The prime objective of the present study is to analyze numerically the steady state fluid flow and heat transfer characteristics of liquid sodium as a coolant flowing past over a rectangular nuclear fuel element having non-uniform volumetric energy generation. Accordingly, employing stream function-vorticity formulation and using finite difference schemes, the equations governing the flow and thermal fields in the coolant are solved simultaneously with energy equation for the fuel element by satisfying the conditions of continuity of temperature and heat flux at the solid-fluid interface. Keeping Prandtl number Pr = 0.005 for liquid sodium as constant. numerical results are presented and discussed for a wide range of aspect ratio A(r), conduction-convection parameter N-cc, total energy generation parameter Q(t) and Reynolds number Re-H. It is concluded that the rate of heat dissipation from the fuel element to the coolant is independent of A(r), N-cc and Q(t), whereas it increases in proportion to the increase in Re-H. It is also found that for a given material of the fuel element, there is an upper limiting value of N-cc and Re-H beyond which decrease in coolant temperature is negligibly small (C) 2010 Elsevier Ltd. All rights reserved.