Calculation of radioactive isotope production cross-sections with FLUKA and their application to radiological studies

During the lifetime of a high-energy accelerator estimations of inducedradioactivity are important in all its phases, such as design, operation anddecommissioning. FLUKA's capability of making predictions for isotope productionin hadronic showers has been subject to extensive benchmark experiments carriedout in the last years. The accuracy of these predictions steadily improved withthe advancements of models implemented into FLUKA, in particular after theintroduction of a new evaporation/ fragmentation model and the improvements andextensions of the PEANUT model. Whereas former activation studies focused onsamples of selected materials and representative source spectra typical forhigh-energy accelerators, this paper gives a more general analysis of calculatedisotope production cross-sections and their application to future radiationprotection needs. In this paper a general approach is presented how to quantifycalculation uncertainties and use pre-calculated cross-sections in order to foldthem with expected energy spectra as encountered around accelerators, thusleading to fast and accurate results. The application of this approach isunderstood to be an indispensable ingredient, for example in order toefficiently calculate radionuclide inventories needed for disposal ofradioactive waste towards the final repositories. Based on a list of materialsand radioactive isotopes, possible reaction channels can be derived for acertain application and energy-dependent isotope production cross-sections arecalculated and compared to experimental data. Depending on the amount andaccuracy of the available experimental data sets, as well as the productionmechanisms of the radioisotopes, respective uncertainty factors can be derived.These factors mainly depend on the production mechanism and the energy range ofinterest, thus allow quantifying uncertainties in isotope production ascalculated with FLUKA in a more global way. Pre-calculated isotope productioncross-sections can then be used to estimate radionuclide inventories by foldingthe cross-sections with expected particle energy spectra. Typical spectra asencountered in high-loss regions of the LHC accelerator are shown and comparedto those used in previous benchmark experiments.