ML23258A055
| ML23258A055 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 08/31/2023 |
| From: | Richard Guzman NRC/NRR/DORL/LPL1 |
| To: | Sinha S Dominion Energy Nuclear Connecticut |
| References | |
| EPID L-2023-LLA-0065 | |
| Download: ML23258A055 (1) | |
Text
{{#Wiki_filter:From: Richard Guzman To: Shayan Sinha Bcc: Richard Guzman
Subject:
Millstone Unit 3 - Setup of Online Reference Portal for the NRC staff"s review of LAR to Use Framatome Small Break and Realistic Large Break LOCA Methodologies (EPID L-2023-LLA-0065) Date: Thursday, August 31, 2023 2:38:00 PM Attachments: image001.jpg
Mr. Sinha,
By application dated May 2, 2023 (ADAMS Accession No. ML23123A279), Dominion Energy Nuclear Connecticut, Inc. (DENC, the licensee) submitted a license amendment request (LAR) to change the Technical Specifications (TSs) for Millstone Power Station Unit 3 (MPS3). The proposed amendment would update the list of approved methodologies in MPS3 TS 6.9.1.6.b to establish the core operating limits included in the Core Operating Limits Report (COLR) for Framatome (FRM) GAIA fuel with M5 cladding.
The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the licensees LAR and determined that a regulatory audit would assist in the timely completion of the review. The audit will be conducted via online reference portal access to non-docketed information set up by the licensee and via webinar. The enclosed audit plan addresses the request for online access to documents and identifies information to be available during the webinar discussion including audit questions.The licensee is requested to provide online access to specific NRC staff and to be read-only (i.e., to establish measures to prevent the downloading, copying, printing, or otherwise storing of any documents).
The online reference portal would allow the NRC staff to audit documents referenced in the request to determine whether the information included in the documents is necessary to reach a safety conclusion on the proposed amendment. If necessary, the licensee will be formally requested to submit information needed to reach a safety conclusion on the NRC docket. Use of the online reference portal is acceptable as long as the following conditions are met:
The online reference portal will be password-protected, and passwords will be assigned to those directly involved in the review on a need-to-know basis; The online reference portal will be sufficiently secure to prevent NRC staff and contractors from printing, saving, or downloading any documents; and Conditions of use of the online reference portal will be displayed on the login screen and will require concurrence by each user.
The NRC staff would like to request that the portal be populated with the information listed Section 4.0 and 8.0 of the audit plan. This is the initial list identified by the NRC staff. The NRC staff may request additional documents during the review via email. The audit/webinar discussions will be conducted on a future date and an agenda will be provided separately. Please provide the NRC staff with access to the portal and send me the information needed for access, such as username and password, as soon as possible. The conditions associated with the online reference portal must be maintained throughout the duration of the audit.
This email communication will be added to ADAMS as an official agency record. The proprietary information shown within the double square brackets (()) in the audit plan will be redacted in the public version of this email communication pursuant to regulations in 10 CFR 2.390.
If you have any questions, please contact me at (301) 415-1030 or by e-mail to Richard.Guzman@nrc.gov.
Thank you,
Richard V. Guzman Senior Project Manager Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Office: O-9C7 l Phone: (301) 415-1030 Richard.Guzman@nrc.gov
========================================================
AUDIT PLAN LICENSE AMENDMENT REQUEST TO USE FRAMATOME SMALL BREAK AND
REALISTIC LARGE BREAK LOSS OF COOLANT ACCIDENT EVALUATION METHODOLOGIES FOR ESTABLISHING CORE OPERATING LIMITS AND EXEMPTION REQUEST FOR USE OF M5TM CLADDING
DOMINION ENERGY NUCLEAR CONNECTICUT, INC. MILLSTONE POWER STATION UNIT 3
DOCKET NO. 50-423
Proprietary information pursuant to Title 10 of the Code of Federal Regulations Section 2.390 is identified within double brackets
- 1. BACKGROUND
By application dated May 2, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23123A279, Dominion Energy Nuclear Connecticut, Inc. (DENC, the licensee) submitted a license amendment request (LAR) to change the Technical Specifications (TSs) for Millstone Power Station Unit 3 (MPS3). The proposed amendment would update the list of approved methodologies in MPS3 TS 6.9.1.6.b to establish the core operating limits included in the Core Operating Limits Report (COLR) for Framatome (FRM) GAIA fuel with M5 cladding.
The audit will be conducted via online access to non-docketed information set up by the licensee and via webinar. This audit plan addresses the request for online access to documents. The audit webinar dates and agenda will be provided separately by the NRC project manager.
