Characterization neutron and gamma beams at the tangential beam port of TRIGA 2000 reactor was done in order to prepare the development of Prompt Gamma Neutron Activation Analysis (PGNAA) facility. Characterization was performed by simulation using Monte Carlo method with MCNPX and PHITS computer codes. The MCNPX code was used to simulate the neutron-gamma fluence and energy spectra in the reactor core from fission reactions. The PHITS code was used to simulate the distribution of the neutron-gamma fluence and energy spectra in the tangential beam port. The simulation was done by modeling the geometry and elemental composition of reactor material and radiation source model in the form of fission reaction in the reactor core. The results indicate that the tangential beam port provides better neutron spectrum and neutron-gamma fluence ratio for PGNAA. These results will be used to simulate the colimator design and neutron interaction with samples in PGNAA facility.

The present work discusses two different models of thorium irradiation in the TRIGA 2000 reactor core to compare the neutronic characteristics of irradiation of thorium dioxide (ThO2) and thorium zirconium hydride (ThZrH). The Monte Carlo N-Particle (MCNP) Transport code, based on the Monte Carlo method, is used to design three dimensional models for TRIGA reactor core at typical operating power 2 MW. These models are used to determine the effective multiplication factor (keff) and neutron flux distribution. The ORIGEN code is used to calculate the 233U isotope production. It is found that decreasing of keff from the effect of hydride irradiation rod is a little lower than the oxide irradiation rod.