Final Safety Evaluation for Framatome Inc. Topical Report ANP-10341P

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FINAL SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION

TOPICAL REPORT ANP-10341P,

“THE ORFEO-GAIA AND ORFEO-NMGRID CRITICAL HEAT FLUX CORRELATIONS”

FRAMATOME INC,

PROJECT NO. 99902041

Enclosure 2

TABLE OF CONTENTS

CONTENTS

1.0 Introduction ...... - 1 -

2.0 Regulatory Evaluation ...... - 2 -

3.0 Technical Evaluation ...... - 3 -

3.1 Review Framework for Critical Boiling Transition Models ...... - 3 - Experiential Data ...... - 4 - Credible test facility ...... - 4 - Accurate Data ...... - 7 - Reproduced Local Conditions ...... - 12 - Model Generation ...... - 20 - Appropriate Mathematical Model ...... - 20 - Model Coefficient Generation ...... - 22 - Model Validation ...... - 24 - Validation Error ...... - 25 - Data Distribution ...... - 25 - Consistent Model Error ...... - 30 - Quantified Model Error ...... - 33 - Model Implementation ...... - 36 -

4.0 Limitations and conditions ...... - 37 -

4.1 Conditions ...... - 37 -

4.2 Limitations ...... - 38 -

5.0 Conclusion ...... - 38 -

6.0 References ...... - 39 -

1.0 INTRODUCTION

By letter dated August 19, 2016 (Reference 1), Framatome Inc. (Framatome, formerly AREVA Inc.) submitted Topical Report (TR) ANP-10341P, “The ORFEO-GAIA and ORFEO-NMGRID Critical Heat Flux Correlations” (Reference 2) to the U.S. Nuclear Regulatory Commission (NRC) for review and approval. The purpose of this TR was to describe the critical heat flux (CHF) models used for the GAIA fuel assembly. The ORFEO-GAIA CHF model is applicable to fuel assemblies with GAIA grids with or without intermediate GAIA mixers (IGM). The ORFEO-NMGRID is applicable to fuel assemblies with non-mixing vane grids.

The complete list of correspondence between the NRC and Framatome is provided in Table 1 below. This includes request for additional information (RAI) questions, responses to RAIs, audit documentation, and any other correspondence relevant to this review.

Table 1: List of Key Correspondence

Sender Document Document Date Reference Framatome Submittal Letter August 19, 2016 1 Framatome Topical Report August 19, 2016 2 NRC Acceptance Letter November 16, 2016 3 NRC RAI – Round 1 October 4, 2017 4 Framatome RAI Response – Round 1 November 10, 2017 5 Framatome RAI Supplement – Round 1 December 15, 2017 6 Framatome Comments on Draft SE June 14, 2018 7 Framatome Supplemental Information August 17, 2018 8

In performing this review, the NRC staff applied a credibility assessment framework which focused on critical boiling transition1 models. The framework is fully described throughout the safety evaluation (SE).

General information for each RAI including its number, its topic, its associated SE section, and the reference(s) of its response are given in Table 2 below.

1 Critical boiling transition is the name given to the phenomena which occurs when a flow regime that has a higher heat transfer rate transitions to a flow regime that has a significantly lower heat transfer rate. Historically, terms such as critical heat flux, departure from nucleate boiling, and critical power have been used. However, the NRC staff needed a way to separate the general phenomena occurring (i.e., critical boiling transition) from a specific type of phenomena which may occur (e.g., departure from nucleate boiling, dryout) and from the specific values of certain parameters which are often used to signify such a transition has occurred (e.g., critical heat flux, critical power).

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Table 2: Listing of RAIs

Main Reference RAI Subject Associated of SE Section Response RAI-SNPB-01 OMEGA Reference 3.1.1.1.1 5 RAI-SNPB-02 Facility Comparison 3.1.1.1.2 5 RAI-SNPB-03 Statistical Design of Experiment 3.1.1.2.2 5 RAI-SNPB-04 Repeat Test Points 3.1.1.2.6 5 RAI-SNPB-05 Heat Losses 3.1.1.2.7 5 RAI-SNPB-06 ORFEO-NMGRID Application 3.1.3.3.2 5 RAI-SNPB-07 Grid Spacer Differences 3.1.1.3.2 5 & 6 RAI-SNPB-08 Simple Support Grids 3.1.1.3.5 5 3.1.3.2.3 & RAI-SNPB-09 Application Domain Data Density 5 3.1.3.2.4 RAI-SNPB-10 Domain Restrictions 3.1.3.2.6 5 RAI-SNPB-11 Potential Non-Conservative Subregion 3.1.3.3.3 5 RAI-SNPB-12 Low Quality 3.1.3.3.3 5

2.0 REGULATORY EVALUATION

Criterion 10 of Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix A, introduces the concept of specified acceptable fuel design limits (SAFDLs). In essence, SAFDLs are those limits placed on certain variables to ensure that the fuel does not fail. One such SAFDL is associated with critical boiling transition (CBT). Critical boiling transition is defined as a transition from a boiling flow regime that has a higher heat transfer rate to a flow regime that has a significantly lower heat transfer rate. If the reduction in the heat transfer rate and resulting increase in surface temperature is large enough, the surface may weaken or melt. In a nuclear power plant, this condition could result in fuel damage.

In order to ensure that such a CBT does not occur, two SAFDLs have been developed, as described in Standard Review Plan, Section 4.4, Thermal and Hydraulic Design (Reference 9):

a) there should be a 95-percent probability at the 95-percent confidence level that the hot rod in the core does not experience a DNB [departure from nucleate boiling] or boiling crisis condition during normal operation or AOOs [anticipated occupational occurrences], or

b) at least 99.9 percent of the fuel rods in the core will not experience a DNB or boiling crisis during normal operation or AOOs.

Typically, SAFDL: (a) is associated with pressurized water reactors (PWRs) and SAFDL (b) is associated with boiling water reactors (BWRs). CBT models such as ORFEO-GAIA and ORFEO-NMGRID, which will be used on PWR fuel, are necessary to ensure that the above SAFDLs can be satisfied. The main objective of this review was to determine if both ORFEO-GAIA and ORFEO-NMGRID could result in accurate predictions, such that there would

- 3 - be a 95-percent probability at the 95-percent confidence level that the hot rod in the core does not experience CBT during normal operation or AOOs.

3.0 TECHNICAL EVALUATION

TR ANP-10341P, "The ORFEO-GAIA and ORFEO-NMGRID Critical Heat Flux Correlations,” describes how two different CHF correlations, ORFEO-GAIA and ORFEO-NMGRID, were developed from experimental data, behave over their respective application domains, and how they will be applied in the future. The NRC staff’s technical evaluation is focused on determining if each respective CBT model is acceptable for use in reactor safety license calculations (i.e., that the model can be trusted). To perform this review, the NRC staff chose to use the review framework described in NUREG/KM-0013, “Credibility Assessment Framework for Critical Boiling Transition Models” (Reference 14).

Typically, a TR focuses on a single CHF model. However ANP-10341P has two distinct CHF models: ORFEO-GAIA and ORFEO-NMGRID. While these models are distinct, they do have similarities. In the evaluation below, the models are treated individually, or combined, depending on the criterion under consideration.

3.1 Review Framework for Critical Boiling Transition Models

This section discusses the review framework for CBT models. The framework is generated from a single main goal. That main goal is then logically decomposed into subgoals. Logical decomposition is the process of generating a set of subgoals which are logically equivalent (i.e., necessary and sufficient) to the main goal. This decomposition is expressed using goal structure notation. Each subgoal can either be further logically decomposed into other subgoals or if no further decomposition is deemed useful, the subgoal is considered a base goal and evidence must be provided to demonstrate that the base goal is true.

For CBT models, the top goal is: The CBT model can be trusted in reactor safety analyses. Based on the experience from multiple NRC technical staff members, a study of previous SEs, and multiple discussions with various industry experts, this goal is decomposed into various subgoals as given in the figures below, starting with the decomposition of the main goal into the three sub-goals given in Figure 1.

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Figure 1: Decomposition of Main Goal (G)

Experiential Data

Experimental data is the cornerstone of a CBT model. Not only is the data used to generate the coefficients of the model and validate the model, but previous data are often used to generate the model’s form. Therefore, it is essential that the experimental data are appropriate. Demonstrating the experimental data is appropriate is accomplished using the three sub-goals given in Figure 2 below.

Figure 2: Decomposing G1 – Experimental Data

Credible test facility

The first sub-goal in demonstrating that the experimental data are appropriate is to demonstrate that the test facility is credible. This is typically demonstrated using the two sub-goals as given in Figure 3 below.

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Figure 3: Decomposing G1.1 – Test Facility

No further decompositions of the sub-goals were deemed useful. Therefore, the evidence demonstrating the following goals were met is provided below.

3.1.1.1.1 Test Facility Description

Test Facility Description

The test facility is well understood.

G1.1.1, Review Framework for CBT Models

ORFEO-GAIA

In Section 4.1 of the TR, Framatome provided a detailed description of its KATHY test facility which included key details on the loop, the loop instrumentation, and the data acquisition system. Additionally, the NRC staff were able to visit the facility to better understand the test facility itself. This description along with the visit provided the NRC staff with a clear understanding of the test facility, what data were obtained, and how the data were obtained.

Because Framatome provided the important details describing the test facility, the NRC staff was able to understand the facility and determine that the test facility is capable of obtaining the data required for CHF model generation and validation. The NRC staff has concluded that this goal has been met for ORFEO-GAIA.

ORFEO-NMGRID

ORFEO-NMGRID used data taken at KATHY, as well as Babcock and Wilcox’s Alliance Research Center (ARC), Columbia University’s Heat Transfer Research Facility (HTRF), and the French Alternative Energies and Atomic Energy Commission’s (CEA) OMEGA loop. Framatome provided references for previous CHF correlations which were reviewed and approved by the NRC that relied on data from ARC (Reference 11), HTRF, and an extensive description of the KATHY facility. Because Framatome provided the important details

- 6 - describing these test facilities or relied on facilities previously determined by the NRC staff to be acceptable, the NRC staff was able determine that these test facilities are capable of obtaining the data required for CHF model generation and validation.

In response to RAI-SNPB-01, Framatome provided a brief description of CEA’s OMEGA loop, as well as the reference for the quality assurance process it was held under while the data was taken. The NRC staff is not as familiar with the OMEGA loop as with other test loops. However, given the limited amount of data used from the OMEGA facility, as well as Framatome’s previous experience with CHF testing and test facilities, the NRC staff have determined that it is reasonable to accept Framatome’s conclusion that this facility is capable of obtaining the data required for CHF model generation and validation. The NRC staff has concluded that this goal has been met for ORFEO-NMGRID.

3.1.1.1.2 Test Facility Comparison

Test Facility Comparison

The test facility has been verified by comparison to an outside source.

G1.1.2, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

In Section 4.1 of their initial submittal, Framatome referenced a benchmark comparing the KATHY facility to the HTRF, ARC, and OMEGA loop. This benchmark demonstrated that the overall CHF measured-to-predicted statistics was very similar in all four loops.

Additionally, in Section 2.2 of Reference 11, Framatome provided details on a bundle which was tested at both KATHY and HTRF. This analysis demonstrated that the CHF measured-to-predicted trends and statistics at KATHY and HTRF were very similar. However, neither the benchmark nor the analyses demonstrated that the CHF measurement of the same state point at each test loop would be consistent with the other loops.

In response to RAI-SNPB-02, Framatome provided a comparison of individual state points measured at HTRF, KATHY, and OMEGA. (The ARC facility did not perform tests on the same bundle, as did these three, and therefore was excluded from this analysis.) Figure 2-1 of the RAI response demonstrates that the test facilities predicted CHF at very similar statepoints. Figure 2-2 of the RAI response demonstrated that the facilities had very similar predictions of CHF at these similar state points.

To compare the data at the ARC facility with the other three facilities, Framatome compared the CHF measured-to-predicted ratio versus each of the predictor variables (e.g., pressure, mass flux, quality). While it would be better to compare the CHF values at similar state points, the fact that the same fuel bundle was not tested in all facilities means that no similar statepoints are available. As it is actually more uncommon to test the same bundle in multiple facilities, the NRC staff finds Framatome’s method to compare facilities by comparing the CHF measured-to-predicted ratio acceptable. This comparison demonstrated that the ARC facility had similar behavior compared to the other three facilities.

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By performing this analysis, Framatome demonstrated that the facilities of KATHY, ARC, OMEGA, and HTRF can reproduce each other’s data and trends, therefore the NRC staff has concluded that this goal has been met for both ORFEO-GAIA and ORFEO-NMGRID.

Accurate Data

The second sub-goal in demonstrating that the experimental data are appropriate is to demonstrate that the experimental data has been collected at a credible test facility. This is typically demonstrated using the seven sub-goals as given in Figure 4 below.

