site are less than 11 ft (3.4 m) above mean sea level and extend for a distance of 1 to 4 miles (mi) (1.6 to 6.4 km) to the west and east of the PSEG complex, although there is significant natural variation. The highest elevations in the vicinity of the Hope Creek site are manmade embankments which intermittently line the river; those embankments are less than 21 ft (6.4 m) high. The plant grade of the powerblock (e.g., all personnel entrances to Category I seismic structures) is at an elevation of approximately 11. 7 ft (3.6 m) NAVD88. The ground floor levels of the turbine and auxiliary buildings are at an elevation of 12.2 ft (3.7 m) NAVD88 (PSEG, 2014a). Lastly, the licensee has previously reported that all exterior doors and penetrations in the Class I (seismic) buildings are watertight up to at least elevation 31.2 ft (9.5 m) NAVD88. (See PSEG, 2014a).

The Hope Creek site itself is generally flat with drainage directing flood waters toward the surrounding estuarine marshes and the Delaware Bay (PSEG, 2014a). At a location approximately 2 miles (3.2 km) south of the PSEG site, the Delaware River transitions into the Delaware Bay which itself is hydrodynamically-coupled with the Atlantic Ocean. Because the bay is broad and enjoys unrestricted access to the sea, both the Delaware Bay and the Atlantic Ocean are the main hydrologic features of interest for the purposes of the Hope Creek FHRR.

The maximum tidal flow measured 20 mi (32.2 km) above the PSEG site (at Wilmington, DE) has previously been reported as 600,000 cubic feet per second (cfs) (17,000 m 3/s) compared to an estimated 12,000 cfs (340 m3/sec) fresh water discharge (measured at Trenton, NJ) from the Delaware River (Miller, 1962). Given the disproportionally high tidal flow conditions at the PSEG site, riverine-based flooding scenarios have been previously viewed to be inconsequential relative to marine-derived ones (Miller, 1962). Based on these facts, the licensee noted that the Hope Creek site is not considered to be susceptible to flooding by rivers, dam failures, ice flooding, or channel migration (PSEG, 2014a). However, the site is adjacent to the coast and, therefore, potentially vulnerable to flooding by marine-based phenomena. The licensee also stated that the Hope Creek site was not vulnerable to flooding due to tsunamis or seiche.

The Hope Creek site has a drainage system that consists of ditches that collect and passively convey surface runoff to pipes that ultimately discharge into the Delaware Estuary (PSEG, 2014a). Other hydrologic features of interest near the Hope Creek site include the Alloway Creek, Hope Creek, and the Chesapeake and Delaware Canal. All of these features are contiguous with the greater Delaware River Basin whose total drainage area is about 12, 765 mi 2 (5, 165 hectares); this river basin is comprised of about 14 distinct watersheds that contain numerous tributaries. It was noted in the 50.54(f) walkdown report that large ocean-generated waves would break before reaching the Hope Creek powerblock owing to the construction of a

seawall along the shoreline adjacent to the PSEG reactor complex (NRC, 2014a). The top elevation of that seawall is reported in the 50.54(f) walkdown report to be 18.2 ft (5.6 m)

NAVD88, or about 8.5 ft (2.6 m) above plant grade.

The service water intake structure (SWIS) was described by the licensee at a location along the strand line of the Delaware Estuary. Vital components of the SWIS are housed in a watertight compartment that is protected to an elevation of 36.2 ft (11.0 m) NAVD88. Protection for the SWIS from runup extends to an elevation of 38.2 ft (11.6 m) NAVD88 (PSEG, 2014). Structures at the site provide protection against waves from the southerly (ocean) direction. Those structures include sheetpile retaining walls and riprap construction, extending 100 ft (30.5 m) on both sides of the SWIS, provide protection against slope failure and minimize shoreline erosion (PSEG, 2014a).

3.1.2 Design-Basis Flood Hazards The COB flood levels for Hope Creek are summarized by flood-causing mechanism in Table 3.1-1. The COB flood hazard for the Hope Creek site is the probable maximum hurricane (PMH) surge occurring in association with wave run up coincident with the 1O percent exceedance high tide. The licensee noted previously that the Hope Creek site is not considered to be susceptible to flooding by LIP, rivers and streams, dam failures, ice flooding, channel migration, tsunamis, or seiche and no water surface elevations (WSEs) were reported for these flood-causing mechanisms {PSEG, 2014a).

The NRC staff reviewed the flood hazard information provided in the Hope Creek FHRR (PSEG, 2014a) and determined that sufficient information on the COB was provided to be responsive to the information request described in Enclosure 2 of the 50.54(f) letter (NRC, 2012a).

3.1 .3 Flood-Related Changes to the Licensing Basis The licensee noted in the Hope Creek FHRR that there have been no flood-related changes or changes to flood protection measures beyond the flood protection measures in place for the COB (PSEG, 2014a). The NRC staff reviewed the flood hazard information provided and determined that sufficient information on the flood-related changes to the licensing basis was provided to be responsive to Enclosure 2 of the 50.54(1) letter (NRC, 2012a).

3.1.4 Changes to the Watershed and Local Area The licensee reported that local changes to the watershed have been minimal since the plant has been licensed to operate. Reported changes within the Hope Creek site itself include the addition of a materials center, a low-level radioactive waste storage facility, a nuclear department administration building, and a processing center and security entrance buildings.

Additionally, a vehicle barrier system (VBS) has been added around the plant for security purposes. Lastly, an independent spent fuel storage installation (ISFSI) storage facility has been added under a separate NRC fuel-cycle license. The ISFSI is situated north of the Hope Creek reactor building and located within the perimeter created by the VBS. None of the additions described have resulted in changes to the site grade (PSEG, 2014a).

PSEG Power LLC and PSEG Nuclear LLC submitted an ESP application in May 2010 for a new nuclear plant that would be located generally to the north of the existing Hope Creek site. The licensee states that the exact location and design of storm water management systems for the new plant have not been determined; however, the licensee noted that it expects to integrate infrastructure for the new proposed reactor with the existing Hope Creek infrastructure. The licensee notes that the addition of a new reactor complex is not expected to impact the hydraulic characteristics of the existing Hope Creek site {PSEG, 2010).

The NRC staff reviewed the flood hazard information provided and determined that sufficient information on changes to the watershed and local area was provided to be responsive to Enclosure 2 of the 50.54(f) letter {NRC, 2012a).

3.1.5 Current Licensing Basis Flood Protection and Pertinent Flood Mitigation Features In the Hope Creek FHRR {PSEG, 2014a), the licensee stated that there were no changes either to the licensing basis flood elevations or to flood protection design features. Details regarding all of these features were previously described by the licensee (PSEG, 2012 and 2013) and reviewed by the NRC staff (NAO, 2014a). In the matter of these design features, the NRC staff reviewed the flood hazard information provided and determined that sufficient information on CLB flood protection and pertinent flood mitigation features was provided to be responsive to of the 50.54(f) letter (NRC, 2012a).

3.1.6 Additional Site Details to Assess the Flood Hazard The licensee made available for review electronic copies of the 1/0 files for the computer models and calculation packages used in connection with the flood hazard reevaluations. The NRC staff reviewed that material and determined that sufficient information had been provided in response to Enclosure 2 of the 50.54{f) letter (NRC, 2012a).

3.1.7 Results of Plant Walkdown Activities The 50.54(f) letter requested that licensees plan and perform plant walkdown activities to verify that current flood protection systems were available, functional, and implementable.

Other requests described in the 50.54(f) letter asked the licensee to report any relevant information from the results of the plant walkdown activities.

By letter dated November 26, 2012, PSEG provided the requisite flood walkdown report for the Hope Creek site (PSEG, 2012). The NRC staff prepared a staff assessment report, dated June 16, 2014 {NRC, 2014a), to document its review of that report. The NRC staff concluded that the licensee's implementation of the flooding walkdown methodology met the intent of the 50.54(f) letter.

3.2 Local Intense Precipitation and Associated Site Drainage The licensee reported in the Hope Creek FHRR that the reevaluated flood hazard, including associated effects, for LIP and associated site drainage is based on a WSE (stillwater) of 12.8 ft (3.9 m) NAVD88 (PSEG, 2014a). The WSEs evaluated at a set of critical door locations, ranged from 9.7 to 12.8 ft (3.0 to 3.9 m) NAVD88. The effects of wind waves and runup were not included in the flood reevaluation for LIP. This flood-causing mechanism is discussed in the licensee's COB, but no probable maximum flood elevation was reported.

3.2.1 Site Drainage and Elevations The licensee reevaluated the flood hazard resulting from LIP and site drainage over the combined power block areas containing both the Hope Creek and the adjacent Salem site. The relatively flat Hope Creek site is bounded on the east and north by tidal marshes and on the west and south by the Delaware River Estuary. The nominal grade for the artificial island containing both reactor sites is 9.0 ft (2.7 m) NAVD88; the Hope Creek powerblock is at elevation of 11.7 ft (3.6 m) NAVD88 (PSEG, 2014a). The composite power block area is drained by a system of ditches that convey meteoric water to an underground drainage system that ultimately discharges into the Delaware River Estuary. In the event of a precipitation event that exceeds the design capacity of the site's drainage system, excess meteoric water would accumulate in catchment basins. The drainage system for the Hope Creek site is shown in Figure 3.2-2 (PSEG, 2014a). Ground-surface elevations being reported were based on a 2008 Light Detection and Ranging (LiDAR) survey of the site whose horizontal resolution was 1 ft (0.3 m). Subsequent changes to site topography were evaluated in a 2013 site walkdown performed in connection with the 50.54(f) letter (PSEG, 2012 and 2013).

