ML18158A484
| ML18158A484 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 07/28/2018 |
| From: | Juan Uribe Beyond-Design-Basis Management Branch |
| To: | Bologna R FirstEnergy Nuclear Operating Co |
| Uribe J, NRR/DLP, 415-3809 | |
| Shared Package | |
| ML18158A438 | List: |
| References | |
| EPID L-2016-JLD-001, EPID L-2016-JLD-002 | |
| Download: ML18158A484 (41) | |
Text
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Mr. Richard D. Bologna Site Vice President UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, O.C. 20555-0001 July 24, 2018 FirstEnergy Nuclear Operating Company Beaver Valley Power Station Mail Stop A-BV-SSB P.O. Box 4, Route 168 Shippingport, PA 15077
SUBJECT:
BEAVER VALLEY POWER STATION, UNITS 1 AND 2-STAFF ASSESSMENT OF RESPONSE TO 10 CFR 50.54(f) INFORMATION REQUEST FLOOD-CAUSING MECHANISM REEVALUATION (EPID NOS. L-2016-JLD-001 AND L-2016-JLD-0002.
Dear Mr. Bologna:
By letter dated March 12, 2012, the U.S. Nuclear Regulatory Commission (NRC) issued a request for information under Title 10 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 2, 2016 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML16063A288),
FirstEnergy Nuclear Operating Company (FENOC, the licensee) responded to this request for Beaver Valley Power Station, Units 1 and 2 (Beaver Valley).
By letter dated February 22, 2017 (ADAMS Accession No. ML17040A011 ), the NRC staff issued an Interim Staff Response (ISR) letter, which provided a summary of the staff's review of Beaver Valley's reevaluated flood-causing mechanisms. The enclosed staff assessment provides the documentation supporting the NRC staff's conclusions summarized in the ISR letter. For Beaver Valley, the reevaluated flood hazard results for the local intense precipitation and streams and rivers flood-causing mechanisms were not bounded by the current design basis, and were considered to be suitable input for additional flooding assessments of plant response.
The NRC staff notes that FENOC has already submitted (and the NRC staff has reviewed) the additional flooding assessments associated with Enclosure 2 to the 50.54(f) letter and the evaluation of mitigating strategies against the reevaluated hazards as described in Nuclear Energy Institute (NEI) 12-06, Revision 2, "Diverse and Flexible Coping Strategies (FLEX)
Implementation Guide" (ADAMS Accession No. ML16005A625). Additional details related to these evaluations are also included in the enclosed staff assessment. transmitted herewith contains Security-Related Information and Critical Electric. Infrastructure Information (CEIi). When separated from Enclosure 1, this document is decontrolled.
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9FFIQl.t.l: W&li &tJI:¥ &liQWAl'Pf Alils.Y:lii& ltJFQAMMIQtJ SEIi 98 N8T AELEA&E This letter closes out the NRC's efforts associated with EPID L-2016-JLD-001 and L-2016-JLD-0002, and all actions associated with Enclosure 2 to the 50.54(f) letter.
If you have any questions, please contact me at (301) 415-3809 or by e-mail at Juan.Uribe@nrc.gov.
Docket Nos. 50-334 and 50-412
Enclosures:
- 1. Staff Assessment of Flood Hazard Reevaluation Report for Beaver Valley (Non-public, Security Related)
- 2. Staff Assessment of Flood Hazard Reevaluation Report for Beaver Valley (Public) cc w/o encl 1 : Distribution via Listserv Sincerely, Juan. Uribe, roject anager Beyond-Design-Basis Management Branch Division of Licensing Projects Office of Nuclear Reactor Regulation 9FFIQl.l:.ls W&lii 9tH111¥ &liQWAI.V AlilaMlii& ltJF9AM.Y:19tJ
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QlrlrlCIOls W&lii QtllsY &liiCWAllY AliilsAl'lig 1*llrQAHOl'IQ*f SEIi 88 U8T RElEA8E STAFF ASSESSMENT BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO FLOODING HAZARD REEVALUATION REPORT NEAR-TERM TASK FORCE RECOMMENDATION 2.1 BEAVER VALLEY POWER STATION. UNITS 1 AND 2 DOCKET NOS. 50-334 AND 50-412
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, under Title 10 of the Code of Federal Regulations (10 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 (NTTF) report (NRC, 2011a).
Recommendation 2.1 in that document was for the NRC staff to 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 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 the NRC staff would provide a prioritization plan indicating the Flooding Hazard Reevaluation Report (FHRR) deadlines for each plant. On May 11, 2012 (NRC, 2012c), the NRC staff issued its prioritization of the FHRRs.
By letter dated March 2, 2016 (FENOC, 2016), FirstEnergy Nuclear Operating Company (FENOC. the licensee) submitted the FHRR for Beaver Valley Nuclear Station, Units 1 and 2 (Beaver Valley). The NRC staff performed an audit as documented in Section 5 and of this staff assessment.
On February 22. 2017 (NRC, 2017), the NRC issued an interim staff response (ISR) letter to the licensee. The purpose of the ISR letter was 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 the NRC staff's basis and conclusions. The flood hazard mechanism values presented in the ISR letter's enclosures match the values in this staff assessment without change or alteration.
As mentioned in the ISR letter, the reevaluated flood hazard results for the local intense precipitation (LIP) and streams and rivers flood-causing mechanisms are 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 (NRC, 2015a), Japan Lessons-Learned Directorate 8FFl8h\\b Y81i 8UbY 8E8YRIW REl.\\TliB IUF8RMATl8N Clill gg NO:r Alilsli t.&lii
QS:FIQl:\\ls Wii QtJlw¥ iiQWAI.V Aliiilsl:Ti& UJl=QAM.\\TIQtJ Qill gg tJQT AilsiAii (JLD) Interim Staff Guidance (ISG} JLD-ISG-2012-01, Revision 1 (NRC, 2016a) and JLD-ISG-2016-01, Revision O (NRC, 2016c}, the NRC staff received and reviewed a focused evaluation for LIP that assessed the impact of the LIP hazard on the site, and evaluated and implemented any necessary programmatic, procedural or plant modifications to address this hazard exceedance. Additionally, for the streams and rivers flood mechanism, the NRC staff received and reviewed a focused evaluation confirming the capability of existing flood protection at the site. Additional details regarding the focused evaluation submittal and the NRC staff's review are provided in Section 2.2.5 of this assessment.
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 respective sites using present-day methods and regulatory guidance used by the NRC staff when reviewing applications for ESPs and COLs. This section 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 plant site with a particular emphasis on the site evaluation factors identified in 10 CFR Part 100. The licensee should have provided 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 Part 50 states that structures, systems, and components (SSCs) important to safety at nuclear power plants shall 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 10 CFR defines "design bases" 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 that 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.
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 8FFl8hltt ttec eULY 8E8tffflifll' RELATES IP4F8RMATl8f4 c,11 go 'IOT Ail iO&i
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2.2 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 requests all power reactor licensees and construction permit holders to reevaluate all external flood-causing mechanisms at each site.
This includes current techniques, software, and methods used in present-day standard engineering practice.
2.2.1 Flood-Causing Mechanisms, Enclosure 2 of the 50.54(f) letter discusses the flood-causing mechanisms for the licensee to address in the FHRR (NRC, 2012a). Table 2.2-1 of this assessment lists the flood-causing mechanisms the licensee should consider and lists the corresponding Standard Review Plan (SRP) (NRC, 2007) section(s) and applicable ISG documents containing acceptance criteria and review procedures.
2.2.2 Associated Effects The licensee should incorporate and report associated effects (AEs) per JLD-ISG-2012-05, "Guidance for Performing the Integrated Assessment for External Flooding" (NRC, 2012d) in addition to the maximum water level associated with each flood-causing mechanism. Guidance document JLD-ISG-2012-05 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 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." It should also be noted that for the purposes of this staff assessment, the terms "combined effects" and "combined events" are synonyms. 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" (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:
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QFFfQlafzla Wlli e,u.v lliQWAl'P( Alilaafzl'lig INFQAMafzl'IQN Qlill liJQ tJQ'f Alila&i.t.&li 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. 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 The flood event duration (FED) was defined in JLD-ISG-2012-05 (NRC, 2012d) 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 the FED parameter.
2.2.5 Actions Following the FHRR For the sites where the reevaluated flood hazard is not bounded by the CDB probable maximum flood elevation for any flood-causing mechanism, the 50.54(f) letter (NRC, 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; and Perform an integrated assessment to: (a) evaluate the effectiveness of the CLB [current licensing basis] (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 CDB flood hazard for each flood-causing mechanism at the site, licensees are not required to perform an integrated assessment.
COMSECY-15-0019 (NRC, 2015a) and JLD-ISG-2016-01, Revision O (NRC, 2016c) outline a revised process for addressing cases in which the reevaluated flood hazard is not bounded by the plant's CDB. The revised process describes an approach in which licensees with a LIP hazard exceeding their CDB flood will not be required to complete an integrated assessment, but instead perform a focused evaluation. As part of the focused evaluation, licensees will assess the impact of the LIP hazard on their site and then evaluate and implement any necessary programmatic, procedural, or plant modifications to address this hazard exceedance.
