The Primary Pumps

The reactor has got four primary pumps immersed in sodium in the main vessel. These pumps were posing a number of specific problems that had to be solved at design time. For example, the shaft line lower bearing is in sodium, which imposes an innovative design. The shaft length also posed dimensioning and then manufacturing problems. To take over expansions between the pump upper part, laid on the slab, and the lower part, connected to the diagrid, needed an original design. The materials were chosen on the basis of Phenix experience feedback and depending either on their use or on their realization mode. Cavitation phenomena, capable to cause erosion, were taken into account from design. Finally, Phenix pump experience feedback was integrated in the design. It should also be noted that studies were conducted on promising domains: use of ferrofluids, supercritical shaft but could not come to an end within the given time. The primary pumps have operated for 16 years with no notable problems, from 1984, when the sodium was filled in the reactor block, to 2000, when their operations were no longer necessary for dismantling operations.