Fuel loading, criticality and control rod worth calculations of the Triga Mark III reactor using Serpent and MCNP

A model of the Triga Mark III reactor of the National Institute for Nuclear Research (ININ) of Mexico was developed with the Monte Carlo codes Serpent and MCNP. The models were verified and validated by means of the experiments carried out as part of the starting tests to change the mixed fuel to Low Enrichment Fuels (LEU) of the TRIGA reactor core. The reactor data used in the V&V process consisted of fuel loading measurements, simulating the different stages of loading of fuel elements to the core to reach the reactor core criticality and the additional loading to achieve the reactivity excess to operate the reactor, as well as the evaluation of the shutdown margin reactivity and the control rods worth. The validated models constitute a trustworthy computational tool to analyse the most important neutronic core parameters as well as to have the numerical capabilities for fuel utilisation studies and analysis for extension of experimental facilities.