For other flood hazard mechanisms that exceed the CDB, licensees can assess the impact of QFFIGIAk W&li &Nia¥ &liGWAl:W AlilsAA"li9 mr&AMA'fl&tJ SEIi 88 HST RELEASE
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By letter dated September 20, 2017 (FENOC, 2017a), the licensee submitted its mitigating strategies assessment (MSA) for Beaver Valley. The MSAs are intended to confirm that licensees have adequately addressed the reevaluated flooding hazards within their mitigating strategies for beyond-design-basis external events. By letter dated March 22, 2018 (NRC, 2018a), the NRC staff issued its assessment of the MSA and concluded that the licensee has demonstrated that the mitigation strategies, if appropriately implemented, are reasonably protected from reevaluated flood hazard conditions.
By letter dated October 16, 2017 (FENOC, 2017b), the licensee submitted the focused evaluation (FE) for Beaver Valley. The focused evaluations are intended to confirm that licensees have adequately demonstrated, for the unbounded mechanism identified in the ISR letter, that: 1) a flood mechanism is bounded based on further reevaluation of flood mechanism parameters; 2) effective flood protection is provided for the unbounded mechanism; or 3) a feasible response is provided if the unbounded mechanism is local intense precipitation. By letter dated March 22, 2018 (NRC, 2018b), the NRC staff issued its assessment of the FE and concluded that the licensee has demonstrated that effective flood protection exists against the reevaluated flood hazards. The FE staff assessment also concluded that FENOC has satisfactorily completed providing responses to the 50.54(f) activities associated with the reevaluated flood hazard for Beaver Valley.
3.0 TECHNICAL EVALUATION
The NRC staff has reviewed the information provided for Beaver Valley in the FHRR. 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 aid in the review, the NRC staff issued an audit plan by letter dated April 26, 2016 (NRC, 2016b), indicating that audits may be conducted, as necessary, to provide additional insights of the FHRR review, such as methodologies used, parameter selection and assumptions, model development and execution, calculations, analyses performed, and supporting documentation. As part of the audit activities, the licensee made several calculation packages available to the NRC staff via electronic reading room. These calculation packages were only found to expand upon and clarify the information already provided on the docket. and so are not docketed or cited. This audit plan stated that an audit report would be issued summarizing the results of the audit.
Section 5 of this assessment provides the audit summary referenced in the audit plan.
The Beaver Valley FHRR (FENOC, 2016) provided elevations using two different vertical datums, the North American Vertical Datum of 1988 (NAVD88) and the National Geodetic Vertical Datum of 1929 (NGVD29), also referred to as mean sea level. Unless otherwise stated, all elevations in this document are given with respect to NGVD29.
3.1 Site Information The 50.54(f) letter (NRC, 2012a) requested that relevant SSCs important to safety be included in the scope of the hazard reevaluation. The licensee included this pertinent data concerning these SSCs in the FHRR (FENOC, 2016). During the NRC staff's review of the FHRR, the staff requested additional clarifying information.
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3.1.1 Detailed Site Information The FHRR (FENOC, 2016) described the site-specific information related to the flood hazard evaluation at the Beaver Valley site. The Beaver Valley site is located on the south side of the Ohio River at river mile 34. 7 in Shippingport Borough in Beaver County, Pennsylvania, about 2.5 miles (mi) northwest of Pittsburgh, Pennsylvania. The total upstream drainage area is about 23,000 square miles (mi2). The Beaver Valley site is characterized by sloping topography with ground elevations ranging from 664.5 feet (ft.) NGVD29 to 1, 160 ft. NGVD29. A small stream, Peggs Run, flows through the eastern portion of the Beaver Valley site and is channeled through a culvert to the Ohio River. Figure 3.1-1 of this staff assessment shows a general layout of the Beaver Valley site.
3.1.2 Design-Basis Flood Hazards The COB flood levels are summarized by flood-causing mechanism in Table 3.1-2. The licensee stated that the probable maximum precipitation (PMP) for Beaver Valley, Unit 1, was 13 inches of rainfall in 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, while the PMP for Unit 2 was 31.3 inches over a 1 O-mi2 area in 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The licensee assumed a complete blockage of all yard and roof drains to determine the peak water surface elevation ran e of 732.4 ft. to 735.4 ft.
. J] While Beaver Valley, Unit 1, does not address LIP, storm surge, seiche, tsunami or channel migration or diversion, the licensee stated that storm surge, seiche, tsunami or channel migration or diversion mechanisms are not applicable to the Beaver Valley, Unit 2, site. Finally, the licensee stated that it is highly unlikely for ice-induced flooding to affect the Beaver Valley site.
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The licensee also stated that the COB includes a low water event with the Beaver Valley plant shutting down when the river level falls below 654 ft. NGVD29.
3.1.3 Flood-Related Changes to the Licensing Basis The licensee stated in its FHRR that there have been no changes to the licensing basis with respect to flooding or flood protection. The NRC staff reviewed the information provided in the Beaver Valley FHRR (FENOC, 2016) and determined that sufficient information was provided to be responsive to Enclosure 2 of the 50.54(f) letter (NRC, 2012a).
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&Ell 88 H&T R:El::EA&E 3.1.4 Changes to the Watershed and Local Area The licensee noted that changes to the watershed include development within the watershed, although this only accounts for a small percentage of the total watershed area. The licensee incorporated these changes into the flood hazard reevaluation.
3.1.5 Current Licensing Basis Flood Protection and Pertinent Flood Mitigation Features
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maximum flood level from LIP at Unit 2 exceeds the lowest access door at 732 ft. NGVD29.
However, the accumulation of water would not exceed 1.3 inches deep, and there are no safety-related connections closer than 2 inches from the floor. Therefore, the licensee determined that no mitigation actions were necessary.
3.1.6 Additional Site Details to Assess the Flood Hazard Additional information was reviewed by the NRC staff during the audit performed. This additional information was related to the flood hazard reevaluations and are documented in Section 5 and Attachment 1 of this assessment.
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 are available, functional, and implementable. Other parts of 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 27, 2012 (FENOC, 2012), as supplemented by letter dated February 25, 2014 (FENOC, 2014), FENOC submitted the Flooding Walkdown Report for the Beaver Valley site. On June 16, 2014 (NRC, 2014 ), the NRC staff issued its assessment of the Walkdown Report and 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 its FHRR that the reevaluated flood hazard for LIP and associated site drainage is based on a stillwater-surface elevation of 735.9 ft. NGVD29 at Beaver Valley, Unit 1, and 735.7 ft. NGVD29 at Beaver Valley, Unit 2. This flood-causing mechanism is not discussed for Unit 1 but is discussed as part of the COB for Unit 2. The CDB flood hazard elevations for LIP is provided in Table 3.1-2.
The licensee utilized a site-specific PMP analysis to evaluate flooding impacts from LIP at the Beaver Valley site. The licensee also performed a LIP analysis using the PMP derived from the applicable hydrometeorological reports (HMR) documents (HMR-51/52) produced by the National Oceanic and Atmospheric Administration (NOAA).
The HMR-based PMP resulted in a maximum precipitation depth of 26.4 inches with a corresponding duration of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. The licensee's site-specific PMP depth was
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As part of the Streams and Rivers hazard mechanism, the licensee developed an inflow hydrograph for a local tributary named Peggs Run that is hydraulically connected to the site. The development of this hydrograph is described in the Streams and Rivers section of this staff assessment. The inflow hydrograph developed by the licensee for Peggs Run was used as input to the site LIP analysis.
The licensee used a Digital Elevation Model (DEM) to define the topography and surface features such as grading, slope, and drainage divides of the Beaver Valley site.
In addition, the licensee obtained land cover information from various sources such as aerial images and site surveys. The licensee incorporated two types of obstructions into the DEM: buildings and other structures that completely block the flow of water regardless of the water surface elevation (WSE), and vehicle and security barriers that block the flow of water unless they are overtopped. The licensee used the FL0-20 hydraulic model to estimate the water surface elevations and velocities at the Beaver Valley site. The licensee assumed the drainage system was non-functional and excluded losses from infiltration.
The NRC staff reviewed the size of the grid used in the FL0-20 model and found it to be reasonable. Additionally, the NRC staff compared the model grid map showing plant structures and barriers with Google Earth aerial imagery and found that the buildings are properly depicted in the FL0-20 model.
The NRC staff reviewed the higher HMR 51/52 rainfall depth for the Beaver Valley site and confirmed that the LIP depths match values reported in the NOAA guidance.
Using the licensees FL0-20 model, the NRC staff performed a FL0-20 analysis using the higher HMR-based precipitation depth to estimate the maximum water surface elevations at the Beaver Valley site. The NRC staff determined that the difference in water surface elevations between the HMR-based and the site-specific PMP-based LIP analyses near safety-related structures was negligible (<0.25 ft). Due to the small differences in maximum water surface elevations near these structures, the NRC staff did not review the site-specific PMP analysis provided by the licensee. The NRC staff confirmed the licensee's conclusion that the flood hazard from LIP and associated site drainage is not bounded by the COB flood hazard. Accordingly, the NRC staff summarized its results in the ISR letter and the licensee used these values as input into the subsequent flooding submittals, as described in Section 2.2.5 of this assessment.
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9FFl&IAI: Y&& 9PJI:¥ &&&YFU'Pf A&l::NF&B INF8AMA"Fl8N Qliill gg NQT AliilsliiAllii On September 21, 2016, the NRC conducted an audit (see Attachment 1 of this assessment) of the licensee's basin-wide site-specific PMP including the methodology and input parameters.
Through the audit process, NRC staff identified several issues and concerns with the licensee's original submittal and site-specific PMP estimates. Using revised input parameters, NRC staff independently estimated basin-wide site-specific PMP values that were greater than the licensee's estimates.
