The design of electromagnetic bearings for use in a radioactive enviro
nment is presented specifically from a control point of view and suppo
rted by experimental results. A pump shaft 2 meters long, weighing 110
kg, is levitated by such bearings and driven by an induction motor ca
pable of spinning at variable speeds of up to 3000 rpm. The experiment
al results demonstrate that this bearing system is stable and robust w
hen the shaft is run through its two critical speeds.