ML21042B321
| ML21042B321 | |
| Person / Time | |
|---|---|
| Site: | Millstone, Surry, North Anna  |
| Issue date: | 02/11/2021 |
| From: | Mark D. Sartain Dominion Energy Services, Dominion Energy |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML21042B320 | List: |
| References | |
| 21-042 | |
| Download: ML21042B321 (42) | |
Text
PROPRIETARY INFORMATION-WITHHOLD UNDER 10 CFR 2.390 Dominion Energy Services, Inc.
5000 Dominion Boulevard, Glen Allen, VA 23060 February 11, 2021 Dominion DominionEnergy.com Energy U.S. Nuclear Regulatory Commission Serial No.21-042 Attention: Document Control Desk NRA/GDM R1' Washington, D. C. 20555 Docket Nos. 50-336/423 50-338/339 50-280/281 License Nos. DPR-65/NPF-49 NPF-4/7 DPR-32/37 VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION ENERGY VIRGINIA)
NORTH ANNA AND SURRY POWER STATIONS UNITS 1 AND 2 .
DOMINION ENERGY NUCLEAR CONNECTICUT, INC. (DENC)
MILLSTONE POWER STATION UNITS 2 AND 3 REQUEST FOR APPROVAL OF APPENDIX E OF FLEET REPORT DOM-NAF-2 QUALIFICATION OF THE FRAMATOME BWU-I CHF CORRELATION IN THE DOMINION ENERGY VIPRE-D COMPUTER CODE By letters dated September 30, 2004 and January 13, 2005 [Serial Nos.04-606 (ADAMS Accession No. ML042800118) and 05-020 (ADAMS Accession No. ML050180257),
respectively] Dominion Energy submitted Topical Report DOM-NAF-2, "Reactor Core Thermal-Hydraulics Using the VIPRE-D Computer Code," and associated Appendices A and 8, as supplemented by letters dated June 30 and September 8, 2005 [Serial Nos.05-328 (ADAMS Accession No. ML051870070) and 05-020A (ADAMS Accession No. ML052510484), respectively] for NRC review and approval. NRC approval of DOM-NAF-2, including Appendices A and 8, was obtained by letter dated April 4, 2006 (ADAMS Accession No. ML060790496) as revised by the NRC in a letter dated June 23, 2006 (ADAMS Accession No. ML061740212).
By letter dated April 4, 2008 [Serial No. 08-0174, (ADAMS Accession No. ML080980229)],
Dominion Energy submitted Appendix C of DOM-NAF-2-A for NRC review and approval.
NRC approval of Appendix C of DOM-NAF-2-A was obtained by letter dated April 22, 2009 (ADAMS Accession No. ML091030639). By letter dated August 28, 2009 and supplemented by letter dated November 20, 2009 [Serial Nos.09-528 (ADAMS Accession No. ML092430338) and 09-528A (ADAMS Accession No. ML093310330), respectively]
Dominion Energy requested approval of the removal of a restriction on the WRB-1 CHF correlation. NRC approval was obtained by letter dated June 21, 2010 (ADAMS Accession No. ML101620034). Dominion Energy provided the approved version of DOM-NAF-2, Rev.
0.2-P-A to the NRC by letter dated August 20, 2010 [Serial No.10-486 (ADAMS Accession No. ML102390421)].
Finally, by letter dated June 26, 2013 [Serial No.13-145 (ADAMS Accession No. ML13179A014)], Dominion Energy submitted Appendix D of DOM-NAF-2-A for NRC review and approval. NRC approval of Appendix D of DOM-NAF-2-A was provided by letter dated August 12, 2014 [Serial No.14-410 (ADAMS Accession No. ML14169A359)].
Attachment 1 contains information that is being withheld from public disclosure under 10 CFR 2.390. Upon separation from Attachment 1, this page is decontrolled.
Serial Number 21-042 Docket Nos. 50-336/423/338/339/280/281 /395 DOM-NAF-2, Appendix E Transmittal Page 2 of 3 Dominion Energy is hereby submitting Appendix E to Fleet Report DOM-NAF-2, "Qualification of the Framatome BWU-I CHF Correlation in the Dominion Energy VIPRE-D Computer Code," for NRG review and approval.
Associated with our request for NRG approval of DOM-NAF-2, Appendix E, the following three documents are provided as Attachments 1, 2, and 3, respectively:
- 1. Appendix E to DOM-NAF-2, "Qualification of the Framatome BWU-I CHF Correlation in the Dominion Energy VIPRE-D Computer Code" (Proprietary)
- 2. Appendix E to DOM-NAF-2 "Qualification of the Framatome BWU-I CHF Correlation in the Dominion Energy VIPRE-D Computer Code" (Non-Proprietary)
- 3. Framatome Affidavit for Withholding Proprietary Information from Public Disclosure contains information proprietary to Framatome Inc. and is supported by an affidavit (Attachment 3) signed by Framatome, the owner of the information. The affidavit sets forth the basis on which the information may be withheld from public disclosure by the Commission and addresses with specificity the considerations listed in paragraph (b)(4) of Section 2.390 of the Commission's regulations. Accordingly, it is respectfully requested the proprietary information be withheld from public disclosure in accordance with 10 CFR 2.390. .
Dominion Energy requests approval of the generic application of Appendix E to DOM-NAF-2.
Plant specific applications of this Fleet Report, including applicable appendices, will be submitted to the NRG for review and approval in accordance with Section 2.1 of DOM-NAF-2-A.
If you have questions or require additional information, please contact Mr. Gary D. Miller at (804) 273-2771.
