ML19218A293
| ML19218A293 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 08/13/2019 |
| From: | Siva Lingam Plant Licensing Branch IV |
| To: | Bement R Arizona Public Service Co |
| Lingam S, 301-415-1564 | |
| References | |
| EPID L-2018 -LLE-0010, EPID L-2018-LLA-0194 | |
| Download: ML19218A293 (12) | |
Text
August 13, 2019 Mr. Robert S. Bement Executive Vice President Nuclear/
Chief Nuclear Officer Mail Station 7602 Arizona Public Service Company P.O. Box 52034 Phoenix, AZ 85072-2034
SUBJECT:
PALO VERDE NUCLEAR GENERATING STATION, UNITS 1, 2, AND 3 - REGULATORY AUDIT
SUMMARY
FOR THE JANUARY 22-23, 2019, AUDIT FOR THE LICENSE AMENDMENT AND EXEMPTION REQUESTS ASSOCIATED WITH FRAMATOME HIGH THERMAL PERFORMANCE FUEL (EPID L-2018-LLA-0194 AND EPID L-2018-LLE-0010)
Dear Mr. Bement:
By letter dated July 6, 2018 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML18187A417), as supplemented by letters dated October 18, 2018, March 1, 2019, and May 17, 2019 (ADAMS Accession Nos. ML18296A466, ML19060A298, and ML19137A118, respectively), Arizona Public Service Company (APS, the licensee) requested changes to the technical specifications (TSs) to support the implementation of Framatome Advanced Combustion Engineering 16x16 High Thermal Performance (HTPTM) fuel design with M5 as a fuel rod cladding material and gadolinia as a burnable absorber for Palo Verde Nuclear Generating Station (Palo Verde), Units 1, 2, and 3. In addition to this license amendment request, APS is requesting an exemption from certain requirements of Title 10 of the Code of Federal Regulations (10 CFR) Section 50.46, Acceptance criteria for emergency core cooling systems [ECCS] for light-water nuclear power reactors, and 10 CFR Part 50, Appendix K, ECCS Evaluation Models, to allow the use of Framatome M5 alloy as a fuel cladding material. In addition, the proposed amendment would revise TS 2.1.1, Reactor Core SLs [Safety Limits]; TS 4.2.1, Fuel Assemblies; and TS 5.6.5, Core Operating Limits Report (COLR).
The proposed amendments would adapt the approved Palo Verde reload analysis methodology to address both Westinghouse and Framatome fuel, including the implementation of Framatome methodologies, parameters and correlations. The ability to use either Westinghouse or Framatome fuel will ensure security of the Palo Verde fuel supply by providing for multiple fuel vendors with reliable fuel designs and geographically diverse manufacturing facilities.
For better understanding of the license amendment request, the U.S. Nuclear Regulatory Commission staff conducted an audit at the Hilton Hotel, 1750 Rockville Pike (near Twinbrook Metro Station), Rockville, Maryland, 20852, on January 22-23, 2019. The regulatory audit summary is enclosed with this letter.
R. Bement If you have any questions, please contact me at 301-415-1564 or via e-mail at Siva.Lingam@nrc.gov.
Sincerely,
/RA/
Siva P. Lingam, Project Manager Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. STN 50-528, STN 50-529, and STN 50-530
Enclosure:
Audit Summary cc: Listserv
Enclosure REGULATORY AUDIT
SUMMARY
PERFORMED AT HILTON FACILITY ON JANUARY 22-23, 2019 IN SUPPORT OF THE FRAMATOME HIGH THERMAL PERFORMANCE FUEL LICENSE AMENDMENT AND EXEMPTION ARIZONA PUBLIC SERVICE COMPANY PALO VERDE NUCLEAR GENERATING STATION, UNITS 1, 2, AND 3 DOCKET NOS. 50-528, 50-529, AND 50-530
1.0 BACKGROUND
By letter dated July 6, 2018 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML18187A417), as supplemented by letters dated October 18, 2018, March 1, 2019, and May 17, 2019 (ADAMS Accession Nos. ML18296A466, ML19060A298, and ML19137A118, respectively), Arizona Public Service Company (APS, the licensee) requested changes to the technical specifications (TSs) to support the implementation of Framatome Advanced Combustion Engineering 16x16 High Thermal Performance (HTPTM) fuel design with M5 as a fuel rod cladding material and gadolinia as a burnable absorber for Palo Verde Nuclear Generating Station (Palo Verde), Units 1, 2, and 3. In addition to this license amendment request (LAR), APS is requesting an exemption from certain requirements of Title 10 of the Code of Federal Regulations (10 CFR) Section 50.46, Acceptance criteria for emergency core cooling systems [ECCS] for light-water nuclear power reactors, and 10 CFR Part 50, Appendix K, ECCS Evaluation Models, to allow the use of Framatome M5 alloy as a fuel cladding material. In addition, the proposed amendment would revise TS 2.1.1, Reactor Core SLs [Safety Limits]; TS 4.2.1, Fuel Assemblies; and TS 5.6.5, Core Operating Limits Report (COLR).
