Radiation Protection Studies for ESS Superconducting Linear Accelerator

Abstract

This paper reports first estimates of the radiation protection shielding required for the ESS machine and provides a preliminary characterization of the residual radiation field inside the accelerator tunnel. Two scenarios were analyzed: (a) an accidental full beam loss during 1 s every day and (b) continuous beam loss of 1 W m-1 , representing normal operation conditions. Representative loss positions along the accelerator at various energies were investigated using a simplified geometry model of the linac to asses the lost proton beam prompt radiation field. Dedicated Monte Carlo (MC) simulations with the PHITS and MCNPX2.6.0 codes were performed to analyze the propagation of neutrons through the tunnel shield wall and its surroundings. The induced radioactivity in the accelerator components, concrete walls, and air inside the tunnel were estimated using the DCHAIN and CINDER'90 codes based on the external neutron source and spallation products derived from MCNPX. Ambient dose equivalent rates due to the residual radiation were calculated with the MCNPX code using photon sources resulting from CINDER.