3.2.2 Local Intense Precipitation The LIP event described in the Hope Creek FHRR was based on the 1-hour {hr), 1-square mile (mi 2 ) probable maximum precipitation (PMP) derived from National Oceanic and Atmospheric Administration (NOAA) National Weather Service (NWS) Hydrometeorological Report (HMR)

Nos. 51 (NOAA, 1978) and 52 (NOAA, 1982). Using these sources, the licensee reported that the 1-hr, 1-mi2 (3-km 2) PMP depth is 18.1 in (46.0 cm). The licensee used multiplier factors from NOAA (1982) to estimate the 30-, 15-, and 5-minute (min} PMP depths for a 1-mi 2 (3-km 2 )

drainage area (PSEG, 2014a). Table 3.2-1 describes the cumulative LIP depths estimated by the licensee. The NRC staff used the location of the Hope Creek site to verify, from HMR 52 (NOAA 1982), that the licensee's LIP depth estimates were reasonable.

The licensee stated that the PMP precipitation hyetograph, shown in Figure 3.2-3 was developed using the methodology described in NUREG/CR-7046 (NRC 2011e). The licensee used 5-min increments to construct the hyetograph, with the most intense precipitation flux applied during the initial 5-min increment with the precipitation rate decreasing during successive time increments (PSEG, 2014a). The NRC staff verified that the licensee followed the example described in Appendix B of NUREG/CR-7046.

3.2.3 Runoff Analysis The licensee reevaluated the flood from an LIP event using the FL0-20 computer model (Build No. 09-13.01.12) (FL0-20 Software, Inc., 2009). The licensee relied on a 10-ft by 10-ft (3.0-m

by 3.0-m) grid system to provide computational coverage of both the Hope Creek and Salem reactor sites. This grid system consisted of 277,011 cells covering an area of 6.4 acres (2.6 hectare) or about 1O mi 2 (25.8 km 2 ). The licensee assigned an average suriace elevation to each grid cell based on the 1-ft (0.3-m) resolution LiDAR data, as well as information obtained in connection with the earlier site walkdown. The licensee also assigned a uniform elevation of 25 ft (7.6 m) NAVD88 to grid cells corresponding to powerblock buildings as well as the intake structure location.

The licensee provided the FL0-2D 1/0 files used to compute the WSE results described in the Hope Creek FHRR for the NRC staff's review (PSEG, 2014b). Using the FL0-2D input files, the NRC staff verified that the configuration of the FL0-2D computational domain used in the LIP analysis was consistent with the description provided in the Hope Creek FHRR. The NRC staff compared available topographic data for the site to the grid elevations at a select number of locations in the FL0-2D computational model and determined that the licensee's computer model accurately represented the actual ground-surface elevation of the Hope Creek site. The NRC staff also determined that the location of the VBS and other building structures within the Hope Creek powerblock were properly represented in the model. In the matter of how meteoric runoff from buildings was treated, the NRC staff determined that the representation of buildings as overland-flow grid cells with elevations significantly higher than the surrounding terrain was a reasonable way to account for these flow effects. The NRC staff also determined that the licensee's use of a uniform elevation of 25 ft (7.6 m) NAVD88 for all grid cells corresponding to powerblock structures was reasonable in this regard in that meteoric water would shed-off the tops of those structures onto the ground surface and in doing so result in relatively uniform flow around those structures.

Furthermore, the NRC staff reviewed the configuration of the computer model and determined that storm water-conveyance structures on-site were assumed to be blocked and that infiltration losses were neglected, consistent with guidance in NUREG/CR-7046 (NRC, 2011e). Because the site grade is well above the average elevation of the Delaware River, the NRC staff found the licensee's use of the normal flow depth of the river as the downstream boundary condition for the FL0-2D computer model was reasonable.

3.2.4 Water Level Determination The licensee reported reevaluated flood elevations at nine critical door locations within the powerblock and at the intake structure location in response to a 1-hr, 1-mi 2 (3-km 2 ) PMP event.

The locations of these critical doors are shown in Figure 3.2-4.

The licensee evaluated the time-dependent flood response of the powerblock site to the local PMP over a 12-hr time period with 0.1-hr output intervals. The licensee reported the maximum reevaluated WSE for each critical door location, the elapsed time to reach the maximum flood elevation, and the period of time the WSE was above the elevation of critical door sills, 12.2 ft (3.7 m) NAVD88. The results reported are shown in Table 3.2-2. As indicated by that table, the maximum reevaluated WSEs range from 9.7 to 12.8 ft (3.0 to 3.90 m) NAVD88. The flood depths estimated by the computer model range from approximately 0.03 to 0.6 ft (0.01 to 0.2 m) above the door sill elevations at five of the nine critical door locations. Flood depths exceeded elevations for three of the door sills within the first 15 min of the local PMP (PSEG, 2014a) and remained above the door sill elevations for up to 2.6 hr.

The NRC staff verified the licensee's results by independently executing the FL0-20 model using the input files provided by the licensee. The NRC staff also reviewed the output produced by that computer model and determined that: (a) mass balance errors were small (less than 0.001 percent); (b) the inundation areas and flow pathways appeared reasonable; and (c) the flow velocities were reasonable, with no indication of numerical instabilities and no supercritical flow conditions near the critical door locations of interest. Based on those results, the NRC staff concluded that the licensee's FL0-20 model was a reasonable basis for evaluating the estimated WSEs and associated site drainage due to LIP.

As stated in the Hope Creek FHRR, and subsequently verified by the NRC staff, the Manning's roughness coefficient n values used by the licensee were at the low end of the ranges recommended in the FL0-20 reference manual. The licensee stated that the use of the lower Manning's n values was consistent with site observations and the active maintenance of the site. The NRC staff conducted an independent LIP simulation using the licensee's FL0-20 computer model using larger Manning's n values (roughly doubled) to evaluate the parametric sensitivity of the WSEs to this particular parameter. The increase in the WSEs based on the parametric sensitivity analysis was less than 1 in (3 cm) at all critical door locations. This increase was judged by the staff to be negligible. Thus, based on the inconsequential change is estimated WSE, the staff determined that the Manning's n values used by the licensee were reasonable.

Based on the LIP and associated site drainage scenario described in the Hope Creek FHRR, the estimated WSE exceeds door sill elevations at multiple locations for critical structures within the Hope Creek powerblock. The computer simulations suggest that the door sill elevations are exceeded within 15 min. of the onset of the LIP event. Because current flood protection procedures require advance notice of 1 to 1.5 hrs to close critical watertight doors, the licensee proposed interim actions to determine the advance notice needed for an LIP flood event and to provide revised operating procedures.

3.2.5 Conclusion The NRC staff confirmed the licensee's conclusion that the reevaluated flood hazard for LIP and associated site drainage is not bounded by the COB flood hazard at the Hope Creek site.

Therefore, the NRC staff expects that the licensee will submit a focused evaluation for LIP and associated site drainage for Hope Creek consistent with the process and guidance discussed in COMSECY-15-0019 (NRC, 2015a).

3.3 Streams and Rivers The licensee reported in the Hope Creek FHRR that the reevaluated flood hazard, including associated effects, for streams and rivers is based on a WSE of 14.4 ft (4.4 m) NAV088 (stillwater). This elevation represents the combined effects of the PMF, 1O percent exceedance high tide, and the 25-yr storm surge. The effect of wind waves and runup was not included in the Hope Creek FHRR analysis. This flood-causing mechanism is discussed in the licensee's COB. The COB PMF elevation for streams and rivers is based on a WSE of 7.5 ft (2.3 m)

NAV088 (stillwater). The COB elevation including wind waves and runup results is 20.0 ft (6.1 m) NAV088.

The licensee's reevaluation of flooding on streams and rivers described in the Hope Creek FHRR included three components: developing PMP events, simulating the PMFs from those storm events, and evaluating the effect of combined events (PSEG, 2014a). The licensee used the analysis described in the PSEG ESP (2015b) to determine the applicable PMP events and the reevaluated PMF for the Delaware River at the Hope Creek site. The licensee (PSEG, 2015b) stated that the methods used followed guidance in ANSl/ANS-2.8-1992 (1992) and NRC (1977). The licensee further stated that the combined events analysis was performed consistent with the guidance contained in ANSl/ANS-2.8-1992 (1992) and NUREG/CR-7046 (NRC, 2011e).

3.3.1 Probable Maximum Precipitation The licensee considered two alternative precipitation scenarios based on PMP depths and methods from HMR Nos. 51 (NOAA, 1978) and 52 (NOAA, 1982). The licensee adjusted the size and orientation of the thunderstorm events to maximize the rainfall depth, and used center-weighted, 96-hr hyetographs (PSEG, 2013). One of the alternative PMP events considered was a 15,000 mi 2 (38,900 km 2 ) storm centered approximately 25 mi (40.2 km) north of Philadelphia and oriented in such a fashion to cover the entire Delaware River watershed, with a peak rainfall intensity of 3.3 in/hr (8.3 cm/hr) and a 72-hr average rainfall depth of 12.1 in (30. 7 cm). The second alternative PMP event considered was a 2, 150 mi 2 (5,570 km 2 ) storm, also centered over Philadelphia, and oriented in such a fashion to maximize rainfall depth in the sub-basin directly upstream of the Hope Creek site, with a peak rainfall intensity of 9.5 in/hr (24 cm/hr) and a 72-hr average rainfall depth of 22.2 in (56.4 cm).

The NRC staff reviewed the documents provided by the licensee (PSEG, 2014b) to develop the respective PMP estimates, and verified that the methods used to derive the PMP depths (PSEG, 2013) were consistent with HMR Nos. 51 and 52. The NRC staff also reviewed the isohyetal patterns of the two preferred PMP events (Figures 2.4.3-2 and 2.4.3-3 of the PSEG ESP (PSEG, 2015b)) and determined that the size and orientation of those rainfall events were consistent with guidance in HMR No. 52 for maximizing surface runoff.

