Induced thermal stresses in Ghana Research Reactor-1 reactor vessel by nuclear fission-related events

Ghana intends to acquire a nuclear power reactor in future, and expertise and techniques of computational science and engineering, mathemetical modeling, simulation and thermal stress analysis are required. This will ensue that various operations of nuclear power plant could be monitored for control and safety. Many structural elements of hollow cylinders are subjected to rapid heat deformation or failure due to induced thermal stresses.The structural integrity of a nuclear reactor vessel is one of the most critical issues in a nuclear power plant design. The consequences of failure as a result of inadequate induced thermal stress distributions are generated by the absorption of gamma rays, coolant heating, sinusoidal and other thermal loadings resulting from turbulant mixing or vortices at the interior surface of the vessel. This research presents mathematical models of the induced thermal stresses in Ghana Research Reactor-1 (GHARR-1) reactor vessel by nuclear fission-related events. In this thesis, analytical models and numerical models based on control volume finite difference method of the transient temperature distributions due to the absorption of gamma rays from the core, coolant heating and sinusoidal loading as a result of turbulant mixing or vortices and consequent thermal stresses in GHARR-I reactor vessel were developed. Solutions algorithms for matlab programming were implemented for generating data for transient analysis and simulation. From the data, the temperature distributions and the subsequent thermal stress deduced were below the limits imposed by the vessel material composition (melting point of 933 oK and allowable yield stress of 480 MPa). In general, there were very good agreement between predictions from analytical models and estimations for temperatures and thermal stresses developed, inspite of the assumptions adopted in the analytical models. Therefore, the analytical model could be used effectively to simply and quickly provide good reference representations for the thermal stress design of cylindrical structural components subjected to gamma ray energy, coolant heating and sinusoidal thermal loading. For all cases of transient scenarios, investigated, the structural integrity of GHARR-1 reactor vessels would be maintained to forestall the incident of crack propagation and fatigue failure associated with induced thermal stresses. (au)