The proposed amendments would adapt the approved Palo Verde reload analysis methodology to address both Westinghouse and Framatome fuel, including the implementation of Framatome methodologies, parameters and correlations. The ability to use either Westinghouse or Framatome fuel will ensure security of the Palo Verde fuel supply by providing for multiple fuel vendors with reliable fuel designs and geographically diverse manufacturing facilities.
For better understanding of the LAR, the U.S. Nuclear Regulatory Commission (NRC) staff conducted an audit at the Hilton Hotel, 1750 Rockville Pike (near Twinbrook Metro Station),
Rockville, Maryland, 20852, on January 22-23, 2019. This document provides a report on the deliberations during the regulatory audit.
2.0 SCOPE AND PURPOSE The audit was held on January 22-23, 2019, at the Hilton Hotel in Rockville, Maryland, and was conducted in accordance with the audit plan provided to the licensee (ADAMS Accession No. ML19011A108). The purpose of the audit was to help the NRC staff better understand the LAR, exemption, related documentation and analysis results through interaction with the licensees technical experts, and to help the staff prepare requests for additional information (RAIs) on those questions where docketed information is needed to complete the review. The details of the audit are discussed in Section 4.0 of this report.
3.0 AUDIT TEAM The following NRC staff members participated in the audit:
Michelle Bales - Technical Reviewer Paul Clifford - Technical Adviser Victoria Huckabay - Technical Reviewer Joshua Kaizer - Technical Reviewer John Lehning - Technical Reviewer Siva P. Lingam - Project Manager Mathew Panicker - Lead Technical Reviewer Jennifer Whitman - Branch Chief Diana Woodyatt - Technical Reviewer The following APS personnel supported the audit:
Chris Cowdin, Engineer II Matthew Cox, Regulatory Affairs Section Leader Michael Dilorenzo, Regulatory Affairs Department Leader Shawn Gill, Senior Engineer Robert Hicks, Senior Engineer Chuck Karison, Reload Analysis Section Leader Ryan Lane, Operations Shift Manager Luke McIntyre, Engineer II Calvin Meddings, Senior Engineer Thomas Remick, Nuclear Fuel Analysis Department Leader Dave Ricks, Transient Analysis Section Leader Thomas Weber, Nuclear Regulatory Affairs Director Jenying Wu, Senior Engineer The following APS consultants also supported the audit:
Mark Drucker Dave Medek Hans Van de Berg The following Framatome personnel supported the audit:
Chris Allison Lisa Gerken Nathan Hottle Greg Kessler Brett Matthews Miao Sun Ryan Swanson 4.0 AUDIT REPORT At the beginning of the audit, APS provided a presentation with slides (ADAMS Accession No. ML19060A298).
4.1 Information Needs The licensee was requested to have the presentations and documents related to the areas of focus listed. The documentation was provided by presentations, documents, and calculation details. The following were the planned major areas of focus for detailed discussion and document review. Additional information needs identified during the audit will be communicated to the designated point of contact.
The deliberations during the audit, along with the original contents of the LAR, and the supplemental information will be used to generate RAIs to complete the comprehensive review of the license amendment and exemption requests. The licensees stated goal of the fuel transition is to increase security of fuel supply through reliable fuel designs and diverse manufacturing, to implement an improved fuel design, and to maintain existing methods to the extent practical.
4.2 Items Discussed during Audit Framatome Fuel Project Palo Verde Reload Design Process Fuel Assembly Mechanical Design Core Thermal Hydraulics Thermal-Hydraulics Code Modification Process Mixed Cores Loss-of-Coolant Accident (LOCA) Analysis Non-LOCA Analysis Setpoints Analysis New Time Requirement for LOCA Mitigation Operator Action Framatome Fuel Project The licensee stated that it is planning to use Framatome Combustion Engineering (CE) 16x16 HTPTM fuel in the spring of 2020 refueling of Palo Verde, Unit 2 with 100 CE 16x16 HTPTM fuel assemblies. The LAR approval is needed for the implementation of the APS reload methodology to address the fuel transition.
