Dose rate determinations in the Portuguese Gamma Irradiation Facility: Monte Carlo simulations and measurements

A simulation study of the Portuguese Gamma Irradiation Facility, UTR, has b een carried out using the MCNP code. The work focused on the optimisation o f the dose distribution inside the irradiation cell, dose calculations insi de irradiated samples and dose calculations in critical points for protecti on purposes. Calculations were carried out at points inside and outside the irradiation cell, where different behaviour was expected (distance from the source, rad iation absorption and scattering in irradiator structure and walls). The co ntributions from source, irradiator structure, sample material, carriers? w alls, ceiling and floor to the photon spectra and air kerma at those points are reported and discussed. Air kerma measurements were also carried out using an ionisation chamber. G ood agreement was found between experimental and calculated air kermas. (C) 2000 Elsevier Science Ltd. All rights reserved.