ML17136A322
| ML17136A322 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 05/19/2017 |
| From: | Frankie Vega Japan Lessons-Learned Division |
| To: | Coffey R Point Beach |
| Vega F, NRR/JLD, 415-1617 | |
| References | |
| CAC MF6100, CAC MF6101 | |
| Download: ML17136A322 (37) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, 0.C. 20555-0001 Mr. Robert Coffey Site Vice President NextEra Energy Point Beach, LLC 6610 Nuclear Road Two Rivers, WI 54241-9516 May 19, 2017
SUBJECT:
POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2-STAFF ASSESSMENT OF RESPONSE TO 10 CFR 50.54(f) INFORMATION REQUEST-FLOOD-CAUSING MECHANISM REEVALUATION (CAC NOS. MF6100 AND MF6101)
Dear Mr. Coffey:
By letter dated March 12, 2012, the U.S. Nuclear Regulatory Commission (NRC) issued a request for information pursuant to Title 1 O 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 that licensees reevaluate flood-causing mechanisms using present-day methodologies and guidance. By letter dated March 12, 2015 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML15071A413),
NextEra Energy Point Beach, LLC (NextEra, the licensee) responded to this request for Point Beach Nuclear Plant, Units 1 and 2 (Point Beach).
By letter dated December 10, 2015 (ADAMS Accession No. ML15321A063), the NRC staff sent the licensee a summary of the staff's review of Point Beach'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, the reevaluated flood hazard results for the local intense precipitation {LIP) flood-causing mechanism was not bounded by its current design basis. In order to complete its response to Enclosure 2 to the 50.54(f) letter, the licensee is expected to submit a focused evaluation for LIP to address this reevaluated flood hazard, as discussed in COMSECY-15-0019, "Closure Plan for the Reevaluation of Flooding Hazard for Operating Nuclear Power Plants," and Japan Lessons-Learned Division (JLD)
Interim Staff Guidance {ISG) JLD-ISG-2016-01, "Guidance for Activities Related to Near-Term Task Force Recommendation 2.1, Flooding Hazard Reevaluation; Focused Evaluation and Integrated Assessment." This closes out the NRC's efforts associated with CAC Nos. MF6100 and MF6101.
If you have any questions, please contact me at (301) 415-1617 or e-mail at Frankie.Vega@nrc.gov.
Docket Nos. 50-266 and 50-301
Enclosure:
Staff Assessment of Flood Hazard Reevaluation Report for Point Beach cc w/encl: Distribution via Listserv Sincerely,
- ct~
Frankie Vega, Project Manager Hazards Management Branch Japan Lessons-Learned Division Office of Nuclear Reactor Regulation
STAFF ASSESSMENT BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO FLOOD HAZARD REEVALUATION REPORT NEAR-TERM TASK FORCE RECOMMENDATION 2.1 POINT BEACH NUCLEAR PLANT. UNITS 1 AND 2 DOCKET NOS. 50-266 AND 50-301
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) (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 (NTFF) 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, 2011 c) and SECY-11-0137 (NRC, 2011 d) directed the NRC staff to issue requests for information to licensees pursuant to 1 O CFR 50.54(f) to address this recommendation. to the 50.54(f) letter (NRC, 2012a) requested that licensees reevaluate 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, 2012b). By letter dated March 12, 2015, NextEra Energy Point Beach, LLC (NextEra, the licensee) provided its FHRR for Point Beach Nuclear Plant (Point Beach), Units 1 and 2 (NextEra, 2015a).
On December 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 NTTF 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 result for the local intense precipitation (LIP) 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 Japan Lessons-Learned Division (JLD) Interim Staff Guidance (ISG)
JLD-ISG-2016-01, Revision O (NRC, 2015b; NRC, 2016b), the NRC staff anticipates that the licensee will perform and document a focused evaluation for LIP that assesses the impact of the Enclosure LIP 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) and associated effects (AE) parameters. These parameters will be used to conduct the mitigating strategies assessment (MSA) and focused evaluation or revised integrated assessment.
2.0 REGULATORY BACKGROUND 2.1 Applicable Regulatory Requirements As stated above, Enclosure 2 to the 50.54(f) letter (NRG, 2012a) requested that licensees reevaluate flood hazards for their sites using present-day methods and regulatory guidance used by the NRG 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 1 O CFR, describes 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 1 O 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 1 O 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 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 1 O CFR defines the design bases as the information which 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 1 O CFR defines the "current licensing basis" (CLB) as "the set of NRG requirements applicable to a specific plant and a licensee's written commitments for ensuring compliance with and operation within applicable NRG 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: 1 O 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 that remains 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 1 O, 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 (1 O CFR 100.20(b)) and the physical characteristics of the site, including the hydrology (10 CFR 100.21 (d)).
2.2 to the 50.54(f) Letter Section 50.54(f) of 1 O 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. JLD-ISG-2012-05 (NRC, 2012e) defines "flood height and associated effects" as the maximum stillwater surface elevation plus:
Wind waves and runup effects; Hydrodynamic loading, including debris; Effects caused by sediment deposition and erosion; Concurrent site conditions, including adverse weather conditions; Groundwater ingress; and Other pertinent factors 2.2.3 Combined Effects Flood The worst flooding at a site that may result from a reasonable combination of individual flood 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 SAP Section 2.4.2, "Areas of Review" (NRC, 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 ANSI/ ANS-2.8-1992 (ANSI/ ANS, 1992), then the NRC staff will document and report the result as part of one of the hazard sections. It should also be noted that for the purposes of this staff assessment, the terms "combined effects" and "combined events" are synonyms. 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 (NRC, 2012c) 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 of this assessment 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 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; and 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 flood-causing mechanisms at the site, licensees were not required to perform an integrated assessment.
COMSECY-15-0019 (NRC, 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, licensees 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 an integrated assessment (NRC, 2015a).
3.0 TECHNICAL EVALUATION
The NRC staff reviewed the information provided for the flood hazard reevaluation of Point Beach (NextEra, 2015a). 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.
To provide additional information in support of the summaries and conclusions in the Point Beach FHRR, the licensee made calculation packages available to the NRC staff via an electronic reading room. The NRC staff did not rely directly on these calculation packages in its review; they were found only to expand upon and clarify the information provided in the Point Beach FHRR, and so those calculation packages were not docketed or cited.
3.1 Site Information The 50.54(f) letter (NRC, 2012a) includes the SSCs important to safety in the scope of the hazard reevaluation. The licensee included pertinent data concerning these SSCs in the Point Beach FHRR. The NRC staff reviewed and summarized this information as follows in the sections below.
3.1.1 Detailed Site Information In its FHRR, the licensee reported that Point Beach is located in Manitowoc County in east-central Wisconsin on the western shore of Lake Michigan, approximately 30 mi southeast of Green Bay and about 90 mi north-northeast of Milwaukee. The licensee also reported that site topographic and bathymetric surveys were performed in 2013 and 2014. In relation to Lake Michigan, a majority of the plant grounds are located at 607.3 ft North American Vertical Datum of 1988 (NAVD88). Additional details of the site are provided in the FHRR.
In its FHRR, the licensee reported that the ground surface elevation at the Point Beach site varies from 584.3 to 639.3 ft NAVD88. All elevations in this staff assessment are given with respect to NAVD88.
The Circulating Water Pump House (CWPH), where the plant draws its circulating water from Lake Michigan, has a ground floor elevation of 588.3 ft NAVD88. The licensee also reported that the ground floor elevation of the Turbine Building (TB) is 589.3 ft NAVD88. Table 3.1-1 of this assessment provides the summary of controlling reevaluated flood-causing mechanisms, including associated effects, that the licensee computed to be higher than the powerblock elevation.
3.1.2 Design-Basis Flood Hazards The COB flood levels are summarized by flood-causing mechanism in Table 3.1-2 of this assessment. The NRC staff reviewed the information provided in the Point Beach FHRR (NextEra, 2015a) and determined that sufficient information was provided to be responsive to of the 50.54(f) letter (NRC, 2012a).
