  We present a new model, developed with the Serpent Monte Carlo code, for
neutronics simulation of the TRIGA Mark II reactor of Pavia (Italy). The
complete 3D geometry of the reactor core is implemented with high accuracy and
detail, exploiting all the available information about geometry and materials.
The Serpent model of the reactor is validated in the fresh fuel configuration,
through a benchmark analysis of the first criticality experiments and control
rods calibrations. The accuracy of simulations in reproducing the reactivity
difference between the low power (10 W) and full power (250 kW) reactor
condition is also tested. Finally, a direct comparison between Serpent and MCNP
simulations of the same reactor configurations is presented.
