The mechanical behaviour of UO2 single crystal is under debate due to the unexpected multi-slip observations in experiments that involve dislocations 12〈110〉{100} slip systems but also 12〈110〉{110} and 12〈110〉{111}. We propose a multi-scale model based on composite which, effect cross-slip, part dislocation density primary can be transferred secondary with lower propensity glide more favourable...