Calculation of kinetic parameters in an accelerator driven subcritical TRIGA reactor using MCNIC method

• We proposed a methodology to calculate importance weighted kinetic parameters.
• Kinetic parameters of the TRIGA reactor have been calculated using MCNIC method.
• The results of the method have been validated.
• Parameter Λ is highly sensitive to the reactor geometry and reflector thickness.
• MCNIC method can efficiently be used to calculate the kinetic parameters in ADSRs.

The effective delayed neutron fraction (βeff) and neutron reproduction time (Λ) play an important role in nuclear reactor control and safety analysis. In this work, calculation of these parameters in an Accelerator Driven Subcritical TRIGA reactor is investigated using MCNIC method. The result of this method has been compared with those obtained by MCNPX code, 1/v poisoning method and reference data. The relative difference between MCNIC method results with MCNPX code and reference data for βeff is −3.0% and 1.7%, respectively. Our results indicate that, the Λ value from MCNIC method has relative differences of −19.4% and −10.3% with MCNPX code and 1/v poisoning method calculations, respectively. These values are increased by increasing the reflector thickness. Finally, this method may be used for better estimation of kinetic parameters rather than the MCNPX code because of using neutron importance function.