Development of a Large Diameter Electromagnetic Pump for 4S Available to Purchase

Toshiba has been developing the Super-Safe, Small and Simple sodium-cooled fast reactor, named as the 4S. This reactor has features of passive safety, long refueling interval up to 30 years and low maintenance requirement.[1] To approach the features, the 4S adopts a high temperature sodium-immersed electromagnetic pump (EM pump) as the primary circulation pump. The rated flow rate and head are 10.6m³/min and 50kPa respectively. EM pump is static equipment with no moving parts, and then it enables the long-term maintenance to be unnecessary. However, there are some technical issues to apply an EM pump to the 4S. The outer diameter of the 4S EM pump is 1.8 times larger than that of 160m³/min EM pump which Toshiba has already developed. [2] Aspect ratio of the 4S EM pump defined by stator diameter to the length is much larger than our EM pump experiences, which may concern generation of flow instability. In order to confirm the design and fabrication procedure, the prototype full-scale EM pump for the 4S was manufactured. This EM pump characteristics were evaluated using electromagnetic flow code named as EAGLE developed by Toshiba, which combined with Maxwell’s equations and Navier-Stokes equation. To confirm characteristic of the completed EM pump, magnetic field in the annuals flow gap was measured in the air along the axial directional in condition of 250V-18Hz. The data were confirmed to agree with the analytical results of EAGLE. In order to demonstrate applicability of EM pump for the 4S, sodium test facility was constructed. The facility consists of one electromagnetic flow meter (EM flow meter), 14 sodium pressure sensors, EM flow meter calibration tank, 600kW cooler and sodium impurity control system. The pump characteristic tests were performed in sodium, it was demonstrated that the EM pump could apply to the 4S as the performance was satisfied with the design rated.