Thermal Performance Characteristics of a Nuclear Fuel Element Dissipating Heat in a Surrounding Medium

This paper deals with the numerical prediction of thermal performance characteristics of a rectangular nuclear fuel element dissipating fission heat in its surrounding medium. Assuming uniform heat generation within the fuel element, the steady, two-dimensional heat conduction equation along with appropriate boundary conditions is solved using second order accurate finite difference scheme. On the basis of axial temperature profiles and the variation of Biot number, Bi and heat generation parameter, Q with respect to maximum temperature, θ_max within the fuel element, results are presented for a wide range of aspect ratio, A_r, Bi, and Q and discussed in detail. It is found that with the increase in Ar, the effect of axial conduction on the temperature profile diminishes rapidly and ultimately for all values of A_r ≥7, it remains confined to the region very close to the leading edge. It is also concluded that for a set of fixed values of A_r and Q, there exists a lower limiting value of Bi below which it cannot be decreased. Similarly, for a set of fixed values of A_r and Q, there also exists an upper limiting value of Q above which θ_max exceeds its allowable limit. Furthermore, it is concluded that the requirement of increase in Bi due to increase in Q, θ_max being within its allowable limit, becomes larger and larger as Q becomes higher and higher.