Figure 4: Decomposing G1.2 – Accurate Data

No further decompositions of the sub-goals were deemed useful. Therefore, the evidence demonstrating the following goals were met are provided below for the KATHY test facility. The conclusion that the HTRF and ARC test facilities can produce accurate data has been previously concluded by the NRC staff (Reference 11).

Framatome provided a description of the OMEGA facility in response to RAI-SNPB-01. While this description did not provide all of the details necessary for the NRC staff to independently verify the above seven goals have been met, given the limited amount of data used from the OMEGA facility, as well as Framatome’s previous experience with CHF testing and test facilities, the NRC staff have determined that it is reasonable to accept Framatome’s conclusion that the OMEGA facility is a credible facility. Therefore, the following evaluation is focused primarily on the data collected at the KATHY facility which was used to support the generation and validation of the ORFEO-GAIA and ORFEO-NMGRID models.

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3.1.1.2.1 Test Procedures

Test Procedures

The test procedure used to obtain the data is appropriate.

G1.2.1, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

In Section 4.2.1 of the TR, Framatome provided a detailed description of test procedures used for collecting data at the KATHY facility. Each measured CHF statepoint is described by nominal values of pressure, mass flux and inlet temperature prescribed in the test requirements document. The pressure is set and then the inlet flow rate and the inlet temperature are set. When the loop is observed to be steady at the boundary conditions specified for the measurement, the power is slowly increased until CHF is detected. The NRC staff finds that these testing procedures are appropriate for generating accurate measurements of CHF as they would ensure a statepoint was maintained while CHF was observed. Additionally, the NRC staff was able to confirm this finding by observing these testing procedures in practice. Due to the NRC staff’s own evaluation and observation of the KATHY test procedures, the NRC staff’s previous evaluation of the HTRF and ARC facilities, and the evaluation given above for the OMEGA facility, the NRC staff has concluded that this goal has been met for ORFEO-GAI and ORFEO-NMGRID.

3.1.1.2.2 Statistical Design of Experiment

Statistical Design of Experiment

The experiment has been appropriately statistically designed (i.e., the value of a system parameter from any test was completely independent from its value in the test before and after it.)

G1.2.2, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

In RAI-SNPB-03, Framatome described the challenges of randomly varying input parameters during an experiment. While such experimental procedures are desirable from a statistical standpoint, there are many practical limitations which often preclude purely random testing. Thus, while Framatome was able to randomly vary certain input parameters, they were not able to randomly vary all input parameters for each test. To ensure that such testing procedures did not create a bias in the measured data, Framatome continually tested a number of statepoints throughout the test campaign and ensured that the same CHF value was measured at those statepoints. Because Framatome uses repeated test points to confirm the test section measurements are within the specified bound, the NRC staff has determined that the experiment has been appropriately statistically designed in that there is active validation that the measurement uncertainty assumed from any analysis is the uncertainty observed through the

- 9 - test. Due to the NRC’s staff evaluation of the KATHY experimental design, the NRC staff’s previous evaluation of the HTRF and ARC facilities, and the evaluation given above for the OMEGA facility, the NRC staff has concluded that this goal has been met for ORFEO-GAI and ORFEO-NMGRID.

3.1.1.2.3 Instrumentation Uncertainties

Instrumentation Uncertainties

The instrumentation uncertainties are low.

G1.2.3, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

In Table 4-2 of the TR, Framatome provided the KATHY loop instrumentation uncertainties. The NRC staff reviewed these uncertainties and found them consistent with CHF testing in general and reasonably low compared with the other uncertainties inherent in the data. Due to the NRC’s staff evaluation of the KATHY instrumentation uncertainties, the NRC staff’s previous evaluation of the HTRF and ARC facilities, and the evaluation given above for the OMEGA facility, the NRC staff has concluded that this goal has been met for ORFEO-GAIA and ORFEO-NMGRID.

3.1.1.2.4 Diverse Instrumentation

Diverse Instrumentation

There is diverse and redundant instrumentation.

G1.2.4, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

In Section 4.1 of the TR, Framatome provided details on the KATHY loop instrumentation. In that description, Framatome confirmed that they had two inlet temperature sensors, three outlet temperature sensors, two pressure transducers, and two independent means to measure the electric current to the test assembly. Mass flow is measured as a pressure drop across an orifice, and two different orifice systems are available (but only one is used during each set of test runs).

Additional information on the KATHY instrumentation can also be found in the response to Question 11 from the ACE/ATRIUM-11 review (Reference 13). [''''''''''''''''' '''''''''''''' '''''''''' ''''' '''''''''''''''''''''''' ''''''''''''''' ''''''''''''''''' ''''' '''''''' '''''''' ''''''''''' ''''''''''''' '''''''''''' ''''' ''''''''''''' '''' '''''''''''' '''' '''' '''''''''''' '''''''' ''''''''' ''''''''' ''''''''''''' '''''''''''''''''''''''''''''''' '''''''' ''''''''''''''''''''''''''''''''' ''''' ''''''''' ''''''''''''' ''''''''''' '''''''''' ''''''''''''' '''''''''''''' '''''''''' ''''''''''' ''''''''' '''''''''''''''''''' ''''''''' '''''''''''' ''''''''' '''''''''' '''' ''''''''''''''''''''' ''''' '''''' '''''''' ''''''''''''' '''' ''''''''' ''''''''''''''''''''''''' '''''''''''''''''' ''''''''''''''''''''''''''''''''' ''''' ''''''''' '''''''' '''''''''''''''' '''''''''' ''''' '''''''''''''''''''''''''' ''''''''' ''''''''' ''''''''''''''''''''''' ''''''''''''''''''''''' ''''''''''''''''''''''''''''' '''''''''''''''''''''' ''''''''''''''''' '''''''''''''''''''''' '''' '''''''''''''''''''''''' ''''' ''''''''' '''''''''' ''''''''''''''''' '''''''''''''' '''''''''''' '''''''' ''''''''''''''''''''' ''''''''''''

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Based on the fact that the key instrumentation is duplicated, and that there are diversities in key measurements, the NRC staff finds that the KATHY loop has appropriate instrumentation. Due to the NRC’s staff evaluation of the KATHY instrumentation, the NRC staff’s previous evaluation of the HTRF and ARC facilities, and the evaluation given above for the OMEGA facility, the NRC staff has concluded that this goal has been met for ORFEO-GAI and ORFEO-NMGRID.

3.1.1.2.5 Instrumentation Calibration

Instrumentation Calibration

The instrumentation is routinely calibrated.

G1.2.5, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

In Section 4.1 of the TR, Framatome provided details on the KATHY loop instrumentation calibration. The NRC staff reviewed the calibration schedule and determined that the given calibration schedule along with the use of repeated test points would ensure that instrumentation drift would be quickly assessed and avoided. Due to the NRC’s staff evaluation of the KATHY instrumentation calibration, the NRC staff’s previous evaluation of the HTRF and ARC facilities, and the evaluation given above for the OMEGA facility, the NRC staff has concluded that this goal has been met for ORFEO-GAI and ORFEO-NMGRID.

3.1.1.2.6 Repeated Test Points

Repeated Test Points

The uncertainty in the critical heat flux or critical power is quantified through repeated tests at the same state points.

G1.2.6, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

In Section 4.2.1 of the TR, Framatome provided details of the repeated test points including CHF state points. [''''''''''''''''''''''''' '''''''''' '''''''''''''''' ''''''''' '''''''''''''''''''''''''' '''''''''''''' ''''''''''' ''''''' '''''''''' '''' ''''''''''' ''''''''''''' ''''' '''''''''''''''' ''''''''' '''''''''' ''''''''''' '''''''''''' '''' '''''''''''''''''''''' '''''''''''' '''''''''' ''''' '''''''' '''''''' ''''''''' ''' '''''''''''' '''' '''''''' ''''''''''''''''''''''' ''''' '''''''''''''''''''''''''''''' '''''''''''''''' '''''''''''']. In response to RAI-SNPB-04, Framatome provided details of the repeated test points which were taken in the KATHY facility. They confirmed that these test points were taken using the same procedures as described in the TR, including confirming the definition of the same statepoint was based on the test parameter criteria identified in

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Tables 4-3, 4-4, and 4-5 of the TR. Further, Framatome provided a listing of the statepoints for each test campaign, as well as the important statistics from the population of those test points. In general, the relative deviation between the critical power measured at the repeated test points was low, between [''''''' ''''''''''''''''''' ''''''''' '''''''''''''''''''].

Because Framatome has described the process for performing the repeat test points, and has supplied the data which demonstrates the high repeatability of the CHF tests, the NRC staff finds that the uncertainty of the CHF or CP is quantified through repeated tests in the KATHY facility. Due to the NRC’s staff evaluation of the KATHY repeated test points, the NRC staff’s previous evaluation of the HTRF and ARC facilities, and the evaluation given above for the OMEGA facility, the NRC staff has concluded that this goal has been met for ORFEO-GAI and ORFEO-NMGRID.

3.1.1.2.7 Quantified Heat Losses

Quantified Heat Losses

The heat losses from the test section is quantified, appropriately low, and duly accounted for in the measured data.

G1.2.7, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

In Section 4.1 of the TR, Framatome quantified the heat losses from the test section. In response to RAI-SNPB-05, Framatome provided an analysis which [''''''''''''''''''''''''''' '''''' '''''''''''' '''''''''''''' ''''' ''''''''''''''''''''''' ''''''' '''''''''''' '''''''''' '''' ''''''' ''''''''''''''''''' '''''''''' ''''''' '''''''''''''''''''''''' ''''''''''''''' '''''''''''''''''' ''''''''''''''''''''''''' '''''''''' '''''''''''''''''''''''''''' ''''''' '''''''''' ''''''''' '''''''''''''''''''''''''''' ''''''''' ''''''' '''''''''''''''''' '''' '''''''''''' '''''''''' '''''''''''''''''''' '''''''''''''''' '' '''''''''''''''' ''''''''''''''''''''''''''''' ''''''' ''''''''''' ''''''''' '''''''''' ''''''''''''''''''' ''''''' '''''''''''' '''''''''' ''''''''''''''''''''''' ''''''' '''''''''''''''''''''''''' '''''''''''''' ''' ''''''''''''''''''''' '''''''''''''''''' '''' '''''''' '''''''''''' ''''''''''''''''''''''''''''''''''''''''''''''''''''' '''''''''' '''''''''''''''''''' ''''''''''''''' '' ''''''''''''''''''' ''''''''''''''''''''''''''' '''''''''''''''''''''''' '''''''''' '''''''''''''' ''''''''' '''''''''''''''''''''''' '''''''''''''''''' '''' '''''''''''''''' '''''''''' ''''''' '''''''''''''''''''''''''''''''' ''''''''''''''''''''''''''' ''' ''''''''' '''''' '''''''''''''' '''''''''''''''''''' '''''''' '''''''''''' '''''''''' '''''''''''''''''' '''''''''' '''''''' ''''''''''''''''' '''' ''''''''''' ''''''''''''' ''''''''' '''''''' ''''''''''''''' '''''''''''' '''''''''''''''' '''''''' '''''''''' ''''''''''''' ''''''''''''''''''''''' '''' '''''''' ''''''''''''''' '''''''''''''' '''''''''''''''' '''' '''''''''''''' ''''''''''''''''''''''' '''''''' ''''''''''''' ''''''''''' '''''''''''' ''''''''' ''''''''''''''' '''''''''' ''''''''''''''''''' ''''''''''' ''''''''''''''' '''''''' ''''''''''''''''''' ''''' '''''''''''''''''''''''' ''''''''''' ''''''''' '''''''''''''''''''''''''''' ''''''''''''''''''''''''''''' '''''''''' '''''''''' '''''' '''''''''''''''''' ''''''''''' ''''''''''''' ''''''''''''' '''' '''''''''''' ''''''''''''''''''''''''''''' '''' '''''''' '''''''''''''''''''''' '''' '''''''' '''''''''' ''''''''''''''''' '''''''''' ''''''''' '''''''''''''''''' ''' '''''''''''''''''''''''''''''''''''''''''''' '''''''''''' ''''''''''''''''''''' ''''''' ''''''''''''''''''''''''''''''''' ''''''''''''''''''''''''''' '''''''''''' '''''''' ''''''''''''''''''' '''''' '''''''' ''''''''''' ''''''''''' '''''''''''''' ''''''''''''''''''''' ''''''''''''''''''''''''''''' ''''' '''''''''''''''' '''''''''''''' ''''''' ''''''''''''''''''''''''''''' '''''''''''' ''' ''''''''''' ''''''''' ''''''''''''''''' ''''''''''' ''''''' ''''''''''''''''''''''''''''' ''''''''''''''''''''''''''''' ''''' '''''''''''' '''''''''''' '''''''''' ''''''' ''''''''''''''' '''''''''''''''' ''''''' '''''''''' '''''''''''' ''''''''''''' '''''''''''''''''''''''''''

Because Framatome has provided an analysis which demonstrates that the impact of the heat losses are minimal compared to the CHF at KATHY, the NRC staff’s previous evaluation of the HTRF and ARC facilities, and the evaluation given above for the OMEGA facility, the NRC staff has concluded that this goal has been met for ORFEO-GAI and ORFEO-NMGRID.

