Sodium pump design features

4 - displacer, 5 - radial-thrust bearing, 6 - shaft seal, 7 - coupling, 8 - motor. 

1- check valve, 2 - lower scroll, 3 - impeller, 4 - upper scroll, 

5 - hydrostatic bearing, 6 - shaft, 7 - cover, 8 - cooler, 9 - level gage, 10 - motor base, 11 - face seal, 12 - check valve drive, 

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The primcay pumps have a top entry, single mixed flow impeller and a flywheel to extend the run-down time on loss of power supply. A decision was taken to opt for a simple design without valves which implies all three pumps must be available for reactor operation. An innovative feature, recently introduced to the pump design, is a magnetic upper bearing with a ferro-fluid seal to eliminate oil and the potential hazard of its ingress into the sodium completely. 

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