3.1.3 Flood-Related Changes to the Licensing Basis In its FHRR, the licensee reported that there have been many changes made to the barriers and to the administrative protections for postulated floods. These changes primarily represent changes to the protection strategy for wave runup. Additional details including the CLB are documented in the Flooding Walkdown Report. The NRC staff reviewed the information provided in the Point Beach FHRR (NextEra, 2015a) and determined that sufficient information was provided to be responsive to Enclosure 2 of the 50.54(f) letter (NRC, 2012a).
3.1.4 Changes to the Watershed and Local Area The licensee indicated in its FHRR that there have been changes to the watershed, primarily in the immediate vicinity of the drainage at the site. It is reported that the changes were mainly to the barriers and the administrative protections for the postulated floods. The NRC staff also examined the Walkdown Report (NextEra, 2012) and the associated Walkdown Staff Assessment (NRC, 2014a) and determined that changes have occurred at the site since the original licensing. Inspections conducted during the site walkdown showed that no changes in land use or topography were observed that would adversely impact the site drainage. It is reported that the natural drainage of the topography designed to provide flow paths in the event of the probable maximum precipitation (PMP) and snowmelt was found to be unchanged except for where newer buildings had been constructed. The changes in these areas are supplemented with a drain system and were deemed to be acceptable.
The NRC staff reviewed the information provided in the Point Beach FHRR (NextEra, 2015a) and determined that sufficient information 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 The Point Beach FHRR (NextEra, 2015a) reports precipitation induced flooding and Lake Michigan flooding as the two flooding hazards evaluated in the CLB. The FHRR states that the CLB precipitation event for Point Beach is combination of a 6-hour rainfall with a 50-year recurrence interval and water content of snow in late March with a 50-year recurrence frequency. This combined volume of water is equivalent to 4.90 inches (in.) over the 6-hour duration.
The probable maximum storm surge (PMSS) on Lake Michigan was also considered as part of the CLB. The PMSS CLB is a lake flood level of 589. 72 ft NAVD88 resulting from a combination of the historical maximum Lake Michigan elevation of 583.0 ft NAVD88 coincident with 0.17 ft wind setup and 6.55 ft wave runup on a vertical surface. The NRC staff reviewed the information provided in the Point Beach FHRR (NextEra, 2015a) and determined that sufficient information was provided to be responsive to Enclosure 2 of the 50.54(f) letter (NRC, 2012a).
3.1.6 Additional Site Details to Assess the Flood Hazard The licensee provided model input and output files and associated hydrologic and bathymetric data for NRC staff's review.
3.1.7 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 20, 2012, NextEra provided the requisite flood walkdown report for the Point Beach site (NextEra, 2012). The NRC staff prepared a staff assessment report, dated June 20, 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 Point Beach FHRR that the reevaluated flood hazard for local intense precipitation and associated site drainage is based on a stillwater surface elevation of 609.6 ft NAVD88. This flood-causing mechanism is discussed in the licensee's COB. The COB probable maximum flood elevation for LIP and associated site drainage is based on a stillwater surface elevation of 608.9 ft NAVD88. In response to NRC staff's questions raised during the audit, the licensee stated that the flood-related elevations of the COB and CLB for Point Beach are the same (NRC, 2015a).
Section 3.1 of the Point Beach FHRR states that the CLB precipitation event for Point Beach is the combination of a 6-hour rainfall with 50-year recurrence frequency combined with the water equivalent of snow in late March with also a 50-year frequency. The licensee stated the combined rainfall-snowmelt CLB/CDB event to be 4.90 in. over a period of 6-hours. Maximum water surface elevations (WSEs) of the CLB at select points of interest (POis) are presented in Table 3.1 of the FHRR. Based on information in the FHRR, the COB PMF elevation for LIP and associated site drainage is a stillwater surface elevation of 608.9 ft NAVD88.
The NRC staff requested additional information from the licensee in order to supplement the information provided in the Point Beach FHRR. The licensee provided this additional information in an audit conducted on October 29, 2015 (NRC, 2016), which is discussed in the appropriate sections below.
3.2.1 Model Input 3.2.1.1 LIP Intensity and Distribution The licensee performed a site-specific LIP evaluation using the recommendations for a storm-based approach described in (ANSI/ANS, 1992; World Meteorological Organization, 2009; and NRC, 2011 ). The licensee stated that the storm-based approach is based on historical data that were then maximized and transpositioned to have the event occurring at the Point Beach site.
The storm-based approach is described in Hydrometeorological Report (HMR) 33 (National Oceanic and Atmospheric Administration (NOAA), 1956) and HMR 51 (NOAA, 1978).
In order to apply the storm-based approach the licensee identified a set of storms which represent extreme precipitation events. Such storm types included thunderstorms and intense rainfall events associated with Mesoscale Convective Complexes. This procedure is similar to the process described in Section 6 of HMR 52 (NOAA, 1982). The licensee selected 21 large historical storms for further evaluation of LIP at the Point Beach site from storms with similar meteorological and topographic setting. The licensee stated that thirteen of the storms were previously analyzed in HMR 33 and HMR 51 by the National Weather Service (NWS) and the U.S. Army Corps of Engineers (USAGE). Each historical storm was modified by an algorithm that performed transpositioning adjustment using a combination of atmospheric moisture and terrain influences. The storms were maximized and transpositioned to the Point Beach site.
The resulting rainfall was the total volume of rainfall to be expected at the Point Beach site with all contributing factors maximized and occurring simultaneously. The May 1943 Mounds, Oklahoma storm event resulted in the largest 1-h rainfall after performing storm maximization and transpositioning. The licensee estimated a 1-h, 1-mi2 PMP depth of 12.8 in. The total precipitation depth estimates were applied into four hyetographs which the licensee named the first, second, third, and fourth quartiles. The first quartile had the most intense precipitation in the beginning of the event and the fourth quartile having the most intense precipitation in the end of the event.
The licensee stated that lack of sub-hourly PMP-type storm data prevented the development of an updated evaluation; therefore, the ratios derived from HMR 52, Figures 36 and 38 (NOAA, 1982) were used for sub-hourly precipitation estimates at the Point Beach site. The site-specific 5-minute, 15-minute, 30-minute, and 1-hour LIP intensities are shown in Table 3.2-1 of this assessment.
In order to determine the appropriateness of the site-specific PMP (ssPMP) values used by the licensee and the resulting LIP flood WSEs at Point Beach, the NRC staff independently evaluated the sensitivity of the licensee's FL0-2D model. The staff compared WSEs from the ssPMP with the WSEs modeled using precipitation values from HMR-52. The 1-hour, 1-mi2 PMP value at the Point Beach site estimated using the HMR-52 method was 16.6 in., compared to the 12.8 in. estimated using the ssPMP; this is a 23 percent difference in total rainfall depth.
The sensitivity analysis resulted in a WSE difference of about 0.44 ft (14 percent) at Units 1 and 2, Door 232, and 0.63 ft (22 percent) at TB Door 11. The results of the staff's sensitivity analysis indicated that the WSEs estimated using the HMR-based event were not significantly higher than the WSEs estimated using the licensee's ssPMP-based event. More importantly, the differences were insignificant at the safety-related structures of Point Beach. Considering the level of conservatism incorporated in the modeling assumptions and in light of the small differences in estimated WSEs, the staff determined that it was not necessary to review the manner in which the licensee's ssPMP estimate was derived. Correspondingly, the staff concluded that the licensee's ssPMP values were reasonable to use in the LIP runoff analysis discussed below.
3.2.1.2 Runoff Model Development The licensee developed the LIP flood model following guidance in NUREG/CR-7046 (NRC, 2011 ). The licensee used FL0-20 Pro software (FL0-2D, 2013) to determine the maximum WSE and maximum flood depths for the LIP event at critical door locations of Point Beach (NextEra, 2015b). The primary input to this model was a digital terrain model (DTM), which was generated in ArcGIS by processing a 2014 topographic survey of the Point Beach site (NRC, 2016). The topographical survey data has a +/-0.1 ft accuracy vertically and +/-0.05 ft accuracy horizontally (NRC, 2016). The data was used by the licensee in ArcGISto create a DTM with elevation points positioned at the centers of 5-ft by 5-ft cells. As shown on Figure 3.2-1 of this assessment, all features and obstructions such as permanent structures, temporary structures, and barriers were represented in the DTM by defining them as raised, flat surfaces from which rooftop runoff discharges directly to the ground surface (NextEra, 2014a). The flow is routed around obstructions without applying FL0-2D flow reduction factors to the corresponding grid cells. The NRC staff reviewed the methodology and determined that because the surface detention is set at a reasonably low value of 0.04 ft, storage on the cells representing obstructions (rooftops) will not significantly reduce runoff discharging from the roof and is therefore considered an acceptable modification to the FL0-2D model approach.
