ML16112A021
| ML16112A021 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 05/18/2016 |
| From: | Juan Uribe Containment and Balance of Plant Branch |
| To: | Edington R Arizona Public Service Co |
| Uribe, J. F., NRC/NRR/JLD, 301-415-3809 | |
| References | |
| CAC MF5546, CAC MF5547, CAC MF5548 | |
| Download: ML16112A021 (17) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 Mr. Randall K. Edington Executive Vice President Nuclear/CNO Arizona Public Service Company P.O. Box 52034, MS 7602 Phoenix, AZ 85072-2034 May 18, 2016
SUBJECT:
NUCLEAR REGULATORY COMMISSION REPORT FOR THE AUDIT OF ARIZONA PUBLIC SERVICE COMPANY'S FLOOD HAZARD REEVALUATION REPORT SUBMITTAL RELATED TO THE NEAR-TERM TASK FORCE RECOMMENDATION 2.1-FLOODING FOR: PALO VERDE NUCLEAR GENERATING STATION, UNITS 1, 2 AND 3 (CAC NOS. MF5546, MF5547 AND MF5548)
Dear Mr. Edington:
The purpose of this letter is to provide you with the final audit report, which summarizes and documents the U.S. Nuclear Regulatory Commission's (NRC) regulatory audit of Arizona Public Service Company's (APS, the licensee) Flood Hazard Reevaluation Report (FHRR) submittal related to the Near-Term Task Force Recommendation 2.1-Flooding for Palo Verde Nuclear Generating Station, Units 1, 2 and 3 (Palo Verde). By letter dated July 7, 2015 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML15177A149), the NRC informed you of the staff's plan to conduct a regulatory audit of APS's FHRR submittal for Palo Verde. The audit was intended to support the NRC staff review of the licensee's FHRR by providing the NRC staff with a better understanding of the analyses of the flooding hazards presented in the FHRR and the subsequent issuance of an interim hazard letter and staff assessment documenting the staff's review.
The audit was conducted over multiple sessions on August 2015 and was performed consistent with NRC Office of Nuclear Reactor Regulation, Office Instruction LIC-111, "Regulatory Audits,"
dated December 29, 2008, (ADAMS Accession No. ML082900195). The details of this audit report have been discussed with Mr. Michael Dilorenzo of your staff.
R Edington If you have any questions, please contact me at (301) 415-3809 or by e-mail at Juan.Uribe@nrc.gov.
Docket Nos. 50-528, 50-529 and 50-530
Enclosure:
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 AUDIT REPORT BY THE OFFICE OF NUCLEAR REACTOR REGULATION FOR THE AUDIT OF ARIZONA PUBLIC SERVICE COMPANY'S FLOOD HAZARD REEVALUATION REPORT SUBMITTAL RELATED TO THE NEAR-TERM TASK FORCE RECOMMENDATION 2.1-FLOODING FOR: PALO VERDE NUCLEAR GENERATING STATION, UNITS 1, 2 AND 3 DOCKET NOS. 50-528, 50-529, AND 50-530 BACKGROUND AND AUDIT BASIS:
By letter dated March 12, 2012, 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 (10 CFR),
Section 50.54(f) "Conditions of license" (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 Review of Insights from the Fukushima Dai-ichi Accident. Recommendation 2.1 in that document recommended that the staff issue orders to all licensees to reevaluate seismic and flooding for their sites against current NRC requirements and guidance. Subsequent Staff Requirements Memoranda (SRM) associated with Commission Papers SECY 11-0124 and SECY-11-0137, instructed the NRC staff to issue requests for information to licensees pursuant to 10 CFR 50.54(f).
By letter dated December 12, 2014 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML14350A466), Arizona Public Service Company (APS, the licensee) submitted its Flood Hazard Reevaluation Report (FHRR) for Palo Verde Nuclear Generating Station, Units 1, 2 and 3 (Palo Verde). The staff has completed a regulatory audit of the licensee to better understand the development of the FHRR. Specifically, the audit sought to allow staff to better understand analyses (and supporting documentation) for areas such as:
selection of model input(s) and parameters, calculations and methodologies, geographical characteristics and plant topography, among others. This audit summary is completed in accordance with the guidance set forth in NRC Office of Nuclear Reactor Regulation, Office Instruction LIC-111, "Regulatory Audits," dated December 29, 2008 (ADAMS Accession No. ML082900195).