Per lnteragency Agreement NRC-HQ-13-1-03-0021, the USACE assisted the NRC in determining the safety significance of hydrologic and geotechnical issues and other features associated with dams that may affect the safe, reliable operation of downstream or nearby nuclear power plants. The USACE analyzed multiple scenarios in assisting the NRC staff to determine the reevaluated flood hazard for the streams and rivers flood-causing mechanism (USACE, 2016). [
On January 26, 2017, the NRC staff conducted a site audit. The purpose of the site audit was to address the peak stillwater surface elevation results using the NRC staff's basin-wide site-specific PMP. During the site audit, the licensee demonstrated that there is minimal change or impact to safety-related SSCs at the site between the CDB flood elevation and the eak flood elevation based on NRC staff's site-specific PMP. [
3.3.2 Peggs Run Stream
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]. This flood-causing mechanism is not discussed for Unit 1 but is discussed in the CDB for Unit 2. The CDB flood hazard elevation for this hazard mechanism is 730 ft. NGVD29 for Unit 2.
For the Peggs Run PMP analysis the licensee considered three alternatives as outlined in NUREG/CR-7046 for floods caused by precipitation events. The controlling scenario is the Alternative 1 all-season PMP based on HMR-51 /52. The licensee used a modified "peaked" National Resources Conservation Service (NRCS) unit hydrograph to account for a non-linear watershed response. The licensee increased the peak by 20 percent and reduced the time to peak by 33 percent, while adjusting other portions of the hydrograph to maintain the same runoff volume. This hydrograph was used in HEC-HMS to estimate the peak runoff from the all-season PMP (Alternative 1) for the 3.6-square-mile Peggs Run watershed. The licensee accounted for infiltration losses using the NRCS curve number methodology. The licensee modeled the watershed for Peggs Run in the HEC-HMS model with two sub-basins. The HMR-9FFl&l.tds Y&lii 9Hls¥ &lii&YA1'5¥ Aliil!!MliiB IHF9AMMl9H
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&Ell 98 tJ&f AEl!:EA&li 51/52 was used to develop the precipitation magnitude and duration. The hydrograph developed for Peggs Run was incorporated into the LIP analysis discussed in Section 3.2.
The NRC staff reviewed the methodology and input parameter values for the curve number methodology such as the weighted curve numbers, the lag time parameters, and the HMR-51 /52 PMP depth-duration parameters. The NRC staff ran the licensee's provided HEC-HMS and Hydrologic Engineering Center-River Analysis System (HEC-RAS) models, and noted that the simulation produced no errors and confirmed the licensee's results.
3.3.3 Maximum Water Level Determination The licensee described a combined event of the PMF for the Ohio River occurrin generated waves including wave runup. [
The NRC staff confirmed the licensee's conclusion that the reevaluated hazard from flooding by streams and rivers is not bounded by the total COB flood hazard elevation. Accordingly, the NRC staff summarized its results in the ISR letter and the licensee used these values as input into the subsequent flooding submittals, as described in Section 2.2.5 of this assessment.
3.4 Failure of Dams and Onsite Water Control/Storage Structures The licensee reported in its FHRR that the reevaluated flood hazard for failure of dams and onsite water control or storage structures is based on analysis performed by the USACE (USACE, 2015) and did not report a water surface elevation for this flood hazard mechanism in the Beaver Valley FHRR (FENOC, 2016). The staff confirmed that the licensee adopted the USACE's values for this hazard mechanism.
Per lnteragency Agreement NRC-HQ-13-1-03-0021, the USACE assisted the NRC in determining the safety significance of hydrologic and geotechnical issues and other features associated with dams that may affect the safe, reliable operation of downstream or nearb nuclear power plants. [
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&&11 ee ue:r R&l!:&A&& The NRC staff confirmed the licensee's conclusion that the reevaluated hazard from flooding by failure of dams and onsite water control or storage structures is bounded by the CDB flood hazard. Accordingly, flooding from failure of dams and onsite water control/storage structures does not need to be included in a focused evaluation or revised integrated assessment.
3.5 Storm Surge The licensee reported in its FHRR that the reevaluated flood hazard for storm surge does not inundate the Beaver Valley site, but did not report a probable maximum flood elevation. This flood-causing mechanism is discussed in the licensee's CDB, but a PMF elevation was not reported. The licensee provided no CDB maximum flood elevation for storm surge in the FHRR.
The licensee stated that because the Beaver Valley site is not located on a coast or adjacent to cooling ponds or reservoirs, flooding from storm surge is not applicable.
The NRC staff confirmed the licensee's conclusion that the reevaluated hazard for flooding from storm surge is not applicable to the Beaver Valley site. Therefore, the NRC staff determined that flooding from storm surge does not need to be analyzed in either a focused evaluation or revised integrated assessment.
3.6 Seiche The licensee reported in its FHRR that the reevaluated hazard for seiche does not inundate the plant site, but did not report a PMF elevation. This flood-causing mechanism is discussed in the licensee's CDB, but a PMF elevation was not reported. The licensee stated that the Beaver Valley site is not located on a coast or adjacent to cooling ponds or reservoirs, therefore flooding from seiche is not applicable.
The NRC staff confirmed the licensee's conclusion that the reevaluated hazard for flooding from seiche is not applicable to the Beaver Valley site. Therefore, the NRC staff determined that flooding from seiche does not need to be analyzed in a focused evaluation or a revised integrated assessment.
3.7 Tsunami The licensee reported in its FHRR that the reevaluated hazard for tsunami does not inundate the plant site, but did not report a PMF elevation. This flood-causing mechanism is discussed in the licensee's CDB, but a PMF elevation was not reported. The licensee stated that the Beaver Valley site is not situated on a coast or adjacent to cooling ponds or reservoirs, therefore tsunamigenic waves are not applicable.
The NRC staff confirmed the licensee's conclusion that the reevaluated hazard for flooding from tsunami is not applicable to the Beaver Valley site. Therefore, the NRC staff determined that QFFIQl.\\ls Wii QJJls¥ ii&WAIW Ail.Mi& IHFQAM.<<t~IQJJ
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3.8 Ice-Induced Flooding The licensee reported in its FHRR that the reevaluated flood hazard for ice-induced flooding is negligible. This flood-causing mechanism is discussed in the licensee's CDB, but a flood elevation was not reported.
The licensee described two mechanisms by which ice jams and ice dams could lead to flooding of a site: 1) collapse of an upstream ice jam creating flood waves, and 2) formation of downstream ice jam causing a flood at the site via backwater effects. The licensee reviewed historical ice effects in the Ohio River in the vicinity of the Beaver Valley site and determined that ice jam events are possible. The licensee searched the USACE Ice Jam Database (USACE, n.d.) and selected the event that produced the maximum flood stage at a specific location. The licensee then used an unsteady-state flow HEC-RAS hydraulic model calibrated using U.S.Geological Survey gage data and. a roughness coefficient based on land use and land cover data. The licensee estimated the maximum reported upstream ice jam to be 28.4 ft.
resulting in a maximum WSE of 700.6 ft. NGVD29. The maximum downstream ice jam would result in a maximum WSE of 719.3 ft. at the Beaver Valley site.
The NRC staff confirmed the licensee's conclusion that the reevaluated hazard for ice-induced flooding is bounded by the CDB flood hazard at the Beaver Valley site. Therefore, the NRC staff determined that ice-induced flooding effects do not need to be analyzed in a focused evaluation or a revised integrated assessment for the Beaver Valley site.
3.9 Channel Migrations or Diversions The licensee reported in its FHRR that the reevaluated hazard for channel migrations or diversions does not inundate the plant site, but did not report a maximum flood elevation. This flood-causing mechanism is discussed in the licensee's CDB, but no maximum flood elevation was reported.
The licensee stated that it used historical records and hydrogeomorphological data to reevaluate the potential for flooding due to channel migrations or diversions of the Ohio River.
The licensee did not evaluate channel migration of Peggs Run due to the small drainage areas and distance to the Beaver Valley site. The licensee consulted topographic maps from 1901, 1954 and 2013 and concluded that there are slight differences between the 1901 and 1954 map, but there is no evidence of channel migration between 1954 and 2013. The licensee determined that the inherent inaccuracy of the methods used to create the 1901 topographical map may account for the differences and therefore concluded that channel migration is not probable at the Beaver Valley site.
The NRC staff confirmed the licensee's conclusion that the reevaluated hazard for flooding from channel migrations or diversions is bounded by the CDB flood hazard. Therefore, flooding from channel migrations or diversions does not need to be analyzed in a focused evaluation or a revised integrated assessment for the Beaver Valley site.
05:5:1£141. !Iii 0111.¥ &lii£!1AIT¥ Aliil.OTliiQ lt:15'.0AII OJ:1011 Cliill QO tlOT Aliil.ifllii
4.0 4.1 8FFl811:I: YSE 8Nkt/ 8E8YAl'R' AEkJ.'fE8 INF8AMJ.'f18tl Sliiill gg tlQ:f AliiilsliiiA&liii REEVALUATED FLOOD HEIGHT, EVENT DURATION, AND ASSOCIATED EFFECTS FOR HAZARDS NOT BOUNDED BY THE CURRENT DESIGN BASIS Reevaluated Flood Height for Hazards Not Bounded by the Current Design Basis Section 3 of this staff assessment' documents the NRC staff's review of the licensee's flood hazard water height results. Table 4.1-1 contains the maximum flood height results, including waves and runup, for flood mechanisms not bounded by the COB. The NRC staff agrees with the licensee's conclusion that LIP, and flooding from streams and rivers are the flood-causing mechanisms not bounded by the CDB.