The NRC staff reviewed the location of obstructions using aerial image,.Y of the Point Beach site (see Figure 3.2-2). Some of the locations identified in the licensee's model as temporary structures (including non-permanent structures and potential future laydown areas) were not readily apparent to the NRC staff from the imagery. During the October 29, 2015, audit, the licensee confirmed that the locations of the temporary structures and areas defined in the FL0-2D model. The licensee provided a sensitivity report for the LIP model (NextEra, 2014), which confirmed the reasonableness of the model. The difference in maximum WSE due to the temporary structures at the three door locations (Doors 209, 310, and 311 ), which are doors to the Service Building, was less than or equal to 0.12 ft.
The roughness coefficients for the model were assigned according to the land cover type (NextEra, 2015b) and licensee-selected values were confirmed by NRC staff to be consistent with the suggested values in the FL0-2D Pro user manual (FL0-2D, 2013). The licensee selected Manning's roughness coefficient n values of 0.02 for asphalt, 0.2 for open ground, and 0.4 for forest litter and/or pasture land cover types, respectively. The licensee provided a graphical representation that shows the spatial distribution of the Manning's roughness coefficient values across the site. Based on the site land cover information, the NRC staff determines that the values used are reasonable and appropriate.
The licensee also assumed no runoff losses and complete blockage of the site's surface-water drainage system based on the recommendations of NUREG/CR-7046. The licensee used a DTM, which accounted for obstructions and surface flow impediments such as buildings, temporary structures, wave barriers, and other topographic features.
3.2.2 Model Simulation The licensee considered two scenarios for the LIP flooding analysis. Scenario A considers the temporary laydown areas completely occupied with equipment/containers. Scenario B is similar to Scenario A, but with additional temporary wave barriers installed adjacent to the CWPH.
When the water level of Lake Michigan exceeds an administratively controlled limit, temporary wave barriers will be installed at the Point Beach site along the roll up doors on the north and south side of the CWPH, as shown on Figure 3.2-3 of this assessment. The licensee created Scenario B to assess the impact of these wave barriers, also referred to as door barriers. The plan for the installation of barriers was updated following a 2014 walkdown, and six barriers of 8 feet (ft) by 25 ft with a height of 3.5 ft were represented in the model as a wider structure of 15 ft by 25 ft (NextEra, 2015a).
In the FHRR, it is stated that during high lake level conditions, 3.5 ft high wave barriers are installed outside the CWPH rollup doors and sandbags are placed to seal the rollup doors.
When the barriers are installed, the maximum LIP flood heights near the CWPH doors are projected to increase to 3.4 ft. The licensee stated during the audit (NRC, 2016) that the 100-yearr high lake level of 1.8 ft-Plant Datum for Lake Michigan was not used in the FL0-2D runoff model since site grade and associated features are at least 3 ft higher than the high lake level.
Accordingly, the elevated lake level would have no appreciable effect on site runoff, as the runoff from the site grade would flow freely down to the beach and into the Lake.
The licensee performed four sensitivity runs for each scenario to test the sensitivity of the models to inclusion of surface depressions, inclusion (unblockage) of the site's surface-water drainage system, a reduction in the area of four temporary structures, and a combination of all three. Each sensitivity test run was performed without wave barrier protection to be comparable to Scenario A results and run with wave barrier protection to be comparable to Scenario B results. The following were the various sensitivity tests:
Test 1 - FL0-20 model that accounts for surface depressions; Test 2 - FL0-20 model that accounts for surface depressions and the Point Beach yard drainage network; Test 3 - FL0-20 model that uses the same topography from Scenario A and Scenario B but has a reduced temporary structure layout; and Test 4 - FL0-20 model that accounts for surface depressions, the Point Beach yard drainage network, and the reduced temporary structure layout.
The final model with all three (primarily) non-conservative assumptions had a maximum WSE that was up to 1.5 ft lower than the original model at the TB. The sensitivity analysis demonstrates the effect of the conservative assumptions used in the original model.
The NRC staff reviewed the FL0-20 simulation model and found that the volume conservation error was less than 0.001 percent, which demonstrates that the model conserves volume and the flood simulation is executed successfully. The licensee noted that coefficients controlling time step and percent change in flow depth within the model were modified as suggested in the FL0-20 Pro Reference Manual to address numerical surging (model numerical instability) which was occurring with default values. The NRC staff confirmed that the final models of the two primary scenarios provided by the licensee did not exhibit numerical surging.
The licensee evaluated 33 doors at 6 onsite buildings as POis for the Point Beach site. The majority of the doors were identified in the CLB and confirmed as POis during a site walkdown conducted by Point Beach staff. The maximum WSE of 609.6 ft NAVD88 occurred at Units 1 and 2, Door 159 during the fourth quartile storm for both of the licensee's LIP scenarios (with and without wave barriers). Maximum WSEs at most buildings exhibit very small differences
(+/-0.1 ft) between the two scenarios. However, because the temporary wave barriers included in Scenario B partially obstruct the normal flow away from the powerblock area toward the CWPH and the lake, the maximum WSEs at the CWPH and the nearby TB doors are greater than the WSEs of Scenario A by 0.3 to 0. 7 ft. The simulation results indicate that Scenario B is the controlling LIP event and has a maximum WSE of 609.6 ft NAVD88 at Door 159 of the Units 1 and 2 Building. The reevaluated maximum flow depths exceed the COB at all POis except Door 601, which remained the same (NextEra, 2015a; NextEra, 2015b; NextEra, 2015c).
Hydrographs at POis of the LIP simulation show that that durations for water ponding with depths greater than 0.05 ft range from an hour or less at some locations to more than 1 O hours at other locations. Flow depths around the switchgear are calculated relative to 26.5 ft Plant Datum (equivalent to 607.8 ft NAVD88), the finished building elevation (NRC, 2016), rather than the ground surface elevation.
The NRC staff notes that the maximum water depth of all the POI locations for Scenario Bis 3.4 ft at Door 338 of the CWPH, which is a different location than the maximum WSE. The maximum hydrodynamic force is also at a different location than the maximum WSE at Door 340 of the CWPH, with a maximum force of 205.2 lb/ft (NextEra, 2015b). Comparisons of the WSEs provided by the licensee and a separate confirmatory analysis performed by NRC staff using different builds of the FL0-20 model are presented in Table 3.2-2 of this assessment.
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. Therefore, the NRC staff expects that the licensee will submit a focused evaluation for LIP and associated site drainage for the Point Beach site.
3.3 Streams and Rivers The licensee reported in the Point Beach FHRR that the reevaluated flood hazard for streams and rivers does not inundate the plant site, but did not report a probable maximum flood elevation. This flood-causing mechanism is discussed in the licensee's COB, but no PMF elevation was reported. The FHRR states that there are no significant streams that flow near the Point Beach site with the exception of two small creeks that drain to the north and to the south; as a result, the licensee did not perform a PMF analysis for streams and rivers for the CLB/CDB.
In its FHRR, the licensee reported that the Point Beach site is located on Lake Michigan and there are no major streams or rivers that could result in flooding at the site. As a result, the licensee determined that the streams and rivers flood-causing mechanism is not applicable to the Point Beach site. The NRC staff reviewed available topographical and hydrological maps and information and confirmed the licensee's conclusion that there are no streams or rivers that could impact the Point Beach site.
The NRC staff confirmed the licensee's conclusion that the streams and rivers flood-causing mechanism could not inundate the Point Beach site. Therefore, this potential flood-causing mechanism does not need to be analyzed in a focused evaluation or an additional assessment.
