In this paper, we propose an analysis of the impact of spatial variation and temporal evolution of thermal properties of fuel pins on a CFV-like core behavior during an ULOF accident. These effects are usually neglected under some a priori conservative assumptions. | Thermal-hydraulics thermal-mechanics temporal coupling for unprotected loss of flow accidents simulations on a SFR EPJ Nuclear Sci. Technol. 2 2 2016 Nuclear Sciences C. Patricot et al. published by EDP Sciences 2016 amp Technologies DOI epjn e2015-50036-x Available online at http REGULAR ARTICLE Thermal-hydraulics thermal-mechanics temporal coupling for unprotected loss of flow accidents simulations on a SFR Cyril Patricot1 Grzegorz Kepisty1 Karim Ammar1 Guillaume Campioni1 and Edouard Hourcade2 1 CEA DEN DM2S SERMA 91191 Gif-sur-Yvette France 2 CEA DEN DER CPA 13108 Saint-Paul-Lez-Durance Cedex France Received 12 May 2015 Accepted 25 November 2015 Published online 11 January 2016 Abstract. In the frame of ASTRID designing unprotected loss of flow ULOF accidents are considered. As the reactor is not scrammed power evolution is driven by neutronic feedbacks among which Doppler effect linked to fuel temperature is prominent. Fuel temperature is calculated using thermal properties of fuel pins we will focus on heat transfer coefficient between fuel pellet and cladding Hgap and on fuel thermal conductivity lfuel which vary with irradiation conditions neutronic flux mass flow and history for instance and during transient mainly because of dilatation of materials with temperature . In this paper we propose an analysis of the impact of spatial variation and temporal evolution of thermal properties of fuel pins on a CFV-like core behavior during an ULOF accident. These effects are usually neglected under some a priori conservative assumptions. The vocation of our work is not to provide a best-estimate calculation of ULOF transient but to discuss some of its physical aspects. To achieve this goal we used TETAR a thermal-hydraulics system code developed by our team to calculate ULOF transients GERMINAL a CEA code dedicated to SFR pin thermal-mechanics calculations and APOLLO3 a neutronic code in development at CEA. 1 Introduction Doppler sodium .