3.3.2 Snowpack and Snowmelt The NRC staff observed that the Hope Creek FHRR did not address flooding due solely to snowpack/snowmelt (PSEG, 2014a). Both ANSl/ANS-2.8-1992 (1992) and NUREG/CR-7046 (NRC, 2011e) recommend that consideration of snowpack/snowmelt-derived flooding take place as part of the PMF analysis. During the June 2015 audit (NRC, 2016a), the licensee stated that snowmelt was not considered as part of the flood hazard reevaluation because it was determined that the WSE attributed to storm surge was estimated to be much greater than any potential WSE due to a streams and rivers PMF that would also take into account the influence of snow melt. In support of this position, the licensee referred to the analysis it conducted in connection with the failure of an ice jam (see Section 3.8 of this staff assessment). The licensee further stated that snowmelt would tend to occur in the spring, whereas storm surge would occur in the summer and fall; because these events are out-of-phase, the licensee indicated that a higher postulated WSE associated with snowmelt was unlikely, as was the case for a combined scenario involving snowmelt discharge and storm surge.

In considering these arguments, the NRC staff was also aware that tidal flux dominates flow conditions at the Hope Creek site as previously reported by Miller (1962). Based on the totality

of the information presented, the NRC staff determined that the licensee's decision to not consider this particular parameter in the PMF calculation was reasonable.

3.3.3 Probable Maximum Flood The licensee estimated the PMF at River Mile 52 (the approximate northern boundary of the Hope Creek site) using the USACE's Hydrologic Engineering Center Hydrologic Modeling System (HEC-HMS) model (USAGE, 2010b) to calculate runoff from the PMP events, and the complimentary Hydrologic Engineering Center River Analysis System (HEC-RAS) computer code (USAGE, 201 Oa) to route the runoff through the Delaware River and its tributaries (PSEG, 2015b). Sub:basins in the HEC-HMS model ranged from 1 to 676 mi 2 (1.6 to 1,088 km 2 ) in size.

The licensee used the Soil Conservation Service hydrograph method (NRCS, 2007) to calculate runoff hydrographs from the sub-basins. The licensee also selected nearly-saturated soil-moisture conditions (impervious) in the model to provide greater surface runoff (PSEG, 2015b).

The licensee described the calculation of base flow values as initial conditions for upland tributaries, and stated that routing of the flood hydrographs did not include attenuation or diffusion processes.

Using input files provided, the NRC staff verified that the configuration of the HEC-HMS model used in the licensee's analysis were consistent with the Hope Creek FHRR description. For example, the NRC staff spot-checked sub-basin soil moisture values and verified they were consistent with nearly-saturated conditions; calculated area-weighted sub-basin losses and determined that they were insignificant (less than 0.25 percent); and evaluated the HEC-HMS input parameters provided by the licensee and determined that they were reasonable for the conditions of the watershed. The licensee reduced the calculated time of concentration for each sub-basin by 40 percent, which the NRC staff notes is consistent with NUREG/CR-7046 (NRC, 2011e). Lastly, the NRC staff independently ran the HEC-HMS model using the licensee's input files and determined that there were no error messages nor any significant warning messages.

The HEC-RAS model extended from Trenton, which is north of the site, to the mouth of the Delaware River at the Delaware Bay. The licensee obtained bathymetric and topographic data from multiple sources, and merged these data into a terrain model to develop 69 cross-sections used in the hydraulic model. The licensee calibrated the Manning's n coefficients for the tidal portion of the HEC-RAS model using astronomical tidal data and Delaware River discharge data for the Trenton location. The licensee also used the HEC-HMS model results as lateral and upstream inflows to the HEC-RAS model, and stated that a downstream boundary condition of 0 ft (0.0 m) NAVD88 was used (PSEG, 2015b).

Using input files provided by the licensee, the NRC staff determined that the configuration of the HEC-RAS model was consistent with the description in the Hope Creek FHRR. The NRC staff verified the distances along the Delaware River using the U.S. Geological Survey's (USGS's)

National Map Viewer (USGS, 2016). The NRC staff observed that five bridges spanning the river were not included in the model, and that in some areas, some cross sections that include lateral inflows appear to have been blocked off. The NRC staff concluded that these

assumptions are reasonable 1

• The NRC staff determined that the primary conservative assumptions in the licensee's models were associated with the HEC-HMS model.

Of the two PMP events considered, the licensee stated that the thunderstorm centered over the greater Philadelphia area resulted in greater flow at River Mile 52; peak discharge for this case was 1,478,000 cfs (41,900 m 3/s) with a corresponding maximum WSE of 2.6 ft (0.8 m) NAVD88 (PSEG, 2015b). Using the HEC-RAS files provided by the licensee, and a constant downstream boundary of elevation Oft (0.0 m) NAVD88, the NRC staff confirmed the licensee's results and determined that maximum WSEs were reasonable.

3.3.4 Combined Events The licensee considered two alternatives to estimate the flooding effects from the combined events flood (PSEG, 2014a). For both alternatives, the PMF in the Delaware River was based on the PMP thunderstorm centered over the Philadelphia area. The NRC staff reviewed the combined events alternatives evaluated by the licensee and determined that they are consistent with guidance in ANSl/ANS-2.8-1992 (1992).

3.3.4.1 PMF Alternative 1 For the first alternative, the licensee combined one-half of the PMF for the Delaware River, the 10 percent exceedance high tide, and the surge and seiche from the worst regional hurricane reported in the literature (PSEG, 2014a). The licensee calculated the one-half PMF by reducing the HEC-HMS hydrographs from the PMF simulation by 50 percent and then used that reduced hydrograph as an input to the HEC-RAS model of the Delaware River basin (described in Section 3.3.3) (PSEG, 2013). Using the 10 percent exceedance high tide (4.5 ft (1.4 m)

NAVD88 at River Mile 52) as a HEC-RAS downstream boundary condition, the licensee calculated a maximum WSE at River Mile 52 of 6.6 ft (2.0 m) NAVD88 (PSEG, 2014a).

The NRC staff reviewed the information presented in PSEG (2015b) and determined that the licensee's calculation of the 10 percent exceedance high tide was consistent with guidance in ANSl/ANS-2.8-1992 (1992). Using the input files provided by the licensee (PSEG, 2014b), the NRC staff also confirmed the licensee's maximum elevation at River Mile 52 for the combined one-half PMF and 10 percent exceedance high tide.

The licensee reviewed available water level data for the Delaware Bay and determined that the 2012 Hurricane Sandy (October 29-30) resulted in the highest storm surge elevation and therefore was the worst storm of record (PSEG, 2014a). Using the combined ADvanced CIRCulation and Simulating WAves Nearshore (ADCIRC/ SWAN) model, the licensee performed a simulation of this particular hurricane event and reported that the storm surge alone (i.e., without the influence of astronomical tides or river discharge) resulted in a maximum WSE 1 In the case of the former modeling assumption, the five bridges that were not included in the HEC-RAS model were upstream of the site at River Mile 81.9, so excluding these could be conservative if their presence would affect the flood wave by blocking (attenuating) downstream flow. In the case of the latter modeling assumption, by blocking-off lateral inflows at some river cross-sections, the potential flux (flood storage) attributed to these inflowing streams would not be included in the model. This reduction in flood storage would tend to increase the downstream flood elevations by virtue of slower river base-flow velocities, and is thus conservative.

at River Mile 52 of 6.5 ft (2 m) NAVD88 (PSEG, 2014a). The NRC staff reviewed the tidal gage data at Reedy Point, DE (located at about River Mile 58.5, to the north of the Hope Creek site) observed during Hurricane Sandy (NOAA, 2015), and determined that the maximum storm surge was about 5.8 ft (1.8 m). Because this observed value is less than the value obtained from the licensee's computer simulation, the NRC staff determined that the licensee's estimate of the surge from the worst storm of record was conservative.

The licensee combined the 2012 Hurricane Sandy WSE (6.5 ft (2 m) NAVD88) with the WSE obtained from the one-half PMF computer simulation and the 1O percent exceedance high tide (6.6 ft (2.0 m) NAVD88), and reported a maximum WSE of 13.1 ft (4.0 m) NAVD88 for the Alternative 1 Scenario (PSEG, 2014a). The NRC staff notes that wind-wave runup for the Alternative 1 scenario were not included. Calculation of wave runup at the PSEG ESP site, coincident with two separate hurricane events (PSEG, 2013), was estimated by the ESP applicant to be 3.1 ft (0.9 m). The NRC staff estimated the maximum total WSE for the PMF Alternative 1 scenario at the Hope Creek site, including wind-wave activity consistent with ANSI/ANS-2.8-1992 ( 1992), was 16.2 ft (4.9 m) NAVD88 (the sum of the licensee's stillwater elevation from the Hope Creek FHRR and the wave runup from (PSEG, 2013)). The maximum WSE for PMF Alternative 1 is also less than the storm surge scenario discussed in Section 3.5 below.

3.3.4.2 PMF Alternative 2 For the second alternative, the licensee combined three scenarios: the PMF for the Delaware River, the 1O percent exceedance high tide, and the 25-yr surge event. Using the 1O percent exceedance high tide as a downstream boundary condition in the HEC-RAS computer model (described in Section 3.3.3), the licensee calculated a maximum WSE at the River Mile 52 location (i.e., the Hope Creek site) of 7.6 ft (2.3 m) NAVD88 (PSEG, 2014a). Using the input files provided by the licensee (PSEG, 2014b), the NRC staff's independent estimate at the same location was 7.6 ft (2.3 m) NAVD88. Although this value is 0.3 ft (0.1 m) higher than the licensee's estimate, the NRC staff determined that the difference was inconsequential and would have no impact on the NRC staff's conclusions regarding the extent of flooding for this hazard mechanism.