Respectfully, Mark D. Sartain Vice President- Nuclear Engineering and Fleet Support Commitments made in this letter: None
Serial Number 21-042 Docket Nos. 50-336/423/338/339/280/281/395 DOM-NAF-2, Appendix E Transmittal Page 3 of 3 cc: U.S. Nuclear Regulatory Commission - Region I 2100 Renaissance Blvd, Suite 100 King of Prussia, PA 19406-2713 U.S. Nuclear Regulatory Commission - Region II Marquis One Tower 245 Peachtree Center Avenue, NE Suite 1200 Atlanta, GA 30303-1257 R. V. Guzman Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 08-C 2 11555 Rockville Pike Rockville, MD 20852-2738 Mr. G. Edward Miller NRC Senior Project Manager - North Anna U.S. Nuclear Regulatory Commission One White Flint North, Mail Stop 09 E-3 11555 Rockville Pike Rockville, MD 20852-2738 Mr. Vaughn Thomas NRC Project Manager - Surry U.S. Nuclear Regulatory Commission One White Flint North. Mail Stop 04 F-12 11555 Rockville Pike Rockville, MD 20852-2738 NRG Senior Resident Inspector Millstone Power Station NRG Senior Resident Inspector North Anna Power Station NRG Senior Resident Inspector Surry Power Station
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 Appendix E to Fleet Report DOM-NAF-2 QUALIFICATION OF THE FRAMATOME BWU-1 CHF CORRELATION IN THE DOMINION ENERGY VIPRE-D COMPUTER CODE (NON-PROPRIETARY)
Virginia Electric and Power Company (Dominion Energy)
Dominion Energy Nuclear Connecticut, Inc.
(DENC)
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 CLASSIFICATION/DISCLAIMER The data, information, analytical techniques, and conclusions in this report have been prepared solely for use by Dominion Energy (the Company), and they may not be appropriate for use in situations other than those for which they are specifically prepared. The Company therefore makes no claim or warranty whatsoever, expressed or implied, as to their accuracy, usefulness, or applicability. In particular, THE COMPANY MAKES NO WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, NOR SHALL ANY WARRANTY BE DEEMED TO ARISE FROM COURSE OF DEALING OR USAGE OR TRADE, with respect to this report or any of the data, information, analytical techniques, or conclusions in it. By making this report available, the Company does not authorize its use by others, and any such use is expressly forbidden except with the prior written approval of the Company. Any such written approval shall itself be deemed to incorporate the disclaimers of liability and disclaimers of warranties provided herein. In no event shall the Company be liable, under any legal theory whatsoever (whether contract, tort, warranty, or strict or absolute liability), for any property damage, mental or physical injury or death, loss of use of property, or other damage resulting from or arising out of the use, authorized or unauthorized, of this report.
ABSTRACT This appendix documents Dominion Energy's benchmark and qualification of the BWU-1 Critical Heat Flux (CHF) correlation with the VIPRE-D code. The benchmark was performed using the same CHF experimental database used in the initial development and licensing of the BWU-1 correlation. The qualification was performed using the initial database with additional test data included to demonstrate applicability of the VIPRE-D/BWU-1 code/correlation pair to fuel designs with AFA-type mixing vane grids and mid-span mixing grids. This appendix summarizes the data evaluations that were performed to benchmark and qualify the VIPRE-D/BWU-1 code/correlation pair, and to develop the corresponding DNBR design limit.
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Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 TABLE OF CONTENTS CLASSIFICATION/DISCLAIMER................................................................................. E-2 ABSTRACT............................................................................................................. E-2 TABLE OF CONTENTS............................................................................................. E-3 LIST OF TABLES..................................................................................................... E-4 LIST OF FIGURES................................................................................................... E-4 ACRONYMS AND ABBREVIATIONS ................................................................... ,....... E-5 E.1 PURPOSE........................................................................................................ E-6 E.2 APPLICABILITY................................................................................................. E-6 E.3 DESCRIPTION OF THE FRAMATOME BWU-I CHF CORRELATION........................... E-7 E.4 DESCRIPTION OF THE VIPRE-D/BWU-I DATABASE AND TEST ASSEMBLIES........... E-8 E.5 VIPRE-D/BWU-I BENCHMARKING AND QUALIFICATION RESULTS.......................... E-18 E.5.1 VIPRE-D/BWU-I EXPERIMENTAL DATABASE RESULTS AND COMPARISON TO LYNX2/BWU-I RESULTS............................................................................ E-19 E.5.2 VIPRE-D/BWU-I COMBINED DATABASE RESULTS AND DETERMINISTIC DESIGN LIMIT............................................................................................... E-22 E.6 CONCLUSIONS................................................................................................ E-35 E.7 REFERENCES.................................................................................................. E-35 E-3
