This paper presents results from absorbed dose calculations carried out using the Monte Carlo N-particles (MCNP) code in the Portuguese Gamma Irradiation Facility. The computer running time was chosen in such a way that the statistical errors were always less than 5%. Dose measurements using Amber Perspex and ceric-cerous dosimeters were performed in order to validate the calculations. Simulated and experimental data show good agreement even at positions with a high gradient dose. This fact indicates that the model is reliable. Consequently: (a) the code was used in a correct way; (b) source and geometry of the installation were well defined; and (c) dimension, composition and density of the product were correctly established. The amount of experimental work with dosimeters can thus be reduced. The results show that Monte Carlo simulations can be used as a predictive tool of dose measurements in an irradiation plant. However, some validation measurements must be performed. (C) 2000 Elsevier Science Ltd. All rights reserved.
