Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Calculations of the shielding and estimates of soil activation for a medical cyclotron are presented in this work. Based on the neutron source term from the 18O(p,n)18F reaction produced by a 28 MeV proton beam, neutron and gamma dose rates outside the building were estimated with the Monte Carlo code MCNP6(1). The neutron source term was calculated with the MCNP6 code and FLUKA(2) code as well as with supplied data by the manufacturer. Soil activation was performed using the FLUKA code.
The estimated dose rate in the public area is about 0.035 μSv/h and thus significantly below the reference value of 0.5 μSv/h(3). After 5 years of continuous beam operation and a subsequent decay time of 30 days, the activity concentration of the soil is about 0.34 Bq/g. Significant discrepancies between the manufacturer supplied data for the neutron source term and the calculations done using the MCNP6 and FLUKA codes were found.