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Reproduced Local Conditions

The third sub-goal in demonstrating that the experimental data are appropriate is to demonstrate that the local conditions in the reactor have been reproduced in the experiment. This is typically demonstrated using the five sub-goals as given in Figure 5 below.

Figure 5: Decomposing G1.3 – Reproduced Local Conditions

No further decompositions of the sub-goals were deemed useful. Therefore, the evidence demonstrating the following goals were met are provided below.

3.1.1.3.1 Equivalent Geometries

Equivalent Geometries

The test bundle used in the experiment should have equivalent geometric dimensions to that of the fuel bundle used in the reactor for all major components.

G1.3.1, Review Framework for CBT Models

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ORFEO-GAIA

In Section 4.2.2 of the TR, Framatome provided details on the test assembly configurations used to support ORFEO-GAIA. Framatome tested both unit and guide tube subchannels for the GAIA grid and tested the various configurations available in the GAIA design. While there were minor geometric differences, they are discussed elsewhere in this SE (Section 3.1.1.3.2 Equivalent Grid Spacers) and the NRC staff determined that these differences would have a minimal impact on the measured CHF. As there were no geometric differences which would cause the test bundle to have different flow behavior compared to the fuel bundle used in the reactor, the NRC staff has concluded that this goal has been met for ORFEO-GAIA.

ORFEO-NMGRID

In Section 4.2.4 of the TR, Framatome provided details on the test assembly configurations used to support ORFEO-NMGRID. Framatome tested both unit and guide tube subchannels using non-mixing grids and tested some of the possible configurations. In general, all non-mixing grids would be expected to have very similar behavior. Additionally, non-mixing CHF correlations should result in conservative predictions for fuel with mixing vanes. In response to RAI-SNPB-06, Framatome clarified that the ORFEO-NMGRID correlation would only be used for the specific fuel which was tested (described in Tables 2-3 and 2-6 of the TR) and with the specific grid designs that were tested (i.e., Westinghouse Electric Company (W) 17x17 HMP non-mixing grids, GAIA 17x17 mixing vane grids).

Downstream of HMP Grids

Towards the end of the review process, Framatome submitted a supplement (Reference 8) which provided further clarification on the ORFEO-NMGRID’s use in regions downstream (i.e., above) the bottom HMP grid. The HMP grid is the bottom grid spacer in the assembly. [''''' '''''''' '''''''''' '''''''''''' ''''''''''''''''''''''''' ''''''''''''' ''' ''''''''''''''''''' '''' '''''''''' ''''''''' '''''''' ''''''''''''''''' '''''' ''''''' ''''''''' '''''''''''''''''''' '''''''''''''''''''' '''''''''''''' '''''''''''' '''''''''''''''''''''' '''''''''''''''' ''''''' '''''''''''''' ''''' ''''''''' ''''''''''''''' ''''''''''''''''''''''''''''' '''''''''''''''''''' '''''''''' '''''''''' '''''''''''' '''' '''''''''''''''''''''' '''''' '''''''' '''''''''''''' ''''''''''''''''''' ''''''''''''''''''''' ''''''' ''''''''''''' '''''''''' ''''''''' ''''''' '''''''''' ''''''''''''''''''' ''''''''' '''''''''' '''''''''' ''''''''' ''''''''''''' '''''''''''''''''' ''''''''''''' '''' '''''' ''''''''''''''''''''' ''''' ''''''''' ''''''''' ''''''''' ''''''''''''''''''' ''''''''''''''''''''''' ''''' '''''''''''' ''''''''''' '''''''''''''

- 14 -

Because the tested fuel was mostly prototypical of both of the fuel types for which ORFEO-NMGRID will be applied and evidence was provided to justify the small differences between the tested bundle and the fuel bundles used in the reactor, the NRC staff determined there were no significant geometric differences. The NRC staff has concluded that this goal has been met for ORFEO-NMGRID.

3.1.1.3.2 Equivalent Grid Spacers

Equivalent Grid Spacers

The grid spacers used in the test bundle should be prototypical of the grid spacers used in the reactor assembly.

G1.3.2, Review Framework for CBT Models

- 15 -

ORFEO-GAIA

In Section 8.0 of the TR, Framatome discussed minor geometric differences between the production and test grid spacers. [''''' '''''''''''' ''''''''''''' '''''''' '''''''''''' '''''''''''''''''''''''' ''''''''''''''''''''''''''' ''''''''''''''''' '''''''''''''' '''''''''''' ''''''' '''''''''''' '''''''''''' ''''''' '''''''''''''''' '''''''''''' '''''''''' ''''''''' ''''''''''''' '''''''''''' ''''''' ''''''' ''''''''''''' ''''''''''' '''''''' ''''''''''''''' '''''''''''' ''''''''''' '''''''' ''''''''''''''''''''''' '''''''''' '''''''' ''''''''''''''''''''''''''''' '''''''''''' ''''''' ''''''''''''''''' ''''' '''''''''''''' ''''''''''''''' '''''''''' ''''''''''' ''' '''''''''''''' '''''''''''''''''' '''''''''''''' '''''''''' '''''''''''' '''''''''''' '''''''' ''''''''' '''' ''''''' ''''''''' ''''''''''' ''''''''''''' ''''''''' '''''''''''''''' '''' ''''''' ''''''''' ''''''''''''''''''' '''''''''' ''''''''''''''' ''''''' ''''' ''''''' '''''''''''

Guide Tube Subchannel Mixing Vanes

[''''''''''''''' ''''''' ''''' ''''''''' ''''''''''''''' ''''''' ''''''''''''''''''' ''' ''''''''''''' ''''''''''''' '''''''''''''''''''''''''''''''' ''''''' ''''''''''''''''''''' ''''''''''''''''''''' ''''''' ''''''''''''''' '''''''''' '''''''''''''''''''''' '''''''''' '''''''''''''''''''' '''''''' ''''''''''''''' ''''''''' ''''''''' ''' '''''''''''''' '''' ''''''' ''''''''''''''' ''''' ''''''' ''''''''''''' ''''''''''' ''''''''''' ''''''' ''''''''''''''''''''''' ''''''''' '''''''''' '''' ''''''''''''''''' '''''''''' '''''''''' '''''' '''''''''''' '''' ''''''' '''''''''''''''''''' ''''' ''''''''''''''''''''''''''''''' '''''''''''''''''' ''''''''' '''''''''''''''''' ''''''''' ''''''' ''''''''''''''''''''''''''''' '''''''''''''' '''''''''''' '''' '''''''''''''''''' '''''''''''''''' '''''''''' '''''''''''''''' ''''''' ''''''''''''''''''''''''''''''''''' '''''''''''''''''' '''''''''''' '''' '''''''''''''''' '''''''''' ''''''''''''''' '''''''''''''''''''''''''''''' '''' ''''''' '''''''''''''''''''''' '''''''''''''''''''''''' ''''''''' ''''' ''''''' ''''''''''''''''''''' '''' ''''''''''''''''''''''' ''''''''' ''''''''' '''''''' '''''''''''''''''' ''''' ''''''''''''''''''''''''' '''''''''''' '''''''''''' '''''''''' '''''' ''' ''''''''''''''''''''''' '''''''''''''''''''''' '''''''''' ''''''''''''''''' '''' '''''''''''''''''''' '''''''''''' '''' ''''''''''' '''' ''' ''''''''''''''''''' '''''''''''''''' '''''''''' '''' ''' '''''''''''''''' '''''''''''''''''''' ''''''''''''''' ''''''''''''''''''''' ''''''''''''''' ''''''''' ''''''''''''''' '''''''''''''''''''''' ''''''' '''''''''''''''' '''''''''''''''' ''''''' ''''''''' '''''''''''' ''''''' ''''''' ''''''''''''''''''' '''' '''''''''''''' '''''''''' ''''''' '''''''''''''''''''''''''''' ''''''''''''''''''''' ''''''' ''''''''''''''''''''' ''''''''''''''' '''' ''''''' ''''''''''''''' '''' ''''''''''''''' ''''''''''''''''''''' ''''''''''''''''''''''''''''''''' ''''''''''''''' '''' ''''''''''''''''''''''' ''''''''' ''''''''''' ''''''''''' ''''''''' ''''''''''''''''''''''''''' ''''''''' ''''''' ''''''''''''''''' ''''' '''''''' ''''''' '''''''''''' '''''''''' '''' '''''''' ''''''''''''' '''''''''' '''''''''''' ''''''''''''''''''''''' ''''''' '''''''''''''''''''' '''''''''''''' '''''''''' ''''''''''''''' ''''''' '''''''''''''''''''' ''''''''''''''''''''''''''' '''' '''''''' '''''''''''''''''''''''''' '''''''''''''''''

- 16 -

Mixing Vane Flap

['''''''''' ''''''''''''''''' ''''''''''' '''''' ''''''' ''''''''' '''''''''''''''' ''''''' ''''''''''''''' '''''''''''''''' ''''''' ''''''''''' '''''''''' '''''''''' ''''''''''''''''''''' ''' '''''''''''''''''''' ''''''''''''' ''''''''''''''' ''''''' '''''''''''''''''''' ''''''' ''''''''''''''''''' ''''''''''''''''''''''''''''' '''' ''''''' '''''''''' ''''''''' '''''''''''''''' ''''' ''''''''''''''' ''''''''''''''' ''''' ''''''''''''''''''''''''''' ''''''''' ''''''''''' ''''''''''''''''' ''''''''''' '''''' ''''''''''''''''''''' '''''''''''''''''' '''''''''''''''''''''''''''''' '''''''''''''''''' ''''''''''''''''''''''''''''' ''''''''''''''' '''''''''''''' '''''' ''''''''''''' ''''''''' '''''''''''' ''''''''' ''''''''''''' '''''''''' ''''''''' '''' ''''''' ''''''''''' '''''''''' ''''''''''''' ''''''''''''''''''' ''''''' '''''''''''''''''' ''''' ''''''' ''''''''''''''''''' ''''''''''' ''''''''' ''''''''''''''''''''' ''''''''' '''''''' '''''''''' '''''''''''' ''''''''''''''''''''''' '''''''' ''''''''''' '''''''''' ''''''''''''''''''''' '''' ''''''''''' ''''''''''' '''''''''''''' ''''''''''''' ''''''''' '''' ''''''''''''''''' '''''''''''''' ''''''''''''''''' ''''' ''''''' ''''''''''' '''''''''' '''''''''' '''''''''''''''''''''' '''''''' '''''''''''' '''''''''''''' '''''''''''''''' ''''''' '''''''''' ''''''''' ''''''' '''''''''''''''''''''' ''' '''''''''''''''''''' '''' ''''''''''''''''''' ''''''''''''' ''''''''' ''''''''' ''''''''''''''''''''''''''''''' '''''' ''''''''''''' '''''''''''' ''''''''''''' ''''''''' '''''''''''' '''''''''''' '''' ''''''''''''''' ''''''''' '''' ''''''''''' ''''''''''' '''''''''' ''' ''''''''''''''' '''''''''' '''' '''''''' '''''''''' '''''''''''' '''''''''' ''' ''''''''''''' ''''''''' '''''' ''''''''''' '''''''''''' '''''''''''' '''''''''''''''''''' ''''''' '''''''''''''' ''''''''''''''''''''' ''''''''''' '''''''''''''''''''''''' ''''''' ''''''''' '''''''''''''''''''''''''''''' '''' ''''''''''''' ''''''''' ''''''''' ''''''''' ''''''''''' '''''''''' ''''''''''' ''''''''''''''''''''''''' ''''''''' '''''''' ''''''''''' '''''''''''' ''''''' '''' ''''''' '''''''''''''''''' '''''''''''''''''''''''''''''''' '''' ''''''''' ''''''''' '''''''''''''''' ''''''''' ''''''''''''''''''''''' ''''''''''''''''' ''' ''''''' ''''''''''''''''''''''''''''''' '''''''''' ''''''''''' ''''''''''''''' '''''''' '''''''''''''' '''''''''' '''''

- 17 -

• [''''''''''''''' ''''''''''''' ''''''''' '''''''''' ''''''''''''''''''''''''' '''' ''''''' ''''''' ''''''''''''''''''''''''''''' ''''''''''''' '''''''' '''''''' '''''''''''''' '''' ''''''' '''''''''''''''''''''''''''''''' ''''''''' ''''''''''''' ''''''''''''' '''''''' ''''''''''''''''''''''' ''''' ''' '''''''''''' ''''''''''''''' '''''''''''''''''''''' '''''''''' ''''''''' '''''''''''''''''' '''''''''''' '''''''''''''''' '''''''''''''' ''''' '''''''' '''''''' '''''''''''''''''''''''''''' ''''''''' '''''''''' ''''''''''' ''''' '''''''''''''' ''''' '''''''' ''''''' ''''''''''''''''''''''''''''' '''''''''' ''''''' '''''''''''' '''''''''''''' ''''''''''''''' '''' '''''''' '''''''''''''''''''' ''''''' '''' '''''''' '''''''' '''''''''''''''''''''''''' '''''''''' '''''''''' '''''''''' ''''''' ''''''' '''''''' ''''' ''''''' ''''''''' ''''''''''''''''''''''''''''']

Conclusions on ORFEO-GAIA

The NRC staff used their own engineering judgment to determine the bias believed necessary to offset the effects of the [''''''''''''''''''''' ''''''''''''' ''''''''''' '''''''''''''''''''''''''''' '''''''''''''''' ''''''''''' ''''''''' ''''''''''''''''' '''''''''''' '''''''' ''''''''''''''''''''''''''''''], as there are too many unknowns to perform a deterministic calculation. In the NRC staff’s judgment, a bias of 0.01 added to the DNBR limit is sufficient to account for these variations between the tested assembly and the fuel assembly which would be used in the reactor. With this bias, the NRC staff finds that the grid spacers used in the test will result in experimentally measured CHF values which would be representative or conservative for the rod bundle used in the reactor. The NRC staff has concluded that this goal has been met for ORFEO-GAIA.

