NEA Mandates and Structures

Expert Group on Reactor Coolants/Components Technology (EGCoCoT)

Mandate (Document reference):

• Summary Record of the 13^th meeting of the Working Party on Scientific Issues of the Fuel Cycle [NEA/SEN/NSC/WPFC(2015)2]
• Summary Record of the 26^th meeting of the Nuclear Science Committee (NSC) [NEA/SEN/NSC(2015)2]
• Summary Record of the 15^th meeting of the Working Party on Scientific Issues of the Fuel Cycle (WPFC) [NEA/SEN/NSC/WPFC(2017)2]
• Summary Record of the 17^th meeting of the Working Party on Scientific Issues of the Fuel Cycle (WPFC) [NEA/SEN/NSC/WPFC(2019)1]
• Summary Record of the 18^th meeting of the Working Party on Scientific Issues of the Fuel Cycle (WPFC) [NEA/NSC/WPFC/DOC(2020)35]
• Mandate of the WPFC Expert Group Reactor Coolants/Components Technology (EGCoCoT) [NEA/SEN/NSC/WPFC(2021)2]
• Summary record of the 20th Meeting of the Working Party on Scientific Issues of Advanced Fuel Cycles (WPFC) held on 24-25 May 2022, [NEA/NSC/WPFC/M(2023)1]
• Summary record of the 7^th Meeting of the Expert Group on Reactor Coolants/Components Technology (EGCoCoT), [NEA/NSC/WPFC/M(2023)12]
• Mandate of the WPFC Expert Group on Reactor Coolants/Components Technology (EGCoCoT) [NEA/NSC/WPFC(2024)3]

Mandate (Document extract):

Extract from document [NEA/NSC/WPFC(2024)3]

Background

The former Expert Group on Heavy Liquid Metal (HLM) technology was active for five 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, and potential activities regarding other innovative coolants of interest, in future work plans of the expert group. Secondly, the expert group was 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 was changed to “Expert Group on Reactor Coolants and Components Technology” (EGCoCoT) in 2020, 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 EGCoCoT 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

Task forces will be established from members of the EGCoCoT which will work in parallel on reactor systems using different innovative coolants, to discuss and compare results in order to identify potential commonalities and synergies.

The activities of the task forces 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.
• Update the HLM handbook;
• Compile a database on coolants.

Interactions

The EGCoCoT will liaise closely with other NEA bodies, particularly those under the NSC and those operating under the guidance of the Committee on the Safety of Nuclear Installations (CSNI) 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  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).

Deliverables

The deliverables of EGCoCoT are technical reports, proceedings of seminars/ 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 EGCoCoT 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.