By letter dated October 8, 2015 (ADAMS Accession No. ML15280A022), the staff issued an interim hazard letter, which summarized its review of the re-evaluated flood-causing mechanisms described in the FHRR.
Enclosure AUDIT LOCATION AND DA TES:
The audit was completed over multiple sessions over a period of 1 month, as described below:
August 20, 2015, from 1 :OOpm to 3:00pm-webinar session August 26, 2015, from 4:00pm to 5:00pm-conference call AUDIT TEAMS:
Title Team Member Organization Team Leader, NRR/JLD Juan Uribe NRC Branch Chief, NRO/DSEA Christopher Cook NRC Technical Lead Laura Quinn-Willingham NRC Technical Support Mike Lee NRC Dept Leader, Nuclear Thomas Weber APS Regulatory Affairs Director, Fukushima Project Michael Powell APS Shift Manager, Operations Randall Eimar APS Sr EnQineer, DesiQn Civil Warren Jones APS Sr Consulting Engineer, Hamid Mortazavi APS Design Mechanical Administration Director, Design Engineering Ken House APS Administration Sr Engineer, Contractor John Conly APS I Certrec Sr Consulting Engineer, Winston Borrero APS Design Mechanical Administration Director, Nuclear Regulatory George Andrews APS Affairs Sr Engineer, Licensing Carl Stephenson APS Section Leader, Nuclear Mike Dilorenzo APS ReQulatorv Affairs EnQineer Ill, Design Civil Will Nau APS Dept Leader, Design Rex Meeden APS Mechanical Administration Sr Engineer, Licensing Paul Hom APS DOCUMENTS AUDITED: of this report details the documents that were reviewed by the NRC staff, in part or in whole, as part of this audit. The documents were located in an electronic reading room (ERR) during staff review. The documents, or portions thereof, that were used by the NRC staff as part of the technical analysis and/or as reference in the completion of the staff assessment, will be submitted by the licensee and docketed for completeness of information, as necessary.
These documents are identified in Table 1.
AUDIT ACTIVITIES:
In general, the audit activities consisted mainly of the following actions:
Review background information on site topography and geographical characteristics of the watershed.
Review site physical features and plant layout.
Understand the selection of important assumptions and parameters that would be the basis for evaluating the individual flood causing mechanisms described in the 50.54(f) letter.
Review model input/output files to computer analyses, such as the Hydrologic Engineering Center (HEC) River Analysis System (RAS) and HEC-Hydrologic Modeling System (HMS) to have an understanding of how modeling assumptions were programmed and executed. of this report contains Table 1, "Technical Topic of Discussion," which provides more detail and summarizes specific technical topics (and resolution) of important items that were discussed and clarified during the audit. The items discussed in Table 1 may be referenced/mentioned in the staff assessment in more detail.
EXIT MEETING/BRIEFING:
On August 26, 2015, the NRC staff closed out the discussion of the technical topics described above.
1. Attachment 1-List of References Reviewed by the NRC staff
- 2. Attachment 2-Information Needs Discussed During Audit ATTACHMENT 1 LIST OF REFERENCES REVIEWED BY NRC STAFF Calculation (Cale) Package 13-5002 F-02 ERR file "Palo Verde FHRR Audit follow-up to NRC Conference Call on 8-20-2015.pdf' FL0-20 Grid Cell Numbers Response Files "CN396-A00005.ROOO (F-02 Effects of LIP)" Parts 1 and 2.
AeroTech (2013a) CN396-A00024.
Letter 484-0861 0.
Confirmatory manual survey topographic elevation(s) "Unit 1 Elevations for LIP," "Unit 2 Elevations for LIP," "Unit 3 Elevations for LIP," "Unit 1 3 Topo - Confirmatory Manual Survey Data," and "Manual Survey Key for Elevations."