Palo Verde Reload Design Process The licensee intends to use NRC-approved APS reload methods to address the Framatome fuel; they are Framatome mechanical design, Framatome LOCA methods, COPERNIC code to describe fuel behavior to model thermal conductivity degradation with exposure, NRC-approved Framatome BHTP (designation for Framatome) critical heat flux (CHF) correlation, and use of VIPRE-01 (Versatile Internals and Component Program for Reactors; Electric Power Research Institute (EPRI)) as an alternative to VIPRE-W (Versatile Internals and Component Program for Reactors; Westinghouse) code. The licensee proposed to add VIPRE-01 from EPRI to be used concurrently with VIPRE-01 from Westinghouse and proposed to implement a software quality assurance program in the implementation of different vendor codes for interchangeable licensing applications. The licensee proposed to use the two-stage version of VIPRE code to be used in the same manner as TORC (Thermal-hydraulics of Reactor Core) code to select the limiting assembly candidates for further evaluation. The licensee proposed to use Generic Letter 83-11, Licensee Qualification for Performing Safety Analyses in support of Licensing Actions, and 10 CFR 50.59, Changes, tests and experiments, processes for the change processes for thermal-hydraulic codes. The licensee proposed to mix and match approved codes with approved correlations, such as, insert BHTP correlation and CE-1 correlations in CETOP (Combustion Engineering Thermal On-Line Program) code and BHTP code in VIPRE-01 and VIPRE-W codes.
Fuel Assembly Mechanical Design The licensee reported that the new Framatome CE 16x16 HTPTM fuel design is essentially the same design as the lead test assemblies at the Palo Verde core. The licensee specified that the fuel mechanical compatibility with the resident fuel with respect to upper and lower tie plates, guide tubes, and instrumentation tubes is maintained during all operating conditions.
Moreover, the acceptance criteria in NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants: LWR [Light-Water Reactor} Edition, Section 4.2, Revision 3, Fuel System Design, dated March 2007 (ADAMS Accession No. ML070740002), during normal operation and anticipated operational occurrences are satisfied.
For faulted condition due to earthquakes and pipe breaks, the structural response will be analyzed by NRC-approved methodology, ANP-10337P-A, Revision 0, PWR [Pressurized-Water Reactor] Fuel Assembly Structural Response to Externally Applied Dynamic Excitations, dated April 2018 (ADAMS Accession No. ML18144A821, publicly available version). For structural response analysis, the co-resident CE16 STD (standard or value-added) and CE16 next generation fuel (NGF) fuel will be considered in the mixed core.
Thermal Hydraulics and Modification Process, Mixed Core Staff Concerns Discussion on Mechanical/Thermal-hydraulic compatibility of the three different fuel types (CE 16x16 STD, CE 16x16 NGF and CE 16x16 HTPTM) with three different cladding materials and three different CHF correlations for departure from nucleate boiling (DNB) ratio calculations. Also discussed the details of the thermal-hydraulic characterization and thermal margin analysis for the mixed core at the Palo Verde Units after the potential fuel transition to Framatome fuel.
Discussion on the use of approved CHF correlations in approved codes that do not have specific approval for using such correlations, thereby changes to approved topical reports, which requires more rigorous review than normal fuel transition LARs. APSs modification of approved codes by inserting new CHF correlations (approved for different codes) (e.g.,: ABB-NV (Westinghouse (ABB) Non-Vane CHF Correlation) or WSSV CHF correlations (Westinghouse Side Supported Vane CHF Correlation) with VIPRE-W and VIPRE-01 codes, CE-1 correlation with VIPRE-W, CETOP-D and TORC codes for use with VIPRE-01 code, and BHTP CHF correlation in VIPRE-01 and VIPRE-W codes with CETOP-D and TORC codes).
VIPRE-W modeling options such as 1-pass and 2-pass models as described in Section 5.1 of the LAR will require detailed review.
Discussion on other issues related to thermal/hydraulic design of the mixed core.
Licensee Response The licensee will perform mechanical and thermal-mechanical compatibility analyses to determine compatibility of the new fuel with the co-resident fuel. The thermal margin assessment for the core configuration will involve inlet flow distribution with detailed full core model with each fuel type. Also, the licensee will perform CETOP-D/VIPRE benchmark calculations for CETOP corrections factors for each fuel type quarter assembly that includes all three fuel types and different spacer grid loss coefficients.
Seismic Analysis for Mixed Core The faulted condition analysis that evaluates structural response of the fuel assembly to externally applied forces such as earthquakes and postulated pipe breaks, based on the criteria established in the recently approved topical report ANP-10377P-A for the mixed core. Specifically, discussion on how the seismic evaluation will be done for Framatome and Westinghouse/CE fuel designs in the Palo Verde core.