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 LIST OF TABLES Table E.4-1: Summary of CHF Tests........................................................................... E-9 Table E.4-2: Grid Pressure Loss Coefficients................................................................. E-13 Table E.4-3: [ ] Operating Conditions and CHF Data........................... E-13 Table E.4-4: [ ] Operating Conditions and CHF Data........................... E-16 Table E.5.1-1: Summary of VIPRE-D/BWU-I Experimental Database Results....................... E-19 Table E.5.1-2: Statistical Analysis of BWU-I Experimental Database Design Limit.................. E-21 Table E.5.1-3: Range of Validity for the BWU-I Experimental Database............................... E-21 Table E.5.1-4: VIPRE-D/BWU-I Comparison to LYNX2/BWU-I Experimental Database DNBR Limits for Pressure Groups......................................................................................... E-21 Table E.5.2-1: Summary of VIPRE-D/BWU-I Results....................................................... E-23 Table E.5.2-2: Summary of VIPRE-D/BWU-I Wand D' Normality Tests............................... E-25 Table E.5.2-3: VIPRE-D/BWU-I M/P CHF Statistical Comparison Tests for Poolability... ... ... ... E-26 Table E.5.2-4: Statistical Analysis of VIPRE-D/BWU-I Combined Database Design Limit......... E-27 Table E.5.2-5: M/P CHF Performance by Independent Variable and Geometry Grouping of the BWU-I Combined Database at 95% Confidence Level................................................ E-28 Table E.5.2-6: VIPRE-D/BWU-I Combined Database DNBR Limits for Pressure Groups......... E-34 Table E.6-1: DNBR Limits for the VIPRE-D/BWU-I Combined Database.............................. E-35 Table E.6-2: Ranges of Validity for the VIPRE-D/BWU-I Combined Database....................... E-35 LIST OF FIGURES Figure E.4-1: Axial Geometry for CHF Test [ ].... .. ... ...... .. .. .. .. .. .. .. ... .. E-1 O Figure E.4-2: Radial Geometry and Power Distribution for CHF Test [ ]. E-11 Figure E.4-3: Axial Power Distribution for CHF Test [ ]... ... ... ...... ........ E-12 Figure E.5.2-1: Measured CHF vs. Predicted CHF for VIPRE-D/BWU-I Combined Database... E-29 Figure E.5.2-2: M/P vs. Pressure for VIPRE-D/BWU-I Combined Database.......................... E-30 Figure E.5.2-3: M/P vs. Mass Velocity for VIPRE-D/BWU-I Combined Database................... E-31 Figure E.5.2-4: M/P vs. Quality for VIPRE-D/BWU-I Combined Database .. .. .. ... ..... .. .. .. .... ... .. . E-32 Figure E.5.2-5: VIPRE-D/BWU-I Probability Density Function............................................ E-33 E-4
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 ACRONYMS AND ABBREVIATIONS ANOVA Analysis of Variance CHF Critical Heat Flux DDL Deterministic Design Limit DNB Departure from Nucleate Boiling DNBR Departure from Nucleate Boiling Ratio GT Guide Tube IFM Intermediate Flow Mixing (Grid)
MDNBR Minimum Departure from Nucleate Boiling M/P Ratio of Measured-to-Predicted CHF MSMG Mid-Span Mixing Grid MVG Mixing Vane Grid OD Outer Diameter P/M Ratio of Predicted-to-Measured CHF (equivalent to DNBR)
PWR Pressurized Water Reactor SS Simple Support STDEV Standard Deviation TIC Thermocouple USNRC US Nuclear Regulatory Commission E-5
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 E.1 PURPOSE The BWU-I Critical Heat Flux (CHF) correlation was developed for predicting departure from nucleate boiling ratio (DNBR) margin in the mixing vane grid (MVG) region of a fuel assembly and belongs to the family of BWU CHF Correlations developed by Framatome such as BWU-Z, BWU-ZM, and BWU-N (see Appendix A).
To be licensed for use, a CHF correlation must be tested against experimental data that span the anticipated range of conditions over which the correlation will be applied. Furthermore, the population statistics of the database must be used to establish a DNBR design limit such that the probability of avoiding departure from nucleate boiling (DNB) will be at least 95% at a 95% confidence level.
This appendix documents Dominion Energy's qualification of the BWU-I correlation with the VIPRE-D code. This qualification of the BWU-I correlation was performed against the same CHF experimental database used by Framatome to develop and license the correlation (Reference E1), as well as additional CHF data from further testing conducted by Framatome (described in Section E.4). The inclusion of this additional test data in the qualification of the VIPRE-D/BWU-I code/correlation pair serves to extend the applicability of the BWU-I CHF correlation to fuel designs with AFA-type mixing vane grids and mid-span mixing grids (MSMGs). This appendix summarizes the data evaluations that were performed to qualify the VIPRE-D/BWU-I code/correlation pair, and to develop the corresponding DNBR design limit for the correlation.
E.2 APPLICABILITY Reference E1 established BWU-I as the basic correlation for fuel assemblies with mixing vane grids. The qualification of the VIPRE-D/BWU-I code correlation pair performed in Section E.5.2 demonstrates the applicability of the correlation to fuel designs with AFA-type mixing vane grids and mid-span mixing grids.
As such, Dominion Energy intends to use the VIPRE-D/BWU-I code/correlation pair for the analysis of Framatome 15x15 and 17x17 fuel assemblies in regions with mixing vane grids and mid-span mixing grids. When evaluating these types of fuels outside of the range of validity of the BWU-I CHF correlation (i.e., non-mixing vane grid regions of the fuel assembly), Dominion Energy intends to use the VIPRE-D/BWU-N code/correlation pair. Use of the VIPRE-D/BWU-N code/correlation pair has previously been approved by the NRC (Reference E3).
The VIPRE-D/BWU-I applications discussed in this appendix are consistent with the generic intended applications listed in Section 2.0 of the main body of this report (Section 2.0). Also, more specifically, Dominion Energy intends to use VIPRE-D/BWU-I to analyze the transients delineated in Table 2.1-1 in Section 2.0 of the main body of this report. The qualification of the BWU-I correlation with the VIPRE-D code has been performed following the modeling guidelines described in Section 4.0 of this report.
This Appendix is submitted to the USNRC for review and approval in order to meet the USNRC's requirement #2 listed in the VIPRE-01 SER, as outlined in Section 2.2 in the main body of this report.