- 2. REGULATORY AUDIT BASES
A regulatory audit is a planned license or regulation-related activity that includes the examination and evaluation of primarily non-docketed information. The audit is conducted with the intent to gain understanding, to verify information, and to identify information that will require docketing to support the basis of a licensing or regulatory decision. Performing a regulatory audit is expected to assist the NRC staff in efficiently conducting its review and gaining insights for licensees processes and procedures. Information that the NRC staff relies upon to make the safety determination must be submitted on the docket.
The audit will be performed consistent with NRC Office Instruction LIC-111, Revision 1, Regulatory Audits, dated October 31, 2019 (ADAMS Accession No. ML19226A274). An audit was determined to be the most efficient approach toward a timely resolution of issues associated with this LAR review, since the staff will have an opportunity to minimize the potential for multiple rounds of requests for additional information (RAIs) and ensure no unnecessary burden will be imposed by requiring the licensee to address issues that are no longer necessary to make a safety determination.
3.0 REGULATORY AUDIT PURPOSE AND SCOPE
The purpose of the remote audit is to:
gain a more detailed understanding of the calculations, analyses, and bases underlying the LAR. confirm the staffs understanding that supports statements made in the LAR. determine whether the information included in the documents is necessary to be submitted to support a safety conclusion; the audit information that the NRC staff determines to be necessary to support the development of the NRC staffs safety evaluation would be requested to be submitted on the docket.
The areas of focus for the regulatory audit are the information contained in the licensees submittal, the enclosed audit information needs, and all associated and relevant supporting documentation (e.g., methodology, process information, calculations, etc.) identified below.
4.0 INFORMATION AND OTHER MATERIAL NECESSARY FOR THE REGULATORY AUDIT
Section 4.4 of ANP-4031P indicates that a delayed RCP trip study was performed to identify the delayed effect of RCP trip on the SBLOCA analysis. It also states ((
)).
Provide the evaluation of an (( )) for audit review.
5.0 AUDIT TEAM
The members of the audit team are:
Richard Guzman, Senior Project Manager (Richard.Guzman@nrc.gov) Summer Sun, Senior Nuclear Engineer (Summer.Sun@nrc.gov)
6.0 LOGISTICS
The audit/webinar meetings will be conducted remotely via MS Teams. A proposed schedule/agenda will be provided to the licensee on a later date. The NRC project manager will coordinate any changes to the audit schedule and logistics with the licensee.
7.0 DELIVERABLES
An audit summary, which may be public, will be prepared within 90 days of the completion of the audit. If the NRC staff identifies information during the audit that is needed to support its regulatory decision, the staff will issue RAIs to the licensee after the audit.
8.0 AUDIT QUESTIONS
AQ-1 Framatome and Westinghouse LOCA Methods in TS 6.9.1.6.b
As stated in Section 1.0 of Attachment 1 to the LAR, TS 6.9.1.6.b would be modified to include Framatome LOCA methods to support the Framatome GAIA fuel in the MPS3 core. In Section 2.4, the licensee also states that the Westinghouse LOCA methods (except the method in TR WCAP-16009-P-A) in the current TS would retain to support the current MPS3 Westinghouse fuel prior to and during the transient to GAIA. The installation of the proposed TS changes would allow co-residence of Framatome and Westinghouse fuel in the MPS3 core (mixed core).
Describe the MPS3 core reload strategy for fuel transition from a full core of Westinghouse fuel to a full core of GAIA fuel. Also, describe the Westinghouse SB-and RLB-LOCA analyses for Westinghouse fuel with mixed core conditions including the Framatome GAIA fuel, and discuss the results of the analyses to show that the applicable acceptance criteria in 10 CFR 50.46(b) are met. Provide the rationale if the Westinghouse LOCA analyses for mixed core conditions including GAIA were not performed.
AQ-2 Framatome SBLOCA Method
As stated in Section 3.1 of Attachment 1 to the LAR, the SBLOCA analysis supporting the GAIA fuel at MPS3 is based on the previously NRC-approved methods, including the methods documents in TR, EMF-2328-P-A Revision 0, Supplement 1-P-A, Revision 0.
