[en] An improved packed fluidized-bed blanket for a fusion reactor is described, the principle object being to provide a blanket which can be refuelled on-line, has high density and is well adapted for power and isotope production. The blanket consists of elongated pressure tubes containing a bed of stationary particles during reactor operation, cooled by a radial flow of coolant. During fuelling/refuelling, an axial flow is introduced into the elongated tubes in stages at various axial locations to fluidized the bed and remove particles from the tubes. (U.K.)