SOLIDUSS: Solid-state diffusion software for radiation protection Ogállar Ruiz, Francisco Theis, Chris Porras Sánchez, José Ignacio Vincke, Helmut Out-diffusion Fire Radionuclide Source term CERN-FLUKA SOLIDUSS The out-diffusion of radionuclides from activated material in case of a fire may represent a non-negligible contribution to the radiological source term of such an event. In order to assess the contribution of this phenomenon, a software package has been designed and implemented. In the present document we briefly introduce the numerical treatment used to tackle the problem prior to the explanation of the software's logic. The document ends with an exemplary simulation and a study carried out to validate the implementation of the algorithm. The presented tool has been named SOLIDUSS, it is mainly written in C++ and uses a Monte Carlo based approach to simulate the diffusion of radioisotopes within solid materials. It is designed to run coupled with CERN-FLUKA, taking advantage of its geometry kernel to carry out diffusion calculations in arbitrarily complex geometries. The user can provide 3D temperature maps along with many other parameters that allow the program to target a wide range of different scenarios. As results SOLIDUSS provides 3D radionuclide concentration maps as well as the amount of radionuclides out-diffused from the selected materials. So far, this software has undergone numerical validation which will be discussed in this paper. Benchmarking against experimental data is currently ongoing. 2021-11-26T10:51:48Z 2021-11-26T10:51:48Z 2022-01 journal article F.O. Ruiz et al. SOLIDUSS: Solid-state diffusion software for radiation protection. Applied Radiation and Isotopes 179 (2022) 109997. [https://doi.org/10.1016/j.apradiso.2021.109997] http://hdl.handle.net/10481/71772 10.1016/j.apradiso.2021.109997 eng http://creativecommons.org/licenses/by/3.0/es/ open access Atribución 3.0 España Elsevier Ltd