[en] It is evident that the flow blockage is basically a local phenomenon, and the main issue to investigate is the thermal-hydraulic behavior of the region downstream from the obstacle because it determines the clad temperature peak. For this reason, a local detailed CFD analysis has been carried out in order to assess the impacts of a flow blockage. The flow blockage events are classified into two types, internal and external blockage, depending on their locations. The objective of this paper is to investigate the influence caused by a flow blockage. A CFD analysis using fully resolved RANS simulations has been carried on the fluid flow and heat transfer in the case of a flow blockage for fuel assemblies in a PGSFR. A fuel assembly with 91 pins instead of all 217 pins was considered for this study. Two main effects can be distinguished in a flow blockage: a locally lower mass flow rate in the wake/recirculation region downstream of the blockage, and the peak temperature behind the blockage. Both of them are closely related. The recirculation region exists within a short distance downstream from the blockage, and it has an effect on the cladding integrity. The maximum cladding temperature is about 1000 .deg. C and is located in the central pins of the blockage region. It could lead to a rupture of the cladding. From these analysis results, the axial blockage size may have a significant impact on the clad integrity