The neutronic safety parameters determine reactor dynamic response. These parameters change as a function of core inventory during reactor cycle. Therefore, assessment of reactor behavior throughout operational cycle is an important issue in reactor safety analysis for transients. The purpose of the present study is to evaluate SMART reactor response to changes in neutronic safety parameters during reactor cycle in reactivity insertion accident condition. MCNPX 2.6 nuclear code is utilized to calculate neutronic safety parameters throughout reactor cycle. The reactor dynamic model is simulated based on point kinetic equations and lumped temperatures to predict reactor response to ramp reactivity insertion. Based on this approach, the effect of neutronic parameters on reactor behavior are investigated in the beginning and end of cycle under reactivity transients. Hot full and zero power operational reactor states are considered in the analysis. Results illustrate that reactor at end of cycle has faster response with smaller transient power peak during reactivity insertion accident compared to beginning of cycle. The neutronic parameters, specifically negative feedbacks at both beginning and end of reactor cycle guarantee the safe performance of reactor at all examined conditions. The detailed comparative results are explained in the paper.
• Variation of neutronic safety parameters versus reactor cycle time is evaluated.
• Reactor behavior is analyzed under ramp reactivity insertion accident.
• Reactor dynamic response is predicted based on point kinetic equations and lumped temperature model.