Base irradiation simulation and its effect on fuel behaviour prediction by TRANSURANUS code: Application to reactivity initiated accident condition

The purpose of the present paper is to investigate the impact of the base irradiation simulation for pre-dicting fuel behavior under Reactivity Initiated Accident (RIA) conditions. A RIA is a scenario challengingthe fuel integrity and consequently, devoted experimental campaigns and related code simulations havebeen extensively performed. In all experiments in which irradiated fuel is tested, the experiment is pre-ceded by in reactor period, i.e. the base irradiation. In the present paper the considered RIA experimentis CIP3-1 performed in CABRI reactor (part of the OECD/NEA WGFS benchmark); a discussion about therelevance of the base irradiation simulation is presented. Such a work is conducted by sensitivities cal-culation in which a single parameter, among a preselected set, is changed. The range of variation of suchparameters is either supplied within the selected RIA test specification or is taken from typical valuesavailable in the open literature. All mentioned calculations have been performed developing a specificmodel in TRANSURANUS code.