APS Study 13-MS-A 135 CN396-A00023.ROOO-Refined LIP-based models of the PVNGS Units, developed by URS Corporation.
ERR file "Palo Verde FHRR Audit follow up to NRC Conference Call on 8-20-2015.pdf' ATTACHMENT 2 TECHNICAL TOPICS OF DISCUSSION-PALO VERDE FHRR AUDIT Table 1: Technical Topics of Discussion Info Need No. I Information Need Description 1
I Local Intense Precipitation - Estimated Probable Maximum Flood Elevations Evaluation of the effects of flooding of local intense precipitation (LIP) on water surface elevations at the Palo Verde Nuclear Generating Station (PVNGS) site is requested in the 50.54 letter. In the PVNGS Flood Hazard Reevaluation Report (FHRR), the licensee described a LIP analysis in Section 3.2.1 that relied on two-dimensional flow modeling, using FL0-20, to estimate flood water surface elevations and maximum flood depths at a set of powerblock door/hatch locations.
Flood depth resulting from this modeling (Case 4) were graphically depicted in Figure 3-3 of the FHRR.
Comparison of the reevaluated flood depths and the current licensing basis were provided in Table 4-3 of the FHRR. In Section 3.2.1.5 of its FHRR, the licensee noted that Case 4 produced a result for which there was a localized (transient) accumulation of LIP-related flood water adjacent to certain power block structures leading to water ingress into those structures. In Section 3.2.1.6 of its FHRR, the licensee acknowledged that it had conducted a room-by-room analysis of the impact of the water ingress on structures, systems and components and concluded that internal flooding would not impact safe shutdown equipment.
Post Audit Status In response to this information need the licensee provided the following responses:
- a. Related to how the water depths on-site were derived, the licensee stated that the transient water accumulation depths of 0.19 to 0.63 feet (ft), presented in FHRR Table 4-3, were based on the results provided in licensee's ERR Calculation (Cale) Package 13-5002 F-02, Tables 7-1 to 7-3, Case 4. The licensee stated that these depths are conservative estimates of the maximum range of transient water accumulation depth during the LIP flood event, where the design-basis LIP elevation would be exceeded and migration of water into structures at the identified pathways is expected. The licensee stated that the flood depths reported in the FHRR excluded pathways 31 (a low grade area in the North Yard) and 55 (an isolated open space, the Tendon Shaft) for all units.
The licensee also stated that pathways 18 thru 25 were excluded for Unit 2 due to discrepancies in the modeling and specific runoff conditions (the area was not susceptible to ponding).
For the three PVNGS reactor units, the licensee reported in ERR file "Palo Verde FHRR Audit follow-up to NRC Conference Call on 8 2015. pdf' the following maximum transient flood elevations (ft NGVD29):
Unit 1: 957.73 Unit 2: 954.80 Info Information Need Description Post Audit Status Need No.
Unit 3: 952.28 Request: In connection with the 50.54 request, it was The licensee also reported that a room-by-room flood analysis expected that the FHRR would include a description of indicated that no safety-related structures are affected by the the specific location(s) where the estimated flooding transient LIP-based flooding scenario.
might occur as the result of a LIP event and specific flood depths or water surface elevations at these location(s).
- b. The licensee stated that the "localized sections near the In the absence of that information, the licensee is powerblock", referred to in FHRR Table 4-3, were areas with requested to provide the following information about the flooding durations greater than about 4.25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> (hrs). During the values of Reevaluated Water Level for Maximum August 20, 2015, audit, the licensee produced a figure, designated Transient Water Accumulation Depths at Safety-Related "Figure E", which illustrated the spatial variation in the duration of Structures for the LIP presented in FHRR Table 4-3:
the LIP flooding and the locations of long-term ponding. With
- a. Describe how the water depths provided in FHRR reference to Figure E, the licensee stated that the transient flood Table 4-3 were derived. In particular how are the depths reported in FHRR Table 4-3 (discussed in a. above) were values presented in FHRR Table 4-3 related to the from areas with flooding durations less than about 3 hrs.
maximum flood depths presented in the ERR in Cale Package F-02 Tables 7-1 to 7-3
- c. In response to the information need request related to the 165
- b. Identify the locations of the "localized sections near Door/Hatch locations, the licensee provided in the ERR a list of the powerblock" at which water depths are reported pathway numbers for each unit and the corresponding FL0-2D in FHRR Table 4-3 to be 1.0 to 1.75 ft below plant model grid cell numbers as "FL0-2D Grid Cell Numbers grade.