- 18 -

ORFEO-NMGRID

ORFEO-NMGRID was developed on non-mixing vane spacers with the same geometry as described in Table 2-6 of the TR. While the presence of a grid spacer can delay CHF, non-mixing spacers would be expected to have a minimal impact on CHF. Additionally, while non-mixing spacers could have different designs, the design changes would be expected to have minimal impact on CHF performance. Because Framatome provided details of their use of ORFEO-NMGRID in response to RAI-SNPB-06 and demonstrated that the correlation could be conservatively applied to grid spacers with mixing vanes, the NRC staff has concluded that this goal has been met for ORFEO-NMGRID.

3.1.1.3.3 Axial Power Shapes

Axial Power Shapes

The axial power shapes in the test bundle should reflect the expected or limiting axial power shapes in the reactor bundle.

G1.3.3, Review Framework for CBT Models

ORFEO-GAIA

In Section 4.2.3 of the TR, Framatome stated that the ORFEO-GAIA correlation was developed [''''''''' '''''''''''' ''''''''''' '''''''''''''''''''' ''''''''' '''''''''''''' ''''''''''''' '''''''''''''''' '''''''' ''''''''''''''''''' ''''''''' ''''''''''' ''''''''''' '''''''''''''''''' ''''''''''''''''''' ''''''''' '''''''''''''''''' '''''''''''''''' ''''''''''''''''']. Because ORFEO-GAIA did not show any bias in predicting any of the power shapes [''''''''' ''''''''''' '''''''''' ''''' '''''''''''''''''' '''''''' ''''''''''''''''' ''''''''''''''' ''''''''''''''' ''''' '''' '''''''''''''''''''''''''''''' ''''''''''''''''''' ''''''''''''' '''''' '''''''''''''''''' ''''''''''' ''''''''' ''''''''''''' '''' ''''''''''''''''''''''''''' ''''''''], the NRC staff has concluded that this goal has been met for ORFEO-GAIA.

ORFEO-NMGRID

In Section 4.2.4 of the TR, Framatome stated that the ORFEO-NMGRID correlation was developed ['''''''''' ''''''''''' '''''''''' ''''''''''''''''''' '''''''''' ''''''''''''''' ''''''''''''''' ''''''''''''''''''' ''''''''' ''''''''''''''''''''' ''''''''' '''''''''' '''''''''''' '''''''''''''''''' ''''''''''''''''' ''''''''' ''''''''''''''''''' ''''''''''''''' '''''''''''''''']. Because ORFEO-NMGRID did not show any bias in predicting any of the power shapes [''''''''' ''''''''''' ''''''''''' '''' '''''''''''''''' ''''''' ''''''''''''''''''' '''''''''''''' ''''''''''''''' '''' ''' ''''''''''''''''''''''''''''' ''''''''''''''''''' ''''''''''' '''''' ''''''''''''''''' '''''''''' ''''''''' ''''''''''''' ''''' ''''''''''''''''''''''''''' ''''''' '''''''''''''''''''''''''], the NRC staff has concluded that this goal has been met for ORFEO-NMGRID.

3.1.1.3.4 Radial Power Shapes

Radial Power Shapes

The radial power shapes in the test bundle should reflect the expected or limiting radial power shapes in the reactor bundle.

G1.3.4, Review Framework for CBT Models

- 19 -

ORFEO-GAIA & ORFEO-NMGRID

In Section 4.2.2 of the TR, Framatome stated that the radial power of the central rods were increased to force CHF closer to the center of the bundle thus ensuring that the channel wall had minimal impact on the flow field at the location of CHF. The NRC staff finds this plan for radial power consistent with CHF testing as it reduces the channel wall effect, which would result in higher fidelity data.

Because Framatome used a strategy which ensures the flow field around the location where CHF occurs is the most representative of the flow fields in the reactor and because the subchannel code which performs the CHF analysis accounts for the various radial powers of the assembly and calculates the flow into and out of each subchannel based on those radial powers, the NRC staff concluded that this goal has been met for both ORFEO-GAIA and ORFEO-NMGRID.

3.1.1.3.5 Differences between Test and Reactor

Differences between Test and Reactor

Any differences between the test bundle and the reactor bundle should be addressed. This includes components which are not in the reactor bundle but are needed for testing purposes.

G1.3.5, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

With the exception of the differences discussed above, the only remaining difference between the test and reactor assemblies was the use of simple support grid spacers. Such spacers are considered a necessity in PWR testing with directly heated rods, where the large heat fluxes applied to the rod can generate bending moments which may distort the test assembly. In response to RAI-SNPB-08, Framatome described the impact of these simple support grids. Framatome discussed an analysis of two tests which were performed at HTRF and the GRAZIELLA loop in France in which CHF data taken with a simple support grid was compared to data taken without a simple support grid. The data showed that [''''''''' '''''''''''''''''''' ''''' ''''''''''''''''' '''''''''''''''' ''''''''''''' '''''''''''''''' ''''' '''''''''''''''''''''' '''''''''''''''''' '''''''''''' ''''' ''''''''' '''''''' ''''''''''''''' '''''''''''' '''''''''' ''''''''''''''' '''''''''''' ''''''''''''''''''''''''' ''''''''''' ''''''''''''''''''''''''' ''''''''' ''''''''' ''''''''''' '''''''''''''''' ''''' '''''''''''''' '''''''''''''''''''''''' ''''''''''''''' '''''''' ''''''' '''''''''''' '''''''' '''''''''''''''' ''''''''''''''''' ''''''''''''' '''''''''''' '''''''''''''''' '''''''''''''''''''''' '''''' ''''''' '''''''''''''''' '''''''''''''''''''' '''''''''''' ''''''''' '''''''' ''''''''''''''''''''''' ''''' '''''''''''''' ''''''''''''''''''''''' '''''' ''''''' '''''''''''''''''' '''''''''' ''''''''''''''''''' '''''''''''''''''''' ''''''''''' ''''''''''''''' '''''''''''' ''''''' ''''' '''''''''''''''''' ''''''' '''''''''''''''''''''''' '''''''''' ''''''''' ''''''''''''''''' ''''''''' '''''''''''''''' ''''' '''''''''' ''''''''''''''' '''''''''''''''''' ''''''''' '''''''''' ''''''''''''''' '''''''''''''''''' '''' ''''''''''' ''''''' '''''''''''''''''''''' ''''' '''''''' '''''''''''''''' '''''''''''''''''''' '''''''''''' '''''''''''''''''''' ''''' '''''''''''''' ''' '''''''''''''''''''''''''''''''' ''''''''' ''''' '''''''''''''''''' ''''''''''''''''''''''''' '''' ''''''' '''''''''''''' ''''''''''' ''''''''' '''''''''''''''']

Because Framatome performed an analysis addressing the impacts of the simple support grids and demonstrated that the data obtained with simple support grids would be conservative compared to the actual fuel bundle, the NRC staff concluded that this goal has been met for both ORFEO-GAIA and ORFEO-NMGRID.

- 20 -

Model Generation

There are numerous ways to generate the CBT model. While some methods of model generation are based on first principle physics, CBT models are still largely empirical in nature. Therefore, there is no single correct way to generate the model. The form of the model is often based on previous model forms, machine learning techniques, and engineering judgment. Demonstrating the model generation is appropriate is accomplished using the two sub-goals given in Figure 6 below.

Figure 6: Decomposing G2 – Model Generation

Appropriate Mathematical Model

The first sub-goal in demonstrating that the model was generated in a logical fashion is to demonstrate that the model’s form is appropriate. This is typically demonstrated using the two sub-goals as given in Figure 7 below.

- 21 -

Figure 7: Decomposing G2.1 – Model Form

No further decompositions of the sub-goals were deemed useful. Therefore, the evidence demonstrating the following goals were met is provided below.

3.1.2.1.1 Model Parameters

Model Parameters

The mathematical form of the model contains all necessary parameters.

G2.1.1, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

In Section 6.2 of the TR, Framatome provided a basic introduction to the ORFEO correlation form and in Sections 6.3 and 6.4 provided details on the specific values chosen for the coefficients of both ORFEO-GAIA and ORFEO-NMGRID. In general, the parameters chosen to correlate CHF were the standard parameters chosen. However, instead of correlating to the heated length, Framatome chose to correlate to the burnout length (distance between the elevation where the equilibrium quality is reached and the elevation where CHF is calculated), as their analysis demonstrated this parameter was a much better predictor of CHF. The NRC staff found this a good approach as it makes the ORFEO model more physical in nature. The only other modeling change of note was ['''''''' '''''''''''''''''''''' '''' ''' '''''''''''' '''''''''' ''''''''''''' ''''' ''''''' ''''''''''''''''''''''''''''''''''''''' ''''''''''''''''''''''''' ''''''''''''''''''''''''' ''' ''''''''''''' '''''''''''' ''''''''''''' '''' ''''''''''' ''''' ''''''''''' '''''''''''''''''' '''''' ''''''''''' '''' '''' ''''''''''''' ''''''''''''''''''''' ''''' '''''''''''''''' ''''''''''''''''''''''''''''''' '''''''''''''''''''''' '''' ''''''''' ''''''''''''''''''''''''''' '''''' '''''''''''' ''''''''' '''' '''''''''''''' '''''''''''' ''''''''''''''''''''''''''' ''''' ''''''''''' ''''''''' ''' ''''''''''''' '''''''''''''' '''''''''''' '''''' '''''''''''' '''' '''''''''''''''''''''' '''' '''''''''''''''''''''''''''''''''' '''''''''''''''''''''' ''''' '''''''''''''''''''''''''''''''''''''''''''''''' '''''''' ''''''''''''''''''''' '''' '''''''' '''''''''''' '''''''''' ''''''' ''''''''''''''''' '''''' '''''''''''''''''''''''''''''''' '''''' ''''''' ''''''''' '''''''''' ''''''''''''''''''''''''' ''''''' '''''''''' ''''''''''''''''''''''' ''''''''''''' '''''''''''' ''''''''''' '''''''''' ''''' '''''''''''''''''' '''''''' '''''''''''''''' ''''''''' ''''''''' ''''''''''' ''''''''' ''''''''''' ''''' '''''''''''''''''''' ''''''' ''''''''''''''''' '''''''''''' ''''' '''''''''''' ''''' '''''''' '''''''''''''' '''''''''''' ''''''''''' ''''''''''' '''''''''''' ''''' '''''''''''''''''''''' ''''''''''''''''''''''''''''''''''''''''' '''''''''' ''''' ''''''''''''''''''' '''' '''''''''' ''''''''''''''''''''''' ''''''''''''''''''''''''''''''' ''''''''''

- 22 -

'''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''''' '''''''''''''''''''''' ''''''' '']. Because Framatome has addressed the expected parameters, and appropriately analyzed any deviations, the NRC staff has concluded that this goal has been met for both ORFEO-GAIA and ORFEO-NMGRID.

3.1.2.1.2 Model Form

Model Form

The reasoning for choosing the mathematical form of the model should be discussed and be logical.

G2.1.2, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

In Section 6.2 of the TR, Framatome provided a detailed discussion of the reasoning behind the mathematical form. In general, Framatome has chosen a model form which allows them to separate the impacts from the local flow conditions from those of the assembly design. The NRC staff found that the reasoning behind this new form was sound and the experimental data demonstrated that the ORFEO form could be successfully used to predict CHF. Therefore the NRC staff has concluded that this goal has been met for both ORFEO-GAIA and ORFEO-NMGRID.

