Finite difference analysis of the transient temperature profile within GHARR-1 fuel element

• Transient heat conduction for GHARR-1 fuel was developed and simulated by MATLAB.
• The temperature profile after shutdown showed parabolic decay pattern.
• The recorded temperature of about 411.6 K was below the melting point of the clad.
• The fuel is stable and no radioactivity will be released into the coolant.

Mathematical model of the transient heat distribution within Ghana Research Reactor-1 (GHARR-1) fuel element and related shutdown heat generation rates have been developed. The shutdown heats considered were residual fission and fission product decay heat. A finite difference scheme for the discretization by implicit method was used. Solution algorithms were developed and MATLAB program implemented to determine the temperature distributions within the fuel element after shutdown due to reactivity insertion accident. The simulations showed a steady state temperature of about 341.3 K which deviated from that reported in the GHARR-1 safety analysis report by 2% error margin. The average temperature obtained under transient condition was found to be approximately 444 K which was lower than the melting point of 913 K for the aluminium cladding.Thus, the GHARR-1 fuel element was stable and there would be no release of radioactivity in the coolant during accident conditions.