Drop Behavior Analysis of Control Rod Assembly for PGSFR using HEXCON code

The PGSFR core is a heterogeneous, uranium-10% zirconium (U-10Zr) metal alloy fuel design with 112 assemblies: 52 inner core fuel assemblies, 60 outer core fuel assemblies, 6 primary control assemblies, 3 secondary control assemblies, 90 reflector assemblies, and 174 B4C shield assemblies and 66 in-vessel storage assemblies. This core is designed to produce 150 MWe with an average temperature rise of 155 ℃. The inlet temperature is 390 ℃ and the bulk outlet temperature is 545 ℃. The active core height is 900 mm and the gas plenum length is 1,250 mm. Mathematical modeling of the CRA under immersed and the fluid flow conditions is carried out. The developed numerical analysis results are compared with the experimental results and validated. The CRA design for PGSFR is satisfied with the stipulated design criteria. In addition to this, the sophisticated damper sufficiently decelerate the drop velocity of the CRA. Therefore, it is demonstrated that this system has no negative impact on the structural soundness of the reactor internals.