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Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 E.3 DESCRIPTION OF THE FRAMATOME BWU-1 CHF CORRELATION In pressurized water reactor (PWR) cores, the energy generated inside the fuel pellets leaves the fuel rods at their surface in the form of heat flux, which is removed by the reactor coolant system flow. The normal heat transfer regime in this configuration is nucleate boiling, which is very efficient. However, as the capacity of the coolant to accept heat from the fuel rod surface degrades, a continuous layer of steam (a film) starts to blanket the tube. This heat transfer regime, termed film boiling, is less efficient than nucleate boiling and can result in significant increases of the fuel rod temperature for the same heat flux.
Since the increase in temperature may lead to the failure of the fuel rod cladding, PWRs are designed to operate in the nucleate boiling regime and protection against operation in film boiling must be provided.
The heat flux at which the steam film starts to form is called CHF or the point of DNB. For design purposes, the DNBR is used as an indicator of the margin to DNB. The DNBR is the ratio of the predicted CHF to the actual local heat flux under a given set of conditions. Thus, DNBR is a measure of the thermal margin to film boiling and its associated high temperatures. The greater the DNBR value (above 1.0), the greater the thermal margin.
The CHF cannot be predicted from first principles, so it is empirically correlated as a function of the local thermal-hydraulic conditions, the geometry, and the power distribution measured in the experiments.
Since a CHF correlation is an analytical fit to experimental data, it has an associated uncertainty, which is quantified in a Deterministic Design Limit (DDL), also referred to as the DNBR design limit. A calculated DNBR value greater than this design limit provides assurance that there is at least a 95% probability at the 95% confidence level that a departure from nucleate boiling event will not occur.
Framatome has developed and uses the B&W-2, the BWC, and the BWCMV CHF correlations. The first two of these correlations apply to fuel assemblies with non-mixing vane spacer grids of lnconel or Zircaloy. The BWCMV correlation applies to fuel assemblies with mixing vane grids (Reference E1).
These correlations are limited to applications in a high flow regime, but modern applications require the use of a correlation in the middle and low flow regimes. Using the response surface model and sequential optimization techniques, Framatome developed a universal local conditions CHF correlation form. This correlation form, designated BWU, was modified and applied to three different fuel design types over the wider required ranges in Reference E1. This reference describes the CHF tests that provide the basis for the new correlations, analyzes the performance of the correlation for each fuel type, ':'nd provides limits and guidelines for its application.
The Framatome BWU CHF Correlations are defined in Reference E1 as:
[ ]
[
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Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2
] The specific formulations for each one of these components, as well as the corresponding constants are Framatome proprietary and can be found in Reference E 1.
E.4 DESCRIPTION OF THE VIPRE-D/BWU-1 DATABASE AND TEST ASSEMBLIES This section provides a summary of the heat transfer facility at which all CHF testing was conducted, as well as a summary of the [ ] used in the qualification of the VIPRE-D/BWU-I code/correlation pair. This section also provides data for additional testing performed by Framatome which is used by Dominion Energy to support the applicability of the BWU-I CHF correlation to fuel designs with AFA-type mixing vane grids and MSMGs.
Framatome developed the BWU-I correlation to be used for fuel designs with lnconel mixing vane grids based on the experimental data obtained at the Heat Transfer Research Facility of Columbia University (HTRF). The HTRF is a ten-megawatt electric facility capable of testing full length (up to 14 ft heated length) rod arrays in up to a 6-by-6 matrix. HTRF testing conditions cover the full range of PWR operating conditions with pressures up to 2,500 psia, mass velocities up to 3.5 Mlbm/hr-ft2 and inlet temperatures approaching saturation (Reference E1). The test assemblies used for development of the BWU-I correlation had 4x4 and 5x5 geometries. The 4x4 test bundles represent a 15x15 subchannel geometry and the 5x5 test bundles represent a 17x17 subchannel geometry (Reference E1). A total of [
] were used to develop the BWU-I CHF correlation (Reference E1).
Additional testing was performed at the Columbia HTRF with test assemblies that consist of AFA-type mixing vane grids and MSMGs. The additional tests were not used in the formulation of the BWU-I CHF correlation form and constants; however, they are used in Dominion Energy's statistical analysis of the BWU-I design limit and to demonstrate the correlation's applicability to those fuel types with AFA-type mixing vane grids and MSMGs. AFA grids are mixing vane and mid-span mixing grids designed by Framatome to provide enhanced structural support and fluid flow mixing for Framatome's nuclear fuel assembly designs. Fuel designs with AFA grids, such as the AFA 3G' design, have a lengthy history of excellent operation in European PWRs such as Ringhals and Tihange.
The [ ] used to develop the BWU-I CHF correlation are used by Dominion Energy to benchmark against Fra.matome results (Section E.5.1 ). A total of [ * ] are used by Dominion Energy to qualify the VIPRE-D/BWU-I code/correlation pair for the analysis of 15x15 and 17x17 fuel assemblies in regions with mixing vane grids and mid-span mixing grids, as described in Section E.2.
Full assembly VIPRE-D models were created for each experimental test section. Table E.4-1 provides a summary of the key information about each test series used in the qualification of the VIPRE-D/BWU-I code/correlation pair.
The geometry and test conditions of the [ ] are included in this appendix as they have not previously been submitted to the NRC, but are the basis for applicability of the BWU-I CHF correlation to fuel designs with AFA-type mixing vane grids and mid-span mixing grids. Figures E.4-1 and E.4-2 show the axial and radial geometry, respectively, for the [ ].
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Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 Figure E.4-3 shows the axial power distribution for the [ ]. Table E.4-2 lists the grid pressure loss coefficients used in [ ]. Tables E.4-3 and E.4-4 list the operating conditions for the [ ].