Model Coefficient Generation

The second sub-goal in demonstrating that the model was generated in a logical fashion is to ensure that the process for generating the model’s coefficients is appropriate. This is typically demonstrated using the three sub-goals as given in Figure 8 below.

- 23 -

Figure 8: Decomposing G2.2– Model Coefficient Generation

No further decompositions of the sub-goals were deemed useful. Therefore, the evidence demonstrating the following goals were met is provided below.

3.1.2.2.1 Training Data

Training Data

The training data (i.e., the data used to generate the coefficients of the model) should be identified.

G2.2.1, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

In Sections 6.3 and 6.4 of the TR, Framatome identified the training data. [''''''''' ''''''''''''''''''''''''''''''''' '''''' '''''''''''''''''''' ''''''''''' ''''''''''' '''''' '''''''''''''''' '''''''''' '''''' '''''''''''''''''' ''''''''''' ''''''''''''''''''''' '''''' '''''''''''''''''''''''' ''''''''''''''''' '''''''' '''''''''''''''' ''''''''''' ''''''' ''''''' '''''''''''''''' ''''''''' '''''''''' ''''''''''' ''''''' '''''''''''''''''' '''''''''''''''' '''''''''''''' ''''''''''''' ''''''' '''''''''''''''''''''''''''''''''''''''''''' '''''' '''''''''''''''' ''''''''' ''''''''''''' '''''' '''''''''''''''''' ''''''''' '''''' '''''''''''''''''' ''''''''' ''''''''''''''''''' '''''' '''''''''''''''''''''''''' '''''''''''''''''' '''''''' '''''''''''''''' '''''''''' ''''''' ''''''' '''''''''''''''' '''''''''' ''''''''''' '''''''''''' '''''''' ''''''''''''''''''' '''''''''''''''' ''''''''''''''' '''''''''''' ''''''''' ''''''''''' '''''''''' '''''''''''''' ''''''''''' '''''] Because Framatome has described the training data, the NRC staff has concluded that this goal has been met for both ORFEO-GAIA and ORFEO-NMGRID.

- 24 -

3.1.2.2.2 Coefficient Generation

Coefficient Generation

The method for calculating the model’s coefficients should be described.

G2.2.2, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

Typically, there is no single best way to calculate the model’s coefficients, and while the coefficients will influence the model error, that error is quantified in the comparison to experimental data. Therefore, this goal is focused on Framatome explaining their method for coefficient generation and that method being reasonable. In Appendix C of the TR, Framatome described the process for determining the coefficients and the NRC staff found that process similar to other methods used previously for generating coefficients for other empirical models. Therefore the NRC staff has concluded that this goal has been met for both ORFEO-GAIA and ORFEO-NMGRID.

3.1.2.2.3 BWR Specific Parameters

BWR Specific Parameters

The method for calculating the R or K factors and the additive constants (for both full length and part length rods) should be described. Further, a description should be provided of how such values are calculated if dryout is not measured on the rod under consideration. (BWRs only).

G2.2.3, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

Both ORFEO-GAIA and ORFEO-NMGRID are for PWRs and therefore the NRC staff has concluded that this goal does not apply to either ORFEO-GAIA or ORFEO-NMGRID.

Model Validation

As defined by Oberkampf and Roy, validation is the accumulation of evidence which is used to assess the claim that a model can predict a real physical quantity (Reference 13). Thus, validation is a never-ending process as more evidence can always be obtained to bolster this claim. However, at some point, when the accumulation of evidence is considered sufficient to make the judgment that the model can be trusted for its given purpose, the model is said to be validated. Demonstrating the model validation is appropriate is accomplished using the four sub-goals given in Figure 9 below.

- 25 -

Figure 9: Decomposing G3 – Model Validation

Validation Error

The correct validation error has been calculated.

G3.1, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

Framatome specified that the validation error as given by the CHF measured-to-predicted values [''''''' ''''''''''''''''''''''''''''' ''''' '''''''' '''''''''''''''''''' '''''''''''''''' '''''''''''''''' '''''' ''''''''''''''''''''''' '''''' ''''''' '''''''''''''''''''''''''''' ''''''''''' ''''''''''''''''' '''''''''' ''''''''''''''''''' '''''' ''' '''''''''' '''''''''''''''''''''''' ''''''''' '''''''' ''''''''''''''''''''''' ''''''''''''''''''''''''''''''' ''''''''''''''''']. Because Framatome has chosen a means to define the validation error which is internally consistent, and also similar to definitions chosen in the past, the NRC staff has concluded that this goal has been met for both ORFEO-GAIA and ORFEO-NMGRID.

Data Distribution

The second sub-goal in demonstrating that the model’s validation was appropriate is to demonstrate that the data is appropriately distributed throughout the application domain. This is typically demonstrated using the six sub-goals as given in Figure 10 below.

- 26 -

Figure 10: Decomposing G3.2 – Data Distribution

No further decompositions of the sub-goals were deemed useful. Therefore, the evidence demonstrating the following goals were met is provided below.

3.1.3.2.1 Validation Data

Validation Data

The validation data (i.e., the data used to quantify the model’s error) should be identified.

G3.2.1, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

In Sections 6.3 and 6.4 of the TR, Framatome identified the validation data. ['''''''' '''''''''''''''''''''''''''''''' '''''' ''''''''''''''''''' '''''''''' '''''''''''' '''''' ''''''''''''''''''' '''''''''' '''''' '''''''''''''''''' '''''''''' '''''''''''''''''''' ''''''' ''''''''''''''''''''''''' ''''''''''''''''' ''''''''' '''''''''''''''''''' ''''''''''' ''''''' ''''''''''''''''' '''''''''''' '''''''''''' '''''''' ''''''''''''''''''' '''''''''''''''' ''''''''''''''' '''''''''' '''''''''''' '''''''' ''''''''''''''''''' ''''''''''' '''''''' ''''''''' '''''''' ''''''''''''''''''''''''''''''''''''''''''''''' '''''' ''''''''''''''''''' '''''''''' ''''''''''' ''''''' '''''''''''''''''' ''''''''' '''''' '''''''''''''''''' '''''''''' ''''''''''''''''''' '''''' ''''''''''''''''''''''' ''''''''''''''''''' ''''''' ''''''''''''''''''''' '''''''''' ''''''' ''''''''''''''''' ''''''''''' ''''''''''' ''''''' '''''''''''''''''''' ''''''''''''''' ''''''''''''''' ''''''''''' ''''''''' '''''''''''' '''''''''''''' ''''''''''' '''''''''''''''''''''''''''''' ''''''''''' '''''''''''' '''''''' '] Because Framatome has described the validation data, the NRC staff has concluded that this goal has been met for both ORFEO-GAIA and ORFEO-NMGRID.

- 27 -

3.1.3.2.2 Application Domain

Application Domain

The application domain of the model should be mathematically defined.

G3.2.2, Review Framework for CBT Models

ORFEO-GAIA

In Section 2.1 of the TR, Framatome identified the application domain of ORFEO-GAIA. The parameter range of the ORFEO-GAIA was given in Table 2-2. This domain consists of limits for pressure, mass flux, and equilibrium quality. Most of these limits are similar to other CBT models, but the maximum quality is higher than normal. However, Framatome does have sufficient validation data at this higher quality to justify the model’s use in that range.

Aside from these three dimensions, ORFEO-GAIA also considers the burnout length. ['''''''''''''''''''' ''''''''''''''''''''''''''' '''''''''''''''''''''''' ''''''' '''''''''''''' '''''''''''''''' '''''''''' ''''''' ''''''''''' '''''''''''''''''''''' ''''''''''''''''' ''''''''''''''''''' '''' ''''''''' ''''''''' '''''''' '''''''''''''''''' '''''''' '''' ''''''''''''''''''''' ''''''''''' '''''''''' ''''''''''''' '''' '''''''' ''''''''' ''''''''''''''''''''''''''''' ''''''''''''''''''''''''' '''''''''''''''''''''' ''''' '''''''''' ''''''''''''''''''' '''' '''''''''''''''''' ''''''''''''''''''' '''''''''''''' ''''''''''' ''''''' '''''''''''''''' '''''''''''''' '''''''''''' ''''''''' ''''''''''''''' ''''''''''' '''''''''''''''' ''' '''''''''''''''''''' '''''''' ''''''''''' '''''''''' '''''' ''''''''''''''''''''''' ''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''''' '''''' '''''''''''''' ''''''''''' '''''''''''''''''''''''''''''''' '''''''''''' '''''''''''''''' ''''' '''''' '''' ''''''''''''''''''''''''''''' ''''''''''' '''''' '''''''' ''''''''''''''''''' ''''''''''''' '''''''''''''''''''''''''' '''''''''' '''''''''''' ''''''''''' '''''''''''' ''''''''' ''''''' ''''''''' '''' '''''''''''''''''' ''''''''''''''' ''''' '''''''''''''' '''''''''''''' '''''''''''''''' '''' '''''''''''''''''''''''''' '''''''''' '''''''''' '''' '''''''' '''''''' ''''''''''' '''''''''' '''''''' ''''''''''''''''''''''''''''''' '''''''''''''' '''''''''''''''''''''' ''''''' ''''''''''''' '''''''''' ''''''''''''' ''''''''' ''' '''''''''''''''''''''' '''' '''''''''''''''''' '''' '''''''''''''''''' ''''''''''''''''' '''''''''''''' '''''''''''''''''''''''' ''] As there is no direct consideration of burnout length in the application domain, and to ensure physical meaning with the burnout length, the NRC staff places the condition that the inlet subcooling must be greater than 0 degrees. This condition (common for BWRs, which use a term similar to burnout length) ensures that the boiling length will remain within the heated length of the bundle. The NRC staff has concluded that this goal has been met for ORFEO-GAIA.

ORFEO-NMGRID

In Section 2.2 of the TR, Framatome identified the application domain of ORFEO-NMGRID. The parameter range of the ORFEO-NMGRID was given in Table 2-5. This domain consists of limits for pressure, mass flux, and equilibrium quality. Most of these limits are similar to other CBT models, but the maximum quality is higher than normal. However, Framatome does have sufficient validation data at this higher quality to justify the model’s use in that range.

As discussed in response to RAI-SNPB-06, Framatome clarified that the ORFEO-NMGRID model would only be applicable to W 17x17 HMP non-mixing grids and GAIA 17x17 grids. In Section 7.2.4 of the TR, Framatome used ORFEO-NMGRID to predict the behavior of GAIA fuel. In all instances, the prediction resulted in a conservative prediction of CHF. Therefore, the NRC staff finds that ORFEO-NMGRID can be used to conservatively predict the CHF performance of GAIA fuel. The NRC staff has concluded that this goal has been met for both ORFEO-NMGRID.

- 28 -

3.1.3.2.3 Expected Domain

Expected Domain

The expected domain of the model should be understood.

G3.2.3, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

In response to RAI-SNPB-09, Framatome provided two-dimensional (2-D) plots of the combination of the input variables for both the ORFEO-GAIA and ORFEO-NMGRID model parameters. [''''' '''''''''''''''''' '''''''' '''''''''''''''''''''' ''''''''''''''''''' '''' ''''''''''' ''''''''''''''' ''''' ''''''' ''''''''''''''''''''''' ''''''''''''''''''''' '''''''''' ''''''''''' '''' '''''''''' '''''''''' '''''''''''''''''''''' '''''''''''''''''' ''''''' ''''''''''''''''''''' '''''''''''''''''' ''''''''' '''''''''''' '''''''''''''' '''''''' '''''''''''''' '''''''''''''''' ''''''''''''' '''''''''' '''''''''''' '''''''''''''''''' ''''''''''''''''' ''''''' '''''' '''''''''''''''''''''''''' ''''''''''''''' '''''''''''' '''''''' '''''' '''''''''''' '''' ''''''' '''''''''''''] Because Framatome provided 2-D plots for each combination of variables in both models, the NRC staff has determined the expected domain is well understood. The NRC staff has concluded that this goal has been met.

3.1.3.2.4 Data Density

Data Density

There should be an appropriate data density throughout the expected domain.

G3.2.4, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

In response to RAI-SNPB-09, Framatome provided 2-D plots of the models’ parameters. These plots demonstrated that the data density in the expected domain was consistent with the NRC staff’s expectations for similar CBT models. The NRC staff has concluded that this goal has been met.

3.1.3.2.5 Sparse Regions

Sparse Regions

Sparse regions (i.e., regions of low data density) in the expected domain should be identified and justified to be appropriate.

