Microdosimetry study of radiobiological facilities at the RSV-Tapiro reactor

The standard irradiation facility of the RSV-Tapiro fast reactor at ENEA Casaccia consists of a vertical channel of 10 cm diameter through which biological samples can be shipped down near to the reactor core. A new irradiation facility was designed by extracting laterally the thermal column to enable irradiation of larger matrices. Microdosimetric measurements were performed using a Rossi counter (d = 2 μm) to provide a quantitative assessment of radiation quality for both facilities. Their characteristics were compared in terms of distributions in lineal energy, and the related averaged quantities, for the total radiation and the neutron component. The lineal energy spectra were also computed using calculated neutron fluence spectra to compare the influence of different energy components, and extend the microdosimetric data to simulated diameters of 1-0.3 μm to be discussed with regard to their relevance for the interpretation of biological results. (Author)