Mandate of the
WPFC Expert Group on Liquid Metal (LM) Technology
Chair:TBD
Members:All NEA member countries
Date of creation:June 2015
Date of expiration:June 2017
Observer (International Organisation): International Atomic Energy Agency (IAEA) (By agreement)
Mandate:Approved at the 26th meeting of the Nuclear Science Committee in June 2015 [NEA/SEN/NSC(2015)X]
Introduction
The Expert Group on Heavy Liquid Metal (HLM) technology has been active for several years. Its main objective up to now 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 is ready for publication,the EGhas re-discussed its scope and future related activities. In particular, as suggested by the Working Party on Scientific Issues of the Fuel Cycle (WPFC), it has been decidedto include liquid Na activities in the future work plan of the EG. Secondly, the EG will aim to take the next step in the assessment of available datato 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. After the discussion the EG proposes to formulate its objectives as follows.
Objectives & Scope
Under the guidance of the Working Party on Scientific Issues of the Fuel Cycle (WPFC), the expert group will undertake activities with the goal to "translate"fundamental scientific understanding to application in support of (1)Development of construction codesused for design (design rules), (2) Key technical issues for licensing, (3) Recommendations for Operation, Inspection and Handling.
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 isto assessthe environmental effectsrelevant 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 is to answerkey technical issues to address radiological impact, operation, handling, maintenanceand inspectionas 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 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 (Na and HLM) will be established. To improve efficiency the taskforces will meet in parallel. At each meeting one plenary session will be organised to discuss and compare results in order to identify potential commonalities and synergies.
Activities
- 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 andcompare existing methodologies to understand the underlying degradation mechanisms
- Identify further R&D 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 keys technical issues and lessons learned forsafe and reliable operation, inspection, handling, and maintenance in support to reactor and system design and future operation.
- Compile and assess dataon 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 R&D needs to improve knowledge of the environmental conditions for materials
- Code-to-code, code-to-experiment benchmark studies
Deliverables
- State-of-the-art report on the liquid metal environmental effects on materials (2017)
- Report on data management requirements forstructural materials and thermal-hydraulic (2017)
- Report on key technical issues and lessons learned for safe and reliable operation, inspection, handling, maintenance, decommissioning and waste management of liquid metal cooled reactors. (2017)
- Report on liquid metal thermal hydraulics (2017)
Links
The expert group will liaise closely with other NEA working groups, especially the Expert on Innovative Structural Materials and those operating under the guidance and theCommittee 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.