Table E.4-1: Summary of CHF Tests E-9
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 Figure E.4-1: Axial Geometry for CHF Test [ 1 E-10
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 Figure E.4-2: Radial Geometry and Power Distribution for CHF Test [ ]
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Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 Figure E.4-3: Axial Power Distribution for CHF Test [ ]
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Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 Table E.4-2: Grid Pressure Loss Coefficients Table E.4-3: [ Test Series CU 47.1 ] Operating Conditions and CHF Data 3
5 E-13
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 E-14
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 E-15
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 Table E.4-4: [ ] Operating Conditions and CHF Data E-16
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 The total number of tests conducted in the [ ];
however, several tests were excluded from the Dominion Energy analyses as there was no measurable occurrence of CHF (gray cells in Table E.4-3 and E.4-4). [
]. A total of [
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Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2
] are used in the Dominion Energy qualification of the BWU-I correlation with VIPRE-D
[ ].
E.5 VIPRE-D/BWU-1 BENCHMARKING AND QUALIFICATION RESULTS Reference E1 describes the mathematical model for each separate test section of the BWU-I Experimental Database by providing the bundle and cell geometry, the rod radial peaking values, the rod axial flux shapes, the spacer grid information (i.e., type, axial locations and form losses) and the thermocouple locations. Section E.4 provides equivalent information for the CU Test Series.
Each test section was modeled for analysis with the VIPRE-D thermal-hydraulic computer code as a full assembly model following the modeling methodology discussed in Section 4 in the main body of this report. For each set of bundle data, VIPRE-D produces the local thermal-hydraulic conditions (mass velocity, thermodynamic quality, heat flux, etc.) at every axial node along the heated length of the test section. The ratio of measured-to-predicted CHF (M/P) is the variable that is normally used to evaluate the thermal-hydraulic performance of a code/correlation pair. The measured CHF is the local heat flux at a given location, while the predicted CHF is calculated by the code using the BWU-I CHF correlation.
The ratio of these two values provides the M/P ratio, which is the inverse of the DNB ratio. M/P ratios are frequently used to validate CHF correlations instead of DNB ratios, because their distribution is usually a normal distribution, which simplifies their manipulation and statistical analysis.
Section E.5.1 summarizes the results, descriptive statistics, and DDL of the VIPRE-D/BWU-I Experimental Database code/correlation pair. The Experimental Database is defined as the [
] described in Reference E1 which are used to correlate the BWU-I correlation constants and coefficients. Section E.5.1 performs a benchmark of the Dominion Energy VIPRE-D results against the Framatome LYNX2 results.
Section E.5.2 summarizes the results, descriptive statistics, and DDL of the VIPRE-D/BWU-I Combined Database code/correlation pair. The Combined Database is defined as the Experimental Database pooled with the CU Test Series described in Section E.4. Section E.5.2 also summarizes the statistics used to determine the poolability of the Experimental Database and the CU Test series.
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Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 E.5.1 VIPRE-D/BWU-I EXPERIMENTAL DATABASE RESULTS AND COMPARISON TO LYNX2/BWU-I RESULTS This section summarizes the VIPRE-D results for the Experimental Database described in Reference E1 using the BWU-I CHF correlation. This section also provides the VIPRE-D overall statistics for the BWU-I experimental tests, generates the DDL for the VIPRE-D/BWU-I Experimental Database code/correlation pair, and performs a benchmark/comparison to Framatome's LYNX2 results.
The BWU-I correlation was developed by Framatome by correlating the CHF experimental results obtained in the tests as described in Reference E1. Framatome used these test data to calculate a DDL of 1.21 for the BWU-I correlation (Reference E1). Dominion Energy used these experimental data to develop the VIPRE-D/BWU-I Experimental Database code/correlation pair DDL for comparison to Framatome results. Table E.5.1-1 summarizes the relevant statistics for each test and calculates the aggregate statistics for the BWU-I Experimental Database.
Table E.5.1-1: Summary of VIPRE-D/BWU-I Experimental Database Results E-19
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 One-sided tolerance theory (Reference E4) is used for the calculation of the VIPRE-D/BWU-I DNBR design limit. This theory allows the calculation of a DNBR limit so that, for a DNBR equal to the design limit, DNB will be avoided with 95% probability at a 95% confidence level.
First, it is necessary to verify that the overall distribution for the M/P ratios is a normal distribution because all statistical techniques used below assume that the original data distribution is normal. To evaluate if the distribution is normal, the D' normality test was applied (Reference E5). A value of D' equal to 16761.69 was obtained for the VIPRE-D/BWU-I Experimental Database. This D' value is within the range of acceptability for [ ] with a 95% confidence level (16655.2 to 16835.2) b_ Thus, it is concluded that the M/P distribution for the VIPRE-D/BWU-I database is normal. Based on the results listed in Table E.5.1-1, the deterministic DNBR design limit is calculated as:
[E.5.1.1]
where M/P = average measured to predicted CHF ratio CTM/P = standard deviation of the measured to predicted CHF ratios of the database KN,c,P = one-sided tolerance factor based on N degrees of freedom, C confidence level, and P portion of the population protected. This number can be obtained from Table 1.4.4 of Reference E4.
Normally, the number of degrees of freedom would be the total number of data minus one. However, because Framatome used these experimental data to correlate [ ] that appear in the BWU-I correlation (Reference E1), the total number of degrees of freedom must be corrected to account for this. In addition, the standard deviation of the database needs to be corrected accordingly to account for this reduced number of degrees of freedom:
[ ] [E.5.1.2]
CTN = CTM/P * [ (n -1 ) I N ] 1/2 The 'N' value, corrected to include the [ ] in the BWU-I correlation, is then used to calculate an appropriate one-sided tolerance factor (KN,c,P). The corrected 'N' value is also used to calculate a corrected standard deviation, CTN. The new values of CTN and KN,c,P are then used in Equation E.5.1.1, alongside,the average M/P value of the database, to calculate the corrected DNBR design limit.