The licensee evaluated the scenario using data obtained from the USACE for a coastal flood study, and reported an elevation of 7.1 ft (2.2 m) NAVD88 for this event, without the tidal component (PSEG, 2014a). The NRC staff reviewed information in (USACE, 1997), which reported 25-yr return period WSEs of 6.1 ft (1.9 m) NAVD88 at Lewes, DE (at the mouth of the bay, about 50 miles to the south of the site), and 5.8 ft (1.8 m) NAVD88 at Reedy Point. Based on these WSE magnitudes as well as the 2012 Hurricane Sandy surge (6.5 ft (2 m) NAVD88, from Section 3.3.4.1 ), the NRC staff determined that the licensee's stillwater value of 7.1 ft (2.2 m) NAVD88 was a reasonable estimate of the maximum WSE at the Hope Creek site for the 25-yr surge event.

The licensee summed the 25-yr surge WSE (7.1 ft (2.2 m) NAVD88) with the combined elevation for the PMF in the Delaware River simulation and the 1O percent exceedance high tide (7.3 ft (2.2 m) NAVD88), and reported a total (maximum) WSE of 14.4 ft (4.4 m) NAVD88 for PMF Alternative 2 scenario (PSEG, 2014a). The licensee stated that this composite elevation does not include coincident wave runup at the site (PSEG, 2014a). As discussed in Alternative 1 PMF scenario, the coincident wave runup for two separate hurricane events was

estimated to be 3.1 ft (0.9 m) (PSEG, 2015b). The NRC staff estimated the maximum total WSE for the PMF Alternative 2 scenario at the Hope Creek site, including wind-wave activity consistent with ANSl/ANS-2.8-1992 (1992), is 17.8 ft (5.4 m) NAVD88.

The maximum flood elevation estimated for the Alternative 2 PMF scenario was 17.8 ft (5.4 m)

NAVD88. Although this WSE exceeds the nominal site grade of 11. 7 ft (3.6 m) NAVD88, it is significantly lower than the COB elevation for storm surge scenario discussed in Section 3.5, below. The NRC staff also notes that the Delaware River PMF contributes less than 3 ft (0.9 m) to the total WSE at the site, while the dominant contributor is the storm surge.

3.3.5 Conclusion In summary, the NRC staff confirmed the licensee's conclusion that the reevaluated hazard for flooding due to streams and rivers is bounded by the COB flood hazard at the Hope Creek site.

Therefore, the NRC staff determined that flooding from streams and rivers does not need to be analyzed in a focused evaluation or an additional assessment consistent with the process and guidance discussed in COMSECY-15-0019 (NRC, 2015a).

3.4 Failure of Dams and Onsite Water Control/Storage Structures The licensee reported in the Hope Creek FHRR (PSEG, 2014a) that the reevaluated flood hazard, including associated effects, for failure of dams and onsite water control or storage structures is a WSE of 7.4 ft (2.3 m) NAVD88 (stillwater). The COB for failure of dams and onsite water control or storage structures is 12.7 ft (3.9 m) NAVD88 (stillwater) and 25.5 ft (7.8 m) NAVD88 including waves/runup.

The licensee stated in the Hope Creek FHRR (PSEG, 2014a) that the evaluation of flooding from dam failure followed the simplified modeling approaches described in JLD-ISG-2013-01 (NRC, 2013). Citing the USACE's National Inventory of Dams (USAGE, 2015b) database, the licensee identified 1,024 dams upstream of the Hope Creek site; dam height and reservoir storage information contained in the database were used in the licensee's dam failure analysis.

Dam heights reported in the database ranged from 3.5 to 280 ft (1.1 to 85.3 m).

The licensee then developed an attenuation function for each dam, as described in Hope Creek FHRR (PSEG, 2014a). Using these attenuation functions, and the distance of each dam from the Salem site, the licensee calculated an attenuated discharge value for each individual dam in the drainage basin. The results of that calculation produced a cumulative discharge of 908,000 cfs (25,700 m3/s) for all 1,024 dams; this cumulative discharge produced a WSE of 0.9 ft (0.3 m) above the base hydrologic conditions. The base hydrologic conditions were a WSE of 6.5 ft (2.0 m) NAVD88, defined by the licensee as the 1O percent exceedance high tide (a WSE of 4.5 ft (1.4 m) NAVD88} plus the 500-yr PMF (2.0 ft (0.6 m)) (PSEG, 2015b). The licensee's attenuated dam failure flood wave added 0.9 ft (0.3 m) to the base hydrologic conditions, resulting in an estimated maximum WSE by the licensee of 7.4 ft (2.3 m) NAVD88 (stillwater) for the dam failure scenario at the Hope Creek site.

In reviewing the Hope Creek FHRR analysis, the NRC staff notes the licensee followed simplified modeling methodologies discussed in JLD-ISG-2013-01 (NRC, 2013). Using information from USAGE (2015b) and Delaware River Basin Commission (DRBC) Reservoirs Map (DRBC, 2015), the NRC staff verified that the licensee included the major Delaware River

Basin reservoirs in the dam failure analysis. For those dams, the NRC staff spot-checked the dam height and storage values used by the licensee, verified the peak discharge values, and determined that the distances from the Hope Creek site were reasonable. The NRC staff verified the licensee's attenuated discharge values at the River Mile 50.8 location (the approximate location of the Salem site). The NRC staff determined that the licensee's linear extrapolation of the stage-discharge relationship would lead to cumulative discharge values approximately equal to 900,000 cfs (25,000 m 3/s); in the NRC staff's estimation, the licensee's estimate of 908,000 cfs (25,700 m3/s) is therefore a reasonable estimate. Lastly, the NRC staff used the stage-discharge relationship described in the Hope Creek FHRR (PSEG, 2014a) to perform a sensitivity analysis. The NRC staff hypothesized an 85 percent increase in the licensee's estimated sum of attenuated discharges and determined that this would only increase the WSE 1.1 ft (0.3 m) above the licensee's estimate at the Hope Creek site.

Coincident wind setup and wave runup activity was not considered as part of the licensee's dam failure scenario in the Hope Creek FHRR. However, as part of the PSEG ESP, the licensee estimated an increase in WSE of 2.6 ft (0.8 m) due to these coincident activities. Therefore, the NRC staff conservatively estimated the maximum dam-failure WSE, including wind-wave activity and discharge uncertainty, to be 11.1 ft (3.4 m) NAV088 (i.e., the sum of the licensee's stillwater elevation 7.4 ft (2.3 m) NAV088 plus 2.6 ft (0.8 m) for setup/runup plus an additional 1.1 ft (0.3 m) for the discharge uncertainty). The NRC staff notes this maximum WSE is much less than the storm surge COB stillwater WSE if 24 ft (7.3 m) NAV088, which is discussed in Section 3.5 below.

In summary, the NRC staff confirmed the licensee's conclusion that the reevaluated hazard for flooding due to the failure of dams and onsite water control or storage structures is bounded by the COB flood hazard at the Hope Creek site. Therefore, the NRC staff determined that flooding from dam failure does not need to be analyzed in a focused evaluation or an additional assessment consistent with the process and guidance discussed in COMSECY-15-0019 (NRC, 2015a).

3.5 Storm Surge The licensee reported in the Hope Creek FHRR (PSEG, 2014a) that the reevaluated flood hazard for storm surge is a stillwater WSE of 22.5 ft (6.9 m) NAV088. The reevaluated total WSE, which includes associated effects for each of the critical locations around the Hope Creek site, are summarized in Table 3.5-1 and are lower than the COB storm surge WSE. The COB stillwater storm surge WSE is 24 ft (7.3 m) NAV088.

The licensee used a probabilistic-deterministic storm surge methodology for developing the 1o-6 annual exceedance probability storm surge flood elevation at the Hope Creek site. The licensee stated that the approach follows the current state-of-practice used by both the Federal Emergency Management Agency (FEMA) and the USACE for storm surge inundation analyses (FEMA, 2012 and Divoky and Resio, 2007) as well as the methodologies discussed in NUREG/CR-7134 (NRC, 2012d).

In lieu of completing the review of the licensee's probabilistic-deterministic methodology, the NRC staff relied on an independent analysis the NRC staff had recently developed for the adjacent PSEG site in connection with the recently-issued ESP (NRC, 201 Sc). For this analysis, the NRC staff performed an independent deterministic storm surge analysis using a

combination of the two-dimensional ADCI RC hydrodynamic model and the SW AN wave model.

For the Hope Creek site, the NRC staff applied these independently-developed models to calculate deterministic WSEs, including site-specific associated effects (wave runup). Wave runup calculations developed for the Hope Creek site by the NRC staff are based upon the latest design guidance found in the USACE's (2002, Chapter Vl-5) Coastal Engineering Manual (CEM) (Taylor, 2015).

Using results obtained from NRC staff's ADCIRC and SWAN models, the NRC staff independently calculated a stillwater elevations at the Hope Creek site. The NRC staff also calculated a maximum total WSE, including wave runup. The NRC staff's independent calculations support the conclusion that the reevaluated flood hazard due to storm surge is bounded by the COB for the Hope Creek site. Further information regarding the NRC staff's independent analysis can be found in Taylor Engineering (Taylor, 2015).

In summary, the NRC staff confirmed the licensee's conclusion that the reevaluated hazard for flooding due to storm surge is bounded by the COB flood hazard at the Hope Creek site.

Therefore, the NRC staff determined that flooding from storm surge does not need to be analyzed in a focused evaluation or an additional assessment consistent with the process and guidance discussed in COMSECY-15-0019 (NRC, 2015a).