4.2 Flood Event Duration for Hazards Not Bounded by the Current Design Basis The NRC staff reviewed information provided in FENOC's 50.54(f) response (FENOC, 2016) regarding the FED parameters needed to perform the additional assessments of plant response for flood-causing mechanisms not bounded by the COB. The FED parameters provided in the FHRR for the two flood-causing mechanisms not bounded by the COB are summarized in Table 4.2-1.
By letter dated September 20, 2017 (FENOC, 2017a), the licensee submitted its MSA, which included the FED parameters for the two controlling scenarios. The NRC staff's review and conclusions regarding the FED parameters provided in the MSA are documented in a separate staff assessment that was issued on March 22, 2018 (NRC, 2018a).
4.3 Associated Effects for Hazards Not Bounded by the Current Design Basis The NRC staff reviewed information provided in FENOC's 50.54(f) response (FENOC, 2016) regarding the AE parameters needed to perform the additional assessments of plant response for flood hazards not bounded by the CDB. The licensee also presented the AE parameters associated with the two, unbounded, flood-causing mechanisms directly related to LIP and PMF with wind waves and runup in the MSA. The AE parameters are presented in Table 4.3-1.
In its MSA, the licensee included these AE parameters for the two controlling scenarios. The NRC staff's review and conclusions regarding the AE parameters provided in the MSA are documented in a separate staff assessment issued on March 22, 2018 (NRC, 2018a). In that MSA staff assessment, the NRC staff agreed with the licensee that the waterborne loads, including hydrostatic, hydrodynamic, debris, and sediment loads, would induce minimal impacts to plant operations due to the low LIP water depths and velocities. They also concluded that other associated effects, including sediment deposition and erosion, concurrent site conditions, and effects on groundwater intrusion are insignificant at the plant site.
4.4.
Conclusion Based upon the preceding analysis, the NRC staff confirmed that the reevaluated flood hazard information defined in Section 4. 1 was appropriate input to the additional assessments of plant response as described in the 50.54(f) letter, COMSECY-15-0019 (NRC, 2015), and the associated guidance.
Q5i5il81af ls Wii,n11sv iiSWAl:i.v Alilsll'liD ltJ5iQAM1+1QtJ Clill DO *101 Ail it&&
8FFl&l.t.l: Wllii 8JJI:¥ liQWAIW Aila.t.;i& UJFQAMl~l8JJ Gill 88 HQ; Aliilsi.ltllii The licensee developed FED parameters and applicable flood AEs to conduct future additional assessments as discussed in NEI 12-06, Revision 2, Appendix G (NEI, 2015), JLD-ISG-2012-05 (NRC, 2012d), and JLD-ISG-2016-01, Revision O (NRC, 2016c). The NRC staff review and conclusions for the FED and AE parameters provided in the MSA (FENOC, 2017a) are documented separately from this staff assessment (NRC, 2018a).
5.0 AUDIT The NRC staff issued ari audit plan by letter dated April 26, 2016 ((Agencywide Documents Access and Management System (ADAMS) Accession No. ML16105A211 ), indicating that audits may be conducted relative to the Beaver Valley FHRR, as necessary, in order to provide additional insights of the review and analysis performed. These insights included, but were not limited to, methodologies used; parameter selection criteria and assumptions; model development, configuration and execution; calculations; reference material; analyses performed, and supporting documentation. of this staff assessment contains additional technical and logistical details of the audits perfonned, such as the clarifying infonnation requested from FENOC and the corresponding resolution of each item. In addition, each information need requested has been discussed in the corresponding Section of this assessment. Following the guidance of NRC Office of Nuclear Reactor Regulation, Office Instruction LIC-111, "Regulatory Audits," dated December 29, 2008 ADAMS Accession No. ML082900195), this staff assessment conveys the results of the audit performed and therefore a separate report is not needed. In conclusion, the audit performed allowed the NRC staff to better understand the Beaver Valley FHRR, supported the completion of the staffs review and the subsequent issuance of an interim hazard letter.
During its review, the NRC staff did not identify any issues or open items and considers the audit completed and closed.
6.0 CONCLUSION
The NRC staff reviewed the information provided for the reevaluated flood-causing mechanisms of the Beaver Valley site. Based on the review of the above, available information provided in FENOC' s 50.54(f) response (FENOC, 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 (1) the reevaluated flood hazard results for LIP and streams and rivers are not bounded by the CDB flood hazard, (2) additional assessments of plant response would need to be performed for LIP and for flooding from streams and rivers and (3) the reevaluated flood-causing mechanism information is appropriate input to the additional assessments of plant response, as described in 50.54(f) letter and COMSECY-15-0019, and associated guidance.
By letter dated September 20, 2017 (FENOC, 2017a), the licensee submitted the MSA whereby they provided additional assessments of the plant response for the LIP and streams and rivers flood-causing mechanisms. The NRC staff review and conclusions for the additional FED and 8FFl&l.t.l: WIiie 8JJ1s¥ &lii&WAIW Aliileslwlii8 IHFQAMMl8N Qill gg HQl' Alilalial181i
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6.0 REFERENCES
Note: 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/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, [available on line at http://www.nrc.gov/reading-rm/basic-ref/srp-review-standards.html.]
NRC, 2011a, "Near-Term Report and Recommendations for Agency Actions Following the Events in Japan," Commission Paper SECY-11-0093, July 12, 2011, ADAMS Accession No. 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. ML111861807.
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, 2011d, "Prioritization of Recommended Actions to be Taken in Response to Fukushima Lessons Learned," Commission Paper SECY-11-0137, October 3, 2011, ADAMS Accession No. ML11272A111.
NRC, 2011e, "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 10 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. ML12053A340.
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 Request for Information Pursuant to Title 10 of the QFFl&IAls W&i 8~Jls¥ &li&WAIW Alil:A'fli9 INF8AMMl8N
&lill 98 H8T A&lsliiA&&
. 8FFl8blcl Y8E 8HLY 8E8YRl:Ji\\f RELATEB IUF8RMM'l8H Cliill PO *10:z AliiL:lii O &Iii Code of Federal Regulations 50.54(() Regarding Flooding Hazard Reevaluations for Recommendations 2.1 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident," May 11, 2012, ADAMS Accession No. ML12097A510.
NRC, 2012d, "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, 2013a, "Guidance for Performing a Tsunami, Surge, or Seiche Hazard Assessment,"
Japan Lessons-Learned Project Directorate, Interim Staff Guidance JLD-ISG-2012-06, Revision 0, 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, 2014, "Beaver Valley Power Station 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-lchi Nuclear Power Plant Accident," ADAMS Accession No. ML14156A233.
NRC, 2015a, "Mitigating Strategies and Flood Hazard Reevaluation Action Plan," Commission Paper COMSECY-15-0019, June 30, 2015, ADAMS Accession Nos. ML15153A104 (Package, two documents): ML15153A105, "Closure Plan for the Reevaluation of Flooding Hazards for Operating Nuclear Power Plants" and ML15153A110, "Enclosure 1 - Mitigating Strategies and Flooding Hazard Re-Evaluation Action Plan).
NRC, 2015b "Report for the Audit of Applied Weather Associates, LLC, Regarding Site Specific Probable Maximum Precipitation Development in Support of Near-Term Task Force Recommendation 2.1 Flood Hazard Reevaluations," May 19, 2015, ADAMS Accession No. ML15113A029.
NRC, 2015c, "Beaver Valley Power Station, Units 1 and 2-Transmittal of U.S. Army Corps of Engineers Flood Hazard Reevaluation Information (TAC Nos MF3286 and MF3287)",
September 15, 2015, ADAMS Accession No. ML15244B198 (Non-Public)
NRC, 2016a, "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-lSG-2012-01, Revision 1 and Comment Resolution, January 22, 2016, ADAMS Accession No. ML15357A142.
NRC, 2016b, "Nuclear Regulatory Commission Plan for the Audit of First Energy Nuclear Operating Company's Flood Hazard Reevaluation Report Submittal Relating To The Near-Term Task Force Recommendation 2.1-Flooding For Beaver Valley Power Station, Units 1 And 2 (CAC Nos. MF3286 and MF3287)." April 26, 2016. ADAMS Accession No. ML16105A211.
8Ffl&IAL wee 8NLY &E&WRIW RELMEB IHF8RMM'l8N Cliill PO NO'l Aliil.i O Iii
QIPIPHwl.t.ls Wii QNls¥ ii~WAIT¥ AilsMig INIPQAM.\\:J'IQ*I 8EII 88 f48'f RELEASE 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.
NRC, 2017, "Beaver Valley Power Station, Units 1 and 2 - Interim Staff Response to Reevaluated Flood Hazards Submitted in Response to 10 CFR 50.54(f) Information Request -
Flood-causing Mechanism Reevaluation (CAC No. MF3286 and MF3287)," February 22, 2017.
ADAMS Accession No. ML17040A011.
NRC, 201 Ba, "Beaver Valley Steam Electric Station, Units 1 and 2, Flood Hazard Mitigation Strategies Assessment Staff Assessment", dated March 22, 2018, ADAMS Accession No. ML18071A169.
NRC, 201 Bb, "Beaver Valley Steam Electric Station, Units 1 and 2, Flood Hazard Focused Evaluation Staff Assessment", dated March 22, 2018. ADAMS Accession No. ML18067A112.
