NEA Mandates and Structures


Expert Group on Reactor Core Thermal-hydraulics and Mechanics (EGTHM)

Chair(s): Alessandro PETRUZZI, Italy
Maria N. AVRAMOVA, United States
Secretary:  Oliver BUSS
(oliver.buss@oecd-nea.org)
Member(s):All NEA member countries*
Russia (Suspended*)
*Russian Federation suspended pursuant to a decision of the OECD Council.
Full participant(s): European Commission
Under the NEA Statute
Observer(s)(International Organisation): International Atomic Energy Agency (IAEA)
By agreement
Date of creation:30 June 2019
End of mandate:31 March 2024

Mandate (Document reference):

  • Draft 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/PROV]
  • Mandate of the Working Party on Scientific Issues of Reactor Systems [NEA/NSC/WPRS/DOC(2019)11]
  • 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 WPRS Expert Group on Reactor Core Thermal-Hydraulics and Mechanics (EGTHM) [NEA/NSC/WPRS/DOC(2020)16]

Mandate (Document extract):

Extract from document [NEA/NSC/WPRS/DOC(2020)16]

Scope

Under the guidance of the Working Party on Scientific Issues and Uncertainty Analysis of Reactor Systems (WPRS), the Expert Group on Reactor Core Thermal-hydraulics and Mechanics 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 simulation.  The considered reactor systems for which core thermo-hydraulic and structural mechanical issues will be studied include but are not limited to:

  • current fleet of light-water and heavy water reactor cores (LWRs/HWRs) as well as present generation of fuel assembly designs;
  • evolutionary and innovative LWRs/HWRs core- and fuel assembly designs;
  • next generation of core and fuel assembly designsincluding water cooled small modular reactors (SMRs),micro-reactors , high temperature gas cooled reactors (HTGR) as well as advanced fast spectrum systems including sodium fast reactors (SFRs) and molten salt reactor systems (MSRs);
  • high-temperature gas reactors (HTGRs);
  • molten salt reactors (MSRs) and other advanced nuclear systems.

Objectives

  • To 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).

  • To 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;
  • techniques for high to low fidelity/resolution model data exchange (Hi2Lo);
  • values and distributions of local safety-related parameters and margins;
  • the expert group also 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 Working Party on Scientific Issues and Uncertainty Analysis of Reactor Systems (WPRS). The EGTHM will meet once per year, with additional meetings in support of particular activities, such as task forces reporting to the EGTHM.

Links to other NEA bodies and international projects

The EGTHM will liaise closely with other relevant NEA bodies, in particular the Expert Group on Physics of Reactor Systems (EGPRS) and the Expert Group on Reactor Systems MUlti-Physics (EGMUP) as well as the Working Group on Analysis and Management of Accidents (WGAMA) under the Committee on the Safety of Nuclear Installations (CSNI), in order to ensure that the respective programmes are complementary, to provide advice and support where required and to undertake common work where appropriate.

Deliverables

  • State-of-the-art report on reactor core thermal-hydraulics multi-scale modelling and simulation and experimental data requirements.
  • Maintenance and further expansion of TIETHYS thermal-hydraulics database with core thermal-hydraulic experiments including expansion of computational fluid dynamics (CFD)-related section.
  • Development of benchmark specifications and organising benchmark activities for blind benchmark on McMaster Core Thermal-hydraulics (McMaster CTH).
  • Report on modular high temperature gas reactor (MHTGR) thermal fluids exercise.
  • Development of sodium-fast reactor (SFR) core thermal-hydraulics benchmark specifications based on the Texas A&M high-resolution wire-wrapped hexagonal fuel bundle experiments and the ORNL Thermal Hydraulics out of Reactor Safety (THORS) experimental data (SFR THORS).
  • Organisation of workshops on preservation of thermal-hydraulics experimental data.