G3.2.5, Review Framework for CBT Models

- 29 -

ORFEO-GAIA & ORFEO-NMGRID

In response to RAI-SNPB-09, Framatome provided 2-D plots of the models’ parameters. These plots demonstrated that there was adequate coverage of experimental data over the expected domains of both ORFEO-GAIA and ORFEO-NMGRID. In general, the plots demonstrated that the majority of the expected domain was adequately covered with experimental data. Further, Framatome clarified that [''''''' ''''''''''''' ''''' ''''''' '''''''''''''''' ''''''''''''''''' ''''' ''''''' '''''''''''' ''' '''''''''''''' ''''''' '''''' ''''''''''''''''''' ''''' '''''''''''''''' '''' ''''''''''' '''''''''' '''''''''''' ''''' ''''''''' ''''''''''''''''''''''''''''' '''''''''' '''' '''''''''''''' '''''''''''''''''''''' '''''''' '''''''''''''''' '''''''''''''''' ''''''''''''' '''' ''''''''''''''''''''''' '''''''''''''''''''''''''''' ''''''''' ''''''''' ''''''' '''''''''''''''''' ''''''''''''''''''''''''' '''' ''''''''''''''' '''''' '''''''''''''''''''''' '''' ''''' '''''''' ''''''''''''''''' ''''''''''''''''''' ''''' ''''''''''''''' ''''''''''' '''' ''' ''''''''''''''' ''''' '''''''''''''''''''''''''''' '''''''''''''''''''''''''' ''''''''''''''' ''''''''''''''''''''''''' '''''''' '''''''''''' ''''''' '''' '''''''''''''''''''' '''' ''''''''''''''''''''''''''' '''''''''''' ''''''''' ''''''''''' ''''''' '''''''''''''''''''''' '''' ''''''' '''''''''' '''''''''''''''' ''''' ''''''' '''''''''''''''''' '''''''''''''''''''''' '''''''''''''' '''''''''''''''''' '''''''' ''''''' ''''''''' ''''' '''''''''''''' '''''''''' '''' '''''''''''''' ''''''''''''''' '''''''''''''''' '''''''' ''''''''''''''' '''''''' '''''''''''''''''''''''''' '''''''''''''' ''''''''''' ''''' ''''''''''''''' ''' ''''''' '''''''''' '''''''''''''''''' ''''''' ''''''''''''''''''''''''''' ''''''''''''''''''''''' ''''''''' ''''''''''''''''''''''''''' '''''''''''' '''''' '''''''''''''''''' '''''''''''''''' '''''''''' '''''''''''''''

''''' '''''''''''''''''' ''''''''''''' '''''''''''''''' ''''''' ''''''''''' '''''''''''''''''''''''''''''''' '''''''''' '''''''''''''''''''''''''''''''''''''' '''''''' '''''''''''''''''''''' '''''''''' '''''''''''''''' ''''''''''''''' '''''' '''''''''''''''''''''''' ''''''''''''''''''''' ''''''''''' ''''''''''''' ''''''''''' ''''''''''''''''''''''''''''''' '''''''''' ''''''''''''''''''''' ''''''''''' '''' ''''''' ''''''''''''''''''''''' '''''''''' '''''''''''' '''''''' '''''''''' '''''''' '''''''''''''''''' ''''' ''''''' '''''''''''' '''''''''''''' ''''''' '''''''''''''''''''''' ''''''''' '''''''''''' '''''''''' ''''''' '''''''''''''''' '''''''''' '''''''''''''' '''''''''''' ''''''''' ''''''' ''''' '''''''' ''''''''''''' '''''''''''''''''''' '''''''' '''''''''''' '''''''''' '''''''''''''''''' '''''''''' '''''''''' '''''''''''''''' '''' ''''''' '''''''''''''''''''''''''''' ''''' ''''''' ''''''''''''''''''''' '''''''''''''''' ''''''''''''' '''''''''' '''''''''' ''''''''''''' '''''''''''''' '''''''' '''''''''''' '''''''''''''''''''' '''''''' ''''''''''''' '''''''''' '''' ''''''''''''' ''''''''''''''''''' ''''' '''''''' ''''''''' ''''''''''''''''''''''''''''''''' ''''' ''''''' ''''''''''' '''' ''' '''''''''''''''''''''''''''' ''''''''''''' ''''''''' '''''''''''''''''' ''''''' '''''''''''''''' ''''''''''''''''' '''' '''''''''''''''''' ''''''''' ''''''''''' ''''''''''''''''''''' ''''' '''''''' ''''''''''' ''''''''' '''''' ''''''''' '''''''''' ''''''''''''''' ''''''''''' '''''''''''' ''''''''''''' '''''''''' ''''''''''''' '''''''''''''''''''''''''''' ''''''' ''''''''''''''''''''''''''' ''''''''' ''''''''' ''''''' ''''''''''''''''''' ''''''''''''''''''''''' '''''' ''''''''''''''''''''''''''''' ''''''''''' '''''' ''''''''''''''''''' ''''''''''''''' '''''''''' '''''''''''''''' '''''''' ''''''''''''''''''' '''' ''''' ''''''''''''''''''''''''''''''''' '''''''''''' ''''' ''''''''''''''''''''''' '''''' ''''''''''' ''''' ''''''''''' '''' '''''''''' ''''''''''''' ''''''''' ''' '''''''''''''''' ''''''''''''' ''''''''' ''''''''''''''''''''''' '''''''' '''''''''' '''''''''''''' '''''''''''' ''''''''''''''''''''' '''''''''''''''' '''''''' ''''''''''''''''' '''''''''''''' '''' ''''''''''''''''''''''''''' ''''' ''''''''''''''' '''''''''''''''''''' ''''''''' ''''''''''''''''''''''' ''''' '''''''''''''' '''' '''''''''''''''' ''''''''''''''''''' '''''''''''''''''''' '''''''''''''''''''''''' ''' ''''''''''''''' ''''''' '''''''''''''''''' ''''''''''''''''''''''''''' '''' '''''''''''''' ''' '''''''''' ''''''''''''' ''''''''''' '''''''''''' ''''''''''''''''' ''''''''' ''''''''' '''''''''''''' '''''''''''''''' '''''' '''''''''' ''' ''''''''''' ''''''''''' ''''''''''''''''' ''''''''''''' '''''''''' ''''''''' '''''''' ''''''''''''''''' '''''' ''''''''''''' '''''''' ''''''''''''''''''''''''''''' ''''''''' '''''''''''''''''''''''' ''''''''''''''''''''''''''' ''''''''''' ''''''''''''''''''' '''''''' '''''''] Because the expected domain does not have any sparse regions which cannot be justified as described by Framatome, the NRC staff have determined that the sparse regions in the ORFEO-GAIA and ORFEO-NMGRID data are adequately addressed. The NRC staff has concluded that this goal has been met.

3.1.3.2.6 Restricted Domain

Restricted Domain

The model should be restricted to its application domain.

G3.2.6, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

In response to RAI-SNPB-10, Framatome clarified that use of either ORFEO-GAIA or ORFEO-NMGRID outside of its application domain would result in a warning message in the output file of the thermal-hydraulic computer code. This alerts the user that the model has been used outside of its approved range. Because Framatome has a system in which the code

- 30 - implementing the CHF model warns the user if the model is used outside of its application domain, the NRC staff have determined the model is restricted to its application domain. The NRC staff has concluded that this goal has been met.

Consistent Model Error

The third sub-goal in demonstrating that the model’s validation was appropriate is to demonstrate that the model error is consistent over the application domain. This is typically demonstrated using the three sub-goals as given in Figure 11 below.

Figure 11: Decomposing G3.3 – Consistent Model Error

No further decompositions of the sub-goals were deemed useful. Therefore, the evidence demonstrating the following goals were met are provided below.

3.1.3.3.1 Poolability

Poolability

The validation error should be investigated to determine if it contains any sub-groups which are obviously not from the same population (i.e., not poolable).

G3.3.1, Review Framework for CBT Models

ORFEO-GAIA

In Section 7.1.1 of the TR, Framatome provided an analysis of the validation data sets for ORFEO-GAIA. ['''''''''' '''''''''''''''''''''' '''''''''''' '''''''''''''''''''''''' ''''''''''' '''''''' '''''''''''''''''''''''' '''''''''' '''''''''' ''''''' '''''''''''' '''''' ''''''''''''''''''''' '''''''''' '''''' ''''''''''''''''''''''' '''''''''''''''''''''''''''' ''''' ''''''''''''''''''''' ''''''''' '''''''''''''''''''' ''''' '''''''''''''''''' '''''''''''''''''' ''''''

- 31 -

''''''''''''''''''''''' ''''''''''''' ''''''''''''''''''''''''' '''''''''''''' ''''''''''' ''''''''''''''''''''''' '''''''' '''''''''' ''''''' '''''''''''''' '''''''''''''''''''''''''' '''''' ''''''' ''''''''' ''''' ''''''' '''''''''''] Because Framatome has performed a statistical analysis demonstrating that there is no reason to suspect that the data comprising the validation error comes from different distribution types, has different means, or has different variances, the NRC staff has concluded that this goal has been met for ORFEO-GAIA.

ORFEO-NMGRID

In Section 7.2.1 of the TR, Framatome provided an analysis of the validation data sets for ORFEO-NMGRID. [''''''''' ''''''''''''''''''''''' ''''''''''' ''''''''''''''''''''''' '''''''''''' ''''''' '''''''''''''''''''''''' ''''''''''' ''''''''' ''''''''' '''''''''' '''''' '''''''''''''''''''''''' '''''''''''' '''''' ''''''''''''''''''''' '''''''''''''''''''''''''''''' ''''' '''''''''''''''''''' '''''''''' ''''''''''''''''' ''''' '''''''''''''''' '''''''''''''''''''' ''''''' '''''''''''''''''''''''''' ''''''''''''' ''''''''''''''''''''''''''' '''''''''''''' '''''''''''' '''''''''''''''''''' '''''''' ''''''''''' ''''''' '''''''''''' '''''''''''''''''''''' ''''' '''''''' ''''''''' '''' '''''''' '''''''''''''] Because Framatome has performed a statistical analysis demonstrating that there is no reason to suspect that the data comprising the validation error comes from different distribution types, has different means, or has different variances, the NRC staff has concluded that this goal has been met for ORFEO-NMGRID.

3.1.3.3.2 Non-Conservative Subregions

Non-Conservative Subregions

The expected domain should be investigated to determine if contains any non-conservative subregions which would impact the predictive capability of the model.

G3.3.2, Review Framework for CBT Models

ORFEO-GAIA

In Section 7.1.2 of the TR, Framatome provided an analysis of the validation data sets for ORFEO-GAIA. [''''' '''''''''' ''''''''''''''''''''' '''''''''''''''''''''''''' ''''''''''''''''''' '''''' ''''''''''''''' '''''''''''''''''''''''''' ''''''''''''''''''''' ''''''' '''''''''''''''''''''''''''''' ''''''''''''' '''''''' '''''''''''''''' '''''''''''' ''''''' ''''''''''''''''''''''''' ''' '''''''''''' ''''''''''''''''''''''''''' ''''' ''''''''''''''''''''''''' '''''''' ''''''' '''''''''''''' ''''''' '''''''''''''''' '''''''''' ''''''''' '''' '''''''''' '''' '''''''''''''''''''' ''' '''' '''''''''''' '''''''''''''''''' ''''' '''''''''''''' '''''''''''''''''''''''''' ''''''''' '''''''''''''''''''''' '''' ''''''' ''''''''''''' '''''''''''''''''''''''''' ''''''''''''''''''''''''''' ''''''''' ''''''''''''''''''' ''' '''''''''''''''''''' '''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''' '''''''''' '''''''''''''''''' ''''''' '''''''''''''' ''''''''' ''''' ''''''''''''''''' '''''' '''''''''' ''''''''''''''''''''''''''' ''''''''''''''''''''''' '''' ''''''''''' ''''''''''' ''''

