1. Subprogramme 6: Physical modelling and separate effect experiments for fuels (M4F) Marjorie Bertolus CEA, DEN, Centre de Cadarache SP6 coordinator

2. JPNM-MATISSE Workshop, Brussels, September 10 th, 2014Page 2 Mechanical effects Temperature Irradiation Chemistry Cracking Fission gas bubble precipitation High Burn up structure Radial migration FP migration interaction A complex behaviour: interconnected effects leading to numerous coupled phenomena FissionAlpha Decay Fission products Helium + recoil nuclei In-pile Fuel Behaviour is Very Complex

3. JPNM-MATISSE Workshop, Brussels, September 10 th, 2014Page 3 Modelling and Separate Effect Experiments for Fuels: Why? To change from “observe and qualify” approach to “design and control” basic studies of advanced nuclear fuel necessary in addition to global irradiations Similar approach to what is done on structural materials in JPNM/SP4, but adapted to fuel material specificities First successes demonstrated during the FP7 F-BRIDGE project (2008-2012)  Produced key basic data / identified relevant mechanisms to be used for a better prediction of fuel and cladding behaviour  Integrated European teams of various countries with various areas of expertise Approach has made progress – still major efforts needed

4. JPNM-MATISSE Workshop, Brussels, September 10 th, 2014Page 4 Modelling and Separate Effect Experiments for Fuels: What do we need?  Need for precise laws governing the evolution of properties as a function of all relevant parameters  Fundamental understanding of underlying elementary mechanisms taking place in the materials during aging and irradiation at appropriate scales  Coupling of the various descriptions and scales to simulate the combined effects of temperature and irradiation on the behaviour of the nuclear fuel during normal, off-normal and accidental conditions  Gen IV fuels: mixed compounds, containing minor actinides O potential for various fuel compositions and T Diffusion coefficient determination using atomic scale methods

5. JPNM-MATISSE Workshop, Brussels, September 10 th, 2014Page 5 Modelling and Separate effect Experiments for Fuels: What do we study? State-of-the-art experimental studies combined with modelling from atomistic to grain scale on mixed fuels behaviour in normal and off-normal conditions and off-normal conditions Microstructure changes under irradiation Fission product chemistry and release Melting behaviour Mechanical integrity Melting temperatures Phase diagrams High temperature thermochemistry Thermal conductivity Transport properties of defects Gas segregation, precipitation and release Non-gaseous fission product behaviour and compounds Consequences of irradiation damage Creation and behaviour of extended defects (cavities, dislocation Role of grain boundaries Mechanisms governing mechanical properties Creep Fracture

6. JPNM-MATISSE Workshop, Brussels, September 10 th, 2014Page 6 Modelling and Separate effect Experiments for Fuels: How? Behaviour of future fuels under irradiation In pile irradiations or experimental simulation (ion irradiation/implantation, doping) Multiscale modelling and simulation Fine characterization at relevant scale (before, under, after irradiation) SP5

7. JPNM-MATISSE Workshop, Brussels, September 10 th, 2014Page 7 Modelling and Separate effect Experiments for Fuels: Status and needs  Large number of organizations involved: CEA, CNRS (France), JRC-ITU (EU), SCK.CEN (Belgium), ENEA (Italy), Chalmers, KTH (Sweden), Aalto University (Finland), NNL, Imperial College, SFTC (UK), PSI (Switzerland)  Effort declared: ~ 15 persons.year in 2014  But currently no collaborative project on this subject F-BRIDGE finished in 2012 A few punctual investigations in FAIRFUELS and PELGRIMM projects  Studies rely almost only on in-kind One proposal on basic research on fuel with Nugenia support in the section 1 of 2014 call  Basic research in danger in several countries  JPNM is a collaborative framework but further integration requires suitable funding