The Fluence Conversion Coefficients method: applications to radiological characterization with the FLUKA and PHITS codes.

Abstract

One of the key aspects of radiation protection is the radiological characterization of components that have been exposed to a radiation environment. For a known material composition, irradiation profile, cool-down time, radionuclide production cross sections and hazard weighting factors (e.g. clearance limits), it is possible to compute coefficients converting particle fluences to the desired radiological hazard factor. One can then apply these pre-computed coefficients during transport calculations performed with a radiation transport Monte Carlo code. After some clarifications on the activation formalism adopted, the document gives an overview of the code that takes care of computing the coefficients illustrating two examples with two different Monte Carlo codes, FLUKA and PHITS. For the former, the FORTRAN user routine applying the coefficients is explained together with the file format chosen for reading/writing the coefficients. Then, the main results of a numerical example are described. For the latter code, instead, there is no need of a user written routine, but some remarks are given on the way the coefficients should be included in the corresponding input file