3.6 Seiche The licensee reported in the Hope Creek FHRR (PSEG, 2014a) that the reevaluated hazard, including associated effects, for site flooding from seiche does not inundate the plant site. The licensee concluded that seiche is not likely at the Hope Creek site for the following reasons: (a) large amplitude oscillations are not possible in the Delaware Bay Estuary, (b) the most probable forcing mechanisms lack a period of oscillation close enough to the fundamental period (corresponding to the dimensions of the Delaware Bay Estuary) to be of concern, and (c) a magnitude and duration great enough to supply a significant amount of energy into the basin is unlikely to occur.

The licensee stated that the free oscillation period of the fundamental mode seiche propagating along the length of the Delaware Bay Estuary from its mouth (at River Mile 0) to the head of tide at Trenton (River Mile 134) is 31 hours1.292 days <br />0.185 weeks <br />0.0425 months <br /> (USAGE, 2002). The periods for wind-generated waves in the Delaware Estuary could range from between one to seven seconds. Since these periods are very much shorter than the fundamental period of free oscillation for the Delaware Estuary (Wong and Garvin, 1984), the licensee concluded that no wave resonance would occur. The licensee also stated that the Delaware Bay would not resonate in response to seismic activity.

Seismic waves generally have a period of 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or less (Oliver, 1962). Lastly, the astronomical tide for this location has a period on the order of 12 hours0.5 days <br />0.0714 weeks <br />0.0164 months <br />, which is approximately one half to one third of the maximum oscillation period of the Delaware Estuary. Thus, the astronomical tide would not provide the forcing mechanism necessary to generate resonance.

The NRC staff applied the seiche equations presented in the USACE's CEM (USAGE, 2002),

and confirmed the primary and secondary mode periods with representative length and depth values for the Delaware Bay Estuary system. According to the CEM, an open basin whose length is 134 mi (216 km) and whose average depth is 20 ft (6.1 m) results in a primary seiche mode equal to 31.1 hours0.0417 days <br />0.00595 weeks <br />0.00137 months <br />. Based on these physical dimensions, the first fundamental seiche

mode (first harmonic) is estimated to be about 10.4 hours0.167 days <br />0.0238 weeks <br />0.00548 months <br />. These seiche periods confirm the values stated by the licensee.

The NRC staff also reviewed the two journal articles (studies) of sub-tidal (lower frequency than the tide) water level fluctuations in Delaware Bay referenced in Section 2.4.5.8, "Seiche and Resonance," of the PSEG ESP SSAR (PSEG, 2015b). The NRC staff's review of those cited journal articles {Wong and Moses-Hall, 1998; and Wong and Garvin, 1984) confirmed the licensee's positions concerning wind effects on sub-tidal water level fluctuations and the periods of those fluctuations.

In summary, the NRC staff confirmed the licensee's conclusion that the reevaluated hazard for flooding due to seiche is bounded by the COB flood hazard at the Hope Creek site. Therefore, the NRC staff determined that flooding from seiche does not need to be analyzed in a focused evaluation or an additional assessment consistent with the process and guidance discussed in COMSECY-15-0019 (NRC, 2015a).

3.7 Tsunami The licensee reported in the Hope Creek FHRR {PSEG, 2014a) that the reevaluated hazard, including associated effects, for site flooding from tsunami does not inundate the plant site. This flood-causing mechanism is described in the licensee's COB. The reevaluated PMF elevation, including associated effects, for site flooding due to tsunami reported in the Hope Creek FHRR is 5.7 ft (1.7 m) NAVD88.

The Hope Creek FHRR analysis began with an examination of the scientific literature to establish the probable maximum tsunami (PMT) at the site based on the published reports.

Next, the licensee performed a numerical tsunami simulation using the Method of Splitting Tsunami {MOST) computer code developed by Titov and others {1997 and 1998). That computer model considered a range of near-field and far-field seismogenic sources capable of generating a tsunami, and could be used to reconstruct the WSEs reported in the literature.

Those seismogenic source-zones (scenarios) considered included a subduction zone event occurring within the Hispaniola Trench (Caribbean), the collapse of a volcanic cone in the Canary Islands (Atlantic Ocean), and a Currituck-like submarine landslide event on the continental shelf margin (North America). The MOST computer simulations suggest that the PMT at the Hope Creek site was found to be due to a Currituck-like submarine landslide event.

The runup values calculated during the MOST simulations were reported to be comparable to the 1O percent exceedance high tide at the site, which serves as the initial static water level condition in the tsunami computer simulations. The 1O percent exceedance high tide is 4.5 ft (1.4 m) NAVD88 and is based on historical observation data from the NOAA tidal gage at Reedy Point (NOAA, 2015). Using the MOST computer model (and ignoring bottom friction effects),

the maximum runup at the Hope Creek site was estimated to be 5.7 ft (1.7 m) NAVD88; by way of comparison, the grade elevation of the powerblock is 11. 7 ft (3.6 m) NAVD88.

The NRC staff conducted an independent analysis to confirm the magnitude of the PMT at the Hope Creek site. The NRC staff performed numerical modeling of three tsunami sources consisting of both the far-field and far-field seismogenic source zones as potential PMT generators (ten Brink et al, 2008). In conducting its independent analysis, the NRC staff relied on the Boussinesq-based Cornell University Long and Intermediate Wave (COULWAVE)

(Lynett and Liu, 2002) computer model to evaluate the three tsunami scenarios described above. In performing those simulations, the NRG staff relied on conservative modeling parameters, some even physically implausible, to provide a highly conservative (absolute upper limit) of a PMT at the PSEG Site. That independent computer analysis found that the PMT at the Hope Creek site was estimated to be 8.5 ft (2.6 m) NAVD88; the seismogenic source for the tsunami was the Currituck-like landslide. This estimate included consideration of both high tide and sea level rise.

In summary, the NRG staff confirmed the licensee's conclusion that the reevaluated hazard for flooding due to tsunamis is bounded by the COB flood hazard at the Hope Creek site.

Therefore, the NRC staff determined that flooding from tsunamis does not need to be analyzed in a focused evaluation or an additional assessment consistent with the process and guidance discussed in COMSECY-15-0019 (NRC, 2015a).

3.8 Ice-Induced Flooding The licensee reported in the Hope Creek FHRR (PSEG, 2014a) that the reevaluated hazard, including associated effects, for site flooding from ice-induced flooding does not inundate the plant site. The licensee reported in the Hope Creek FHRR that the reevaluated flood hazard for ice-induced flooding is 5.3 ft (1.6 m) NAVD88. When wind waves and runup effects were considered, the resulting WSE was 8.1 ft (2.5 m) NAVD88.

The licensee stated that the evaluation of ice-induced flooding is applicable to the Hope Creek site (PSEG, 2013). In its evaluation of this flood-causing mechanism, the licensee initially queried the Cold Regions Research and Engineering Laboratory (CAREL) ice jam database maintained by the (USAGE, 2015a) for information on water levels and discharges associated with past ice jams reported on the Delaware River. Based on that review, the licensee determined that the most severe event reported in the CAREL database was a 1904 event, with an estimated water level of 29.6 ft (9.0 m) NAVD88 at Trenton (USGS, 2014). The licensee then used the HEC-RAS computer model (USAGE, 201 Oa) to simulate the consequences of the failure of that 1904 ice dam, routing the discharge downstream to the location of the PSEG ESP site (PSEG, 2015b). The computer simulation included consideration of the 10% exceedance high tide (4.5 ft (1.4 m) NAVD88 at the PSEG ESP site) as well as average spring base flow which, when combined, produced a WSE of 5.2 ft (1.9 m) NAVD88 at the location of the PSEG ESP site. The licensee's simulation of the 1904 ice dam failure resulted in increase in the river elevation of 0.1 ft (0.03 m) at the PSEG ESP site leading to a stillwater elevation of 5.3 ft (1.6 m)

NAVD88 (PSEG, 2013). The licensee stated that coincident wave runup, taking into account a 2-yr wind speed in the critical-direction, contributed an additional 2.8 ft (0.9 m) of flooding, resulting in a total WSE of 8.1 ft (2.5 m) NAVD88 (PSEG, 2014a) at the site.

In connection with their independent review of the Hope Creek FHRR, the NRC staff also reviewed the CAREL ice jam database (USAGE, 2015a) for records of historical ice jams on the Delaware River, and found that the ice jams reported nearest to the Hope Creek site were at Trenton. The NRC staff verified that the 1904 ice jam resulted in the highest reported WSE at Trenton (USGS, 2014). The NRC staff found no other accounts of ice dams occurring on the main stem of the Delaware River below Trenton. Under the flooding scenario considered by the licensee, the WSE at the Hope Creek site increased only 0.1 ft (0.03 m) following failure of the 1904 ice dam. The NRC staff did a comparison of the magnitude of the discharges considered in connection with the review of the dam failure scenarios (earlier Section 3.4), the NRC staff

determined that the ice dam failure-induced flood elevation at the Hope Creek site would be less than the elevation resulting from any credible dam failure scenario within the Delaware River watershed.

In summary, the NRG staff confirmed the licensee's conclusion that the reevaluated hazard for flooding due to ice jams is bounded by the CDS flood hazard at the Hope Creek site. Therefore, the NRG staff determined that flooding from ice jams does not need to be analyzed in a focused evaluation or a revised integrated assessment consistent with the process and guidance discussed in COMSECY-15-0019 (NRG, 2015a).

3.9 Channel Migrations or Diversions The licensee reported in the Hope Creek FHRR (PSEG, 2014a) that the reevaluated hazard, including associated effects, for channel migrations or diversions does not impact the plant site.

The Hope Creek FHRR (PSEG, 2013) states that the Delaware River has existed in its current location for at least the last 10,000 yrs. The licensee further noted that there was no geomorphic/geologic evidence of channel diversion within the greater Delaware River basin.

