The Effect of Burnup on ITU TRIGA Mark II Research Reactor Control Parameters

The fuel temperature, control rod worth, pool water temperature, reactor power, and prompt temperature coefficient are important parameters to define the research reactor system design basis. In this study, change in control rod worth, excess reactivity, neutron flux, and delayed neutron fraction of ITU TRIGA Mark II Research Reactor was calculated for fresh and 55 day-burnt fuel. 3D full core MCNP 6.2 model was used for burnup calculations to obtain the fuel composition in each of the 69 fuel elements. The new core configuration was modelled numerically to create integral rod worth curves of transient, safety, and regulating rods. ENDF/B-VII.1 library was used for the cross section data and rod insertion method was employed for numerical analysis of control rod worth. The rod worth calculation methodology, as well as MCNP model and simulations were benchmarked against the fresh core configuration results for validation and verification. The results showed the change in safety related parameters. The rod worth and excess reactivity are decreased with the burnup. Therefore, a new core configuration is necessary to retrieve the lost reactivity due to burnup by shuffling and/or fresh fuel addition.