The NRC SE (ADAMS ML15210A257) for the TR, EMF-2328-P-A Revision 0, Supplement 1-P-A, Revision 0 imposed modelling requirements in the following area:
- 1. Spectrum of break sizes
- 2. Breaks in the attached piping
- 3. Delayed RCP trip
- 4. Maximum safety injection tank/refueling water tank fluid temperature
- 5. Core bypass-flow path in the reactor vessel
- 6. Reactivity feedback
- 7. Loop seal clearing and cross-over leg modelling
- 8. Core nodalization
Sections 4.1, 4.3, 4.4, and 4.5 of Attachment 3 (ANP-4031P) to the LAR have provided information addressing the modelling requirements in above items 1 through 4. Provide information addressing compliance with the modelling requirements in above item 5 through 8 for the SBLOA analysis.
AQ-3 Acceptance Criteria for SBLOCA Analysis
Section 3.1 of Attachment 3 (ANP-4031P) to the LAR indicates that the SBLOCA analysis is analyzed to meet the first four acceptance criteria in 10 CFR 50.46(b). specifically, the fourth criterion requires a coolable geometry. Discuss the SBLOCA analysis for all break sizes to address the compliance with the above fourth criterion.
AQ-4 S-RELAP5 Nodalization Schemes for SBLOCA Analysis
The S-RELAP5 nodalization schemes used for MPS3 SBLOCA analysis are shown in the following figures in ANP-4031P of the LAR: Figure 3-1 for Reactor Coolant System; Figure 3-2 for Secondary System; and Figure 3-3 for Reactor Vessel.
Identify and justify any modifications to the above nodalization schemes that were not previously reviewed and approved by the NRC during the review of the TRs, EMF-2328-P-A Revision 0, and EMF-2328-P-A Revision 0 Supplement 1-P-A, Revision 0.
AQ-5 Values of Plant Parameters used in the SBLOCA Analysis
Table 3-1 of ANP-4031P in the LAR lists the values of 24 plant parameters used as input for the SBLOCA analysis. Identify and justify the listed values that are different from that of the corresponding parameters assumed in the applicable SBLOCA analysis of record or in Chapter 15.6 of the final safety analysis report (FSAR) for MPS3.
AQ-6 Safety Injection Flow Rates Assumed for the SB-and RLB-LOCA Analysis
The safety injection (SI) flow rates used for the MPS3 SBLOCA analysis are shown in the following Tables of ANP-4031P in the LAR:
Table 3-2 for Total Intact Loops Flow and Broken Loop Flow from the High Head SI (HHSI) System for Cold-Leg Pump Discharge Break Spectrum; Table 3-3 for Total Intact Loops Flow and Broken Loop Flow from the Intermediate Head SI (IHSI) System for Cold-Leg Pump Discharge Break Spectrum; and Table 3-4 for Total Intact Loops Flow and Broken Loop Flow from the Low Head SI (LHSI) System for Cold-Leg Pump Discharge Break Spectrum.
Table 4-1 items 3.n, 3.m, and 3.l of Attachment 5 (ANP-4032P) to the LAR show that the SI flow rates used in the RLBLOCA analysis are the same for SBLOCA analysis. Discuss how the HHSI, IHSI, and LHSI flow rates in Tables 3-2 to 3-4 are determined. Also, identify and justify the listed HHSI, IHSI and LHSI flow rates that are different from that assumed in the applicable LOCA analysis of record or in Chapter 15.6 of the FSAR for MPS3.
AQ-7 Axial Power Shapes Used in the SBLOCA Analysis
Figure 3-4 of ANP-4031Pin the LAR shows the input axial power shape and axial power shape adjusted to the Technical Specifications total and radial peaking factors for the SBLOCA analysis.
Identify and justify the input axial power shape that is changed from that assumed in the applicable SBLOCA analysis of record or in Chapter 15.6 of the FSAR for MPS3. In addition, specify the values of the total and radial peaking factors used for adjusting the axial power shape to show the peaking factors are consistent with the corresponding TS values.
AQ-8 Delayed Reactor Coolant Pump (RCP) Trip Study
The SBLOCA analysis assumed that the RCP trip occurred at reactor trip. Section 4.4 of ANP-4031P in the LAR indicates that a delayed RCP trip study was performed to identify the delayed effect of RCP trip on the SBLOCA analysis. The study assumed the delayed RCP trip time of 5-minute after the specified trip criteria were met for operators to trip all four RCPs
Justify that the assumed 5-minute RCP trip delayed time is adequate to identify the delayed effect on the PCT for the SBLOCA analysis, considering that the PCT (Table 4-2 of ANP-4031P) for break sizes from 5.0 to 8.7 inches would occur within 5 minutes from initiation of the LOCA and that for those break size LOCA, the RCP may not trip at the time when the PCT occurs. Also, justify from the human engineering consideration that the available operator action time for operators to trip all four RCPs is adequate.