The licensee stated that the potential for flooding from landslides, mudslides, or other temporary channel diversions is highly unlikely due to the relatively low topography of the terrain contiguous to the Delaware River and the shallowness of the river channel itself (PSEG, 2014a).

Lastly, there are no levees on the main stem of the Delaware River that would be used to prevent the river from demonstrating natural meander behavior {Leopold and Wolman, 1960) further suggesting the absence of channel migration.

The NRG staff guidance described in NUREG/CR-7046 {NRG, 2011e) acknowledges that there are no well-established predictive models for estimating the potential for channel diversion in a riverine environment. However, the potential for channel migrations or diversions to take place at a particular location can be assessed by reviewing certain types of information, such as topographic maps, that are generally recognized to reflect evidence of the horizontal movement (meandering) of rivers and streams. If there were evidence of channel migration or river meandering in the past, there would be evidence to that effect present on the topographic map reviewed of the area. The particular geomorphic features of interest are generally recognized to include river meanders, meander belts, flood plains, oxbow lakes, natural levees, and the like (Salisbury and Atwood, 1908). The NRC staff's review of this topic involved reviewing the USGS's historic topographic map digital data base (USGS, 2015). The goal was initially to identify the earliest map published for the area and then inspecting those map for geomorphic evidence of channel diversion {including river meandering). After completing that review, the NRG staff would then inspect more recently-prepared map of the reactor site to see if there had been changes in the topography in the intervening years.

The NRG staff's review of the USGS's historic data base of topographic map of the Hope Creek site and environs did not reveal any evidence of meandering. This comparison leads the NRG staff to conclude that there is no physical evidence of river meandering and/or channel diversion for at least the last century. In addition, the NRG staff also independently reviewed USGS (1982) and confirmed from this publication that landslide incidence in the lower Delaware River is low. Lastly, the Delaware River shoreline adjacent to the PSEG site is known to be protected from erosion through the use of rip-rap, groins, or other engineered devices.

In summary, the NRC staff confirmed the licensee's conclusion that the reevaluated hazard for flooding due channel migration or diversion is bounded by the COB flood hazard at the Hope Creek site. Therefore, the NRC staff determined that flooding from channel migration or diversion does not need to be analyzed in a focused evaluation or a revised integrated assessment consistent with the process and guidance discussed in COMSECY-15-0019 (NRC, 2015a).

4.0 REEVALUATED FLOOD ELEVATION, EVENT DURATION, AND ASSOCIATED EFFECTS FOR HAZARDS NOT BOUNDED BY THE COB 4.1 Reevaluated Flood Elevation for Hazards Not Bounded by the COB Section 3 of this staff assessment documents the NRC staff review of the licensee's flood hazard water elevations results. Table 4.1-1 contains the maximum results, including waves and runup, for flood mechanisms not bounded by the COB presented in Table 3.1-1. The NRC staff agrees with the licensee's conclusion that LIP is the only hazard mechanism not bounded by the COB. Consistent with the process and guidance discussed in COMSECY-15-0019 (NRC, 2015a), NRC staff anticipates the licensee will submit a focused evaluation for LIP and associated site drainage.

4.2 Flood Event Duration for Hazards Not Bounded by the COB The NRC staff reviewed information provided in PSEG's 50.54(f) response (PSEG, 2014a; PSEG, 2014b; and NRC, 2016) regarding the FED parameters needed to perform the additional assessments of plant response for flood hazards not bounded by the COB. The FED parameter values for the flood-causing mechanisms identified in Section 4.1 of this staff assessment are summarized in Table 4.2-1.

The licensee provided FED parameter values for the LIP flood-causing mechanism. Based on the LIP analysis and associated site *drainage scenario described in the Hope Creek FHRR, the WSEs estimated by the licensee exceeds door sill elevations at multiple locations for critical structures within the Hope Creek powerblock. The licensee's computer simulations suggested that the door sill elevations at certain locations are exceeded within 15 minutes of the onset of the LIP event and remained above those door sills for approximately 5 to 8 hours0.333 days <br />0.0476 weeks <br />0.011 months <br /> (PSEG, 2014a). Because current flood protection procedures require advance notice of 2 hours0.0833 days <br />0.0119 weeks <br />0.00274 months <br /> to close critical watertight doors, the licensee proposed interim actions to determine the advance notice needed for an LIP flood event and to provide revised operating procedures.

The licensee is expected to use the estimated LIP FED parameter values reported in the Hope Creek FHRR (PSEG, 2014a) when it conducts the MSA and focused evaluations.

4.3 Associated Effects for Hazards Not Bounded by the COB The NRC staff reviewed information provided in PSEG's 50.54(f) response (PSEG, 2014a; PSEG, 2014b; and NRC, 2016) regarding AE parameters needed to perform future additional assessments of plant response for flood hazards not bounded by the COB. The AE parameters directly related to the maximum WSE, such as wave height and runup, are provided in Table 4.1-1 of this staff assessment. The AE parameters not directly associated with a

maximum WSE are listed in Table 4.3-1. The AE parameters not submitted as part of the Hope Creek FHRR are designated as "not provided" in this table.

The licensee is expected to develop AE parameters for LIP to conduct the MSA and focused evaluations or revised integrated assessments. The NRC staff will review the values for these parameters as part of future assessments of the plant response to the identified flood-causing mechanism, if applicable.

4.4 Conclusion Based upon the preceding analysis, the NRC staff confirmed that the reevaluated flood hazard information defined in the Section 4 is an appropriate input to the additional assessments of plant response as described in the 50.54(f) letter (NRC, 2012a), COMSECY-15-0019, and associated guidance.

The licensee is expected to develop missing AE parameters to conduct the MSA and the focused evaluations or revised integrated assessments. The NRC staff will evaluate the missing associated effects marked as "not provided" in Table 4.3-1 during its review of the MSA and focused evaluations.

5.0 CONCLUSION

The NRC staff has reviewed the information provided for the reevaluated flood-causing mechanisms for the Hope Creek site. Based on the review of available information provided in PSEG's 50.54(f) response (PSEG, 2014a; PSEG, 2014b; and NRC, 2016), the NRC staff concludes that the licensee conducted the hazard reevaluation using present-day methodologies and regulatory guidance used by the NRC staff in connection with ESP and COL reviews.

Based upon the preceding analysis, the NRC staff confirmed that the licensee responded appropriately to Enclosure 2, Required Response 2, of the 50.54(f) letter, dated March 12, 2012.

In reaching this determination, NRC staff confirmed the licensee's conclusions that (a) the reevaluated flood hazard results for LIP are not bounded by the CDS flood hazard, (b) additional assessments of plant response will be performed for the LIP flooding mechanism, and (c) the reevaluated flood-causing mechanism information is appropriate input to the additional assessments of plant response as described in the 50.54(f) letter and COMSECY-15-0019 (NRC, 2015a), and associated guidance.

The NRC staff has no additional information needs with respect to PSEG's 50.54(f) response.

6.0 REFERENCES

Notes: ADAMS Accession Nos. refers 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 (NRC) Documents and Publications:

NRC (U.S. Nuclear Regulatory Commission), 1977, "Design Basis Flood for Nuclear Power Plants," Regulatory Guide 1.59, Revision 4, 1977.

NRC, 2007, "Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition," NUREG-0800, 2007. ADAMS stores the Standard Review Plan as multiple ADAMS documents, which are most easily accessed through the web page http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/ sr0800/.

NRC, 2011a, "Near-Term Report and Recommendations for Agency Actions Following the Events in Japan," SECY-11-0093, July 12, 2011, ADAMS Accession No. ML11186A950.

NRC, 2011 b, "Recommendations for Enhancing Reactor Safety in the 21st 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. ML111861807.

NRC, 2011c, "Recommended Actions To Be Taken without Delay from the Near-Term Task Force Report," SECY-11-0124, September 9, 2011, ADAMS Accession No. ML11245A158.

NRC, 2011 d, "Prioritization of Recommended Actions to be Taken in Response to Fukushima Lessons Learned," Commission Paper SECY-11-0137, October 3, 2011, ADAMS Accession No. ML11272A111 .

NRC, 2011 e, "Design-Basis Flood Estimation for Site Characterization at Nuclear Power Plants in the United State of America," NUREG/CR-7046, November 2011, ADAMS Accession No. ML11321A195.

NRC, 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, "Request for Information Pursuant to Title 1O of the Code of Federal Regulations 50.54(f) Regarding the Recommendations 2.1, 2.3, and 9.3, of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident," March 12, 2012, ADAMS Accession No. ML12056A046.

NRC, 2012b, 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, "Issuance of Order to Modify Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events," Order EA-12-049, March 12, 2012, ADAMS Accession No. ML12054A736.

NRC, 2012c, 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,

"Prioritization of Response Due Dates for Information Pursuant to 10 CFR 50.54(f) Regarding Flooding Hazard Reevaluations for Rec. 2.1 of the NTTF Review of Insights from the Fukushima Dai-ichi Accident," May 11, 2012, ADAMS Accession No. ML12097A510.

NRC, 2012d, "The Estimation of Very-Low Probability Hurricane Storm Surges for Design and Licensing of Nuclear Power Plants in Coastal Areas," NUREG/CR-7134, October 2012.

NRC, 2012e, "Guidance for Performing the Integrated Assessment for External Flooding,"

Japan Lessons-Learned Project Directorate, Interim Staff Guidance JLD-ISG-2012-05, Revision 0, November 30, 2012, ADAMS Accession No. ML12311A214.

NRC, 2013, "Guidance For Assessment of Flooding Hazards Due to Dam Failure," Japan Lessons-Learned Project Directorate, Interim Staff Guidance JLD-ISG-2013-01, Revision 0, July 29, 2013, ADAMS Accession No. ML13151A153.