Response."
C.
Provide a table of FL0-2D model grid cell numbers corresponding to the 165 Door/Hatch locations listed
- d. In response to the information need request concerning Cale in Tables 7-1 to 7-3 of ERR Cale Package F-02.
Package F-02, the licensee placed in the ERR a complete version
- d. In reference to Cale Package F-02, the document is of Calculation No. 13-5002 F-02 that included the identified purported to be 272 pages long. However, there are missing pages, as files "CN396-A00005.ROOO (F-02 Effects of only 99 pages present in the version found in the LIP)" Parts 1 and 2.
ERR. The licensee is requested to provide missing pages 100-272 of Cale Package F-02.
The NRC staff had additional questions regarding the maximum transient flood elevations provided in the response by the licensee.
These are described in info need #4 and request confirmation of the pathways excluded bv the licensee when reportinQ maximum
Info Need No.
2 Information Need Description Local Intense Precipitation - Topographic Data Evaluation of the effects of flooding of LIP on water surface elevations at the PVNGS site is requested in the 50.54 letter. In its FHRR, flood depths reported by the licensee in PVNGS Cale Package F-02, Tables 7-1 to 7-3 were significantly higher (about 0.8 ft higher) around certain portions of Unit 2 than around the corresponding areas of Units 1 and 3. The licensee identified "sustained ponding" in several areas of the model, including areas adjacent to Unit 2, and attributed this ponding to inaccuracies in the site topographic data, citing AeroTech (2013a) (Cale Package F-02, page 75 of 271). The licensee stated that the accuracy tolerance reported for the topographic data was +/-0.237 ft. The licensee also stated, based on a manual survey of the powerblock site (PVNGS, 2013b), that such ponding "is not possible" and dismissed the simulated results as an artifact of the topographic data. In the internal flooding calculations, the licensee noted that it did not use the flooding depths at Unit 2, but applied the flood depths at Units 1 and 3 instead (Cale Package F-02, page 75 of 271).
Post Audit Status (transient) flood depths and elevations. The NRC staff requested that the figure designated as "Figure E" be placed on the docket to support the development of the PVNGS staff assessment.
The NRC staff concluded that the information provided by the licensee in response to this information need request was sufficient.
The licensee provided the following information in response to the staff's information need.
- a. AeroTech (2013a) was provided via the ERR with the file name CN396-A00024.
- b. PVNGS (2013b) was provided via the ERR through Letter 484-08610. In addition, confirmatory manual survey topographic elevation data were provided via the ERR as "Unit 1 Elevations for LIP," "Unit 2 Elevations for LIP," "Unit 3 Elevations for LIP," "Unit 1 3 Topo - Confirmatory Manual Survey Data," and "Manual Survey Key for Elevations."
- c. In reference to staff questions concerning the estimated errors associated with the topographic data obtained from the manual survey, citing from the Certificate of Calibration, Specifications/
Accuracy (designated "LIMITED USE"), the licensee reported that the manual survey accuracy was calculated to +/- 30 arc seconds (+/-
0.001 inches). By comparison, the licensee noted that the accuracy of the flyover aerial survey data was +/- 0.237 ft.
- d. In reference to staff questions concerning the identification of differences (if any) between the topographic data from AeroTech Info Information Need Description Post Audit Status Need No.
Request: In connection with the 50.54 request, the (2013a) and PVNGS (2013b) references, the licensee identified licensee is requested to provide the following two areas for which there were differences. They were the area information:
between the Diesel Generator and Operations Support Buildings
- a. the site topographic data from AeroTech 2013a, (identified by the licensee as potential flooding pathways 8 to 12) which was the basis for the FL0-2D LIP model; and the breezeway between the Auxiliary and the Turbine Buildings
- b. the site topographic data from the manual survey, (identified by the licensee as potential flooding pathways 18 to 26 PVNGS 2013b; and 32). The licensee also deferred additional discussion of this
- c. estimated errors for topographic data from the topic in its responses to another staff information request, as manual survey; described below.
