NEA Mandates and Structures


Expert Group on Reactor Coolants/Components Technology (EGCoCoT)

Chair(s): Paul SCHUURMANS, Belgium
Secretary:  Gabriele GRASSI
(gabriele.grassi@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 2015
End of mandate:31 March 2024

Mandate (Document reference):

  • Approved at the 26th meeting of the Nuclear Science Committee in June 2015 [NEA/SEN/NSC(2015)2]
  • Revised and extended at the 15th Meeting of the Working Party on Scientific Issues of the Fuel Cycle in February 2017 [NEA/SEN/NSC/WPFC(2017)2]
  • Mandates of the Working Party on Scientific Issues of the Fuel Cycle (WPFC) and its Expert Groups  [NEA/SEN/NSC/WPFC(2018)1]
  • Summary Record of the 17th meeting of the Working Party on Scientific Issues of the Fuel Cycle held on 6 February 2019 [NEA/SEN/NSC/WPFC(2019)1]
  • Mandates of the Working Party on Scientific Issues of the WPFC and its Expert Groups [NEA/SEN/NSC/WPFC(2019)2]
  • Summary Record of the 18th meeting of the Working Party on Scientific Issues of the Fuel Cycle (WPFC) [NEA/SEN/NSC/WPFC(2020)35]
  • Revised Mandate of the Working Party on Scientific Issues of Advanced Fuel Cycles (WPFC) for approval under the written procedure [NEA/SEN/NSC/WPFC(2020)3]
  • Mandate of the WPFC Expert Group on Reactor Coolants/Components Technology (EGCoCoT) [NEA/SEN/NSC/WPFC(2021)2]

Mandate (Document extract):

Extract from document [NEA/SEN/NSC/WPFC(2021)2]

Background

The former Expert Group on Heavy Liquid Metal (HLM) technology was active for several years. Its main objective was to issue a handbook with a collection of theoretical approaches and experimental data in order to deliver recommendations relevant for the design of HLM nuclear systems. Since the second version of the handbook has been published, the expert group has re-discussed its scope and future related activities. In particular, as suggested by the Working Party on Scientific Issues of Advanced Fuel Cycle (WPFC), it has been decided to include liquid sodium (Na) activities in the future work plan of the expert group. Secondly, the expert group will aim to take the next step in the assessment of available data to bring it closer to application in design, construction and licensing issues on the one hand, and operation, in-service inspection, handling and maintenance on the other hand. To better reflect the scope, the name of the expert group is changed to “Expert Group on Reactor Coolants and Components Technology” (EGCoCoT), where the latter term indicates that not only the properties of the coolants themselves are covered but also the effects that a particular coolant has on reactor parts such as, but not limited to, structural materials, chemistry control, thermal hydraulics, component behaviour, safety issues etc.

Scope

Under the guidance of the WPFC, the EGCoCoT will undertake activities with the goal to collect, evaluate and preserve relevant scientific data and to "translate" fundamental scientific understanding into application in support of (1) the Development of construction codes used for design (design rules), (2) Key technical issues for licensing, (3) Recommendations for Operation, Inspection and Handling.

Objectives

The topical areas and objectives of the expert group are:

  • Environmental conditions and factors that affect materials behaviour relevant for the structural integrity of confinement barriers and components. These include the impact on mechanical properties from the environment such as irradiation effects and liquid metal embrittlement as well as environmental assisted property effects like corrosion.

The objective for this topical area is to assess the environmental effects relevant for construction standards via a fundamental understanding of materials behaviour (corrosion and mechanical properties in the liquid metals and under irradiation). The possibility of experimental data sharing among participants and analyses is to be investigated.

  • Coolant and cover gas issues. The focus is placed on issues relevant for radiological impact assessment, operation, including maintenance, inspection and handling, etc. Topics to be addressed are the chemistry, radiochemistry and physics of the coolant, its interaction with the cover gas, the impact of irradiation, the influence of corrosion, transport of radionuclides in the coolant, etc.

    The objective for this topical area is to answer key technical issues to address radiological impact, operation, handling, maintenance and inspection as relevant for licensing.

  • Thermal-hydraulics for liquid metals. Thermal-hydraulic behaviour of the coolant is a crucial factor in the sense that it essentially determines a large part of the environmental conditions for materials and the cooling such as the flow distribution and mixing, temperatures distribution, stratification and instabilities, pressure variations, coolant structure interactions, etc.

The objective for this topical area is to collect and assess experimental data in order to improve knowledge of the environmental conditions for materials and the coolant behaviour.

Working Methods

Two taskforces will be established from members of the EGCoCoT which will work in parallel on heavy liquid metal and sodium reactor systems to discuss and compare results in order to identify potential commonalities and synergies.

The activities of the two taskforces are to:

  • Survey current fundamental knowledge on the effect of liquid metal environment on material behaviour;
  • Assess data management requirements with regards to the type of data, type of test and access conditions;
  • Compile and assess data on the effect of liquid metal environment on material behaviour;
  • Survey and compare existing methodologies to understand the underlying degradation mechanisms;
  • Identify further research and development needs to complement experimental databases and improve the modelling methodologies;
  • Generate status report on liquid metal environmental effects (on materials);
  • Compile and assess data for operation, inspection, handling, and maintenance of liquid metal reactors, with due account to operating experience feedback;
  • Identify key technical issues and lessons learned for safe and reliable operation, inspection, handling, and maintenance in support to reactor and system design and future operation;
  • Compile and assess data on liquid metal thermal hydraulics (for Na the analysis will focus on data related to environmental conditions for materials);
  • Provide assessment of thermal-hydraulic experiments and identify further research and development needs to improve knowledge of the environmental conditions for materials;
  • Carry out code-to-code and code-to-experiment benchmark studies.

Deliverables

The deliverable of the EGCoCoT will be the following:  

  • State-of-the-art report on the liquid metal environmental effects on materials including key technical issues and lessons learned for safe and reliable operation, inspection, handling, maintenance, decommissioning and waste management of liquid metal cooled reactors.
  • Update of the HLM handbook;
  • Compile a database on coolants.

Interactions

The expert group will liaise closely with other NEA bodies, in particular those under the NSC and those operating under the guidance of the Committee on the Safety of Nuclear Installations (CSNI) in order to ensure the respective work programmes are complementary and to provide advice and support where required and undertake common work where appropriate. The EGCoCoT will also work in co-operation with the IAEA Nuclear Power Technology Development Section and in particular the Technical Working Group on Fast Reactors (TWG-FR). Key sources of experimental data to be reviewed include (but are not limited to) output from IAEA Coordinated Research Project on Sodium properties and safe operation of experimental facilities in support of the development and deployment of Sodium Cooled Fast Reactors (NAPRO) and the Material Database of the European Commission (MatDB).