The studies presented in this paper are performed in the general framework of transient coupled calculations with accurate neutron kinetics models able to characterize spatial decoupling in the core. An innovative fission matrix interpolation model has been developed with a correlated sampling technique associated to the Transient Fission Matrix (TFM) approach. | Towards spatial kinetics in a low void effect sodium fast reactor core analysis and validation of the TFM neutronic approach EPJ Nuclear Sci. Technol. 3 17 2017 Nuclear Sciences A. Laureau et al. published by EDP Sciences amp Technologies DOI epjn 2017008 Available online at http REGULAR ARTICLE Towards spatial kinetics in a low void effect sodium fast reactor core analysis and validation of the TFM neutronic approach Axel Laureau Laurent Buiron and Bruno Fontaine CEA DEN DER Cadarache 13108 Saint-Paul Les Durance Cedex France Received 11 November 2016 Received in final form 4 March 2017 Accepted 17 March 2017 Abstract. The studies presented in this paper are performed in the general framework of transient coupled calculations with accurate neutron kinetics models able to characterize spatial decoupling in the core. An innovative fission matrix interpolation model has been developed with a correlated sampling technique associated to the Transient Fission Matrix TFM approach. This paper presents a validation of this Monte Carlo based kinetic approach on sodium fast reactors. An application case representative of an assembly of the low void effect sodium fast reactor ASTRID is used to study the physics of this kind of system and to illustrate the capabilities provided by this approach. To validate the interpolation model developed different comparisons have been performed with direct Monte Carlo and ERANOS deterministic SN calculations on spatial kinetics parameters flux redistribution reactivity estimation etc. together with point kinetics feedback estimations. 1 Introduction kinetics during transient coupled calculations in order to take into account the evolution of the system during the Low void effect sodium fast reactors provide an improved transient TFM is associated to specific interpolation behavior during accidents thanks to a negative feedback models. The innovative interpolation model produces on coefficient due to sodium expansion. .