3.4 Failure of Dams and Onsite Water Control/Storage Structures The licensee reported in the Point Beach FHRR that the reevaluated hazard for failure of dams and onsite water control or storage structures does not inundate the plant site, but did not report a probable maximum flood elevation. This flood-causing mechanism is discussed in the licensee's COB, but no probable maximum flood elevation was reported.
In its FHRR, the licensee reported that there are no dams located upstream or downstream of the Point Beach site. As a result, the licensee concluded that there is no potential for dam breach related flooding at the site.
The NRC staff reviewed available topographical and hydrological maps and information and including the USACE National Inventory of Dams database (USACE, n.d.) and verified that there are no dams in the contributing watershed that would cause a flooding hazard at the Point Beach site. Therefore, the NRC staff confirmed the licensee's conclusion that there are no dams or onsite water storage structures that would affect the site area.
The NRC staff confirmed the licensee's conclusion that the flooding from failure of dams and onsite water control or storage structures flood-causing mechanism could not inundate the Point Beach site. Therefore, this potential flood-causing mechanism does not need to be analyzed in a focused evaluation or an additional assessment.
3.5 Storm Surge The licensee reported in the Point Beach FHRR that the reevaluated flood hazard for storm surge is based on a stillwater surface elevation of 585.8 ft NAVD88. Including wind waves and runup results in an elevation of 589.7 ft NAVD88.
This flood-causing mechanism is discussed in the licensee's COB. The COB PMF elevation for storm surge is based on a stillwater surface elevation of 583.2 ft NAVD88. Including wind waves and run up results in an elevation of 589. 7 ft NAVD88.
The licensee reviewed the historical record and concluded that most of the historical instances of sustained winds over 50 mph in the Great Lakes region are associated with deep low extratropical cyclones which move through the region from the southwest to the northeast. Due to these preferred track directions, the licensee concluded that the vast majority of the strongest sustained winds would occur from the south or southwest. In its review of these storms, the licensee discovered that pressure centers as low as 955 mbar (equivalent to a Category 3 hurricane) have occurred near Point Beach. The licensee also stated that tropical systems making landfall along the Gulf of Mexico coast or U.S. east coast and move inland (e.g.,
Hurricane Hazel in 1954, Hurricane Sandy in 2012) have reached the Great Lakes region, but transitioned into extratropical cyclones.
The licensee used the Delft3D Version 4.00.01 software package (Deltares, 2011) to estimate the PMSS and associated wave effects from a suite of theoretical design storms. The licensee's Wave transformation in Delft3D-WAVE was performed using Simulating WAves Nearshore (SWAN) (Booij et al., 1999; Deltares, 2014; TUDelft, n.d). The licensee calibrated and validated both models to observed historical windstorms (December 1, 1985; December 2, 1990; and October 25, 2010). The licensee stated that the antecedent lake level (e.g., 100-year high lake level) of 575.6 ft was included in the numerical model simulations.
The licensee used observed storm surge time series recorded at NOAA tide stations to calibrate the simulated storm surges (FHRR Table 4.5; FHRR Figure 4.12). The licensee calibrated the simulated wave fields using the observed wave characteristics time series recorded at NOAA buoy stations (FHRR Tables 4.6; FHRR Figure 4.13). The licensee stated that the October 25, 2010, storm was selected as the calibration event due to the finer temporal resolution of the atmospheric wind and pressure data as well as the availability of observed storm surge and wave characteristics (FHRR Tables 4.5 and 4.6). The licensee used the remaining historical storms discussed above for model validation.
Due to the size, bathymetry, and geometry of the Great Lakes, the licensee used six Delft3D-FLOW domains with the coarsest grids representing conditions over Lake Michigan and Lake Huron. The extents of the domains were chosen to include the surrounding coast up to approximately 66 ft above the 100-year lake level of 583.4 ft. The licensee selected a horizontal resolution of 6,562 ft to represent the bathymetric contours of Lake Michigan and Lake Huron away from Point Beach (FHRR Figure 4.10). Near Point Beach, the licensee selected a grid resolution of 19.0 ft to represent Point Beach's coastline and nearshore bathymetry (FHRR Figure 4.11 ).
The licensee developed the synthetic probable maximum synoptic events in accordance with applicable guidance documents (ANSI/ANS, 1992; NRG, 2011 ), which provided the basis for the site-specific storm methodology. The licensee evaluated 3-hour or 6-hour wind and pressure data for 31 historical synoptic events from 1907 to 2012 which produced 45 maximized, potential synoptic PMWS scenarios (FHRR Table 4.4). The licensee then maximized and transposed each scenario to occur directly over the Point Beach site. Finally, the licensee applied the overwater wind adjustments and sampling interval adjustments described in FHRR Section 4.4.9.5 and FHRR Section 4.4.9.6, respectively, to the bounding PMWS synoptic event (i.e. Scenario 13) to determine the PMSS and peak water level at the Point Beach site.
The licensee's PMSS results are presented in FHRR Table 4.12 and FHRR Figure 4.25, where the wave run up on a gently-sloping impermeable surface reached a maximum of 589. 7 ft (FHRR Figure 4.26). The licensee stated that the majority of the plant elevations are located at an elevation of 607.3 ft. The licensee stated that the only exception to this is the area near the CWPH where the plant draws its circulating water from Lake Michigan and has a ground floor elevation of 588.3 ft. In addition, the CLB requires the installation of concrete barriers and sandbags to provide a flooding barrier at the CWPH that would protect equipment in the CWPH and TB from the flood waters up to 590.3 ft. Thus, the licensee concluded that no interim measures are required for this hazard since reevaluated PMSS levels would not adversely affect critical structures because the reevaluated PMSS levels do not inundate the site.
The NRC staff reviewed the NOAA databases cited by the licensee, including the climatology of Lake Michigan (USACE, 2012a), and confirmed that the controlling storm for PMSS calculations is an extratropical storm. The NRC staff concluded that the licensee applied the appropriate storm parameters per ANSl/ANS-2.8-1992 consistent with NUREG/CR-7046 (NRC, 2011),
ANSl/ANS-2.8-1992 (ANSI/ANS, 1992) and JLD-ISG-2012-06 (NRC, 2013), the licensee determined based on the performance of a statistical analysis of NOAA-observed water level data (NOAA, 2016a, and 2016b; Canada, 2016; USACE 2016a and 2016b).
The NRC staff independently ran the NOAA Great Lakes Storm Surge Planning Program (SSPP) model for a sustained wind speed of 100 miles per hour (mph) and varied the wind direction in 10 degree increments between 1 O and 360 degrees to determine the wind direction which results in the greatest surge elevation at the site (Schwab et al, 1981 ; 1987). The resulting SSPP predicted a PMSS maximum still water level of 586.6 ft compared to the licensee's 585.8 ft using Delft3D (Deltares, 2011 ). The FHRR maximum PMSS stillwater level was below the grade elevation at the CWPH and TB POis, therefore Point Beach would not be inundated from the PMSS event.
Thus, the NRC staff confirmed the licensee's conclusion that the PMF from reevaluated hazard for flooding from storm surge is bounded by the COB flood hazard for the Point Beach site. The NRC staff also confirmed the licensee's conclusion that the flood hazard from storm surge alone would not inundate the site. Therefore, flooding from storm surge does not need to be analyzed in a focused evaluation or an additional assessment.
3.6 Seiche The licensee reported in the Point Beach FHRR that the reevaluated flood hazard for seiche is based on a stillwater surface elevation of 583.1 ft NAV088, including wind waves and runup results in an elevation of 584.1 ft NAV088. This flood-causing mechanism is discussed in the licensee's COB, but no PMF elevation was reported.
The numerical model (Oelft30) (Oeltares, 2011) used by the licensee in the PMSS evaluation (FHRR Section 4.4) was also used to estimate the maximum seiche from a suite of theoretical design storms. Synthetic squall line (derecho) events were developed in accordance with applicable guidance documents (e.g., ANSI/ANS, 1992; NRG, 2011 ; NRG, 2013), which provide the basis for the site-specific storm methodology. The licensee evaluated the peak seiche stillwater level at Point Beach from a combination of the maximum seiche with wind-wave activity and lesser of the 100-year or maximum controlled water level.
