Field parameters and dosimetric characteristics of a fast neutron calibration facility: experimental and Monte Carlo evaluations

At the ENEA Institute for Radiation Protection (IRP) the fast neutron calibration facility consists of a remote control device which allows locating different sources (Am–Be, Pu–Li, bare and D2O moderated 252Cf) at the reference position, at the desired height from the floor, inside a 10×10×3 m3 irradiation room. Either the ISO reference sources or the Pu–Li source have been characterised in terms of uncollided H*(10) and neutron fluence according to the ISO calibration procedures. A spectral fluence mapping, carried out with the Monte Carlo Code MCNPTM, allowed characterising the calibration point, in scattered field conditions, according to the most recent international recommendations. Moreover, the irradiation of personal dosemeters on the ISO water filled slab phantom was simulated to determine the field homogeneity of the calibration area and the variability of the neutron field (including the backscattered component) along the phantom surface. At the ENEA Institute for Radiation Protection the calibration of neutron area monitors as well as personal dosemeters can now be performed according to the international standards, at the same time guaranteeing suitable conditions for research and qualification purposes in the field of neutron dosimetry.