Codes and Standards and Other References ANSI/ANS (American National Standards Institute/American Nuclear Society), 1992, ANSI/ANS-2.8-1992, "Determining Design Basis Flooding at Power Reactor Sites," American Nuclear Society, LaGrange Park, IL, July 1992.
American Society of Civil Engineers (ASCE), 2010, ASCE 7-10, Minimum Design Loads for Buildings and Other Structures, Reston.
FENOC (FirstEnergy Nuclear Operating Company), 2012, "FENOC Response to NRC Request for Information Pursuant to 1 O CFR 50.54(f) Regarding the Flooding Aspects of Recommendation 2.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident," November 27, 2012, ADAMS Accession No. ML12335A341.
FENOC, 2014, "FENOC Supplemental Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding the Flooding Aspects of Recommendation 2.3 of the Near-Term Task Force Review of Insights from the Fukushima Dai-ichi Accident," February 25, 2014, ADAMS Accession No. ML14057A548.
FENOC, 2016, "FirstEnergy Nuclear Operating Company (FENOC) Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding the Flooding Aspects of Recommendation 2.1 of the Near-Term Task Force (NTTF) Review of Insights from the Fukushima Dai-ichi Accident," March 2, 2016. ADAMS Accession No. ML16063A288.
FENOC, 2017a, "Mitigating Strategies Assessment for Flooding (CAC Nos MF3286 and MF3287), Beaver Valley Power Station, Units Nos. 1 and 2, Docket Nos. 50-334 and 50-412, License Nos. DPR-66 and NPF-73, "dated September 20, 2017. ADAMs Accession No. ML17263A122.
FENOC, 2017b, "Focused Evaluation Regarding Near-Term Task Force Recommendation 2.1 for Flooding CAC Nos. MF3286 and MF3287," dated October 16, 2017. ADAMS Accession No. ML17290A033.
8FFl&ll.k W&i 9Hk¥ &li&WAIPI' Rlil:l.lli9 INF8RM.t.=Fl8N Gill DO *IOI Ail iO&li
8FFIGIAk W&li &Nia¥ &&i&WAl;J¥ A&i......:F&i9 ltJF8AMAifl8H
&&II 98 tJQif Alils&A&li NOAA, n.d., "Global Historical Tsunami Database" (YVeb site),
https://www.ngdc.noaa.gov/hazard/tsu_db.shtml.
NOAA, 1978, "Probable Maximum Precipitation Estimates, United States, East of the 105th Meridian," NOAA Hydrometeorological Report No. 51, June 1978.
USACE (U.S. Army Corps of Engineers), n.d., "Ice Jam Database," U.S. Army Corps of Engineers, Cold Region Research and Engineering Laboratory (CRREL), available online at http://icejams.crrel.usace.army.mil/. Staff accessed on June 7, 2017.
USACE, 2008, "Coastal Engineering Manual," Engineer Manual 1110-2-1100, available online at http://www.publications.usace.army.mil/USACEPublications/EngineerManuals.
USACE, 2010, "River Analysis System (HEC-RAS), Version 4.1. 0," Hydrologic Engineering Center, U.S. Army Corps of Engineers, January 2010.
USACE, 2013, "National Inventory of Dams," available online at http://nid.usace.army.mil.
USACE, 2016,"Evaluation of Upper Ohio River Basin Dams and Potential Flood Hydrographs at the Beaver Valley Nuclear Power Plant", US Army Corps of Engineers, October 2016.
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8FF181AL tl81! 8NL'/ 81!8tlfUFY ftl!LAJl!B lflF8ftMA"Fi8f4 Qill 9Q tJQT Ailsi!.&i Table 2.2-1. Flood-Causing Mechanisms and Corresponding Guidance Flood-Causing Mechanism SRP1 Section(s) and JLD-ISG Local Intense Precipitation and Associated SRP 2.4.2 Drainage SRP 2.4.3 SRP 2.4.2 Streams and Rivers SRP 2.4.3 Failure of Dams and Onsite Water SRP 2.4.4 Control/Storage Structures JLD-ISG-2013-01 SRP 2.4.5 Storm Surge JLD-ISG-2012-06 SRP 2.4.5 Seiche JLD-ISG-2012-06 SRP 2.4.6 Tsunami JLD-ISG-2012-06 Ice-Induced SRP 2.4.7 Channel Migrations or Diversions SRP 2.4.9 Notes:
1. SRP is the Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR Edition (NRC, 2007)
- 2.
JLD-ISG-2012-06 is the "Guidance for Performing a Tsunami. Surge, or Seiche Hazard Assessment" (NRC, 2013a)
- 3. JLD-ISG-2013-01 is the "Guidance for Assessment of Flooding Hazards Due to Dam Failure" (NRG, 2013b)
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(NGVD29)
Beaver Valley Power Station 735.3 ft.
Minimal 735.3 ft.
FHRR Section 2.1.1 &
Unit 2: Fuel and UFSAR Table 2.4-6 Decontamination Building (1 Door)
Beaver Valley Unit 2 Fuel and 735.3 ft.
Minimal 735.3 ft.
FHRR Section 2.1.1 &
Decontamination Building UFSAR Table 2.4.6 (3 Doors)
Beaver Valley Unit 2:
732.4 ft.
Minimal 732.4 ft.
FHRR Section 2.1.1 &
Emergency Diesel Generator UFSAR Table 2.4.6 Building (3 Doors)
Beaver Valley Unit 2: Main 732.5 ft.
Minimal 732.5 ft.
FHRR Section 2.1.1 &
Steam Valve Building Area UFSAR Table 2.4.6 Beaver Valley Unit 2:
732.5 ft.
Minimal 732.5 ft.
FHRR Section 2.1.1 &
Safeguards Building UFSAR Table 2.4.6 Beaver Valley Unit 2: Auxiliary 735.4 ft.
Minimal 735.4 ft.
FHRR Section 2.1.1 &
Building (3 Doors)
UFSAR Table 2.4.6 Beaver Valley Unit 2: Control 735.4 ft.
Minimal 735.4 ft.
FHRR Section 2.1.1 &
Building (3 Doors; South)
UFSAR Table 2.4.6 Beaver Valley Unit 2: Control 735.4 ft.
Minimal 735.4 ft.
FHRR Section 2.1.1 &
Building (1 Door; North)
UFSAR Table 2.4.6 Beaver Valley Unit 2: Service 732.5 ft.
Minimal 732.5 ft.
FHRR Section 2.1.1 &
Building (1 Door; $830-8)
UFSAR Table 2.4.6 Beaver Valley Unit 2: Reactor 735.1 ft.
Minimal 735.1 ft.
FHRR Section 2.1.1 &
Containment (Equipment UFSAR Table 2.4.6 Hatch)
Beaver Valley Unit 2:
732.5 ft.
Minimal 732.5 ft.
FHRR Section 2.1.1 &
Emergency Diesel Generator UFSAR Table 2.4.6 Building (1 Door)
Beaver Valley Unit 2: Service 732.5 ft.
Minimal 732.5 ft.
FHRR Section 2.1.1 &
Building (1 Door)
UFSAR Table 2.4.6 Streams and Rivers Probable Maximum Flood
[
.))
FHRR Section 2.1.2 &
Table 3 Peggs Run - Beaver Valley Not Not included in Not included in FHRR Section 2.1.2 &
Unit 1 included in DB DB Table 3 DB QlililQl..lals W81ii Q~ll.¥ 81iiQWAl'Pf Aliils.t..:liia ltlfQAM.ft:r.lQtl Qliill gg NQf Aliilsli O &Ii
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&ill 88 H8'f Ril:EA&E Peggs Run - Beaver Valley No Impact No Impact on No Impact on FHRR Section 2.1.2 &
Unit 2 on the Site the Site the Site Table 3 Identified Identified Identified Combined Event - Probable Maximum Flood with Wind [-..
--11 FHRR Section 2.1.8 &
Wave for Units 1 & 2 at the Intake Structure Table 3 Failure of Dams and Onsite Water Control/Storage Structures Conemaugh Dam with [-
-*))
FHRR Section 2.1.3 &
Standard Project Flood - Units Table 3 1&2 Storm Surge Beaver Valley Unit 1 Not Not Included in Not Included in FHRR Section 2.1.4 &
Included in DB DB Table 3 DB Beaver Valley Unit 2 No Impact No Impact on No Impact on FHRR Section 2.1.4 &
on Site Site Identified Site Identified Table 3 Identified Seiche Beaver Valley Unit 1 Not Not Included in Not Included in FHRR Section 2.1.4 &
Included in DB DB Table 3 DB Beaver Valley Unit 2 No Impact No Impact on No Impact on FHRR Section 2.1.4 &
on Site Site Identified Site Identified Table 3 Identified Tsunami Beaver Valley Unit 1 Not Not Included in Not Included in FHRR Section 2.1.5 &
Included in DB DB Table 3 DB Beaver Valley Unit 2 No Impact No Impact on No Impact on FHRR Section 2.1.5 &
on Site Site Identified Site Identified Table 3 Identified Ice-Induced Flooding Beaver Valley Unit 1 No Impact No Impact on No Impact on FHRR Section 2.1.6 &
on Site Site Identified Site Identified Table 3 Identified QFFl&IAk W&li QtJlsY &l!QWAl"Pf Alikl.:r:l!a ltlFQAM.*.:r::l&tJ
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on Site Site Identified Site Identified Table 3 Identified Channel Migrations/Diversions Beaver Valley Unit 1 Not Not Included in Not Included in FHRR Section 2.1.7 &
Included in DB DB Table 3 DB Beaver Valley Unit 2 No Impact No Impact on No Impact on FHRR Section 2.1.7 &
on Site Site Identified Site Identified Table 3 Identified Note:
- 1. Reported values are rounded to the nearest one-tenth of a foot.