The Point Beach FHRR states that historical squall lines (or derechos) can produce some of the highest instantaneous recorded wind gusts, but last only for a limited time (i.e., less than 30 minutes) at a given location. The licensee analyzed seventeen historical squall lines between 1909 and 2012 to develop maximized, transposed squall lines (derechos). These synthetic storms were then evaluated or potential seiches independent of the PMSS. The licensee stated that this result is for a single squall line event. In order to amplify the initial seiche amplitude, forcing would need to be applied to the lake at a resonant frequency to the basin geometry.
Therefore, the licensee performed a fast Fourier transform to establish Lake Michigan's natural periods of oscillations. The dominant natural frequencies were found to be 40, 90, and 110 minutes. Based on a 30 minute squall line duration, the licensee concluded that strong squall lines would require a spacing of at least 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> in order for the necessary meteorological conditions to recharge. Thus, a series of squall line or derecho events occurring at the lake's characteristic resonant frequencies are physically impossible and seiche amplification above the
+ 1.0 ft produced in the model simulations is implausible at Point Beach.
The NRG staff reviewed the licensee's results and confirmed the licensee's statements regarding wind effects on seiche resonance. The NRG staff concurs with the licensee's conclusion that squall lines initially move offshore at Point Beach and the potential flooding impact from seiche would be indirect. The primary storm surge will occur along the eastern and/or southern shorelines of Lake Michigan with potential seiches propagating to the west and/or north after the squall line has passed completely over Lake Michigan. For Lake Michigan, the mean seiche period for primary mode oscillation along the long axis should be about 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> while the cross-lake primary mode period should be roughly 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> with typical seiche events lasting for 1 to 3 days with amplitudes of 1 to 5 ft (USAGE, 2012b). Therefore, the Point Beach site could not be inundated from these types of events.
The NRG staff confirmed the licensee's conclusion that the seiche flood-causing mechanism could not inundate the Point Beach site. Therefore, this potential flood-causing mechanism does not need to be analyzed in a focused evaluation or an additional assessment.
3.7 Tsunami The licensee reported in the Point Beach FHRR that the reevaluated flood hazard for tsunami does not inundate the plant site, but did not report a PMF elevation. This flood-causing mechanism is not discussed in the licensee's COB.
In its FHRR, the licensee reported that tsunami was not considered a plausible flood-causing mechanism at the Point Beach site, as indicated in the CLB. The Point Beach FHRR also states that there were no earthquakes, landslides, or volcanic eruptions that would generate a tsunami in Lake Michigan near the Point Beach site. Therefore, the licensee concluded that Point Beach is not affected by flooding from tsunamis.
The licensee analyzed observational records and current scientific literature to evaluate the potential sources of a tsunami for the Point Beach site. In addition, the FHRR stated that queries were performed in the National Geophysical Data Center tsunami, earthquake, and volcano databases to determine whether any historical events were reported regionally or near Point Beach (NOAA, 2014). The United States Geological Survey (USGS) database was queried for possible tsunamigenic landslide activities in the Great Lakes, specifically Lake Michigan (USGS, 2014a; USGS, 2014b). The licensee found no historical evidence of a potential tsunami occurring at or near Point Beach due to earthquake, landslide, or volcanic activity (Lockridge et al., 2002). The Point Beach FHRR states that the only historical "tsunami runup" events located in the databases were related to meteorological events which were not classified as true tsunami events but rather seiches.
The NRC staff reviewed the methodologies and references used by the licensee to determine the severity of the tsunami phenomena reflected in this analysis and noted that they are consistent with present-day methodologies and guidance. In the context of the above discussion, the NRC staff finds the licensee's analysis and use of these methodologies acceptable. In summary, the NRC staff confirmed the licensee's conclusion that flooding from tsunami could not inundate the site.
The NRC staff confirmed the licensee's conclusion that the tsunami flood-causing mechanism could not inundate the Point Beach site. Therefore, this potential flood-causing mechanism does not need to be analyzed in a focused evaluation or an additional assessment.
3.8 Ice-Induced Flooding The licensee reported in the Point Beach FHRR that the reevaluated hazard for ice-induced flooding does not inundate the plant site, but did not report a PMF elevation. This flood-causing mechanism is not discussed in the licensee's COB.
The licensee reported in the Point Beach FHRR that the licensee queried the USAGE Ice Jam Database (USAGE, 2014) to obtain information on historical ice events recorded in the Manitowoc-Sheboygan Watershed. The query results indicated that no ice jams were recorded; therefore, the licensee determined no further analysis was necessary to determine flooding from ice.
The licensee obtained ice cover data for the lake from the U.S. National Ice Center (USNIC) website (USNIC, 2014). The record consisted of daily ice analysis charts which are digitally available from 1995 to present. Based on the results of the query, the licensee determined that further consideration of ice-induced flooding (including the effects of frazil ice) was not required.
The NRC staff reviewed the available information including the databases of the USAGE National Ice Jam Database (USAGE, 2015) and the USNIC and verified that there are no significant ice events of record that could potentially result in ice-induced flooding at the Point Beach site. The NRC staff also did not find documented accounts of flooding from ice in the area surrounding the Point Beach site. Therefore, the NRC staff confirmed that the licensee's conclusion about flood hazard from ice-induced flooding events is appropriate.
The NRG staff confirmed the licensee's conclusion that the ice-induced flood-causing mechanism could not inundate the Point Beach site. Therefore, this potential flood-causing mechanism does not need to be analyzed in a focused evaluation or an additional assessment.
3.9 Channel Migrations or Diversions The licensee reported in the Point Beach FHRR that the reevaluated flood hazard for channel migrations or diversions does not inundate the plant site, but did not report a probable maximum flood elevation. This flood-causing mechanism is not discussed in the licensee's COB.
In its FHRR, the licensee reported that the Point Beach site is located on Lake Michigan and that no major streams exist in the surrounding area, therefore channel migration is not a plausible flood-causing mechanism. The NRG staff reviewed available topographical and hydrological maps and information and confirmed that the licensee's conclusion about the flood hazard from channel migration is appropriate.
The NRG staff confirmed the licensee's conclusion that the channel migrations or diversions flood-causing mechanism could not inundate the Point Beach site. Therefore, this potential flood-causing mechanism does not need to be analyzed in a focused evaluation or an additional assessment.
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 NRG staff review of the licensee's flood hazard water height results. Table 4.1-1 of this assessment contains the maximum results, including waves and runup, for flood mechanisms not bounded by the COB presented in Table 3.1 -1. The NRG staff agrees with the licensee's conclusion that the LIP mechanism is not bounded by the COB. The NRG 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 NRG staff reviewed the information provided in the Point Beach FHRR (NextEra, 2015a) regarding the FED parameters needed to perform the additional assessment of plant response for flood hazards not bounded by the COB. The FED parameters for flood-causing mechanisms not bounded by the COB are summarized in Table 4.2-1 of this assessment and the NRG staff considers the values reported to be reasonable.
The licensee provided FED parameter values for the LIP flood-causing mechanism, but it did not provide the flood warning time in the FHRR (NextEra, 2015a).
The NRC staff determined that the licensee could use guidance provided in Nuclear Energy Institute (NEI) 15-05 (NEI, 2015) to estimate the LIP warning time for future analyses, if needed.
Periods of inundation and recession were not provided in the FHRR; however, duration values were contained in the calculation packages discussed with staff as part of the audit. The staff reviewed the duration values, including the model simulation results, and found the duration results to be reasonable. The NRC staff documented the periods of inundation and recession in the Audit Summary Report (NRC, 2016). The period of inundation for significant water depth ponding is approximately 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> at critical POis, and the model-simluated period of recession is 4.25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br />.
The NRC staff reviewed the FED parameters provided in the licensee's FHRR (NextEra, 2015a) and determined that they are reasonable for use in future assessments of plant response.
4.3 Associated Effects for Hazards Not Bounded by the COB The NRC staff reviewed information provided in the Point Beach FHRR (NextEra, 2015a) regarding AE parameters needed to perform future additional assessments of plant response for flood hazards not bounded by the COB. The AE parameters not directly associated with a maximum WSE are listed in Table 4.3-1 of this assessment.
