RESUMO
The computer simulation of radiation processing in an industrial panoramic gamma facility generates a number of complex scientific and technical problems; for example, the product is manually loaded onto turntables and rotates during the entire irradiation and the Monte Carlo MCNP three-dimensional geometry simulation is static. This causes the first problem; for this it is necessary to introduce additional approaches to describe the real irradiation process. It is important to properly represent the irradiation process and the specific conditions of the irradiator to correctly reproduce the measured results and guarantee also through the use of the model developed the most accurate dose map formations in an irradiated product, improving the service quality provided to the customer. The objective of this study is to apply the proposed source model of a panoramic gamma irradiator on dose distributions in containers of different geometric shape of an irradiated product with use of the Monte Carlo code. The influence was studied with use of a new homogenized annular source model. The validation of the MCNPX model of the GammaBeam 127 source was performed by measurements. The validation of the proposed model was based on comparative evaluation of the MCNPX absorbed-dose rates (Gy/h) in the irradiated product between the real source model and the new model. The comparative results for the MCNPX absorbed-dose rate showed that the new source model provides a better description of the irradiation process in a panoramic gamma irradiator. This indicates that the physical and mathematical MCNPX models developed are reliable and correct, and the new source model adequately reproduces the observed dose distributions in the different geometric shapes of the irradiated product.
RESUMO
The use of gamma irradiation technologies generates a number of complex scientific and technical problems; for example, the target is manually loaded onto turntables and is rotated during the entire irradiation process and the MCNPX three-dimensional geometry simulation is kept static. For this, it is necessary to introduce additional approaches. In this paper, two new methodologies are proposed for the simulation of irradiation process in panoramic gamma irradiator. The study was performed at the gamma irradiation facility at the Nuclear Technology Development Center of the National Nuclear Energy Commission, Brazil. The source can be reproduced with a homogenized geometry. Validation of MCNPX calculations of gamma doses were performed by thorough comparison with the experimental measurements. The contribution of this proposed source models has opened new lines of research. The results of this study showed that the proposed source models effectively represent the irradiation process.
