Final characterization of the first critical configuration for the TRIGA Mark II reactor of the University of Pavia using the Monte Carlo code MCNP

•Monte Carlo model of a TRIGA Mark II reactor.•Reproduction of the reactor configuration after the first startup.•Simulation of critical configurations and control rod calibration curves.•Statistical and systematic error were accounted for.•Good agreement with experimental data proves model reliability.

A methodological approach based on Monte Carlo code for the neutronic analysis of the TRIGA Mark II research reactor of the University of Pavia in the configuration of cold and clean nuclear fuel is presented. The complete implementation of the code is based on the construction characteristics with the validation of the results obtained by benchmarking the experimental and operational data reported in the reactor Fist Criticality Final Report. The 3-D continuous-energy Monte Carlo code MCNP5 was used. The description of the geometrical structure of the reactor core and the fuel configuration were designed with great accuracy and good detail. The comparison between simulated and measured data allows the creation of a complete reconstruction model of the TRIGA Mark II reactor.