The licensee provided estimates of hydrostatic and hydrodynamic loads for the LIP event. The hydrostatic loads were computed based on the modeled WSEL at each POI. The hydrodynamic loads were estimated from the modeled velocity time series at each POI. The total waterborne load was estimated as the summation of the two loads as presented in Table 3.2-3 of this assessment. As stated in the FHRR, the reevaluated combined hydrostatic and hydrodynamic loads at the POis were bounded by the maximum tornado impact pressure by a significant margin for Class I structures. The staff reviewed the simulated water surface elevations and velocities and determined that the information provided by the licensee is appropriate and reasonable for the FHRR review.
In order to estimate the debris load, the licensee used guidance provided in ASCE 7-10 (ASCE, 2010). The analysis considered a conservative waterborne debris load and a range of potential flow velocities consistent with the guidance. The reevaluated waterborne projectile impact pressures were compared to the CLB/CDB tornado missiles, and found that sufficient margin existed for Class I structures, even at the highest range of expected flood velocities.
Furthermore, the surface water elevation resulting from the PMSS event does not reach the CWPH POis or further inland. Therefore, it was determined that waterborne projectiles will not impact any POI considered in the flood hazard reevaluation resulting from PMSS. The staff reviewed the maximum velocities from the model outputs, consistent with the guidance provided in ASCE 7-10 (ASCE, 2010) and determined that the approach is acceptable for the purpose of the FHRR review.
The NRC staff reviewed the AE parameters provided by the licensee and the NRC staff confirms the licensee's AE parameter results are reasonable for use in future assessments of plant response.
4.4 Conclusion Based on the preceding analysis, NRC staff confirmed that the reevaluated flood hazard information discussed in Section 4 of this assessment is an appropriate input to the additional assessments of plant response as described in the 50.54(f) letter (NRG, 2012a), COMSECY 0019 (NRG, 2015a) and associated guidance.
5.0 CONCLUSION
The NRG staff reviewed the information provided for the reevaluated flood-causing mechanisms for Point Beach. Based on its review of available information provided in NextEra's 50.54(f) response (NextEra, 2015a), the NRG staff concludes that 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.
Based upon the preceding analysis, the NRG 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, NRG staff confirmed the licensee's conclusions that: (1) the reevaluated flood hazard results for LIP is not bounded by the COB flood hazard; (2) additional assessments of plant response will be performed for the LIP flood-causing mechanism; and (3) 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 (NRG, 2015a) and associated guidance. The NRG staff has no additional information needs with respect to NextEra's 50.54(f) response (NextEra, 2015a).
6.0 REFERENCES
Note: ADAMS Accession No. 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/reading-rm/adams.html.
U.S. Nuclear Regulatory Commission Documents and Publications NRC (U.S. Nuclear Regulatory Commission), 2007, "Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition", NUREG-0800, 2007.
Available online at http://www.nrc.gov/reading-rm/basic-ref/srp-review-standards.html NRC, 2011 a, "Near-Term Report and Recommendations for Agency Actions Following the Events in Japan," Commission Paper 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-ichi Accident," Enclosure to Commission Paper SECY-11-0093, July 12, 2011, ADAMS Accession No. ML11186A950.
NRC, 2011c, "Recommended Actions to be Taken Without Delay from the Near-Term Task Force Report," Commission Paper SECY-11-0124, September 9, 2011, ADAMS Accession No. 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, dated March 12, 2012,
Subject:
"Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(f)
Regarding Recommendations 2.1, 2.3, and 9.3, of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident," ADAMS Accession No. ML12056A046.
NRC, 2012b, 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, dated May 11, 2012,
Subject:
"Prioritization of Response Due Dates for Request for Information Pursuant to Title 10 of the Code of Federal Regulations 50.54(f) Regarding Flooding Hazard Reevaluations for Recommendation 2.1 of the Near-Term Task Force Review of Insights From the Fukushima Dai-ichi Accident", ADAMS Accession No. ML12097A510.
NRC, 2012c, "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, 2012d, Order EA-12-049, "Order Modifying Licenses with Regard to Requirements for Mitigation Strategies for Beyond-Design-Basis External Events," March 12, 2012, ADAMS Accession No. ML12054A736.
NRC, 2013a, "Guidance for Performing a Tsunami, Surge, or Seiche Hazard Assessment,"
Japan Lessons-Learned Project Directorate, Interim Staff Guidance JLD-ISG-2012-06, Revision O, January 4, 2013, ADAMS Accession No. ML12314A412.
NRC, 2013b, "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, Point Beach Nuclear Plant, Units 1 and 2 - Staff Assessment of the Flooding Walkdown Report Supporting Implementation of Near-Term Task Force Recommendation 2.3 Related to the Fukushima Dai-ichi Nuclear Power Plant Accident (TAC Nos. MF0266 and MF0267). June 20, 2014, ADAMS Accession No. ML14147A011.
NRC, 2014b, Letter from William M. Dean, Director, Office of Nuclear Reactor Regulation dated November 21, 2014 to All Power Reactor Licensees on the Enclosed List,
Subject:
"Response Requirements for Request for Information Pursuant to Title 1 O of the Code of Federal Regulations 50.54(f) Regarding Flooding Hazard Integrated Assessments for Recommendation 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident,"
ADAMS Accession No. ML14303A465.
NRC, 2015a, "Mitigating Strategies and Flood Hazard Reevaluation Action Plan," Commission Paper COMSECY-15-0019, June 30, 2015, ADAMS Accession No. ML15153A104.
NRC, 2015b, "Point Beach Nuclear Plant, Units 1 and 2 - Interim Staff Response to Reevaluated Flood Hazards Submitted in Response to 1 O CFR 50.54(f) Information Request -
Flood-Causing Mechanism Reevaluation (TAC NOS. MF6100 AND MF6101)", December 10, 2015, ADAMS Accession No. ML15321A063.
NRC, 2016, "Nuclear Regulatory Commission Report for the Audit of NextEra Energy Point Beach, LLC'S Flood Hazard Reevaluation Report Submittals relating to the Near-Term Task Force Recommendation 2.1-Flooding for: Point Beach Nuclear Plant, Units 1 and 2 (CAC NOS.
MF6100 AND MF6101)", July 26, 2016, ADAMS Accession No. ML16160A344.
Codes and Standards ANS, 1992; 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.
ASCE, 2010; ASCE (American Society of Civil Engineers), Standard 7-10, "Minimum Design Loads for Buildings and Other Structures," Chapter C5, 201 O.
Other References Booij, N, L.H. Holthuijsen, and R. Ris, 1989. "A Third-generation Wave Model for Coastal Regions, 1. Model Description and Validation," Volume 104 (C4), pp. 7649-7666, 1999.
Canada, 2016. Historical Monthly Mean Water Levels from the Coordinated network for each of the Great Lakes. Fisheries and Oceans Canada. Government of Canada website:
http://www. tides. gc. ca/C&A/network_means-eng. html Deltares, 2011. "Delft3D Computer Program," Version 4.00.04.757, 2600 MH Delft, The Netherlands, 2011.
Deltares, 2014. "Delft3D-FLOW User Manual," Version 3.15, Revision 33641, Available at http://oss.de1tares.nl/documents/183920/185723/Delft3D-FLOW _User _Manual.pdf (Accessed on December 1, 2014).
FL0-2D Software Inc., 2013, FL0-20 Reference Manual, FL0-2D Software, Inc., Nutrioso, AZ.
Lockridge, P.A., L.S. Whiteside, and J.F. Lander, 2002, "Tsunamis and Tsunami-Like Waves of the Eastern United States," Science of Tsunan1i Hazards, Volume 20 (3), pp. 120-157.
NextEra, 2015a, Point Beach, Units 1 and 2, Response to NRC 1 O CFR 50.54(f) Request for Information Regarding Near-Term Task Force Recommendation 2.1, Flooding - Submittal of Flooding Hazards Revaluation Report. March 12, 2015, ADAMS Accession No. ML15071A413.
NextEra, 2015b, Receipt of CD Containing Revised 1/0 Files from NextEra RE: Point Beach Nuclear Plant Flood Hazard Re-Evaluation Report (CAC Nos. MF6100 and MF6101 ). June 1, 2015. ADAMS Accession No. ML16072A036.