NRC, 2014a, "Hope Creek Generating Station - Staff Assessment of Response to Enclosure 4 of the March 12, 2012, 10 CFR(f) Information Request - Flooding Walkdowns (TAC No.

MF0226)," June 16, 2014, ADAMS Accession No. ML14042A329.

NRC, 2014b, "Salem Nuclear Generating Station, Units 1 and 2 - Request for Additional Information Regarding Flooding Hazard Reevaluation (TAC Nos. MF3790 and MF3791 )," June 28, 2014, ADAMS Accession No. ML14168A242.

NRC, 2015a, "Closure Plan for the Reevaluation of Flooding Hazards for Operating Nuclear Power Plants," COMSECY-15-0019, June 30, 2015, ADAMS Accession No. ML15153A104.

NRC, 2015b, "Hope Creek Nuclear Generating Station - Interim Staff Response to Reevaluated Flood Hazards Submitted in Response to 10 CFR 50.54(f) Information Request - Flood-Causing Mechanism Reevaluation (TAC No. MF0236)," September, 10, 2015, ADAMS Accession No. ML15238B655.

NRC, 2015c, "Final Safety Evaluation Report for the PSEG Site Early Site Permit Application,"

September 25, 2015, ADAMS Accession No. ML15229A119.

NRC, 2016a, "Nuclear Regulatory Commission Report for the Audit of PSEG Nuclear LLC's Flood Hazard Revaluation Report Submittals Relating to the Near-Term Task Force Recommendation 2.1-Flooding for Hope Creek Generating Station Unit 1 (CAC No. MF3789),"

January 8, 2016, ADAMS Accession No. ML15364A055.

NRC, 2016b, "Compliance with Order EA-12-049 Order to Modify Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events," Interim Staff Guidance JLD-ISG-2012-01, Revision 1 and Comment Resolution, January 22, 2016, ADAMS Accession No. ML15357A142.

NRC, 2016c, "Guidance for Activities Related to Near-Term Task Force Recommendation 2.1, Flooding Hazard Reevaluation; Focused Evaluation and Integrated Assessment," Interim Staff Guidance JLD-ISG-2016-01, Revision 0, July 11, 2016, ADAMS Accession No. ML16162A301.

Codes and Standards ANSI/ANS (American National Standards Institute/American Nuclear Society), 1992, ANSl/ANS-2.8-1992, "Determining Design Basis Flooding at Power Reactor Sites," American Nuclear Society, LaGrange Park, IL, July 1992.

Other

References:

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Delaware River Basin Commission, available at:

http://www.state. nj. us/drbc/library/documents/maps/reservoirs2. pdf, accessed January 16, 2015.

Divoky, D., and D.T. Resio, 2007, "Performance of the JPM and EST Methods in Storm Surge Studies," in Joint WMO/IOC Technical Commission for Oceanography and Marine Meteorology, Proceedings of the 10th International Workshop on Wave Hindcasting and Forecasting and Coastal Hazard Symposium, North Shore, Oahu, Hawaii, November 11-16, 2007.

FL0-2D Software, Inc., 2009, "FL0-2D Reference Manual," Nutrioso, Arizona, Available at www.flo-2d.com.

FEMA (Federal Emergency Management Agency), 2012, Operating Guidance No. 8-12, "Joint Probability- Optimal Sampling Method for Tropical Storm Surge Frequency Analysis".

Leopold, L.B., and M.G., Wolman, 1960, River meanders. Geological Society of America Bulletin, 71 (6): 769-793, June 1960.

Lynett, P., and P.L.F. Liu, 2002, "A Numerical Study of Submarine-Landslide-Generated Waves and Run up," Proceedings of the Royal Society of London, A, Vol. 458: pp 2885-2910, December 2002.

Miller, E.G., "Observations of Tidal Flow in the Delaware River," U.S. Geological Survey Water-Supply Paper 1586-C, 1962.

NOAA (National Oceanic and Atmospheric Administration), 1978, "Probable Maximum Precipitation Estimates, United States, East of the 105th Meridian," NOAA Hydrometeorological Report No. 51, June 1978.

NOAA, 1982, "Application of Probable Maximum Precipitation Estimates, United States, East of the 105th Meridian," NOAA Hydrometeorological Report No. 52, August 1982.

NOAA, 2015, "Observed Water Levels at 8551910, Reedy Point, DE, from 2012/10/24 00:00 GMT to 2012/11/02 23:59 GMT," Accessed from:

http://tidesandcurrents.noaa.gov/stations. html?type=Water+Levels, January, 2015.

NEI (Nuclear Energy Institute), 2015, "Diverse and Flexible Coping Strategies (FLEX)

Implementation Guide," NEI 12-06 Revision 2, December 2015, ADAMS Accession No. ML16005A625.

Oliver, J., 1962, "A summary of observed seismic surface wave dispersion," Bulletin of the Seismological Society of America 52(1): 81-86, January 1962.

PSEG Nuclear LLC (PSEG), 2012a, "Hope Creek Generating Station Updated Final Safety Analysis Report," Revision 19, 2012.

PSEG, 2010, "Application for Early Site Permit for the PSEG Site." dated May 25, 2010, ADAMS Accession No. ML101480484.

PSEG, 2012, "Hope Creek - Response to Recommendation 2.3: Flooding Walkdown of the Near-Term Task Force Review of Insights from the Fukushima Dai-lchi Accident," dated November 26, 2012. ADAMS Accession No. ML12334A452.

PSEG, 2013, "Response to Recommendation 2.3: Flooding Walkdown of the Near-Term Task Force Review of Insights from the Fukushima Dai-lchi Accident - Changes to Hope Creek Generating Station's Flood Walkdown Report,", dated April 12, 2013. ADAMS Accession No. ML13106A066.

PSEG, 2014a, "Hope Creek - Response to Request for Information Regarding Flooding Aspects of Recommendation 2.1 of Near-Term Task Force Review of Insights from the Fukushima Dai-lchi Accident - Flood Hazard Reevaluation," March 7, 2017, ADAMS Accession Package No. ML14071A505.

PSEG, 2014b, "PSEG Nuclear LLC's 30-day Response to Request for Additional Information Regarding Flooding Aspects of Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident," dated July 28, 2014, ADAMS Accession No. ML14211A010.

PSEG, 2015a, "Submittal of Revision 4 of the Early Site Application for the PSEG Site dated June 5, 2015, ADAMS Accession No. ML15168A201.

PSEG, 2015b, "PSEG Power, LLC (Site Safety Analysis Report) Rev, 4 Chapter 02 - Site Characteristics and Site Parameters - Sections 2.0 - Appendix 2AA," dated June 5, 2015, ADAMS Accession No. ML15169A282.

Taylor Engineering, 2015, "Technical Evaluation Report Salem Generating Station Storm Surge Hazard Reevaluation Review," Jacksonville, Florida, May 2015, ADAMS Accession No. ML16280A523.

Brink, U., D. Twichell, E. Geist, J. Chaytor, J. Locat, H. Lee, B. Buczkowski, R. Barkan, A.

Solow, B. Andrews, T. Parsons, P. Lynett, J. Lin and M. Sansoucy, 2008, "Evaluation of Tsunami Sources with the Potential to Impact the U.S. Atlantic and Gulf Coasts," USGS administrative report to the U.S. Nuclear Regulatory Commission, 300 pp., August 22, 2008.

Titov, V.V., and F.I. Gonzalez et al., 1997, "Implementation and testing of the Method of Splitting Tsunami (MOST) model," NOAA Technical Memorandum ERL PMEL 112, Pacific Marine Environmental Laboratory.

Titov, V.V. and C.E. Synolakis, 1998, "Numerical Modeling of Tidal Wave Runup," Journal of Waterway, Port, Coastal, and Ocean Engineering. 124(4):157-171.

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USAGE, 2002, "Coastal Engineering Manual," Engineer Manual EM 1110-2-1100, Revision 1, 6 vols., U.S. Army Corps of Engineers, 2006.

USAGE, 201 Oa, "River Analysis System (HEC-RAS), Version 4.1.0," Hydrologic Engineering Center, U.S. Army Corps of Engineers, January 2010 (2010a).

USAGE, 2010b, "Hydrologic Modeling System (HEC-HMS), Version 3.5.0," Hydrologic Engineering Center, U.S. Army Corps of Engineer, August 2010 (2010b).

USAGE, 2015a, "Ice Jam Database", U.S. Army Corps of Engineers, Cold Region Research and Engineering Laboratory (CRREL), available at:

http://www.crrel. usace.army. mil/technical_areas/hh/, accessed January, 2015.

USAGE, 2015b, "National Inventory of Dams," accessed from http://nid.usace.army.mil.

Accessed on multiple occasions.

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USGS, 2016, U.S. Geological Survey National Map Viewer, http://viewer.nationalmap.gov/viewer, Accessed July 18, 2016.

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Geological Survey Professional Paper 60.

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Wong, K-C., and RW. Garvin, 1984, "Observations of Wind-Induced, Subtidal Variability in the Delaware Estuary," Journal Geophysical Research (Oceans), 89(C6):10,589-10,597, November 20, 1984.

Wong, K-C, and J.E. Moses-Hall, 1998, "On the Relative Importance of the Remote and Local Wind Effects to the Subtidal Variability in a Coastal Plain Estuary," Journal of Geophysical Research (Oceans), 103(C9):18,393-18,404, August 15, 1998.