- d. identification of differences in the topographic data from AeroTech (2013a) and PVNGS (2013b);
- e. In response to staff questions during the audit regarding the
- e. a description of the analysis used to conclude that description of the analysis used by the licensee to conclude that the simulated sustained ponding is not possible; the sustained ponding is not possible based on the FL0-2D
- f.
justification for using known inaccurate topographic modeling simulations, the licensee responded that its decision was data in the FL0-2D simulations used as the basis for based on both plant walkdowns, past observation of surface the FHRR; drainage during rain events, and the results of manual
- g. Copies in the ERR of AeroTech (2013a) and PVNGS (topographic) surveys at certain locations within the powerblock.
(2013b).
The specific area corresponds to a common passageway adjacent to both the Diesel Generator and Operations Support buildings at Units 2 and 3 (designated as Pathways 8, 9 and 10). The licensee noted that the area is both described and evaluated in Cale Package F-02. A licensee-provided photograph, designated as "Figure C", illustrated what one area of the pathway under discussion looks like in plan map view. The licensee stated that the FL0-2D model grid cell elevations in this area were corrected using the manual survey data. The licensee showed the model results ("Figure A" and "Figure B" in the licensee's response) for Pathway 9 at the Unit 2 location before and after the correction.
- e. In reference to the NRC staff's request for the licensee to provide a justification or explanation for its decision to use known Info Information Need Description Post Audit Status Need No.
inaccurate topographic data in the FL0-20 simulations that were later used as the basis for the FHRR LIP estimates, the licensee noted that it was not known until much later in the project that a portion of the model in the congested areas of the powerblock was susceptible to so-called "shadowing effects" from the buildings, leading to lower topographical resolution in the aerial survey. To address the resolution issue, the licensee reported that it conducted manual (field) surveys to improve the topographic data for the model for the three units when the results of the hydrographs revealed large discrepancies between the units.
The licensee noted that most data resolution discrepancies were resolved except for a few areas/locations within the Unit 2 breezeway. Based on the plant walkdown, the manual survey results, and past observations of surface drainage during rain events, the licensee concluded that the breezeway area in question was determined to not be susceptible to sustained ponding during a LIP event. Because the as-built designs of the three power reactor units are substantially the same (identical), the licensee reasoned, using engineering judgment, that these similarities between the three units allowed the use of the other two unit's (Units 1 and 3) results to examine the areas of large discrepancies at Unit 2.
In support of its decision, the licensee relied on a contractor study (APS Study 13-MS-A 135) that consisted of a room by room analysis that utilized a bounding flood depth value for all three units, considering grade and curb features, where several of the pathways used the larger Unit 2 flood depth value and in some pathways, a corrected flood value between the three units was used, resulting in no effect to equipment necessary for achieving a safe shut down condition/state.
Info Information Need Description Post Audit Status Need No.
Lastly, the licensee noted that more refined LIP-based models of the PVNGS Units, subsequently developed by URS Corporation and documented in CN396-A00023. ROOO, utilizing all of the manual surveys taken, showed significantly smaller values of peak flood depths and duration, resulting in additional margin in the evaluations performed in APS Study 13-MS-A 135 (the licensee referred the staff to the FHRR margin discussion at p. 29).
Based on the licensee's initial explanation, as well as discussion in connection with Information Item 2, the staff asked the licensee to provide additional explanation of its reasoning for the acceptability of applying "engineering judgment" to use flood modeling results from Units 1 and 3 and apply those to flooding simulations for Unit 2. In response to a staff request, the licensee prepared a supplemental description of its reasoning concerning the use of the Units 1 and 3 analog data at Unit 2, and provided to staff the flood depths used in the room-by-room analysis of the effects of water ingress to safety structures during the LIP event. In summary, the licensee explained that the designs of the three units at the PVNGS are substantially the same. Accordingly the licensee reasoned that all three units would have the same response to a LIP event. The staff reviewed the licensee's explanation of its engineering reasoning and found it acceptable.
