The present work investigates the time to cool down a Water-Cooled Lithium-Lead (WCLL) Breeding Blanket (BB) sector of the EU DEMO fusion reactor, starting from the after-shutdown condition of 300°C towards the prescribed temperature for Remote Maintenance (RM) operations, 150°C. First part of the analysis foresees air in natural convection as cooling medium. Weighted solid properties and decay heat load of WCLL have been evaluated and implemented in a 3D transient conjugate heat transfer model, already developed for HCPB BB concept. Comparison between the two concept is carried out. Air in forced convection is the second investigated cooling strategy. The previous 3D model has been properly modified to take into account the presence of turbulence, which significantly rises the complexity of the problem.