The DNBR design limit for the VIPRE-D and the BWU-I correlation can be calculated as shown in Table E.5.1-2.
b From Table 5 in Reference E5 D' Lower Limit[ ][P = 0.025] = 16655.2 D' Upper Limit [P =0.975] =16835.2 E-20
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 Table E.5.1-2: Statistical Analysis of BWU-I Experimental Database Design Limit The VIPRE-D/BWU-I Experimental Database code/correlation deterministic DNBR design limit is 1.23, which is higher than the limit of 1.21 reported by Framatome in Reference E1.
Table E.5.1-3 summarizes the ranges of validity for the VIPRE-D/BWU-I code/correlation pair as defined by the Experimental Database. These ranges are identical to those submitted by Framatome and approved by the NRC (Reference E1).
Table E.5.1-3: Range of Validity for the BWU-I Experimental Database VIPRE-D/LYNX2 Pressure [psia] 745 - 2455 Mass Velocity [Mlbm/hr-ft 2] 0.40-3.88 Thermodynamic Quality, x at CHF < 0.65 In Reference E1, the USNRC identified that the performance of the BWU-I correlation might be deficient at the very low end of the pressure range. For that reason, Framatome developed individual DNBR design limits for each low-pressure group in the database. This approach allows for use of the BWU-I correlation at low pressures but imposes a higher DNBR limit to ensure that the correlation is used conservatively.
Table E.5.1-4 summarizes the VIPRE-D/BWU-I Experimental Database DNBR limits calculated for the different pressure groups and compares them with the DNBR design limits obtained by Framatome in Reference E 1.
Table E.5.1-4: VIPRE-D/BWU-I Comparison to LYNX2/BWU-I Experimental Database DNBR Limits for Pressure Groups VIPRE-D DNBR LIMIT 1.574 1.135 1.224 LYNX2 DNBR LIMIT 1.568 1.133 1.208 E-21
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 As seen from Table E.5.1-4, the VIPRE-D/BWU-I Experimental Database DNBR limits are similar to those determined by Framatome in Reference E1. Therefore, concurrence with Framatome's LYNX2/BWU-I code/correlation limit has been demonstrated.
E.5.2 VIPRE-D/BWU-1 COMBINED DATABASE RESULTS AND DETERMINISTIC DESIGN LIMIT This section summarizes the VIPRE-D results for all [ ] (Table E.4-1) using the BWU-I CHF correlation, the associated descriptive statistics, and the statistical tests used to demonstrate poolability of the BWU-I Experimental Database and the CU Test Series. The CU Test Series is included and pooled with the BWU-I Experimental Database to demonstrate that the BWU-I CHF correlation may be applied to fuel products with AFA-type mixing vane grids and MSMGs. This section also shows the variation of the M/P ratio with each independent variable to demonstrate that there are no biases in the data and generates the DDL for the VIPRE-D/BWU-I Combined Database.
Dominion Energy used the BWU-I Experimental Database (Reference E1) along with the CU Test data documented in Section E.4 to develop the VIPRE-D/BWU-I Combined Database code/correlation pair DDL which is applicable to fuel products with AFA-type mixing vane grids and MSMGs.
Table E.5.2-1 summarizes the relevant statistics for each test and calculates the aggregate statistics for the Experimental Database (from Section E.5.1), the CU Test data used by Dominion Energy, and the Combined Database.
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Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 Table E.5.2-1: Summary of VIPRE-D/BWU-I Results Statistical tests examine the BWU-1 Correlation database and additional CHF data to determine the appropriate manner for establishing the code/correlation DDL such that it ensures that the probability of avoiding DNB will be at least 95% at a 95% confidence level. This is done by determining first if the datasets are normally distributed and if they are of the same population. If so, the datasets may be combined, and parametric statistics may then be used to determine the one-sided 95/95 code/correlation DDL.
To develop a DDL for [ ], it must first be demonstrated that the BWU-1 Experimental Database and the CU Tests dataset are normally distributed and not of different statistical populations (i.e., they are poolable). Prior to performing any statistical tests, the datasets are examined for outliers. The W test and D' test are used to demonstrate normality of the datasets (Reference ES).
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Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 The F-Test for Equality of Two Variances and a subsequent two-tailed t-Test are used to demonstrate poolability (Reference E2).
The results of the F-Test determine the type oft-Test to be conducted. If the F-Test results show that the variances of the two datasets being compared are equal, at-Test assuming equal variances is conducted.
Otherwise, at-Test assuming unequal variances is conducted. A significance level of 5% (a= 0.05) is used for all statistical tests.
No points were eliminated as outliers in any dataset. The results of the W and D' normality tests are presented in Table E.5.2-2. The D' test is applied to groups of 50 data points or more. The Wtest is used for groups of less than 50 data points. The results of the statistical tests for determining poolability of the datasets are presented in Table E.5.2-3.
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Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 Table E.5.2-2: Summary of VIPRE-D/BWU-1 Wand D' Normality Tests E-25
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 Table E.5.2-3: VIPRE-D/BWU-1 M/P CHF Statistical Comparison Tests for Poolability The results of the F-Test indicate that the variances of the two datasets are unequal, as F < Fcritical and the p-value is significantly less than the significance level of the test. Therefore, a t-Test assuming unequal variances must be conducted to determine if the two datasets are of two different populations.
A two-tailed t-Test was selected to ensure the possibility of a relationship in both directions was tested.
Results of the t-Test indicate that the means of the two datasets may be considered equal, as t < tcritical and the p-value is greater than the significance level of the test. Therefore, the datasets may be pooled together, and the BWU-I CHF correlation is shown to be applicable to fuel assemblies with AFA-type mixing vane grids and mid-span mixing grids (MSMGs).
