Background

The former Expert Group on Heavy Liquid Metal Technology (EGLMH) 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 relevant recommendations for the design of HLM nuclear systems. After the publication of the second version of the handbook, it was decided to expand the scope and objectives of the expert group to i) include liquid sodium (Na) activities, and ii) go further 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. As a consequence, the name of the expert group was changed to “Expert Group on Reactor Coolants/Components Technology” (EGCoCoT). The new denomination 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 Working Party on Scientific Issues of Advanced Fuel Cycles (WPFC), the Expert Group on Reactor Coolants and Components Technology (EGCoCoT) undertakes activities with the goal to collect, evaluate and preserve relevant scientific data and "translate" fundamental scientific understanding into application in support of the following areas: 

• Development of construction codes used for the design (design rules), 
• Key technical issues for licensing,
• Recommendations for operation, inspection and handling.

Topical areas and objectives

The topical areas and objectives of the expert group are the following.

Environmental conditions and factors that affect materials' behaviour relevant to 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 to 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 to radiological impact assessment and 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, the 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.