NextEra, 2015c, Point Beach, Units 1 and 2 - Response to Request for Information Supporting Flooding Hazards Reevaluation Report Audit. November 6, 2015, ADAMS Accession No. ML15310A170.
NextEra, 2016, "Point Beach Nuclear Plant - Mitigating Strategies Assessment (MSA) Report Submittal for Flooding Documentation Requirements", November 22, 2016, ADAMS Accession No. ML16327A099.
NOAA (National Oceanic and Atmospheric Administration), 1956, Seasonal Variation of the Probable Maximum Precipitation East of the 1051h Meridian for Areas from 1 O to 1,000 Square Miles and Durations of 6, 12, 24 and 48 Hours, NOAA Hydrometeorological Report No. 33, April 1956. Available online at http://nws.noaa.gov/oh/hdsc/PMP _documents/HMR33.pdf.
NOAA, 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, 2014, National Oceanographic and Atmospheric Administration (NOAA), National Geophysical Data Center/World Data Service (NGDC/WDS): Global Historical Tsunami Database, National Geophysical Data Center, Available at:
http://ngdc.noaa.gov/hazard/tsu_db.shtml, Accessed February 28, 2014.
NOAA, 2016a. NOAA Great Lakes Water Levels. NOAA Great Lakes Environmental Research Laboratory website: http://www.glerl.noaa.gov/data/wlevels/
NOAA, 2016b. NOAA Great Lakes Water Level Dashboard. NOAA Great Lakes Environmental Research Laboratory website: http://www.glerl.noaa.gov/data/dashboard/GLWLD.html NEI (Nuclear Energy Institute), 2015, NEI 15-05, "Warning Time for Local Intense Precipitation Events," Revision 6, April 8, 2015. ADAMS Accession No. ML15104A158.
Schwab, D.J., J.R. Bennett, and A.T. Jessup. 1981. A two-dimensional lake circulation modeling system. NOAA Tech. Memo. ERL-GLERL-38, 79 pp.
Schwab, D.J., and E. Lynn, 1987. "Great Lakes Storm Surge Planning Program (SSPP), NOAA Tech. Memo. GLERL-65, 12 pp, National Oceanic and Atmospheric Administration.
TUDelft (Delft University of Technology), n.d., "SWAN," (Web page for the SWAN (Simulating Waves Nearshore) model), http://www.swan.tudelft.nl/
USACE (U.S. Army Corps of Engineers), 2012a. "Wave Height and Water Level Variability on Lakes Michigan and St Clair," ERDC/CHL TR-12-23, Great Lakes Coastal Flood Study, 2012 Federal Inter-Agency Initiative, U.S. Army Corps of Engineers, Engineer Research and Development Center Coastal and Hydraulic Laboratory, October 2012.
USACE, 2012b. "Great Lakes Coastal Flood Study, 2012 Federal Inter-Agency Initiative: Wave Height and Water Level Variability on Lakes Michigan and St Clair," 2012 Federal lnteragency Initiative. ERCE/CHL TR-12-23.
USACE, 2015, "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 on December 28, 2015 and January 19, 2016 (http://rsgisias.crrel.usace.army.mil/apex/f?p=524:9:0::NO).
USACE, n.d., "National Inventory of Dams", (Web site), http://nid.usace.army.mil USGS (United States Geological Survey), 2014a. "Landslide Hazards Program," Available at http://landslides.usgs.gov, Accessed on March 4, 2014.
USGS, 2014b. "Landslide Monitoring," Available at http://landslides.usgs.gov/monitoring, Accessed on March 4, 2014.
WMO (World Meteorological Organization), 2009. "Manual for Estimation of Probable Maximum Precipitation," Operational Hydrology Report No. 1045, Geneva.
Table 2.2-1. Flood-Causing Mechanisms and Corresponding Guidance Standard Review Flood-Causing Mechanism Plan Section(s) and JLD-ISG Local Intense Precipitation and Associated SAP 2.4.2 Drainage SAP 2.4.3 Streams and Rivers SAP 2.4.2 SAP 2.4.3 Failure of Dams and Onsite Water SAP 2.4.4 Control/Storage Structures JLD-ISG-2013-01 Storm Surge SAP 2.4.5 JLD-ISG-2012-06 Seiche SAP 2.4.5 JLD-ISG-2012-06 Tsunami SAP 2.4.6 JLD-ISG-2012-06 Ice-Induced SAP 2.4.7 Channel Migrations or Diversions SRP 2.4.9 SRP is the Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition (NRC, 2007)
JLD*ISG-2012-06 is the "Guidance for Performing a Tsunami, Surge, or Seiche Hazard Assessment" (NRC, 2013a)
JLD*ISFG-2013-01 is the "Guidance for Assessment of Flooding Hazards Due to Dam Failure" (NRG, 2013b)
Table 3.0-1. Summary of Controlling Flood-Causing Mechanisms at the Point Beach site Reevaluated Flood-Causing Mechanisms and Associated Effects that May Exceed the Powerblock Elevation ELEVATION [NAVD88]
589.3 ft 1 Local Intense Precipitation and Associated Drainage 609.6 ft 1 Flood height and associated effects as defined in JLD-ISG-2012-05 (NRG, 2012c).
Table 3.1-1. Current Design Basis Flood Hazards for the Point Beach Site (NextEra, 2015a)
Stillwater Current Design Basis Flood Mechanism Elevation Waves/Runup Elevation Reference
[NAVD88]
[NAVD88]
Local Intense FHRR Precipitation and 608.9 ft Minimal 608.9 ft Table 3.1 Associated Drainage Not discussed in Not discussed Not discussed in CDS FHRR Streams and Rivers CDS in CDS Section 3.3 Failure of Dams and Not discussed in Not discussed Not discussed in CDS Onsite Water CDS in CDS Control/Storage Structures 583.2 ft, including 6.6 ft due to 589.7 ft FHRR Storm Surge tides wave runup Section 3.4 Seiche No impact on site No impact on No impact on site identified identified site identified Not discussed in Not discussed Not discussed in CDS Tsunami CDS in CDS Not discussed in Not discussed Not discussed in CDS Ice-Induced CDS in CDS Channel Migrations or Not discussed in Not discussed Not discussed in CDS Diversions CDS in CDS Table 3.2-1 Site-Specific Sub-hourly Point Beach LIP Precipitation Depths Time (min)
Precipitation Depths (in.)