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Oliiliil£1 tis Uili ONI.¥ ili£UAIT¥ Alia..n;&g INliiOAH t°'ION SEIi 88 HST RELEASE Table 4.1-1. Reevaluated Flood Hazard Elevations for Flood-Causing Mechanisms Not Bounded by the CDB Flood-Causing Stillwater Reevaluated Elevation Waves/Run up Flood Reference Mechanism Hazard Local Intense Precipitation Beaver Valley Unit 1 : Main 735.5 ft.
Minimal 735.5 ft.
FHRR Section 3.8.4 Steam Cable Vault (MS-35-1)
NGVD29 NGVD29
& Tables 1 & 3 Beaver Valley Unit 1 : Diesel 735.3 ft.
Minimal 735.3 ft.
FHRR Section 3.8.4 Generator Building (G-35-2)
NGVD29 NGVD29
& Tables 1 & 3 Beaver Valley Unit 1 : Diesel 735.3 ft.
Minimal 735.3 ft.
FHRR Section 3.8.4 Generator Building (G-35-3)
NGVD29 NGVD29
& Tables 1 & 3 Beaver Valley Unit 1 : Diesel 735.2 ft.
Minimal 735.2 ft.
FHRR Section 3.8.4 Generator Building NGVD29 NGVD29
& Tables 1 & 3 (Removable Shield E)
Beaver Valley Unit 1 : Diesel 735.3 ft.
Minimal 735.3 ft.
FHRR Section 3.8.4 Generator Building NGVD29 NGVD29
& Tables 1 & 3 (Removable Shield W)
Beaver Valley Unit 1 :
735.6 ft.
Minimal 735.6 ft.
FHRR Section 3.8.4 Coolant Recovery Tanks (TA-NGVD29 NGVD29
& Tables 1 & 3 35-1)
Beaver Valley Unit 1 :
735.6 ft.
Minimal 735.6 ft.
FHRR Section 3.8.4 Coolant Recovery Tanks NGVD29 NGVD29
& Tables 1 & 3 (Removable Panel)
Beaver Valley Unit 1:
735.4 ft.
Minimal 735.4 ft.
FHRR Section 3.8.4 Safeguards (SG-4 7 -1 )
NGVD29 NGVD29
& Tables 1 & 3 Beaver Valley Unit 1: Fuel 735.9 ft.
Minimal 735.9 ft.
FHRR Section 3.8.4 Building (F-35-1; F-35-3)
NGVD29 NGVD29
& Tables 1 & 3 Beaver Valley Unit 1: Fuel 735.6 ft.
Minimal 735.6 ft.
FHRR Section 3.8.4 Building (F-35-2)
NGVD29 NGVD29
& Tables 1 & 3 Beaver Valley Unit 1 : Fuel 735.7 ft.
Minimal 735.7 ft.
FHRR Section 3.8.4 Building (F-35-4)
NGVD29 NGVD29
& Tables 1 & 3 Beaver Valley Unit 1:
735.2 ft.
Minimal 735.2 ft.
FHRR Section 3.8.4 Decontamination Building (D-NGVD29 NGVD29
& Tables 1 & 3 35-1)
Beaver Valley Unit 1 :
735.3 ft.
Minimal 735.3 ft.
FHRR Section 3.8.4 Decontamination Building (D-NGVD29 NGVD29
& Tables 1 & 3 35-2)
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&Ell 88 HST AELEA8E Beaver Valley Unit 1:
735.5 ft.
Minimal 735.5 ft.
FHRR Section 3.8.4 Service Building (S-35-44)
NGVD29 NGVD29
& Tables 1 & 3 Beaver Valley Unit 1:
735.5 ft.
Minimal 735.5 ft.
FHRR Section 3.8.4 Service Building (S-35-48)
NGVD29 NGVD29
& Tables 1 & 3 Beaver Valley Unit 1 :
735.5 ft.
Minimal 735.5 ft.
FHRR Section 3.8.4 Service Building (S-35-49)
NGVD29 NGVD29
& Tables 1 & 3 Beaver Valley Unit 1 :
735.5 ft.
Minimal 735.5 ft.
FHRR Section 3.8.4 Service Building (35-67)
NGVD29 NGVD29
& Tables 1 & 3 Beaver Valley Unit 1 :
735.5 ft.
Minimal 735.5 ft.
FHRR Section 3.8.4 Warehouse (W-35-1)
NGVD29 NGVD29
& Tables 1 & 3 Beaver Valley Unit 1 : Waste 735.6 ft.
Minimal 735.6 ft.
FHRR Section 3.8.4 Gas Storage Area (DT-27-1)
NGVD29 NGVD29
& Tables 1 & 3 Beaver Valley Unit 1:
735.2 ft.
Minimal 735.2 ft.
FHRR Section 3.8.4 Containment (Equipment NGVD29 NGVD29
& Tables 1 & 3 Hatch)
Beaver Valley Unit 1 : Control 735.6 ft.
Minimal 735.6 ft.
FHRR Section 3.8.4 Building (0-35-1)
NGVD29 NGVD29
& Tables 1 & 3 Beaver Valley Unit 1: Control 735.6 ft.
Minimal 735.6 ft.
FHRR Section 3.8.4 Building (S-35-71)
NGVD29 NGVD29
& Tables 1 & 3 Beaver Valley Unit 1 : Control 735.8 ft.
Minimal 735.8 ft.
FHRR Section 3.8.4 Building (S-35-72)
NGVD29 NGVD29
& Tables 1 & 3 Beaver Valley Unit 1 : Control 735.6 ft.
Minimal 735.6 ft.
FHRR Section 3.8.4 Building (S-35-74)
NGVD29 NGVD29
& Tables 1 & 3 Beaver Valley Unit 2:
734.7 ft.
Minimal 734.7 ft.
FHRR Section 3.8.4 Safeguards (SG-37-4)
NGVD29 NGVD29
& Tables 2 & 3 Beaver Valley Unit 2: Diesel 732.3 ft.
Minimal 732.3 ft.
FHRR Section 3.8.4 Generator Building (DG-32-5)
NGVD29 NGVD29
& Tables 2 & 3 Beaver Valley Unit 2:
735.7 ft.
Minimal 735.7 ft.
FHRR Section 3.8.4 Auxiliary Building (A-35-1)
NGVD29 NGVD29
& Tables 2 & 3 Beaver Valley Unit 2:
735.6 ft.
Minimal 735.6 ft.
FHRR Section 3.8.4 Auxiliary Building (A-35-3)
NGVD29 NGVD29
& Tables 2 & 3 Beaver Valley Unit 2:
735.6 ft.
Minimal 735.6 ft.
FHRR Section 3.8.4 Auxiliary Building (A-35-5)
NGVD29 NGVD29
& Tables 2 & 3 Beaver Valley Unit 2: Fuel 735.5 ft.
Minimal 735.5 ft.
FHRR Section 3.8.4 Building (F-35-1)
NGVD29 NGVD29
& Tables 2 & 3 Beaver Valley Unit 2: Fuel 735.4 ft.
Minimal 735.4 ft.
FHRR Section 3.8.4 Building (F-35-2)
NGVD29 NGVD29
& Tables 2 & 3 8FFl81Al W&E SUL¥ 8E8WFIIW FIELM'EB INF8FIMATl8N
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~
9FFl&IAk Y&ii 9~Jls¥ &iiQYAl'Pf AiilsAl'iig INF9AMAl'19N Qlill gg ~JQ'f Alilsli.t.lli Beaver Valley Unit 2:
734.6 ft.
Minimal 734.6 ft.
FHRR Section 3.8.4 Containment (Equipment NGVD29 NGVD29
& Tables 2 & 3 Hatch)
Beaver Valley Unit 2 Main 732.5 ft.
Minimal 732.5 ft.
FHRR Section 3.8.4 Steam Cable Vault (MS-35-3)
NGVD29 NGVD29
& Tables 2 & 3 Beaver Valley Unit 2 732.5 ft.
Minimal 732.5 ft.
FHRR Section 3.8.4 Safeguards (SG-37-5)
NGVD29 NGVD29
& Tables 2 & 3 Beaver Valley Unit 2 Fuel 735.3 ft.
Minimal 735.3 ft.
FHRR Section 3.8.4 Building (F-35-3)
NGVD29 NGVD29
& Tables 2 & 3 Streams and Rivers Combined Event-Probable 4
[...
])
USACE 2015 Maximum Flood with Wind
]
Evaluation of Upper Wave for Unit 1 Turbine Ohio River Basin Building North Wall FHRR Section 3. 7 &
Table 3 Combined Event - Probable 4
[...
))
USACE 2015 Maximum Flood with Wind
]
Evaluation of Upper Wave for Unit 2 at Ground Ohio River Basin Slope Approaching Reactor FHRR Section 3.7 &
Building Table 3 Combined Event - Probable 4
[...
))
USACE 2015 Maximum Flood with Wind
))
]
Evaluation of Upper Wave at Ground Slope Ohio River Basin Approaching the Emergency FHRR Section 3. 7 &
Outfall Structure Table 3 Notes:
- 1.