AQ-9 RWST Drain-Down Time
Section 4.6 of ANP-4031P in the LAR discusses the RWST drain-down time analysis. It states that [
)).
Confirm that the [
].
AQ-10 ECCS Temperature Sensitivity Study
Section 4.5 of ANP-4031P in the LAR indicates that for the ECCS temperature sensitivity study ((
)).
As shown in item h of Section 2.0 on page 4-4 of ANP-4032P in the LAR, the operating temperature range for water in the accumulator is 750F-1250F. Also, as shown on page 15.6-40 of the MPS3 FSAR, the operating temperature range for the accumulator fluid is 670F - 84 0F. [ )).
((
)) the lowest operating temperature of 75 0F specified in ANP-4032P, or 67 0F in the FSAR.
AQ-11 Thermal Conductivity Degradation (TCD)
NRC Information Notice 2009-23 (ADAMS Accession No. ML091550527), Nuclear Fuel Thermal Conductivity Degradation (TCD), discusses an issue related to the ability of legacy thermal-mechanical fuel modeling codes to predict the exposure-dependent degradation of fuel thermal conductivity accurately. A safety concern with TCD in a LOCA would be that fuel temperatures modeled incorrectly would affect the initial stored energy, resulting in the LOCA evaluation model to underpredict PCTs.
Discuss the TCD model included in the SBLOCA and LBLOCA analyses. Provide rationale if the TCD model is not included.
AQ-12 LOCA Analyses for Mixed Core Configurations Including Westinghouse RFA-2 Fuel
On page 3-8 of ANP-4032P in the LAR, it states that ((
)). Also, it states that the RLB-LOCA analysis include considerations for the mixed core scenario and, that ((
)). In addition, Limitation 3 in Table 3-1 of ANP-4032P restricts that the RLBLOCA evaluation methodology (EM) in EMF-2103(P)(A), Revision 3 is approved based on models that are specific to AREVA proprietary M5 fuel cladding. The application of the model to other cladding types has not been reviewed.
Address the compliance with Limitation 3 above for the RLB-LOCA analysis with consideration of mixed core configurations including ((
)). Also, discuss how (( )) is modeled in the SB-and RLB-LOCA analysis for mixed core configurations and discuss the results of the SB-and RLB-LOCA analysis for the mixed core conditions to show that the applicable acceptance criteria in 10 CFR 50.46(b) are met and the analysis is applicable to any core design that includes (( )).
AQ-13 S-RELAP5 Nodalization Schemes for RLBOCA Analysis
The S-RELAP5 nodalization schemes used for MPS3 RLBLOCA analysis are shown in the following figures in ANP-4032P of the LAR: Figure 3-1 for Primary System; Figure 3-2 for Secondary System; and Figure 3-3 for Reactor Vessel.
Identify and justify any modifications to the above nodalization schemes that were not previously reviewed and approved by the NRC during the review of the TR, EMF-2103-P-A Revision 3.
AQ-14 RLBLOCA Analysis - Plant Initial Operating Conditions
Sections 2.0 and 3.0 of Table 4-1 in ANP-4032P of the LAR list the plant initial operating conditions for the RLBLOCA analysis.
Justify for each initial condition the values used in the RLBLOCA analysis in ANP-4032P that are different from the corresponding conditions included in FSAR Table 15.6-3 for use in the Full Spectrum LBLOCA analysis of record in FSAR 15.6-5.
AQ-15 Acceptance Criteria for the RLBLOCA Analysis
Section 3.1 in ANP-4032P of the LAR indicates that the RLBLOCA analysis is analyzed to meet the first three criteria regarding PCT, maximum local oxidation and core wide oxidation in 10 CFR 50.46(b). The final two criteria regarding coolable geometry and long-term cooling are treated in separate plant-specific evaluations.
Discuss the analytical methods used in the evaluations for meeting the final two criteria to assure that none of the proposed LOCA methods in the LAR will be used. If the coolable geometry analysis and long-term cooling analysis involve the proposed LOCA methods, provide the analyses for the NRC staff to review and approve.
AQ-16 Compliance with the Limitations for use of GALILEO
The licensee addressed in Table 3-2 of ANP-4032P its compliance with the limitations for use of the GALILEO code in the RLBLOCA analysis. As stated in Section 3.3 of ANP-4031P, the GALILEO code is also used in the SBLOCA analysis.
Confirm that the information in Table 3-2 of ANP-4032P for the RLBLOCA analysis is applicable to the SBLOCA analysis in ANP-4031P to satisfy the limitations for use of GALILEO.
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