5 4.4 15 6.9 30 9.9 60 12.8
Building Table 3.2-2. Comparison of Maximum Water Surface Elevations and Durations of Inundation (Using different FL0-20 builds of the Point Beach LIP flooding model)
Scenario COB 004 (Scenario A)
OWBQ4 (Scenario B)
Peak Duration Peak Licensee NRG staff flood of flood NRG staff flood Maximum dept depth Licensee Maximum dept Door Water Maximum Maximum h (ft)
>0.05 ft Maximum Water h (ft)
Nam FL0-20 Surface Water Water (hr)
Water Surface Cell Surface Surface Surface e
Elevation, ft Elevation, ft Elevation, ft Elevation ft Elevation, ft NAVD88 NAVD88 NAVD88 NAVD88 NAVD88 (NRG staff)
Flo-20 Build Version 13.11.06 14.08.09 13.11.06 14.08.09 1
73814 589.4 591.2 591.2 1.9 3
591.8 591.8 2.5 2
73820 589.4 591.2 591.2 1.9 2
591.8 591.8 2.5 Turbine 4
73817 1.9 2
2.5 Building 589.4 591.2 591.2 591.8 591.8 11 73840 589.5 591.4 591.4 2.0 3
591.9 591.9 2.6 13 73842 589.5 591.4 591.4 2.0 3
591.9 591.9 2.6 101 73220 608.2 607.7 607.7 0.17 1
607.7 607.7 0.17 Diesel 102 72901 608.5 609.3 609.3 0.09 1
609.3 609.3 0.09 Generato 108 69785 608.9 609.3 609.3 0.45 1
609.3 609.3 0.45 r
603 69782 608.6 609.1 609.1 0.25 1
609.1 609.1 0.25 604 69789 608.9 609.3 609.3 0.65 1.5 609.3 609.3 0.65 151 49324 607.4 609.0 609.0 1.8 2.5 609.0 609.0 1.8 152 47609 607.5 609.3 609.3 2.1 4
609.3 609.3 2.1 154 49342 607.6 609.5 609.5 2.3 9
609.5 609.5 2.3 Unit 1 &
159 63856 2.4 9
2.4 Unit 2 609.6 609.6 609.6 609.6 167 61096 609.5 609.5 2.2 5
609.5 609.5 2.2 209 57578 607.2 608.4 608.3 1.0 1.5 608.3 608.4 1.0 210 50358 607.4 609.0 609.0 1.8 3
609.1 609.0 1.8 Du ratio n of flood depth
>0.05 ft (hr) 2.5 2
2 3
3 1
1 1
1 1
2.5 4
9 9
5 1.5 3
231 57303 607.9 609.5 609.5 2.2 6
609.5 609.5 2.2 6
232 60063 607.9 609.5 609.5 2.5
>10 609.5 609.5 2.5
>10 310 61353 607.0 607.7 607.7 1.0 4
607.7 607.7 1.0 4
311 57911 607.0 608.0 608.0 1.0 4
608.0 608.0 1.0 2
Service 312 57912 1.0 4
1.0 2
Building 607.1 608.1 608.1 608.1 608.0 313 57921 607.2 608.3 608.3 1.0 4
608.3 608.3 1.0 2
314 57923 607.2 608.4 608.3 1.0 4
608.3 608.4 1.0 1.8 336 80021 588.9 590.5 590.5 n/a n/a 591.1 591.1 2.5 8
338 78305 589.0 591.1 591.1 1.0 4
591.8 591.8 3.4 8
CWPH 1.0 4
3.3 9
339 78322 589.1 591.3 591.3 591.8 591.8 340 80401 588.9 590.9 590.9 n/a n/a 591.2 591.1 2.6 9
G5-43119 2.0 3.5 2.0 3.5 01 609.2 609.2 609.2 609.2 G5-43118 2.0 3.5 2.0 3.5 02 609.2 609.2 609.2 609.2 G5 G5-41392 2.2 8
2.2 8
Building 03 609.3 609.3 609.3 609.3 G5-41386 2.0 4
2.0 4
04 609.2 609.2 609.2 609.2 G5-41377 1.8 3
1.8 3
05 609.0 609.0 609.0 609.0 The results presented as peak flood depth and approximate duration of flood depth of greater than 0.05 ft are compiled from NextEra (2014a).
Table 3.2 Hydrostatic and Hydrodynamic Loads during LIP Event Scenario A Scenario B Door Static Impact Total Static Impact Total
- Force, Force,
- Force, Force,
- Force, Force, (lbs/ft)
(lbs/ft)
(lbs/ft)
(lbs/ft)
(lbs/ft)
(lbs/ft) 1 112.6 1.0 113.7 195.0 3.5 198.5 Turbine 2
112.6 1.9 114.5 195.0 6.7 201.7 4
112.6 0.7 113.3 195.0 3.5 198.5 Building 11 137.6 2.7 140.2 210.9 7.4 218.3 13 137.6 3.2 140.8 210.9 7.0 217.9 600 1.2 0.1 1.3 1.2 0.1 1.3 Diesel 601 0.3 0.0 0.3 0.3 0.0 0.3 602 7.8 0.5 8.3 7.8 0.4 8.2 Generator 603 2.8 0.7 3.5 2.8 0.7 3.5 604 15.3 0.1 15.4 15.3 0.1 15.4 151 112.6 1.3 113.9 112.6 1.4 114.0 152 137.6 6.6 144.2 137.6 8.3 145.9 154 165.0 6.0 171.0 165.0 3.4 168.4 Unit 1 &
159 179.7 6.6 186.3 179.7 4.5 184.2 Unit 2 167 151.0 5.4 156.4 151.0 3.5 154.5 209 31.2 1.1 32.3 31.2 1.1 32.3 210 112.6 0.7 113.4 112.6 1.0 113.7 231 165.0 5.6 170.6 165.0 5.8 170.9 232 195.0 8.2 203.2 195.0 8.7 203.7 310 31.2 2.4 33.6 31.2 4.3 35.5 Service 311 25.3 27.5 52.8 25.3 26.7 52.0 312 25.3 24.3 49.6 25.3 23.2 48.4 Building 313 44.9 11.2 56.1 44.9 9.1 54.1 314 37.8 2.2 39.9 37.8 2.1 39.9 336 137.6 140.6 278.2 195.0 70.3 265.3 CWPH 338 244.6 22.3 266.9 360.7 69.9 430.5 339 244.6 21.2 265.8 339.8 29.4 369.1 340 165.0 102.7 267.7 210.9 205.2 416.2 G501 137.6 2.2 139.8 137.6 2.9 140.5 GS G502 137.6 1.1 138.7 137.6 1.2 138.8 G503 151.0 0.4 151.4 151.0 0.7 151.8 Building G504 124.8 6.7 131.5 124.8 4.1 128.9 G505 101.1 38.2 139.3 101.1 31.2 132.3 Source: FHRR Table 4.1 (NextEra, 201 Sa)
Table 4.1-1. Reevaluated Flood Hazards for Flood-Causing Mechanisms Not Bounded by the COB Flood-Causing Stillwater Reevaluated Elevation, Associated Effects Flood Hazard Reference Mechanism NAVD88 NAVD88 Local Intense Precipitation and 609.6 ft Minimal 609.6 ft FHRR Table 4.2 Associated Drainage Table 4.2-1. Flood Event Duration for Flood-Causing Mechanisms Not Bounded by the COB Time Available Duration of Flood-Causing Mechanism for Preparation Inundation of Site for Flood Event Local Intense Precipitation NEI 15-05 (NEI,
-1 hour1 and Associated Drainage 2015)
Source: (NextEra, 2015a; NextEra, 2015b and NextEra, 2016)
Notes:
Time for Water to Recede from Site
-4.25 hour2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br />s2 1Duration of inundation from the hydrograph presented in the FHRR (NextEra, 2015a) [FHRR Figure 4.9 LIP TB Door 13 Water Depth Time Series - Scenario B].
2Time of recession from the MSA document (NextEra, 2016).
Table 4.3-1 Associated Effects Inputs for Flood-Causing Mechanisms Not Bounded by the COB Flood-Causing Mechanism Associated Effects Parameter Hydrodynamic loading at plant grade Debris loading at plant grade Sediment loading at plant grade Sediment deposition and erosion Concurrent conditions, including adverse weather Other pertinent factors (e.g., waterborne projectiles)
Source: (NextEra, 2015a)
Notes:
Local Intense Precipitation 430.5 lb/ft at CWPH (includes 360.7 lb/ft hydrostatic and Minimal Minimal Minimal Minimal Minimal (1) Lb/ft stands for pounds per linear feet of structure in length.
(2) Source: FHRR Table 4.15 69.9 lb/ft hydrodynamic)(2l flood event du ration site preparation period of 6
recession of Conditions are met for entry into flood procedures or notification of impending flood for flood event inundation water from site Arrival of flood waters on site Water begins to recede from site Figure 2.2-1 Flood Event Duration Source: JLD-ISG-2012-05 (NRC, 2012c), Figure 6.
Water completely receded from site and plant in safe and stable state that can be maintained indefinitely Figure 3.2-1. Permanent and Temporary Structures of the Point Beach Site, TS1 and TS2 are the temporary structures referenced in the Scenario A section. Source: FHRR Figure 4.5 Figure 3.2-2. Point Beach Imagery (Source: Google Earth, 2015)
Figure 3.2-3. Location of Temporary Wave Barriers as Described for Scenario B Source: FHRR Figure 4.8
POINT BEACH NUCLEAR PLANT, UNITS 1AND2-STAFF ASSESSMENT OF RESPONSE TO 10 CFR 50.54(f) INFORMATION REQUEST-FLOOD-CAUSING MECHANISM REEVALUATION DATED May 19, 2017 DISTRIBUTION:
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04/06/2017 OFFICE NRR/JLD/JHMB/BC NRR/JLD/JHMB/PM NAME NSanfilippo FVega DATE 05/19/2017 05/19/2017 OFFICIAL RECORD COPY