Refer to (FENOC, 2017) and (NRC, 2018a).
- 2.
Reevaluated hazard mechanisms bounded by the COB (see Table 3.1-1) are not included in this table.
- 3.
Reported values are rounded to the nearest one-tenth of a foot.
- 4. [
J]
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£ill go *1or Alil.lit&li Table 4.2-1. Flood Event Duration for Flood-Causing Mechanisms Not Bounded by the COB Flood-Causing Mechanism Time Available Duration of Time for Water for Preparation Inundation of to Recede from Local Intense for Flood Event Site Site Precipitation Unit 1 Note 1 Note 1 Note 1 Unit2 Note 1 Note 1 Note 1 Streams and Rivers Combined Event - PMF Note 1 Note 1 Note 1 with Wind Wave for Unit 1 Turbine Building North Combined Event - PMF Note 1 Note 1 Note 1 with Wind Wave for Unit 2 at Ground Slope Approaching Reactor Building Combined Event - PMF Note 1 Note 1 Note 1 with Wind Wave for Unit 2 at Ground Slope Approaching the Emergency Outfall Structure Note:
- 1. Refer to (FENOC, 2017) and (NRG, 2018a).
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Flooding Mechanism Local Intense Combined Event -
Combined Event Combined Event Precipitation PMF with Wind
-PMFwlth
- PMF with Wind Associated Units 1 and 2 Wave for Unit 1 Wind Wave for Wave for Unit 2 Effects Factor Turbine Building Unit 2 at Ground at Ground Slope North Slope Approaching the Approaching Emergency Reactor Outfall Structure Building Hydrodynamic loading at Plant Note 1 Note 1 Note 1 Note 1 Grade Debris loading at Note 1 Note 1 Note 1 Note 1 plant grade Sediment loading Note 1 Note 1 Note 1 Note 1 at plant grade Sediment deposition and Note 1 Note 1 Note 1 Note 1 erosion Concurrent Conditions, Note 1 Note 1 Note 1 Note 1 including adverse weather Groundwater Note 1 Note 1 Note 1 Note 1 ingress Other pertinent factors (e.g.,
Note 1 Note 1 Note 1 Note 1 waterborne projectiles)
Note:
- 1.
Refer to (FENOC, 2017) and (NRC, 2018a).
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~
recession of
~
Conditions are met for entry into flood procedures or notification of impending flood for flood event inundation water from site Anival offlood waters on site Water begins to recede from site Figure 2.2-1 Flood Event Duration {NRC, 2012c)
Water completely receded from site and plant in safe and stable state that can be maintained indefinitely 8FFl81AL Y8E 8NLY 9E8YRl'P\\< RELMEB IHF8RMAt~8H Clill 1)0 NOI Alil Iii O &Iii
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ATTACHMENT 1 Audit Summary Report I.
Background:
By letter dated April 26, 2016 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML16105A211 ), the NRC staff issued an audit plan indicating that audits may be conducted related to the Beaver Valley FHRR, as necessary, in order to provide additional insights of the review and analysis performed. Audits were conducted following the guidance of NRC Office of Nuclear Reactor Regulation, Office Instruction LIC-111, "Regulatory Audits," dated December 29, 2008 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML082900195).
II.
Scope:
The scope of the audit was detailed in the audit plan and included, but was not limited to, a) The methodologies used in the analyses, b) Parameter selection criteria and assumptions, c) Model development, configuration and execution; d) Calculations, reference material; analyses performed, and supporting documentation. contains additional technical and logistical details of the audits performed and provides the full scope of the review.
Ill L og1st1ca ID t *1 e a1 s:
Audit Date Audit Location Audit Partici12ants September 21, 2016 Teleconference Call NRG: Chris Cook, Kenneth See, Brad Harvey, Aida Rivera, Mohammed Shams, Gregory Bowman, Juan Uribe January 26, 2017 Beaver Valley Site FENOC: Phil Lashley, Kathleen Nevins, Tom Lentz, Collin Keller, Mark Manoleras IV.
Technical Evaluation:
The Audit Table contains the technical details regarding the clarifying information requested from FENOC, and the corresponding resolution of each item. In addition, each information need requested is discussed in the corresponding Section of this assessment.
As part of the audit activities, the licensee made several calculation packages available to the NRC staff via electronic reading room. These calculation packages were only found to expand upon and clarify the information already provided on the docket, and so are not docketed or cited.
V.
==
Conclusion:==
The audit performed satisfactorily allowed the NRC staff to better understand the Beaver Valley FHRR, supported the completion of the NRC staffs review and the subsequent issuance of an interim hazard letter. During its review, the NRC staff did not identify any issues or open items and considers the audit completed and closed.
0FFl81AL ~8E 0NLY 8E8~RITV RELATES ltff0RMATIOP4 ill 99 JJ9T RlibliAili
Info Need 1
8FFl81AL li8E SUL¥ SE8ijRIW RELMEB lt4F8RMM18N Audit Table Summary of Information Reviewed Beaver Valley Power Station, Units 1 and 2 Information Need Description Action (Post-Audit)
Observed De12th-Area Duration Data Discre12ancy The licensee indicated that the SPAS-based DAD values
Background:
The NRC staff requested clarifying information provided to NRC staff as a part of the initial information regarding the complete list of storms used in the storm request were actually the results of a sensitivity case. This analysis. In response, the licensee provided the complete case was conducted as a part of the site-specific PMP storm analysis information for the all-season and cool-season (ssPMP) for the Conowingo dam safety study, and storms, including electronic files, storm analysis reflected the combination of both the Wellsville, NY and spreadsheets (which include observed depth-area-duration Zerbe, PA storm centers that occurred during the June
[DAD] data and adjustment factors), SPAS output data, and 1972 storm. The licensee stated that Beaver Valley other pertinent information. After reviewing the information ssPMP study only considers the Wellsville, NY storm provided, NRC staff noticed discrepancies between the storm center to be transpositionable to the Beaver Valley output DAD values and the DAD values used by the licensee watershed and that the corresponding values were used to as a part of the site-specific PMP evaluation for Beaver develop the FHRR-based DAD values without Valley. Specifically, staff noticed discrepancies in DAD transpositioning the Zerbe, PA storm center. The licensee values for the following storm:
also provided the observed DAD tables for both storm centers and the SPAS isohyetal plot of the full storm.
Wellsville, NY - June 1972 storm occurring in New York. For example, the SPAS-based observed 72-hour, 20,000-mi2 depth is 10.2 inches (from The NRC staff notes that the Zerbe, PA storm center SPAS_ 1276_DAD_ Template.xlsx), compared to a exceeds the Wellsville, NY storm center for the 72-h value of 6.4 used by the licensee for storm analysis 20,000-mi2 depth. Since both storm centers resulted from (from Wellsville-NY-06-1972-the same tropical storm system, NRC staff issued a follow-SPAS_ 1276_Zone1.xlsx).
up information need to seek justification for separating the Request: For the Wellsville, NY storm, explain why the June 1972 storm into two storm centers (see Information observed SPAS-based DAD output values do not match with Need #1a).
the final values used by the licensee. Clarify which set of values should be used as the observed DAD values. If corrections are warranted, provide updated envelopment curves. AEFICI Al I ISF Ot:11 X SECI IRIIY REI AXED **1EORH AIIA*I
Info Need 1a 8FFIBhlt MSE 8f4L'f*SEB~fUP.<< R:EtA,EB lt4F8R:MAfl8t4 Information Need Description Follow-Up: Depth-Area Duration Values for the June 1972 Storm
Background:
NRC staff issued Information Need #1 related to differences in the SPAS-based and FHRR-based DAD values provided by the licensee for the Wellsville, NY June 1972 storm. In response, the licensee clarified that the SPAS-based DAD values provided in response to the initial NRC request for supplemental information were from an internal sensitivity analysis that Allied Weather Associates (AWA) completed as a part of the Conowingo site-specific PMP analysis. The licensee stated that the sensitivity combined both storm centers from the June 1972 storm, one east of the Appalachians near Zerbe, PA and one near Wellsville, NY. The licensee clarified that only the Wellsville, NY storm center was used as a part of the Beaver Valley study.
The response provided by the licensee for the initial information need raised additional questions about the approach used for the June 1972 storm. Specifically, NRC staff requested additional clarifying information for separating the June 1972 storm into two storm centers based on the Eastern Continental divide.
Request: Provide justification for separating the June 1972 storm into two storm centers. As a part of the response, describe the extent to which the National Weather Service (NWS) HMRs split rainfall into separate storm centers. In addition, provide the adjusted DAD values for the June 1972 storm when applying the full storm (i.e., combined storm center data) to the Beaver Valley location. Action (Post-Audit)
The licensee stated that the use of separate storm centers for DAD analysis has been employed by the HMRs and is determined by timing of rainfall, differences in synoptic meteorological environment, and differences in topographical controls, which all help determine whether separate storm centers are warranted.
The licensee provided material from the USACE/NWS Black Book which exemplifies cases in which separate storm centers were analyzed for the same storm system.
The NRC staff notes, however, that the June 1972 storm centers were of closer proximity than these other cases and occurred within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of each other. The Wellsville, NY storm center experienced peak rainfall intensity prior to the Zerbe, PA storm center, and the licensee stated that the Wellsville, NY rainfall utilized low-level moisture from the Gulf of Mexico. However, NRC staff finds it unlikely that the Wellsville, NY storm center pulled from a different moisture source than the Zerbe, PA storm center as the timing of the storm track and rainfall and the significant distance of Wellsville from the Gulf do not support a Gulf moisture source for Wellsville (the hurricane was located near the North Carolina coast around the time of major rainfall in Wellsville). The storm track provided by the licensee and available from online sources indicates that the hurricane formed in the Gulf of Mexico, the storm clearly weakened as it crossed the Florida panhandle, Georgia, and the Carolinas before strengthening as it pulled moisture from the Atlantic.