- 32 -

ORFEO-NMGRID

In Section 7.2.2 of the TR, Framatome provided an analysis of the validation data sets for ORFEO-NMGRID. ['''' ''''''''' ''''''''''''''''''''' ''''''''''''''''''''''''''' ''''''''''''''''' '''''' ''''''' '''''''''''''''''''''''''' ''''''''''''''' '''''''''''''''''''''' ''''''' '''''' ''''''''''''''''''''''''''' '''''''''''''' ''''''' ''''''''''''''''' ''''''''''' '''''' ''''''''''''''''''''''' ''' '''''''''''' ''''''''''''''''''''''''' ''''' ''''''''''''''''''''''' '''''''' '''''' '''''''''''''''' ''''''' '''''''''''''''' '''''''''' '''''''' ''''''''' '''' '''''''''' ''' ''''''''''''''''''''' ''' ''' '''''''''''' '''''''''''''''' '''' ''''''''''''' ''''''''''''''''''''''''' '''''''' ''''''''''''''''''''''' '''' ''''''' ''''''''''''' ''''''''''''''''''''''''' '''''''''''''''''''''''' '''''''' ''''''''''''''''''' '''' ''''''''''''''''''' '''''''''''''''''''''''''''''''''''''' ''''''''''''''''''''''''' ''''''''' '''''''''''''' '''''''' '''''''''''''''' '''''''''' '''' '''''''''''''''''''' ''''''' ''''''''' '''''''''''''''''''''''''' ''''''''''''''''''''''' ''' '''''''''''' ''''''''''' ''''' ''''''''''' '''''''''' ''''''''''' ''''''''' '''''''''''''' ''''''''''''''''''''''''''''' ''''''''' '''''''''''''''''''''' '''''''''' '''''''''''''''''''''''' '''''' ''''''''''''' '''''''''''' ''''''''''''''''''''''''''''''''''''' ''''''''''''''''''''''' '''''' '''''''''' ''''''''' '''''''''''' '''''''''' ''''''''''''''''''''''' ''' '''''''''''''''''''''' ''''''''''''''''''''''''''''''''''''''''' ''''''''''''''''''''''''' ''''''''''''''''''''' ''''''''''''''''''' ''''''''''''''''' '''' ''''''' '''' ''''''' ''''''''''''''''' '''''''''' ''''''''''''' ''''''''' ''''''''''''' '''''''''''''''''' ''''''''' ''''''''' ''''''''''' '''''''''''''''''''''' ''''''' ''''''''''''''' '''''''''''''''''' '''''''''''''''''''' ''''''''' ''''''''''''''''''''''' ''''''''''''''''''' '''''''''''' ''''''''' '''''' '''''''''''''''''''''''''''''''' ''''' ''''''''''''''''''''''' ''''' '''''''''''''''''''''''''''''''''''' ''''''''''''''''''''''''''' '''''''''''''''''''''' ''''''''' '''''''''' ''''''''''' ''' '''''''''''''''''''''''''''''''''''''''' '''''''''''''''''''''''''' ''''''' ''''''''''''''''''''''''''''''''' ''''''''' ''''''''' ''''''''''''''' '''' '''''' '''''''''''''''''''''' ''''''''''' ''''''''' ''''' ''''''' '''''''''''''' ''''''''''''''''''''''''''' ''''''''''''''''''''''''' '''''' '''''''''''''''''''''' '''''''''''''''' ''''' '''''''''''''''''''''''''' '''''''''''''' ''''''' '''''''''''''' ''''''''''''''' ''''''''' '''''' ''''''''''''''''' ''''' '''''''' '''''''''''''''' ''''' ''' '''' ''' ''''''''''''''''''' '''''''''' '''''''''''''' '''''''''''''' ''''''' '''''''''''' ''''''''' '''''''''''''''''''''''''' '''''''''''''''' '''''''''''''''' '''''''''''''''''''' ''''' ''''''''''''''' '''''' ''''''''''''' '''''''' ''''''''''' '''' ''''''' ''''''''''' ''''''' '''''''''''''''''' ''''''''''' '''''''''''''' ''''''''''''''' '''''''' '''''''''''''' ''''''''' ''''' '''''''' '''''''''''''' '''''''''''''' '''''''' ''''''''] The NRC staff finds that Framatome’s justification is acceptable, but places a condition on ORFEO-NMGRID, such that if the reload analysis significantly changes such that calculations are no longer far removed from this region, the non-conservatism must be quantified and appropriately applied to the predicted CHF value.

Because Framatome has performed an analysis to identify non-conservative subregions, has increased the DNBR design limit to account for such regions as identified, and will account for future non-conservative subregions if needed, the NRC staff has concluded that this goal has been met for ORFEO-NMGRID.

3.1.3.3.3 Model Trends

Model Trends

The model is trending as expected in each of the various model parameters.

G3.3.3, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

In Sections 7.1.2 and 7.2.2 of the TR, Framatome provided plots of the validation error trends for ORFEO-GAIA and ORFEO-NMGRID respectively. In general, the plots demonstrated that the CHF model’s behavior was consistent over the various model inputs. ['''''''''' ''''''''''''' '''''''''' '''''''''''' '''''''''' ''''''''''' ''''''''''''''''' ''''' '''''' ''' '''''''''''''' ''''''''''''''''''''''''''''''''''''''''''' '''''''''''' ''''''''' '''''''''''''''''''''''''' '''''''''''''''' '''''''''' '''''''''''' '''''''''' '''''''''''''''''''''''''' ''''''' ''''''''''''''''''' ''''''''''''''' '''' '''''''''' '''' '''''''''''''''''''''''''''''''' ''''''''''''''''''''''''''''' ''''''''' '''''''''''''''' ''''''''''''' '''''''''' '''''''''''''''''''''''' ''''''''' '''''''''''''' '''' ''''''''''''''''''''' ''''' '''''''''''''''''''''''''''''''''''''' ''''''''''''''''''''''''''''' ''''''''''''''''''' '''' '''''''''''''''''' ''''''''''''''''' ''''' ''''''' '''''''''' '''''''''''''' '''''''''' '''''''''''''' ''''' '''''''''''' '''''''''''''''''''''' '''''''''''' ''''''''''''''' '''''''''' ''''''''''''' ''''''''''''''''''' ''''''' ''''''''''''''' '''' '''''''''''''''' '''' ''''''''''' ''''''''''''''''' ''''''''''' '''''''''''''' ''''''''''''''' ''''''''' '''''''''''' '''''''''''' '''' ''''''' '''''''''''''''''''''' ''''' '''''''' ''''''''' '''''''''''''' '''''''''''''' '''' '''''' ''''''''''''''''''''''' '''''''''''''' ''''''''''''''''' '''''''''''''' ''''''''' ''''''''''' '''' '''' '''''''''''''''''''''''' ''''''''''''''' ''''' ''''''' '''''''''''''' ''''''''''''''' '''' ''''''' '''''''''' '''''''''''''''''''''''' ''''''''''''' ''''' ''''''' '''''''''''''''''''''''''''' ''''' ''''''''' '''''''''''''''''''' ''''''''' '''''' '''''''''''' '''''''' ''''''''''''''''''''''' ''''''''''''''' '''''''''''' ''''''''''' ''''''''''''''''' '''''''''''''''''''''''''''' '''''''''''''''' ''''''''''''

- 33 -

''''''''''''''''''''''' ''''''''''''''' ''''''''''' '''''''''''' '''''''''''''' ''''''' '''''' '''''' ''''''''''''''''''''''''' '''''''''''''''''''''''''''' '''''' ''''''''''''''''' ''''''''''''' ''''' ''''''''''''' ''''' ''''''''''''''''''' '''''''''' ''''''''''''''''''' ''''' ''''''''' ''''''' ''''''''''''''' '''''''''' '''''''''''''''' ''''''' '''''''''''''''''''''''' '''' ''' '''''''''''''''' '''''''''' ''''''''''''''''''''''''' ''''''''''''''''''''''' ''''' '''''''' ''''''''''''''''''''''' ''''''''' '''''''''''''''''''''' '''''''''''''' '''''' '''''''''''''''''''''''''' ''''''''' ''''''''''''''''''''' ''''' '''''''''''''' '''''''''''''''''''''' ''''''' '''''''''''''' '''''''''''''''''''''''' ''''''''''' ''''''''''''''' ''''''''''' ''''' '''''''''''''''''''''''''' '''' '''''''''' ''''''''''''''''' '''''''' '''''''' ''''''''''''''''''''' ''''''''''''' ''''''''''''''''''' '''''''''''''' ''''''' ''''''' '''''''''''''''''''''''''''' '''' ''' ''''''''''''''' ''''''''''''' '''''' ''''''''' ''''''''''''' ''''''''''''''' '''''''''' '''''''''''''' ''''''''' '''''''''''' ''''''''''''''' '''''''''' '''''''''''' '''''''''''''''''''''''''''' ''''''''''''''''''''''''' ''''' ''''''''''''' ''''''''' '''''''''''''''''''''' ''''''''' '''''''''''''''''''''''''''' '''''''''''''' '''''' ''''''''''' ''''' ''' '''''''''''''''''''''''' ''''''''''''' '''''''''''''' ''''''''''''' '''''' ''''''''''''''''''' '''''''''''''''' ''''''''''''''''''''' ''''''' '''''''''''''''''''''''''''''''' ''''''''''''' '''' ''''''' '''''''''''''''''''''''''''' '''' ''''''''''''''' '''''''''''' '''''''''''''''''''''''''''''''' '''''''' '''''''''''''''' '''''''''''''' ''''''''''''''' '''''''''' ''''' '''''''''''''' ''''''''''' ''''' '''' '''''''' ''''''''''''''''' ''''''''' '''''''' ''''''''''''' ''' '''''''''''' '''''''''''''''''' ''''''''''' ''''' ''' ''''''''''''' '''''''''''''''''' ''''' '''''''''''''' '''''''' ''''''''''''''''''''' '''''''' '''''''''' '''''''''''''''''' '''''''''''' '''''''''''''' '''''''''' '''''' '''''''''''''''''''''''''' ''''''''' '''''''''''' ''''''''''' ''''''''''' ''''''''' ''' '''' ''''''''''' ''''''''''''' '''''''''' ''''''' '''''''' ''''''''''''''''''''' '''''''' '''''''''' ''''' ''''''''''''' ''''''''''' '''''''''' '''''''''''''' '''''' '''''''''''' '''''''''''''''''''''''''''' '''''''''''''' '''''''''''''''''''''''''' ''''' ''''''''' '''''''''''''''''' ''''''''' ''''''''''''' ''''''''' '''''''' ''''''''' ''''''''''''''''''''''''''''' ''''''''''''''''''''''' '''''''' ''''''''''' ''''''''''' ''''''''''' '''''''''' '''''''' ''''''''' '''' '''''''''''''' '''''''''' '''''''''' '''' ''''''''''''''''''''''''''

Because Framatome has demonstrated that both ORFEO-GAIA and ORFEO-NMGRID are trending with the various parameters as expected, has supplied additional validation data for lower qualities, and will provide additional validation data should either correlation’s use in the lower quality region be significantly increased, the NRC staff has concluded that this goal has been met for both ORFEO-GAIA and ORFEO-NMGRID.

Quantified Model Error

The fourth sub-goal in demonstrating that the model’s validation was appropriate is to demonstrate that the model error has been appropriately quantified over the application domain. This is typically demonstrated using the three sub-goals as given in Figure 12 below.

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Figure 12: Decomposing G3.4 – Quantified Model Error

No further decompositions of the sub-goals were deemed useful. Therefore, the evidence demonstrating the following goals were met is provided below.

3.1.3.4.1 Error Data Base

Error Data Base

The validation error statistics should be calculated from an appropriate database.

G3.4.1, Review Framework for CBT Models

ORFEO-GAIA

In Section 7.1.2 of the TR, Framatome describes the calculation of the design limit for ORFEO-GAIA and the validation error database the limit was based upon. Framatome [''''''''''' '''''''' '''''''''''''''''''''' ''''''''''''''''''''' '''''''''''' ''''''''' '''''''''''''''''''' '''''''''' '''''''''''''''' '''''''''' '''''''''' ''''' ''''''''''''''''''''''''' '''''''' '''''''''''''' '''''''''' ''''''''' ''''''''''''' '''''''''' ''''''''''''' '''''''' ''''''''''''''''' '''''''''''''''''''''''''''' '''''' ''''''' ''''''''''' ''''''''' '''''''''' ''''''''''''''''' ''''''''''''''''''' '''''''''''''''''''''' ''''''''''' '''''''''''''' '''''''''' '''''''''' ''''''''' ''''''''''''''''''''''' ''''''''''''''''''''' ''''''''''' ''''''''''''''' '''''''''''' '''''''''''''''''''''''''''' '''''''''' '''''''''''''' ''''''''''''''''''' ''''''''''''' ''''''''''''' '''''''''''''''''' ''''''''''' ''''''' '''''''''''''''''''''''' ''''''''''' ''] Because Framatome is using a database which has slightly conservative behavior compared to the validation error data base, the NRC staff has concluded that this goal has been met for ORFEO-GAIA.