The NRC staff concluded that the information provided by the licensee in response to this information need request was sufficient.
3 All Flood Causing Mechanisms -
Com~arison of In response to this information need the licensee noted that the CLB Reevaluated Flood Hazard with Current Design Basis and the COB had been used interchangeably in the PVNGS FHRR as The FHRR for the PVNGS site provides comparisons of they were viewed to be synonymous. In response, the staff noted the reevaluated flood hazards with the current licensing Info Information Need Description Post Audit Status Need No.
basis (CLB) for all flood-causing mechanisms described that the terms have distinct regulatory meanings but that the issue in Section 3.0. Table 4-3 of the FHRR is a summary of was resolved.
this comparison. However, the 50.54(f) letter requested a comparison of the reevaluated flood hazard with the The NRC staff concluded that the information provided by the "current design basis" (COB}, not the CLB. It would also licensee in response to this information need request was sufficient.
appear that the term CLB is used repeatedly throughout the FHRR text when the licensee was intending to refer to the COB.
The licensee is requested to provide clarification regarding the inconsistencies identified in the FHRR text and table(s) with regard to the comparison of the reevaluated flood hazard to the COB and submit a revised hazard comparison consistent with the instructions provided in the 50.54(f) letter.
4 ERR Files and LIP Reevaluated Elevations This information need was transmitted to the licensee via an email Following the recent PVNGS audit, the staff had a from the NRC staff on September 16, 2015, as a follow-up to question concerning new information placed in the ERR information need No. 1, above. The licensee provided a response via by the licensee in response to a subsequent staff email to the staff on September 17, 2015.
query. The licensee's assistance is requested in In its response, the licensee stated that the flood depths reported in clearing-up the confusion concerning the new information FHRR Table 4-3 were based on pathways 1 thru 30 and 32 thru 54 in the ERR.
(i.e., pathways 31 and 55 were excluded for all three units) with the exception of Unit 2, for which pathways 18 thru 25 were also ERR file "Palo Verde FHRR Audit follow up to NRC email excluded.
from 8-26-2015.pdf' indicates that the flood depths of 0.19 to 0.63 ft reported in FHRR Table 4-3 were based With reference to the maximum water surface elevations at each of on pathways 1 thru 30 and 32 thru 54 (i.e., pathways 31 the units, the licensee described the basis for the differences in the and 55 were excluded for all three units) with the elevations provided in ERR file "Palo Verde FHRR Audit follow up to exception of Unit 2, for which pathways 18 thru 25 were NRC Conference Call on 8-20-2015.pdf' and the maximum elevations also excluded. Tables 7-1 to 7-3 (Case 4) in Cale in Cale Package F-02, Tables 7-1 to 7-3 for Case 4. The licensee also stated in its response that the maximum Case 4 elevations in Info Information Need Description Post Audit Status Need No.
Package F-02 are identified as the source of the flood Tables 7-1 to 7-3 are acceptable replacements for the maximum depth values.
elevations provided in ERR file "Palo Verde FHRR Audit follow up to NRC Conference Call on 8-20-2015.pdf'.
ERR file "Palo Verde FHRR Audit follow up to NRC Conference Call on 8-20-2015.pdf' provides the Based on this information, the staff concluded that, for the three maximum water surface elevation at each unit and PVNGS reactor units, the following maximum transient flood identifies Tables 7-1 to 7-3 (Case 4) in Cale Package F-elevations (ft NGVD29}, taken from results presented in ERR Cale 02 as the source for these values. However, this Package 13-5002 F-02, Tables 7-1 to 7-3, Case 4, are appropriate:
document does not indicate which pathways were excluded in determining the maximum water surface Unit 1: 957.73 elevations. For example, it appears to the staff that the Unit 2: 955.04 pathways 26 and 32 at Units 2 and 3 were excluded in Unit 3: 952.37 determining the maximum water surface elevations.
