1. Expert Group Task Leaders
Expert Group on Multi-Physics Experimental Data, Benchmarking and Validation (EGMPEBV) NC State University Validation Workshop June 27, 2017
T. Valentine, J. Dydra, JP Hudelot, U. Rohatgi, M. DeHart, JC LePallec, K. Ivanov, K. Velkov and M. Avramova
Expert Group Task Leaders

2. Motivation and Objectives
Computational analysis methods are evolving in many nuclear power countries to meet the needs of the R&D community, designers, operators and safety regulators.
Desire is to improve predictive accuracy and precision and to evaluate complex operational or accidental scenarios.
Codes allow modelling of highly complex scenarios at a very high level of spatial, phenomenological and/or temporal resolution and with demonstrated high precision.
The ability to conduct validation experiments has for some applications progressed at a slower pace than for computational methods, or in some cases it has significantly regressed (through shutdown of facilities, or through retirement of experts).
Furthermore, as modelling capabilities are reaching deeper levels in single areas and in coupled behaviours, appropriate experimental techniques simply do not yet exist.

3. National and International Programs
Variety of programs are under development nationally and internationally (e.g. CASL, MEMPHIS, MOOSE, NURESAFE, SHARP, etc ).
Programs are at varying stages of development and have differing approaches to coupling multiple physical phenomena.
The optimal coupling mechanism for solution accuracy or computational expediency may depend on the degree to which multiple physical phenomena are coupled
Coupling mechanisms can also impact uncertainty propagation and extrapolation approaches
However, all programs will need validation data and a validation hierarchy as well as means to extrapolate uncertainties beyond the validation domain
CASL

4. Experiments for Validation of Multi-physics Simulations
Conceptual simulation diagram
List of experiments prepared by EGMPEBV**
Missing IEs, Extrapolation Domain
Comment that the development of database tools and frameworks for the various type of experiments differ significantly. ICSPBEP and IRPhE have well defined databases and access tools. This is lacking for thermal hydraulics. Neutronics and thermal hydraulics are the principle datasets for validation of multi-physics M&S tools.
Multi-Physics validation presupposes validation for individual physics
The information and data for many of these experiments reside at the OECD-NEA. Many TH-data set reside in other countries and NEA provides a vehicle to make them available to US Community.

6. Organization between TF1 & TF2

7. To limit the size and scope the MPEBV initial focus is on specific challenge problems
Task1:
Definition of the scope of multi-physics applications
Task1:
Definition of challenge problems
Task 3:
Major challenges and priorities for the validation of multi-physics modeling and simulation tools
Characterization of challenge problems
Task5:
Development of Validation Matrices for Specific Problems
Create validation matrices for specific challenge problems
Task 4:
Recommendations and implementation of processes for evaluating existing experimental data for multi-physics modeling and simulation
Evaluate the suitability of existing experimental datasets for the challenge problems
Task 3:
Major challenges and priorities for the validation of multi-physics modeling and simulation tools
Establish mechanisms for creating new experimental datasets

8. Definition of the scope of multi-physics applications
Task-Force 1: Experimental Data Qualification and Benchmark Evaluation - TF Leader: Jean-Pascal Hudelot, CEA Cadarache
Definition of the scope of multi-physics applications
Report on definition and scope of multi-physics application - completed Dec
Current status and expected needs for the validation of multi-physics modeling and simulation tools
Report on traditional multi-physics M&S tools and uncertainty treatment - completed February 2017
Report on novel multi-physics M&S tools and uncertainty treatment – 50% completed with final draft by Sep. 2017
Summary report on experimental data for validation of multi-physics M&S tools – final completed May 2017
Report on multi-national efforts in the development of novel multi-physics M&S tools – final draft by August 2017

9. Task-Force 1: Experimental Data Qualification and Benchmark Evaluation (continued)
Major challenges and priorities for the validation of multi-physics modeling and simulation tools
Report on challenges and priorities using existing data for validation of traditional M&S tools completed June 2017
Development of phenomena assessment and ranking chart (PARC) to support PCI workshop – on-line survey tool for implementing the phenomena importance ranking table (PIRT)
Report on priorities and mechanisms for creating new data for validation of traditional and novel M&S tools – awaiting input from Subtask 5 of Task Force Two
Recommendations and implementation of processes for evaluating existing experimental data for multi-physics modeling and simulation
Report on methodologies to evaluate relevance of past experimental data sets and demonstration of methodologies and recommendations – awaiting input from Subtask 5 of Task Force Two

10. Implementation of guidance for developing multi-physics benchmarks
Task-Force 1: Experimental Data Qualification and Benchmark Evaluation (continued)
Needs, options, recommendations and mechanisms for conducting experiments specifically for validation of multi-physics modeling and simulation tools
Report on options and availability of reactor commissioning tests for validation – report delayed because of need for new coordinator (Task leaders have not been available due to personal reasons)
Traditional and novel measurement methods for validation of multi- physics modeling and simulation tools
Report on traditional measurement methods and limitations – to be drafted by Dec with a focus on specific challenge problems
Report on potential novel measurement methods – to be drafted by June 2018 with a focus on Russian facilities, CABRI, TREAT and others – technical meeting to be held in Sep in conjunction with next MPEBV meeting
Implementation of guidance for developing multi-physics benchmarks
Benchmark evaluation guidance template drafted March 2016 – benchmark evaluation guide to be drafted by Dec. 2017