Setpoints Analysis Staff Concerns:
Review of digital setpoints (COLSS (core operating limits supervisory system)/CPCS (core protection calculator system)) system at Palo Verde, Units 1, 2, and 3 for mixed core with Framatome HTPTM, Westinghouse NGF, and Westinghouse STD fuel design.
When Palo Verde switched to CE 16x16 NGF, the CE setpoint (COLSS/CPCS) methodology was implemented using the approved topical report WCAP-16500-P-A, Supplement 1, Revision 1, Application of CE Setpoint Methodology for CE 16x16 Next Generation Fuel (NGF). However, transition to Framatome CE 16x16 HTPTM fuel should have a similar methodology, either generic or plant-specific. No plant specific or a generic methodology to support the new fuel transition was submitted for review.
Discussion of detailed setpoint analysis for the mixed core is expected of the license during the site audit planned for June 2019.
Licensee Response The licensee will exclusively use CEN-356(V) (Revision 1-PA) methodology for digital Setpoints; COLSS and CPCS for digital CE plants such as Palo Verde. CETOP code with CE-1 correlation will be used for the analysis of setpoints. For the determination of setpoints, the licensee intends to use a modified statistical combination of uncertainties. The parameters that are determined include: uncertainty factors (95 percent probability/95 percent confidence, system parameter uncertainties for engineering hot channel factors, CHF correlations, etc.) and state parameter uncertainties.
The licensee augments the CEN-356(V)-P-A methodology by using the NRC-approved WCAP-16500 -P-A, Supplement 1, Revision 1, methodology. Methodology changes will address biases introduced by different CHF correlations; axial dependent COLSS/CPCS constants, which serve as heat flux penalties for DNB ratio calculations and DNB ratio power operating limit error calculation with temperature/pressure/flow. Mixed core effects will be included in the analysis.
Non-LOCA Transients Staff Concerns:
Demonstration that fuel centerline melt temperature will not be exceeded, considering inadequacy of 21 kilowatts/foot limit at certain times in cycle life and simultaneous separate burnup dependent limits for Westinghouse and Framatome fuel.
Understanding of which transients utilize input from the COPERNIC computer code.
Basis for use of the convolution method for Framatome fuel.
Understanding of DNB probability distribution function for Framatome fuel and how it impacts applicable transient analysis.
Basis for continued use of DNB propagation analysis including evidence of strain behavior for Framatome fuel.
Evidence of comparisons for M5 cladding to Zircaloy-4 discussed in Section 6.4 of of the LAR dated July 6, 2018.
Understanding of how Framatome fuel parameters (Hgap (fuel-to-clad gap coefficient of conductance), Gadolinia effects) are accounted for in CENTS and HERMITE codes.
Understanding of how updated guidance on reactivity-initiated accidents will be addressed in the updated final safety analysis report following the fuel transition.
Licensee Response:
For the control element assembly ejection analysis, Framatome will use the COPERNIC fuel performance code to implement thermal conductivity degradation effects and the corrosion model. State parameters will be generated with STRIKIN-II and DNB ratio values generated with VIPRE/BHTP.
For the hot zero power control element assembly withdrawal, minimum and maximum gap conductance from COPERNIC is bounded by current safety analysis.
Loss-of-Coolant Accident Staff Concerns:
Performance of HTPTM fuel design relative to Generic Safety Issue-191 concerns associated with debris blockage.
With regard to the determination of figures of merit for large-break and small-break LOCA analyses, review of certain data points that appear to be outliers relative to main body of data.
Basis for large-break LOCA analysis having adequately addressed break locations on the intermediate and hot legs.
Basis for assumptions concerning the conservatism of the analyzed reactor coolant pump (RCP) trip timing in the small-break LOCA analysis, particularly in light of the tendency or potential for larger small breaks to set limiting results. In such cases, using the maximum trip delay for the RCPs may be tantamount to running the RCPs throughout the event, which is expected to be non-limiting.
Treatment of thermal conductivity degradation for the larger range of small-break LOCA events.
Treatment of switchover to sump recirculation in small-break LOCA analyses.
Treatment of mixed cores in LOCA analyses.
Explanation for hot assembly mixture level behavior in Figure 4-22 of ANP-3640NP (Attachment 9 in the letter dated July 6, 2018).
Technical Specifications Staff Concerns:
Specificity of wording in safety limits for fuel centerline melt (e.g., Framatome supplied fuel), and whether more specific wording or reference to an applicable topical report could prevent unintended interpretations or applications.
