The scope of this Technical Meeting will encompass design and safety assessment of LMFRs with special emphasis on hypothetical severe accidents, including modelling and analysis of the severe accident progression, numerical code development and validation, and regulatory approaches and licensing.
The event is intended to cover the following topics:
- Scenarios leading to core degradation in LMFRs (such as loss of flow, local instantaneous blockage, reactivity insertion, loss of heat sink, cumulated with the failure of shutdown systems);
- Design and safety assessment of LMFR for prevention and mitigation of severe accidents:
- Design orientations for the prevention of accidental sequences leading to severe accidents and elements of the supporting safety demonstration;
- Intrinsic safety features based on the natural behaviour of sodium cooled and lead cooled fast reactors with various nuclear fuel options (e.g. oxide, nitride, metal), primary system types (pool-type, loop-type) and layout;
- Definition of core damaged plant state used for the demonstration of the effectiveness of mitigation features;
- Elements of the safety demonstration associated to the consideration of accidental sequences leading to severe accidents (including implementation of defence-in-depth, deterministic safety analysis, probabilistic safety assessment, classification of structures, systems and components, risk-informed performance-based approaches, etc.);
- Practical elimination of sequences leading to large or early radioactive releases.
- LMFR severe accident phenomena and analysis models:
- Mechanistic models for core degradation under severe accident conditions;
- Fuel pin behaviour (fuel-cladding interaction, in-pin fuel movement, reactivity effects);
- Initiation/primary phase (including two-phase thermal-hydraulics);
- Event termination or transition/secondary phase (hexcan failure, fuel-coolant interaction, melt propagation and material movement and associated reactivity effects, potential secondary power excursions due to recriticality effects);
- Expansion phase (expansion of sodium vapor bubble, pressure increase and release of mechanical energy);
- Material relocation (debris formation, thermochemistry effects, jet impingement)
- Long-term behaviour (coolability, recriticality).
- Radioactive material release and transport in-vessel and ex-vessel (including sodium fires);
- Conservative simplified/parametric models during the core degradation phases;
- Code development and performance optimization, multi-physics approaches, platform architecture;
- Experimental programs, code validation, uncertainty analyses.
- Experiences in the regulation and licensing of LMFRs.
- International programs on LMFR design and safety