ORFEO-NMGRID

In Section 7.2.2 of the TR, Framatome describes the calculation of the design limit for ORFEO-NMGRID and the validation error database the limit was based upon. Framatome ['''''''''''' ''''''' '''''''''''''''''''''' '''''''''''''''''' '''''''''' '''''''' ''''''''''''''''''''''''' ''''''''' ''''''''''''''''''' ''''''''''' ''''''''''' '''' '''''''''''''''''''''''' ''''''' '''''''''''''''' '''''''''''' ''''''''' ''''''''''' ''''''''''' '''''''''''''' '''''''' '''''''''''''''' '''''''''''''''''''''''''''' '''''' ''''''' '''''''''''' '''''''''' ''''''''' ''''''''''''''' ''''''''''''''''''''' '''''''''''''''''''' '''''''''' ''''''''''''' '''''''''''''' ''''''''''''' ''''''' ''''''''''''''''''' '''''' '''''''' '''''''''''''''''''''' ''''''''''' ''''''' ''''''''''' ''''''''''''''' '''''''''''''''' ''''''''' ''''''''''''''''''''''' ''''''''' ''''''''''''''''''''''''''' ''''''''''''''''''''''' '''''''''' ''''''''' '''''''''''''''''''''''' '''''''''''''''''''' ''''''''''''''''''''''' ''''''''''''''''' '''''''''' ''''''''''''''''''''''''''''''''' ''''''''''''''' '''''''''' '] Because Framatome is using a database which has

- 35 - slightly conservative behavior compared to the validation error data base, the NRC staff has concluded that this goal has been met for ORFEO-GAIA.

3.1.3.4.2 Statistical Method

Statistical Method

The validation error statistics should be calculated using an appropriate method.

G3.4.2, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

In Sections 7.1.2 and 7.2.2 of the TR, Framatome describes the calculation of the design limits for ORFEO-GAIA and ORFEO-NMGRID. Framatome uses ['''''''''''''''''' '''''''''''''' '''''''''''''''''''''''''''' '''''' ''''' ''''''' '''] to calculate the 95/95 design limit. Because both of the populations are normal, have a consistent variance, and there is no reason to believe that the data in the populations are not independently distributed, the NRC staff finds that this is an appropriate method for validating the validation error. The NRC staff has concluded that this goal has been met for ORFEO-GAIA and ORFEO-NMGRID.

3.1.3.4.3 Appropriate Bias for Model Uncertainty

Appropriate Bias

The model’s error should be appropriately biased in generating the model uncertainty.

G3.4.3, Review Framework for CBT Models

ORFEO-GAIA

In Section 7.1.2 of the TR, Framatome describes the calculation of the design limit for ORFEO-GAIA. Because Framatome identified a potential non-conservative subregion and biased the model to ensure that its predictive capability would not be diminished in that subregion, and because no other such subregions were found, the NRC staff has concluded that this goal has been met for ORFEO-GAIA.

ORFEO-NMGRID

In Section 7.1.2 of the TR, Framatome describes the calculation of the design limit for ORFEO-NMGRID. Because Framatome identified a potential non-conservative subregion and biased the model to ensure that its predictive capability would not be diminished in that subregion, and because no other such subregions were found, the NRC staff has concluded that this goal has been met for ORFEO-NMGRID.

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Model Implementation

The fifth sub-goal in demonstrating that the model’s validation was appropriate is to demonstrate that the model will be implemented in a manner consistent with its validation. This is typically demonstrated using the two sub-goals as given in Figure 13 below.

Figure 13: Decomposing G3.5– Model Implementation

No further decompositions of the sub-goals were deemed useful. Therefore, the evidence demonstrating the following goals were met are provided below.

3.1.3.5.1 Same Computer Code

Same Computer Code

The model has been implemented in the same computer code which was used to generate the validation data.

G3.5.1, Review Framework for CBT Models

ORFEO-GAIA & ORFEO-NMGRID

In Section 5.0 of the TR, Framatome identified COBRA-FLX as the computer code which was used to perform the validation. Because the validation was performed with COBRA-FLX, this approval of both CHF models is limited to use in COBRA-FLX. This limitation will be reflected below in the Limitations and Conditions section of this SE. The NRC staff has concluded that this goal has been met for ORFEO-GAIA and ORFEO-NMGRID.

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3.1.3.5.2 Same Methodology

Same Methodology

The model’s prediction of the critical boiling transition is being applied using the same methodology as it was when predicting the validation data set for determining the validation error.

G3.5.2, Review Framework for CBT Models

In Section 5.0 of the TR, Framatome provided a Table 5-1 which identifies important models and code options which were used in performing the validation. Because the validation was performed with these models and options, this approval of both CHF models is limited to these models and options. This limitation will be reflected below in the Limitations and Conditions section of this SE. The NRC staff has concluded that this goal has been met for ORFEO-GAIA and ORFEO-NMGRID.

3.1.3.5.3 Transient Prediction

Transient Prediction

The model results in an accurate or conservative prediction when it is used to predict transient behavior.

G3.5.3, Review Framework for CBT Models

In Section 6.1 of the TR, Framatome stated that it is common practice to assume the CHF during a transient situation will be exceeded when the local instantaneous conditions are equivalent to those causing its occurrence under steady state conditions. While not explicitly stated, this is the positon taken by the NRC staff in every previous review of a CHF model and the current NRC staff also finds this practice adequate. The NRC staff has concluded that this goal has been met for ORFEO-GAIA and ORFEO-NMGRID.

4.0 LIMITATIONS AND CONDITIONS

4.1 Conditions

The following conditions must be true for the use of either the ORFEO-GAIA or ORFEO-NMGRID CHF models, unless otherwise specified.

1. The inlet subcooling must be greater than 0 degrees. This is to ensure that the burnout length is limited to the fuel region.

2. For ORFEM-NMGRID, Framatome should confirm that the reload calculation performed for set points, AOOs, and accidents are far removed from the ['''''''''' ''''''''''''''''''''''' ''''''''' '''''''''] subregion. If the calculations are not far removed from this region, then Framatome

- 38 -

must quantify the additional uncertainty of the region and apply that increased uncertainty in the analysis.

3. While both ORFEO-GAIA and ORFEO-NMGRID are approved over their entire application domain, this approval is given under the assumption that their use in the low quality region (i.e., equilibrium qualities below -0.1) has minimal impact on the limiting minimum DNBR values. Limiting minimum DNBR is defined as the scenario in which the event is approaching the design limit. Application of the ORFEO-GAIA and ORFEO-NMGRID CHF correlations for events in which the limiting DNBR is sufficiently far from the design limit is not subject to this condition regardless of the local quality. Should this assumption no longer be true and should the low quality domain become a limiting domain, Framatome would need to provide additional analysis in quantifying the uncertainty in this domain.

4.2 Limitations

The ORFEO-GAIA and ORFEO-NMGRID CHF models are limited as given by the following.

1. ORFEO-GAIA is approved for use in predicting the CHF downstream of GAIA and IGM mixing grids in GAIA fuel. This prediction must be made in the subchannel code COBRA-FLX with the modeling option as specified in Table 5.1 of the TR with a design limit of 1.12 over the application domain specified in Table 2-2 of the initial submittal of the TR. The approved design limit contains a bias of 0.01 which the NRC staff believed was necessary to account for variations between the tested fuel assembly and the production fuel assembly which will be used in the reactor.

2. ORFEO-NMGRID is approved for use in predicting the CHF downstream of W 17x17 HMP non-mixing grids and GAIA and IGM mixing grids in GAIA fuel. This prediction must be made in the subchannel code COBRA-FLX with the modeling option as specified in Table 5.1 of the TR with a design limit of 1.15 over the application domain specified in Table 2-5 of the initial submittal of the TR.

Any application deviation from the modeling options or the use of COBRA-FLX would require re-validation similar to the validation provided in the TR. Any application to a new fuel type or new mixing vane spacer type, any decrease in the design limits, or any expansion of the application domain would require NRC review and approval.

5.0 CONCLUSION

Based on evidence provided in Section 3.1 of this SE, the NRC staff concludes that the experimental data supporting both ORFEO-GAIA and ORFEO-NMGRID are appropriate. Based on the evidence in Section 3.2 of this SE, the NRC staff concludes that both ORFEO-GAIA and ORFEO-NMGRID were generated in a logical fashion. Based on the evidence in Section 3.3 of this SE, the NRC staff concludes that both ORFEO-GAIA and ORFEO-NMGRID have sufficient validation as demonstrated through appropriate quantification of their error. Therefore, based on the cumulative evidence, the NRC staff concludes that both ORFEO-GAIA and ORFEO-NMGRID can be trusted in reactor safety analysis subject to the Limitations and Conditions listed in Section 4.0 of this SE.

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6.0 REFERENCES

1. G. A. Peters, AREVA Inc., letter to NRC, “Request for Review and Approval of ANP-10341P, ‘The ORFEO-GAIA and ORFEO-NMGRID Critical Heat Flux Correlations,’" August 19, 2016 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML16238A073).

2. ANP-10341P, “The ORFEO-GAIA and ORFEO-NMGRID Critical Heat Flux Correlations,” AREVA Inc., August 2016 (ADAMS Accession Nos. ML16238A076 (Non-Publicly Available) and ML16238A078 (Publicly Available)).

3. K. Hsueh, NRC, letter to G. Peters, AREVA Inc., “Acceptance for Review of AREVA Inc. Topical Report ANP-10341P, ‘The ORFEO-GAIA and ORFEO-NMGRID Critical Heat Flux Correlations’ (CAC NO. MF8400),” November 16, 2016 (ADAMS Accession No. ML16301A427).

4. J. Rowley, NRC, letter to G. Peters, AREVA Inc., “Request for Additional Information Regarding AREVA Inc. Topical Report ANP-10341P, ‘The ORFEO-GAIA and ORFEO-NMGRID Critical Heat Flux Correlations’ (CAC NO. MF8400),” October 4, 2017 (ADAMS Accession Nos. ML17251A705 (Publicly Available), ML17251A686 (Non-Publicly Available), and ML17285B195 (Publicly Available)).

5. G. A. Peters, AREVA Inc., letter to U.S. Nuclear Regulatory Commission, “Response to Request for Additional Information Regarding Topical Report ANP-10341P, ‘The ORFEO-GAIA and ORFEO-NMGRID Critical Heat Flux Correlations,’" November 10, 2017 (ADAMS Accession Nos. ML17318A100 (Publicly Available), ML17318A102 (Non-Publicly Available), and ML17318A101 (Publicly Available)).

6. G. A. Peters, AREVA Inc., letter to U.S. Nuclear Regulatory Commission, “Supplemental Response to Request for Additional Information Regarding Topical Report ANP-10341P, ‘The ORFEO-GAIA and ORFEO-NMGRID Critical Heat Flux Correlations,’” December 15, 2017 (ADAMS Accession Nos. ML17353A219 (Publicly Available), ML17353A222 (Non-Publicly Available), and ML17353A221 (Publicly Available)).

7. G. A. Peters, AREVA Inc., letter to U.S. Nuclear Regulatory Commission, “Response to Request for Comment on Draft Safety Evaluation for ANP-10341P, ‘The ORFEO-GAIA and ORFEO-NMGRID Critical Heat Flux Correlations,’” June 14, 2018 (ADAMS Accession Nos. ML18169A159 (Non-Publicly Available), and ML18169A158 (Publicly Available)).

8. G. A. Peters, AREVA Inc., letter to U.S. Nuclear Regulatory Commission, “Additional Information Regarding ANP-10341P, ‘The ORFEO-GAIA and ORFEO-NMGRID Critical Heat Flux Correlations,’” August 17, 2018, NRC:18:032, (ADAMS Accession Nos. ML18234A134 (Publicly Available), ML18234A135 (Non-Publicly Available), and ML18234A136 (Publicly Available)).

9. NUREG-0800 – Chapter 4, Section 4.4, Revision 2, “Thermal and Hydraulic Design,” March 2007 (ADAMS Accession No. ML070550060).

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10. EMF-92-153(P)(A), Revision 1, “HTP: Departure from Nucleate Boiling Correlation for High Thermal Performance Fuel,” AREVA Inc., January 2005 (ADAMS Accession Nos. ML051020019 (Non-Publicly Available) and ML051020017 (Publicly Available)).

11. ANP-10269P-A, Revision 0, “The ACH-2 CHF Correlation for the U.S. EPR Topical Report,” AREVA Inc., December 2007 (ADAMS Accession Nos. ML080790191 (Non-Publicly Available) and ML080790193 (Publicly Available)).

12. G. A. Peters, AREVA, letter to U.S. NRC, “Response to a Request for Additional Information Regarding Topical Report ANP-10335P, Revision 0, ‘ACE/ATRIUM 11 Critical Power Correlation,’” August 11, 2016 (ADAMS Accession Nos. ML16229A160 (Publicly Available), ML16229A162 (Non-Publicly Available), and ML16229A161 (Publicly Available)).

13. W. L. Oberkampf, and C. J. Roy, Verification and Validation in Scientific Computing, Cambridge University Press, Cambridge, United Kingdom, 2010.

14. J. S. Kaizer, R. Anzalone, E. Brown, M. Panicker, S. Haider, J. Gilmer, T. Drzewiecki, and A. Attard, "Credibility Assessment Framework for Boiling Crisis Transition Models,” NUREG/KM-0013, 2018.

Attachment: Comment Resolution Table

Principal Contributor: J.S. Kaizer, NRR/DSS/SNPB

Date: September 24, 2018