The complexity of the loads involved and the extremely fine analysis required necessitates extensive design calculations for the Superphénix 1 primary and secondary pumps and associated expansion tanks, aiming toward detailed design validation, after slight adjustments, mainly to the secondary pumps and expansion tanks. The component parts to be built were far larger than those for the previous pumps (Rapsodie, Phénix), with very low manufacturing tolerances, which led to precision machining and welding operations, together with numerous dimensional inspections and materials characterization tests to achieve the required quality standards.