It is necessary to verify that the overall distribution for the M/P ratios is a normal distribution because all statistical techniques used below assume that the original data distribution is normal. Based on the above discussed tests, the Combined Database was shown to be normally distributed. The D' value, 19099.72, was within the range of acceptability for [ ] at a 95% confidence level (19061.0 to 19258.0)c. Since the Combined Dataset is shown to be normally distributed, parametric statistics (i.e.,
one-sided tolerance theory) may be applied to determine a code/correlation limit.
One-sided tolerance theory (Reference E4) is used for the calculation of the VIPRE-D/BWU-I DNBR design limit. This theory allows the calculation of a DNBR limit so that, for a DNBR equal to the design limit, DNB will be avoided with 95% probability at a 95% confidence level.
Based on the results listed in Tables E.5.2-1 through E.5.2-3, the deterministic DNBR design limit for the combined database is calculated with Equation E.5.1.1, where the standard deviation is again corrected to account for the reduced number of degrees of freedom using equation E.5.1.2.
c From Table 5 in Reference E5
=0.025] = 19061.0 D' Lower Limit [
D' Upper Limit l [P
[P =0.975] = 19258.0 E-26
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 The 'N' value from Equation E.1.2, corrected to include the [ ] in the BWU-I correlation, is used to calculate an appropriate one-sided tolerance factor (KN,c,P), The corrected 'N' value is also used to calculate a corrected standard deviation, CTN. The new values of CTN and KN,c,P are then used in Equation E.5.1.1, alongside the average M/P value of the database, to calculate the corrected DNBR design limit.
The DNBR design limit for the VIPRE-D/BWU-I code/correlation pair based on the combined database is calculated as shown in Table E.5.2-4.
Table E.5.2-4: Statistical Analysis of VIPRE-D/BWU-I Combined Database Design Limit The VIPRE-D/BWU-I code/correlation deterministic DNBR design limit is 1.23, which is identical to the limit calculated for the experimental database in Section E.5.1.
Figures E.5.2-1 through E.5.2-4 display the performance of the M/P ratio and its distributions as a function of the pressure, mass velocity, and quality, respectively. The objective of these plots is to aid in visually identifying biases in the M/P ratio distribution and to get a better understanding of the BWU-I correlation as it relates to the three variables of interest (i.e., pressure, mass velocity, and quality). The plots show a mostly uniform scatter of the data and no obvious trends or slopes. These plots also include the DNBR design limit line. Note that [ ] are above the DNBR design limit, and that these data in excess of the limit are distributed over the variable ranges tested.
A more formal determination of the lack of bias of the average M/P ratio can be done using the analysis of variance test (ANOVA) shown in Table E.5.2-5. ANOVA tests are normally applied to highly controlled situations, but they can be useful in CHF testing and correlation. While the ANOVA test cannot be used as the sole measure of the performance of a CHF correlation, it would indicate an extremely bad mismatch (with a very large F statistic). The variables analyzed were pressure, quality, mass velocity, test cell type, test array, and test array arrangements. The ANOVA results forVIPRE-D/BWU-I exceed the critical values of F for all variables analyzed except for mass velocity, but other comparisons prove the hypothesis that all the groups belong to the same distribution; i.e., that there is no bias in the results regarding the analyzed variables. Furthermore, when looking at the figures in this section, there is no visible trend or bias in the data. Therefore, these comparisons prove the hypothesis that all the groups belong to the same distribution and it can be concluded that the VIPRE-D/BWU-I M/P ratio database is independent of the pressure, quality, and mass velocity.
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Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 Table E.5.2-5: M/P CHF Performance by Independent Variable and Geometry Grouping of the BWU-1 Combined Database at 95% Confidence Level E-28
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 Figure E.5.2-1: Measured CHF vs. Predicted CHF for VIPRE-D/BWU-I Combined Database E-29
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 Figure E.5.2-2: M/P vs. Pressure for VIPRE-D/BWU-1 Combined Database E-30
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 Figure E.5.2-3: M/P vs. Mass Velocity for VIPRE-D/BWU-1 Combined Database E-31
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 Figure E.5.2-4: M/P vs. Quality for VIPRE-D/BWU-1 Combined Database E-32
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 The [ ] of the VIPRE-D/BWU-1 M/P distribution calculated by Dominion Energy were used to create the empirical probability density function. These data points were distributed among 18 equal bins that covered the entire range of M/P in the VIPRE D/BWU-1 distribution, and the frequency of data in each bin was determined. The resulting empirical probability density functions for the VIPRE-D/BWU-1 distribution were then compared with the probability density function of a normal distribution of [ ], which is the mean and standard deviation for the VIPRE-D/BWU-1 distribution calculated in Section E.5 above.
Figure E.5.2-5 displays the resulting empirical probability density function for the VIPRE-D/BWU-1 M/P distribution and compares it with the probability density function of the normal distribution of
[ ].
Figure E.5.2-5: VIPRE-D/BWU-1 Probability Density Function E-33
Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 In Reference E1, the USNRC identified that the performance of the BWU-I correlation might be deficient at the very low end of the pressure range. For that reason, Framatome developed individual DNBR design limits for each low-pressure group in the database. This approach allows for use of the BWU-I correlation at low pressures but imposes a higher DNBR limit to ensure that the correlation is used conservatively. Table E.5.2-6 provides the VIPRE-D/BWU-I DNBR limits for the Combined Database calculated by Dominion Energy for the different pressure groups.