The licensee also provided non-public working notes from the NWS that were produced durinq evaluation of the Zerbe, PA storm.
9FFIQl:O.ls W&i 9Hb¥ &iQWRITV RibMiQ l~IF9RM.1'7Fl9H
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.)) The NRC staff notes that many major historical storms produced multiple storm centers and that separation of such storm centers should be used with caution. In the case of the June 1972 storm, the licensee's response does not provide clear evidence that the Zerbe, PA storm is not transpositionable to the Beaver Valley watershed.
To test the sensitivity of how the full June 1972 storm (i.e.,
both storm centers included) would impact the Beaver Valley ssPMP, the NRC staff performed an independent ssPMP evaluation to adjust the storm to the Beaver Valley watershed. The NRC staff computed independent values for the storm representative dew point, in-place maximum dew point climatology, transpositioned maximum dew point climatology, and in-place average elevation. The results indicate that the June 1972 storm's adjusted DAD for 72-h, 20,000-mi2 may be estimated as 10.4 inches, compared to the licensee's all-season ssPMP of 10.0 inches (a 4% increase). However, this ssPMP estimate was bounded by the NRC staff's analysis of the Big Rapids, Ml storm (see Information Need #2).
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8FFlelAL tc.181'.: 8fJLV 8E8~FUPI RELAifEB IUF8RMA'ifl8U Info Information Need Description Action (Post-Audit)
Need 2
Big Rapids Dew Point Values The licensee described the process involved in identifying
Background:
As a part of it ssPMP review process, the NRC the moisture source location and timing associated with the 1986 Big Rapids, Ml storm. The basic procedure for staff has collected observational dew point data for use in identifying storm moisture source involves several key conducting independent ssPMP evaluations similar to AWA's considerations, including ensuring that the storm moisture process. The NRC staff independently computed values for source location is upstream of the precipitation and storm representative dew point, in-place maximum dew point, outside of the rain shield and that the moisture track and transpositioned maximum dew point. The NRC staff excludes intervening barriers which would reduce reviewed the Beaver Valley short list storms for cool-season moisture. The licensee also stated that when identifying and all-season ssPMP and identified various differences in these dew point values, particularly for the Big Rapids, Ml all-the moisture source location, observed dew point values should be elevated and display similarities in both time season storm.
and space. In some cases (partially applicable to Big As described in the AWA Audit Report (ADAMS Accession Rapids), the analysis is limited by data availability, and No. ML15113A029, Section 2b), "the final determination of professional judgment may be needed.
what stations to use in assigning the storm representative The licensee explained that the Big Rapids, Ml storm is an dew point temperature is subject to professional judgment."
extremely large historical rainfall event and often controls After evaluation, the NRC staff concluded that:
PMP values (and in some cases produces PMP values in
- 1. The storm representative dew point for the Big excess of HMR 51 ). The licensee suggests that since the Rapids, Ml all-season storm may be more storm is so significant, additional scrutiny, analysis, and conservatively estimated as 68.5 F, compared to the consideration is needed when compared to other storms.
licensee's value of 70.5 F.
Since the storm was so large, the licensee argues that the The NRC staff's evaluation includes differences related to calculated in-place maximization factor of 1.38 is two features: 1) the storm representative dew point significantly larger than would be expected for such an timeframe and 2) the storm representative dew point location.
event, and was "unreasonable" for Big Rapids, Ml.
Regarding the storm representative dew point timeframe, The licensee provided description of the timing of the Big staff made the following observations:
Rapids rainfall event and the storm dynamics that were observed for the storm. The observed dew point value a) The timeframe for which the station-based storm was selected using the KMMO station (Marseilles, Illinois) representative dew point temperature was selected and was determined to be 70.5 °F. The KMMO station is occurs after the rainfall event starts. For KMMO, the located approximately 230 miles southwest of Big Rapids.
24-hour storm representative dew point was selected Given the average wind speed during the selected 24-hour from 9/10/1900UTC to 9/11/1800UTC (from storm representative dew point time period was 13.5 mph BigRapids obs data.x/sx), when nearly one third of at KMMO, the licensee suaaested that it would take OlalilCI.OI., lrJili 0*11..v: iliCll5Ul¥ Aliil..Olli(.) 1*11a0Aau110*1
o,1a1c1 O L. I.Iii 0*11..v iliiCI.IRITY RliiL. Ollig 1*11rORH O 110*1 Info Information Need Description Action (Post-Audit)
Need the precipitation has occurred before the timeframe approximately 17.0 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> for moisture to travel from (from SPAS 1206 Mass Curve.x/sx). This timeframe KMMO to Big Rapids. Using HYSPLIT trajectories and is also inconsistent with licensee's HYSPLIT analysis daily synoptic weather maps, the licensee identified that back calculated Big Rapids' moisture trajectory potential regions of moisture inflow.
since 9/9/1200UTC (i.e., Big Rapids' starting time).
During an audit held September 21, 2016, the licensee Regarding the storm representative dew point location, staff noted that the selected moisture source location and made the following observations:
timeframe was appropriate for the Big Rapids storm. The b) When using a timeframe for averaging that is NRC staff questioned whether the selected timeframe consistent with the storm rainfall period and is adequately represented the first half of the precipitation informed by the HYSPLIT trajectories, a more event. The licensee stated that the dew point value of appropriate storm representative dew point location 70.5 °F was reasonable and was representative of the last may be in Iowa, where the storm representative dew half of the precipitation event. Since rainfall occurred over point could be approximated as 68.5 F.
a multi-day period, while the licensee used a 24-h period to compute storm representative dew point, the current Request: Provide justification for selecting a storm approach does not allow for representation of the full representative dew point value of 70.5 degrees Farenheit rainfall event.
(°F) for the Big Rapids, Ml all-season storm. As a part of the The NRC staffs independent analysis reveals a storm response, discuss the rationale for selecting the timeframe and location of the station-based storm representative dew representative dew point value of approximately 68.5 °F point temperatures used for the Big Rapids storm which found from assessing a different timeframe and location appear to be inconsistent with the period of rainfall. If than used by the licensee. The difference results in an in-corrections are warranted, provide updated envelopment place maximization factor of 1.50, which increased the Big Rapids DAD values and resulted in an increase to the curves.
ssPMP values. Sensitivity runs were performed by the USACE and the results and resolution is documented in Section 3.3 of this assessment. QF~IQl:A:b Wilii QtJb¥ iliiQI.IAITV Ali.b.,;li.Q ltJFQAM.o.:FIQ~J
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Information Need Description Initial Storm Long List Screening
Background:
After reviewing the initial storm list developed by the licensee for the all-season ssPMP evaluation, it is not clear to the NRC staff why one storm was removed. As a result, further clarification is requested. The screening criteria used to exclude this storm should be clearly stated.
- 1. Golconda, IL - October 1910 storm occurring in Illinois, with an observed 72-hour, 20,000-mi2 rainfall of 10.7 inches (according to the USACE Black Book).
This storm is listed as being removed due to being "Not PMP Storm Type".
Request: Provide further reasoning for the removal of the above storm. If corrections are warranted, provide updated envelopment curves. Action (Post-Audit}
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10 20 30 40 50 60 70 so 90 Storm Event Hour The licensee clarified that the reason for excluding the Golconda, IL storm from the short storm list was because the storm was not transpositionable to the Beaver Valley basin.
To support its claim, the licensee presented hand-drawn maps of transposition limits established by the NWS for other historical storms occurring in the Midwest and Great Plains. None of these documents were made public and meteorological justification for setting the transposition limits of these storms was not provided. Most of the storms used for comparison were much further west or occurred at a different time of year than the Golconda storm, and the transposition limits for Golconda were not explicitly defined by the NWS. The licensee relied upon professional judgement to determine the storm is not transpositionable to the Beaver Valley watershed and stated that the Golconda storm was not used for PMP development in HMR 51.
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Need The licensee also presented an initial evaluation of the Golconda, IL storm in an attempt to transposition it to Beaver Valley and assess the impacts on the Beaver Valley ssPMP. The results indicated that the storm would not impact the ssPMP values and that the total adjustment factor was approximately 0.83. Using the storm representative dew point location and storm center location provided by the licensee, the NRC staff conducted an independent assessment for Golconda and determined that the Golconda, IL storm would not impact ssPMP and estimated a total adjustment factor of 0.86. QlaFICI O I. I !iii 0*11.x iii Cl lliUlY A.ii. OJig 1*11zolilH 0110*1
ML18158A438 (Pkg.); ML18158A375 (Non-Public Letter/Enclosure 1);
ML18158A484 (Cover Letter/Redacted Enclosure 2)
- by input dated OFFICE NAME DATE OFFICE NAME DATE NRR/DLP/PBMB/PM NRR/DLP/PBMB/LA NR0/0SEA/RHM2/TR JUribe SLent KSee*
6/7/18 6/7/18 4/17/2018 NR0/0SEA/RHM2/BC NRR/DLP/PBMB/BC NRR/DLP/PBMB/PM CCook*
BTitus(a)
JUribe 4/17/2018 7/23/18 7/24/18