The NRC staff concluded that the information provided by the It is requested that the licensee confirm the pathways licensee in response to this information need request was sufficient.
that were excluded for each unit when reporting (a) flood depths in FHRR Table 4-3, and (b) maximum water surface elevations in ERR file "Palo Verde FHRR Audit follow up to NRC Conference Call on 8 2015.pdf'. Identify and justify any differences in the excluded pathways for flood depth and water surface elevation.
Additional Interactions with the licensee to capture in the audit summary outside of the table We had a clarification call on August 26, 2015. On August 25, 2015, the staff sent an email to the licensee requesting a call to discuss FHRR Table 4-3. Specifically the staff requested the following clarification:
"Specifically, the table provides a range of flood depth values for LIP, however, the NRC is in the process of completing the interim hazard letters which provides maximum flood elevations at the site. Therefore, the staff wants to discuss and make sure it understands, the correlation (for LIP) regarding the depth values vs. site elevations needed for the Tables."
On August 26, 2015, the staff held a teleconference call with the licensee to get clarification on the values presented in its FHRR for LIP. It was unclear if the values in the FHRR for the reevaluated LIP hazard in the FHHR were depths or elevations. The 50.54(f) letter requested that licensees prepare and submit to the NRC reevaluated elevations for flooding hazards, unless they can be justifiably screened. During the call the licensee clarified the values in the FHRR were in fact depths and committed to providing the elevations for use in the interim staff response letter in the ERR. The requested elevation information for each unit was placed in the ERR:
Unit 1: 957.73 Unit 2: 955.04 Unit 3: 952.37 We also had the following clarifications via email.
In the course of reviewing the documentation uploaded to the ERR as a result of the August 20, 2015, audit and the August 26, 2015, teleconference, the staff noticed that the documents titled "Palo Verde FHRR Audit, follow up to NRC Conference Call on 8-20-2015" and "Palo Verde FHRR Audit, follow-up to NRC email from 8-25-2015" appeared to contain the same information. In addition, the NRC staff noticed that the FHRR did not contain the COB for the Hassayampa River, which was needed in a referenceable document for the interim staff response letter. On September 9, 2015, the NRC staff sent an email requesting the following clarifications.
- 1.
A verification/confirmation regarding the last two ERR docs uploaded correspond to the requests for which they were created since they appear to be duplicate items. For background, the two documents relate to:
- a.
the engineering judgement/technical basis for Unit 2 elevations as derived from Unit 1 and Unit 3 in-situ survey performed to determine elevations
- b.
the correlation (for LIP) regarding the depth values vs. site elevations needed for the NRC [Mitigating Strategies Flood Hazard Information] MSFHI Tables. The staff is looking for the Max elevations for each unit including information about the flow paths that were excluded (which I believe are solely on the breezeway).
- 2.
A verification/confirmation about the COB hazard elevation for the Hassayampa River to verify if this value was intentionally omitted from the FHRR for security/ safety-related reasons. All other elevations for washes/Rivers were included in the FHRR Section 2.2.2 and/or Table 2-2. If the value can be made public, then the NRC will proceed with the developmenUissuance of the MSFHI letter in a public forum. If the value is to remain from public domain, then the staff wants to understand the reason and proceed with a redacted table for Palo Verde, if applicable.
The licensee responded on September 9, 2015, by providing which document was to correspond to which topic outlined in the clarification email and corrected the ERR by uploading the correct version of Palo Verde FHRR Audit, follow up to NRC Conference Call on 8-20-2015" for the staff to review. The also indicated that the design-basis for the Hassayampa River was not security-related information and provided the staff with the design-basis value. The licensee's response was placed on the docket under ADAMS Accession No. ML15266A226.
ML16112A021 OFFICE NRR/JLD/JHMB/LA NAME JUribe Slent DATE 05/1712016 05/17/2016 RidsNRRJLD Resource RidsNroDsea Resource RidsNrrPMPaloVerde Resource RidsOgcMailCenter Resource CCook, NRO ACampbell. NRO BHarvey, NRO
- via email NRR/JLD/JHMB/BC NRR/JLD/J MS hams JUribe 05/18/2016 05/18/2016