NEA Mandates and Structures
Expert Group on Reactor Core Thermal-hydraulics and Mechanics (EGTHM)
| Chair(s): |
Alessandro PETRUZZI, Italy
Maria N. AVRAMOVA, United States
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Secretary: |
Oliver BUSS
(oliver.buss@oecd-nea.org)
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| Member(s): | All NEA member countries* |
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| Russia (Suspended*) |
| *Russian Federation suspended pursuant to a decision of the OECD Council. |
| Full participant(s): |
European Commission
Under the NEA Statute
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| Observer(s)(International Organisation): |
International Atomic Energy Agency (IAEA)
By agreement
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| Date of creation: | 30 June 2019 |
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| End of mandate: | 31 March 2026 |
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Mandate (Document reference):
- Summary Record of the 16th meeting of the Working Party on Scientific Issues of Reactor Systems (WPRS) held on 22 February 2019 [NEA/NSC/WPRS/DOC(2019)5]
- Mandate of the WPRS Expert Group on Scientific Issues in Reactor Core Thermal-hydraulics (EGRCTH) [NEA/NSC/WPRS/DOC(2019)15]
- The NSC Working Party on Scientific Issues of Reactor Systems (WPRS): Proposal for Prioritisation and Restructuring [NEA/NSC/WPRS/DOC(2020)19]
- Summary record of the 31st meeting of the Nuclear Science Committee in September 2020 [NEA/SEN/NSC(2020)20]
- Mandate of the Expert Group on Reactor Core Thermal-hydraulics and Mechanics (EGTHM) [NEA/NSC/WPRS/DOC(2020)16]
- Summary record of the 5th meeting of the on Reactor Core Thermal-hydraulics and Mechanics held on 20 February 2024 (EGTHM) [NEA/SEN/NSC/WPRS(2024)X] (forthcoming)
- Mandate of the WPRS Expert Group on Reactor Core Thermal-Hydraulics and Mechanics (EGTHM) [NEA/NSC/WPRS(2024)5]
Mandate (Document extract):
Extract from document [NEA/NSC/WPRS(2024)5]
Background
The WPRS has created the Expert Group on Scientific Issues in Reactor Core Thermal-hydraulics (EGRCTH) in 2019. As a result of the NSC prioritisation process conducted in 2020/2021, the mandates of the WPRS, as well as the mandates of its subsidiary bodies were redefined. To better reflect the renewed mandate, the EGRCTH has been renamed as Expert Group on Reactor Core Thermal-hydraulics and Mechanics (EGTHM).
Scope
Under the guidance of the WPRS, EGTHM will perform specific tasks associated with multi-scale core thermal-hydraulics and mechanics of present and future nuclear power systems with focus on multi-phase flow heat transfer mechanisms. Coupling aspects of fluid structural mechanical interactions for normal and/or deformed core configurations will be considered, as will problems requiring high fidelity multi-scale core simulations.
Reactor types considered include, but are not limited to the following:
- Current fleet of light-water and heavy water reactors (LWRs/HWRs) as well as present generation of fuel designs.
- Evolutionary and innovative LWR/HWR systems along with advanced and accident tolerant fuel designs.
- Next generation reactor systems including high temperature gas cooled reactor (HTGR), sodium fast reactor (SFR), lead fast reactors (LFR), and molten salt reactor (MSR) systems.
- Reactor systems of different scales including large scale reactors, small modular reactors (SMRs), and micro-reactors.
Objectives
- Provide expert advice to the WPRS and the nuclear community on the development needs (data and methods, validation experiments, scenario studies) for multi-scale core thermal-hydraulics modelling and simulation of existing and proposed nuclear reactor systems.
- A key activity associated with this objective is the identification and preservation of appropriate experimental data. In addition, the EGTHM will provide member countries with guidance and processes for certifying the experimental data for its use as a stand-alone core thermal-hydraulic validation or coupled thermal-hydraulics and structural mechanics.
- The role of thermal-hydraulics as part of validation pyramid of multi-physics modelling and simulation tools will be done in close collaboration with the Expert Group on Reactor System Multi-Physics (EGMUP). EGTHM will also support the EGMUP to investigate artificial intelligence and machine learning applications related to the above.
- Provide specific technical information regarding:
- the status of national and international programmes on reactor core thermal-hydraulics including experimental capabilities;
- the state-of-the-art reactor core thermal-hydraulics methodologies on different modelling scales;
- the provision of experimental data for model development and validation to the International Experimental Thermal HYdraulicS (TIETHYS) database;
- to provide TIETHYS with a methodology for a systematic and standardised process for collecting facility hardware and experimental test data;
- to monitor, steer and support the continued development of the TIETHYS database;
- the status and the state-of-the-art in the domain of reactor core mechanics;
- techniques for high to low fidelity/resolution model data exchange (Hi2Lo) for core thermal-hydraulics and mechanics;
- values and distributions of local safety-related parameters and margins;
3. EGTHM will facilitate the dissemination of technical information and knowledge through activities such as workshops, benchmark studies and training activities.
Working Methods
The EGTHM will report to the WPRS. The EGTHM will meet once per year, with additional meetings in support of particular activities, such as task forces reporting to the EGTHM.
Deliverables of the EGTHM will be developed in task or benchmark groups, whose work will be organised in a project-like manner with outcomes and milestones.
Interactions
The EGTHM will liaise closely with other relevant NEA bodies, in particular with the Expert Group on Physics of Reactor Systems (EGPRS) and the Expert Group on Reactor Systems Multi-Physics (EGMUP) the Expert Group on Reactor Coolants/Components Technology (EGCoCoT) of the Working Party on Scientific Issues of Advanced Fuel Cycles (WPFC), as well as the Working Group on Analysis and Management of Accidents (WGAMA) under the Committee on the Safety of Nuclear Installations (CSNI). The TIETHYS database could serve as input to the Thermal-Hydraulics Experimental Meta-Data Preservation, Collection and Qualification (THEMPo) effort with WGAMA, and vice-versa.
Deliverables
The deliverables of EGTHM are technical reports, proceedings of seminars or workshops, state-of-the-art reports, and technical or collective opinion papers, databases, and comparison or benchmark studies. This work will be done in task or benchmark groups, whose work will be organised in a project-like manner with outcomes and milestones. The EGTHM will also organise specialist meetings and workshops to further its objectives. The detailed list of deliverables will be tracked in the semi-annual NSC progress reports.
Priority for the 2024-2026 period is given to the finalisation of the reports, and benchmarks set forth hereunder, the development of the TIETHYS database, and fostering of core mechanics related activities:
- Benchmark on liquid metal fast reactor core thermal-hydraulics based on Texas A&M University (TAMU) separate effect test data and the ORNL Thermal Hydraulics out of Reactor Safety (THORS) experimental data (SFR THORS).
- Benchmark on lead fast reactor core thermal-hydraulics based on ALFRED design.
- Benchmark on high temperature gas reactor core thermal-hydraulics based on measurements at High Temperature Test Facility (HTTF) at Oregon State University (USA).
- State-of-the-art report on reactor core thermal-hydraulics multi-scale modelling and simulation and experimental data requirements.