Table 2.2-1. Flood-Causing Mechanisms and Corresponding Guidance STANDARD REVIEW PLAN FLOOD-CAUSING MECHANISM (SRP) SECTION(S) AND JLD-ISG SAP 2.4.2 Local Intense Precipitation and Associated Drainage SAP 2.4.3 SAP 2.4.2 Streams and Rivers SAP 2.4.3 Failure of Dams and Onsite Water Control/Storage SAP 2.4.4 Structures JLD-ISG-2013-01 SAP 2.4.5 Storm Surge JLD-ISG-2012-06 SAP 2.4.5 Seiche JLD-ISG-2012-06 SAP 2.4.6 Tsunami JLD-ISG-2012-06 Ice-Induced SAP 2.4.7 Channel Migrations or Diversions SAP 2.4.9 Table 3.0-1. Summary of Controlling Flood-Causing Mechanisms at the Hope Creek Site Reevaluated Flood-Causing Mechanisms and Associated ELEVATION Effects That May Exceed The Powerblock Elevation (9.7 ft (NAVD88)

(3 m) NAVD88)<1l Local Intense Precipitation and Associated Drainage 12.8 ft (3.9 m)(2)

( 1) Flood Height and Associated Effects as defined in JLD-ISG-2012-05 (2) Maximum water-surface elevation at critical door sills.

Table 3.1-1. Current Design Basis (COB) Flood Hazards for the Hope Creek Site (PSEG, 2014a)

DESIGN STILLWATER WAVES/RUN BASIS MECHANISM REFERENCE ELEVATION UP HAZARD ELEVATION Local Intense 12.1 ft 12.1 ft Precipitation and Minimal FHRR Table 3.1 Associated Drainage Streams and Rivers Powerblock & Service 7.5 ft 12.5 ft 20.0 ft FHRR Section 1.2.2 Water Intake Structure Failure of Dams and Onsite Water 12. 7 ft 12.Bft 25.5 ft FHRR Section 1.2.3 Control/Storage Structures Storm Surge Powerblock A Location 24.0 ft 6.2 ft 30.2 ft FHRR Table 3-1 (Western portion of site)

Powerblock B Location 24.0 ft 10.6 ft 34.6 ft FHRR Section 1.2.4 (Southern portion of site)

Service Water Intake 24.0 ft 20.6 ft 44.6 ft FHRR Section 1.2.4 Structure No Impact on No Impact on No Impact on the Seiche the Site the Site FHRR Section 1.2.5 Site Identified Identified Identified No Impact on No Impact on No Impact on the Tsunami the Site the Site FHRR Section 1.2.6 Site Identified Identified Identified No Impact on No Impact on No Impact on the Ice-Induced Flooding the Site the Site FHRR Section 1.2.7 Site Identified Identified Identified No Impact on No Impact on Channel No Impact on the the Site the Site FHRR Section 1.2.8 Migrations/Diversions Site Identified Identified Identified Note 1: Reported values are reported as NAVD88 and rounded to the nearest one-tenth of a foot.

Note 2: Based on the NRG staff's independent (deterministic) hazard assessment using present-day regulatory guidance and methodologies of storm surge, the staff concludes that the site's current design basis remains bounding.

For this reason, the staff concludes it is appropriate to utilize the current design basis storm surge elevation in conjunction with the mitigating strategies assessment.

Table 3.2-1. Local Intense Precipitation Depths for the Hope Creek Site DURATION AREA CUMULATIVE DEPTH MULTIPLIER APPLIED TO (min) (mi2) (in) 18.10 60 1 --- --- (HMR-52, Fig. 24) 0.753 1-hr, 1 mi2 30 1 13.63 (HMR-52, Fig. 38) (3 km 2) PMP 0.525 1-hr, 1 mi2 15 1 9.50 (HMR-52, Fig. 37) (3 km2) PMP 0.334 1-hr, 1 mi2 5 1 6.05 (HMR-52, Fig. 36) (3 km 2) PMP Source: PSEG, 2014a (FHRR, Table 2.1-1)

Table 3.2-2. LIP Maximum Water-Surface Elevations (NAVDBB) at Hope Creek Critical Door Locations DURATION OF TIME TO MAXIMUM FLOOD FLOOD FLOODING DOOR SILL MAXIMUM DOOR WATER DEPTH ABOVE DOOR ELEVATION(bl FLOOD ID(al SURFACE ABOVE SILL DEPTH ELEVATION DOOR SILL ELEVATION (hr)

(hr) 12.2 ft 12.7ft 0.5 ft 1 0.99 2.60 (3.7 m) (3.9 m) (0.2 m) 12.2ft 12.8 ft 0.6 ft 2 1.00 2.50 (3.7 m) (3.9 m) (0.2 m) 12.2 ft 12.5 ft 0.3 ft 3 0.17 1.90 (3.7 m) (3.8 m) (0.1 m) 12.2 ft 12. 7 ft 0.5 ft 4 1.00 1.90 (3.7 m) (3.9 m) (0.1 m) 12.2 ft 12.2 ft 0.03 ft 5 1.00 0.05 (3.7 m) (3.7 m) (0.01 m) 12.2 ft 12.0 ft N/Alc) 6 0.99 0.00 (3.7 m) (3.7 m) 12.2 ft 11.9 ft 7 N/A 1.01 0.00 (3.7 m) (3.6 m) 12.2 ft 9.7ft 8 N/A 0.08 0.00 (3.7 m) (3.0 m) 12.2 ft 9.7 ft 9 N/A 0.08 0.00 (3.7 m) (3.0 m)

Source: PSEG, 2014a (FHRR, Table 2.1-3)

(a) Door ID locations are shown in Figure 3.2-4.

(b) To implement flood protection above this elevation, water tight doors must be closed (PSEG, 2014a).

(c) N/A: Not Applicable (water surface elevation is less than door sill elevation).

Table 3.5-1. Storm Surge Maximum Total Water Surface Elevations TOTAL WATER SURFACE ELEVATIONS (NAVD88)

HCGS POWER BLOCK LOCATION*

Meters Feet 1 7.3 23.9 2 9.6 31.5 3 10.9 10.9 4 8.0 26.2 5 6.7 22.0 6 10.9 35.8 7 10.8 35.6 8 7.9 25.8 9 7.5 24.7 10 7.8 25.4 11 9.0 29.4 12 9.0 29.4 13 8.4 27.5 14 8.5 27.9 15 8.0 26.2 16 7.0 23.1 17 6.7 22.0 18 7.3 23.9 19 7.9 26.0 20 9.0 29.7 21 6.7 22.0 22 8.1 26.4

• Most locations are noted in Figure 3.2-4; however, FHRR Figure 2.1-3 (PSEG, 2014a) provides complete location.

(Modified from FHRR Table 2.4-14 (PSEG, 2014a))

Table 4.1-1. Reevaluated Hazard Elevations (NAVD88) for Flood-Causing Mechanisms Not Bounded by the Hope Creek's COB REEVALUATED STILLWATER MECHANISM WAVES/RUN UP HAZARD REFERENCE ELEVATION ELEVATION I

Local Intense 12.Sft 12.8 ft FHRR Section Minimal Precipitation NAVD88 NAVD88 3.1 Note 1: The licensee is expected to develop flood event duration parameters and applicable flood associated effects to conduct the MSA. The staff will evaluate the flood event duration parameters (including warning time and period of inundation) and flood associated effects during its review of the MSA.

Note 2: Reevaluated hazard mechanisms bounded by the current design basis (see Table 3.1-1) are not included in this table.

Note 3: Reported values are rounded to the nearest one-tenth of a foot.

Table 4.2-1. Flood Event Duration Parameters for Flood-Causing Mechanisms Not Bounded by the Hope Creek's COB TIME AVAILABLE TIME FOR FOR DURATION OF WATER TO MECHANISM PREPARATION INUNDATION OF REFERENCE RECEDE FROM FOR FLOOD SITE EVENT SITE

~*

Local Intense Precipitation and PSEG, 24 hrs 1.0 hr 8. 10 hrs I Associated 2014a Drainage I

Table 4.3-1. Associated Effects Parameters not Directly Associated with Total Water Height for Flood-Causing Mechanisms not Bounded by the Hope Creek's COB FLOOD-CAUSING MECHANISM ASSOCIATED EFFECTS FACTOR Local Intense Precipitation and Associated Drainage Hydrodynamic Loading at Plant Grade Not provided Debris Loading at Plant Grade Not provided Sediment Loading at Plant Grade Not provided Sediment Deposition and Erosion Not Applicable Concurrent Conditions, Including Adverse Not provided Weather Other Pertinent Factors Not provided (e.Q., Waterborne Projectiles)

flood event du ration site preparation period of recession of for flood event inundation water from site Conditions are met Arrival of flood Water begins to Water completely for entry into flood waters on site recede from site receded from site procedures or and plant in safe notification of and stable state impending flood that can be maintained indefinltely Figure 2.2-1 Flood Event Duration (NRC, 2012e)

Kl.Y PSEG Nuclear. LLC Flooding Reevaluation Layout and Drainag Figure 3.2-1. PSEG Site Showing Hope Creek and Salem Reactor Complexes. Modified from PSEG (2014a)

Figure 3.2-2. PSEG Site Layout and Drainage (detail from FHRR Figure 1.1-2 (PSEG, 2014a))

7.0 6.0

- 5.0

~

I ll u

• -;;c: 4.0 Q.

4J

-0"= 3.0

-*-c: 2.0

~

a:

1.0 0.0 0 5 10 15 20 25 30 s 0 so 5 60 Time (minutes)

Figure 3.2-3. Precipitation Hyetograph Used in the Local Intense Precipitation Analysis (FHRR Figure 2.1-2 (PSEG, 2014a))

Figure 3.2-4. Critical Door Locations Used for Local Intense Precipitation Analysis at the HCGS Site (modified detail from FHRR Figure 2.1-3 (PSEG, 2014a)

ML16266A281 *via email OFFICE NRR/JLD/JHMB/PM NRR/JLD/LA NRO/DSENRHM1/TR* NRO/DSENRHM1/TM*

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