Thermal-hydraulic design concerning reactor upper plenum and large diameter piping for the innovative sodium-cooled fast reactor

Fujii, Tadashi; Konomura, Mamoru; Kamide, Hideki ; Yamaguchi, Akira; Toda, Mikio*

An innovative sodium-cooled fast reactor (JSFR) has been investigated on the Feasibility Study on Commercialized Fast Reactor (FR) Cycle Systems. In order to reduce plant construction cost, JSFR adopts compacted reactor vessel and reduction of loop number. According to adoption of compacted cooling system, sodium flow velocities in the reactor upper plenum and the pipings of the cooling system exceed to those of conventional design, therefore, flow optimization in the reactor upper plenum and structural integrity of the piping system to flow-induced vibration (FIV) have been actualized as thermal-hydraulic issues. To solve above issues, some water experiments have been performed. The thermal-hydraulic design of the primary cooling system including the reactor vessel has been advanced reflecting these experimental results.