Table E.5.2-6: VIPRE-D/BWU-1 Combined Database DNBR Limits for Pressure Grou s Dominion Energy will take the VIPRE-D/BWU-I DNBR Design limit to be 1.23 (rounded up from 1.225) for pressures equal to or greater than 1500 psia and take 1.51 (rounded up from 1.503) at pressures less than 1500 psia.
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Serial No.21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 2 E.6 CONCLUSIONS The BWU-I correlation has been qualified with Dominion Energy's VIPRE-D computer code. Table E.6-1 summarizes the DNBR design limit for VIPRE-D/BWU-I that yields a 95% non-DNB probability at a 95% confidence level.
Table E.6-1: DNBR Limits for the VIPRE-D/BWU-I Combined Database DNBR limit below 1500 psia 1.51 DNBR limit at or above 1500 psia 1.23 Table E.6-2 summarizes the ranges of validity for the VIPRE-D/BWU-I code/correlation pair, which are the same as those determined based on the experimental database with both LYNX2 and VIPRE-D in Table E.5.1-3.
Table E.6-2: Ranges of Validity for the VIPRE-D/BWU-I Combined Database Pressure [psia] 745 - 2455 2
Mass Velocity [Mlbm/hr-ft ] 0.40-3.88 Thermodynamic Quality, x at CHF < 0.65 E.7 REFERENCES E1. Technical Report, BAW-10199P-A, "The BWU Critical Heat Flux Correlations,"
Framatome Cogema Fuels, January 1996, including Addendum 1, December 2000.
E2. Handbook, "Experimental Statistics - Handbook 91," M.G. Natrella for the United States Department of Commerce National Bureau of Standards, October 1966.
E3. Letter from C. I. Grimes (NRC) to D. A. Christian (Dominion), "Millstone Power Station, Unit Nos. 2 and 3 (Millstone 2 and 3), North Anna Power Station, Unit Nos. 1 and 2 (North Anna 1 and 2), and Surry Power Station, Unit Nos. 1 and 2 (Surry 1 and 2) -
Approval of Dominion's Fleet Report DOM-NAF-2, 'Reactor Core Thermal-Hydraulics Using the VIPRE-D Computer Code' (TAC Nos. MC4571, MC4572, MC4573, MC4574, MC4575, and MC4576)," April 4, 2006.
E4. Technical Report, Tables for Normal Tolerance Limits, Sampling Plans and Screening,"
R. E. Odeh and D. B. Owen, 1980.
ES. Technical Report, "Assessment of the Assumption of Normality (employing individual observed values)," American National Standards Institute, ANSI N15.15.1974.
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Serial Number 21-042 Docket Nos. 50-336/423/338/339/280/281 Attachment 3 FRAMATOME AFFIDAVIT FOR WITHHOLDING PROPRIETARY INFORMATION FROM PUBLIC DISCLOSURE Dominion Energy Nuclear Connecticut, Inc.
(DENC)
Millstone Power Station Units 2 and 3 Virginia Electric and Power Company (Dominion Energy Virginia)
North Anna and Surry Power Stations Units 1 and 2
- 1. My name is Gayle Elliott. I am Deputy Director, Licensing & Regulatory Affairs for Framatome Inc. (Framatome) and as such I am authorized to execute this Affidavit.
- 2. I am familiar with the criteria applied by Framatome to determine whether certain Framatome information is proprietary. I am familiar with the policies established by Framatome to ensure the proper application of these criteria.
- 3. I am familiar with the Framatome information contained in a Transmittal of Dominion Energy DOM-NAF-2 Appendix E, entitled, "Qualification of the Framatome BWU-I CHF Correlation in the Dominion Energy VIPRE-D Computer Code," and referred to herein as "Document." Information contained in this Document has been classified by Framatome as proprietary in accordance with the policies established by Framatome for the control and protection of proprietary and confidential information.
- 4. This Document contains information of a proprietary and confidential nature and is of the type customarily held in confidence by Framatome and not made available to the public. Based on my experience, I am aware that other companies regard information of the kind contained in this Document as proprietary and confidential.
- 5. : This Document has been made available to the U.S. Nuclear Regulatory Commission in confidence with the request that the information contained in this Document be withheld from public disclosure. The request for withholding of proprietary information is made in accordance with 10 CFR 2.390. The information for which withholding from disclosure is requested qualifies under 10 CFR 2.390(a)(4) "Trade secrets and commercial or financial information."
- 6. The following criteria are customarily applied by Framatome to determine whether information should be classified as proprietary:
(a) The information reveals details of Framatome's research and development plans and programs or their results.
(b) Use of the information by a competitor would permit the competitor to significantly reduce its expenditures, in time or resources, to design, produce, or market a similar product or service.
(c) The information includes test data or analytical techniques concerning a process, methodology, or component, the application of which results in a competitive advantage for Framatome.
(d) The information reveals certain distinguishing aspects of a process, methodology, or component, the exclusive use of which provides a competitive advantage for Framatome in product optimization or marketability.
(e) The information is vital to a competitive advantage held by Framatome, would be helpful to competitors to Framatome, and would likely cause substantial harm to the competitive position of Framatome.
The information in this Document is considered proprietary for the reasons set forth in paragraphs 6(d) and 6(e) above.
- 7. In accordance with Framatome's policies governing the protection and control of information, proprietary information contained in this Document has been made available, on a limited basis, to others outside Framatome only as required and under suitable agreement providing for nondisclosure and limited use of the information.
- 8. Framatome policy requires that proprietary information be kept in a secured file or area and distributed on a need-to-know basis.
- 9. The foregoing statements are true and correct to the best of my knowledge, information, and belief.
I declare under penalty of perjury that the foregoing is true and correct.
Executed on: December 2, 2020