Definition of the term zirconium-alloy in proposed TS 4.2.1.
Wording of TS 4.2.1 with respect to lead test assemblies, and whether the intended meaning is reflected by a literal interpretation of the proposed wording.
Wording of TS 5.6.5, and whether it is necessary to specify which types of fuel the COLR references apply to in light of the licensee plans to maintain multiple vendors methods in the COLR indefinitely.
The compatibility of the core operating limits references in TS 5.6.5, as well as the reload analysis methodology report, with mixed batches fresh of fuel - demonstration that mixed batches of fresh fuel may be acceptably handled, or placement of limits to prevent such loadings.
Containment Analysis Discussion of the need for a quantitative versus qualitative evaluation to confirm any stated analyses of record remain bounding.
Expected differences in stored energy and decay heat between currently licensed fuel and requested amendment fuel.
Mass and Energy release for short and long-term containment response New Time Requirement for LOCA Mitigation Operator Action The licensee stated that the new time requirement to stop all RCPs within five minutes following pressurizer pressure dropping below the RCP net positive suction head limit was determined based on the small-break LOCA analysis. The new time limit does not affect the emergency operating procedures that would be used during a LOCA event. Instead, the 5-minute time limit will be added to the Time Critical Action program procedure. The new time requirement will be added to periodic evaluation, to be conducted every 4 years, where continued ability of operators to complete the manual operator action within 5 minutes will be verified. In addition, the new time requirement will be added to the operator training program and included in the appropriate lesson plan and training program evaluation criteria.
4.3 Supporting Information from the Licensee The licensee was requested to make the appropriate personnel or contractors, who are familiar with the proposed LAR, available for the audit (either in person or on the phone).
The NRC staff also requested the licensee to have the supporting documents related to the above topics available and be prepared to discuss them with the staff during the audit. The documents could be provided by paper copies or electronically. The NRC staff may require the licensee to provide appropriate documents to the NRC docket that would enable an accelerated and effective review of the LAR.
List of Documents Reviewed during the Audit
- 1.
Document No. APS-CP-001, Implementation and Testing of the BHTP CHF Correlation into VIPRE-01 Thermal-Hydraulic Computer Code via DLL, Revision 1, March 28, 2018.
- 2.
Engineering Evaluation, PV-E0897, V7, ENG WO #: 17-14728-009, January 2018.
- 3.
Analysis No. RA-13-C00-2018-014, Framatome Fuel LAR; VIPRE-W to VIPRE-01 Benchmarking Comparison with BHTP CHF Correlation, PV-E1729P, Ver. 5a, October 26, 2018.
- 4.
Letter from R. A. Clark (NRC) to A. E. Lundvall, Jr. (Baltimore Gas and Electric)
Forwards Safety Evaluation Accepting HERMITE/MacBeth Critical Heat Flux, dated July 15, 1983.
- 5.
VDP Number A-15835, APS Log Number 13-N001-1301-01228-0, System 80 tm Inlet Flow Distribution Supplement 1-P to Enclosure 1-P to LD-82-054, February 1993.
- 6.
VDP Number A12908, APS Log Number 13-M001-1301-1251-2, Statistical Combination of Uncertainties, October 26, 1995.
- 7.
80DP-0CC03, Revision 20., Non-Process Software Quality Assurance Program Implementation.
- 8.
80DP-0CC02, Revision 19., Non-Process Software Quality Assurance Program.
- 9.
TA-13-C00-2018-208, this document relates to M5 Cladding.
- 10.
Documents related to Service Analysis of Framatome Fuel.
5.0 CONCLUSION
Through the audit, the NRC staff obtained an enhanced understanding of the licensees submittal and the details of the included safety analyses and their results. There was open communication throughout the audit, and this helped the NRC staff to communicate concerns about the submittal and have them answered by APS and Framatome. The NRC staff will develop the draft RAIs much before the second audit that will take place at the site so that the licensee can provide the draft responses for the NRC review before the site audit. Because of the discussions that were conducted at this audit, the number of potential draft RAIs has been reduced and the scope of the remaining questions has been focused directly on the topic of concern.
- Audit Summary by memo OFFICE NRR/DORL/LPL4/PM NRR/DORL/LPL4/LA NRR/DSS/SNPB/BC*
NAME SLingam PBlechman RLukes DATE 8/8/19 8/8/19 6/5/19 OFFICE NRR/DORL/LPL4/BC NRR/DORL/LPL4/PM NAME RPascarelli SLingam DATE 8/9/19 8/13/19