Subprogramme 6: Physical modelling and separate effect

experiments for fuels (M4F)

Marjorie BertolusCEA, DEN, Centre de Cadarache

SP6 coordinator

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Mechanical effectsTemperature Irradiation Chemistry

Cracking Fission gas bubble precipitation

High Burn up structure Radial migration

FP migration interaction

A complex behaviour: interconnected effectsleading to numerous coupled phenomena

Fission Alpha Decay

Fission products Helium + recoil nuclei

In-pile Fuel Behaviour is Very Complex

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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

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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

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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

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0

5

10

15

20

25

0 100 200 300 400 500 600 700 800 900 1000

Profondeur (nm)

dpa

0

0,2

0,4

0,6

0,8

1

1,2

Au 4 MeV 2e15

He 7 keV 5e15 % atom

ique

Cartographie en µ-NRA

Cartographie en µ-NRA

Microscopie optique

Rôle des joints de grains dans la diffusion

Microscopie optique

Rôle des joints de grains dans la diffusion

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

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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 projectsStudies 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