11. Existing procedures and guidelines for multi-physics validation
Task-Force 2: Validation Guidelines and Needs TF Leader: U. Rohatgi, BNL
Existing procedures and guidelines for multi-physics validation
Report on guidelines for current multi-physics validation and uncertainty qualification – draft report to be completed by July 2017
Implementing validation processes for novel methods
Development of validation matrices for specific challenge problems
Effort to develop phenomena assessment ranking chart (PARC) for aiding in development of PIRT for the PCI multi-physics validation workshop is proceeding

12. Task-Force 3: Application of Validation Experiments TF Leader: K
Task-Force 3: Application of Validation Experiments TF Leader: K. Velkov, GRS
Russian participants have proposed 5 different transient experiments from startup and commissioning data from VVER reactors
Two VVER-1000 transient benchmarks have been identified with details of one of them having been compiled for coupled neutronics & thermal hydraulics data including data for creating sub-channel models
Reference benchmark data has been specified for a specific transient on reactivity compensation with diluted boron by stepwise insertion of control rode cluster into the VVER-1000 core
Reference benchmark to be released by June 2017 for review
KI is preparing data for assembly wide analysis by June 2017
KI is preparing data for full core pin-by-pin analysis between 2018 to 2020
French and US participants interested in pursuing the availability of fuel transient experiments from the CABRI reactor at Cadarache, France
Proposal to develop simplified benchmark of commissioning tests of CABRI – issues with proprietary data to be resolved.

13. Task-Force 3: Application of Validation Experiments (continued)
US participants intend to provide experimental data from the TREAT transient facility once the facility is operational in Idaho, USA
Availability of data will depend on successful resumption of operations and resolution of any proprietary data issues
University reactors will be also used to provide validation data for multi- physics calculations
Efforts are under review to explore the use of research reactor data from Penn State and NC State for multi-physics validation
Multi-Physics Benchmark Based on the CASL Watts Bar Unit 1 Cycle 1 Benchmarks

14. PCI Workshop Objective Lead: A. Petruzzi, NINE, Italy
Demonstrate validation principles and practices for a specific challenge benchmark
Focus on methodologies for validation of single and coupled physics phenomena including sensitivity and uncertainty analysis along with uncertainty propagation
Outcome of modeling and simulation effort less important than principles
Develop a benchmark multi-step problems based on experimental measurements that involve coupled physical phenomena of different disciplines (at least Reactor Physics, Thermal-Hydraulics, Fuel Behaviour,..)
Experimental data that is publicly available would be preferred
Need adequate information on measurement methods, instrument calibration, and uncertainty data

15. Test on nuclear fuel -> multi-physics by nature
Reactor physics <-> Thermal-Hydraulics <-> Fuel Performance
Tests performed in R2 Research Reactor (operated by STUDSVIK) seem very promising
Over 1000 ramp tests performed and nearly 150 were internationally supported specifically for PCI/PCMI problems
Significant amount of data in the IFPE database
Test pre-selection has been started
High pressure loops in the core operated under both BWR and PWR conditions
Coupling of multi-physics phenomena including neutronics, thermal-hydraulics and fuels
Multi-physics measurements (other than those documented in public reports) can be available

16. Rod av. burn-up [MWd/kgU] 62.8 27 22.8 CPL [kW/m] 16 20 23 RTL [kW/m]
M5-H1 & M5-H2
xM2 & xM3
2653
2383, 2384
Fuel type
PWR 17x17
BWR 10x10 SVEA-96S
Cladding M5
ZIRLO
Zry-2, LK2+/L
Zry-4
Diameter [mm]
9.5
9.62
Pellet
UO2
Enrichment [%wt]
3.7
4.5
2.22
3.5
Reactor
Ringhals 4
Vandellos-II
Forsmark-2
Ringhals-3
Irradiation
Number of cycles 5 2 3
Rod av. burn-up [MWd/kgU]
62.8 27
22.8
CPL [kW/m] 16 20 23
RTL [kW/m] 40
50, 70
56.8
47, 41
Failed/non-failed
NF, NF
F, NF NF
comment
Long / short hold time
Single / step ramp
Cold ramp test terminated by reactor scram
Above / below PCI failure threshold

17. Finalization of Benchmark Committee
End of March 2017
MPCIV workshop & preliminary benchmark specification
To be held in Lucca (Italy) hosted by NINE, August 2017
Benchmark specification finalization: December 2017
1st Workshop for benchmark publication: February 2018
2nd Workshop for benchmark results collection: Spring 2019
3rd Workshop to summarize results for validation phase

18. Summary
Progress has been made toward completing the deliverables for several of the reports under the three task forces
Development of a multi-physics workshop on code validation for the PCI challenge problem is proceeding well with the leadership of NINE in Italy – access to Studsvik data being investigated
Development of benchmark specifications for VVER reactor transient start-up tests are progressing well – the issue of sharing of proprietary data needs to be resolved through the NEA with a standardized non-disclosure agreement
ANS summary on NEA/OECD EGMPEBV activities – accepted for the 2017 Annual ANS Meeting in June, 2017

19. Thank you for your attention and support of this activity