RADIOLOGICAL DOSE CALCULATIONS FOR THE PARTICLE-BEAM FUSION ACCELERATOR UPGRADE (PBFA-U)

Biological dose rate calculations are performed for different location s in the vicinity of the target chamber and diode of the particle beam fusion accelerator upgrade (PBFA-U) facility. The facility is to be u sed for research on light ion beam driven inertial confinement fusion. Depending on the diagnostic shots, Bremsstrahlung radiation as well a s neutrons are produced. On interacting with the diode material, the B remsstrahlung radiation results in the emission of photoneutrons. Resu lts of the activation analysis show that photoneutron production has a negligible contribution to the dose rate at the outer casing of the d iode following fusion shots. The dose rates are dominated by the contr ibution from fusion neutrons streaming into the diode. The dose rate i n the vicinity of the diode following non-fusion shots is minimal, all owing it to be accessed immediately for hands-on maintenance. However, several shifts of maintenance personnel are required if the outer cas ing of the diode needs to be accessed following fusion shots to minimi ze individual exposure. The use of steel as structural material for th e chamber and diode casing results in lower dose rates compared with t he use of aluminum for up to several months following fusion shots. Us ing steel, chamber and diode can be accessed 1 day after shots for a m aximum of 15 min per maintenance shift. Using the aluminum alloy would delay hands-on maintenance to several days following shots.