The development of TM2-RIA code for TRIGA type research reactors

This work presents the development of indigenous code TM2-RIA for steady-state and transient analyses of TRIGA type research reactor at Istanbul Technical University Energy Institute. The 2-dimensional code adapts piecewise constant function for solving point kinetics equation linked with thermal–hydraulic equations for cylindrical fuel type. TM2-RIA provides flexibility of implementing different delayed neutron parameters, it also offers different thermal-hydraulics structure options (number of channels and control volumes). The code is tested against the experimental data and calculations of EUREKA-2/RR code. Considering many experimental uncertainties, the TM2-RIA 5-channels model agrees acceptably with the steady-state experimental results. In the transient analyses, three pulsing scenarios are investigated, based on the results, the code has performed differently with different neutronic sets and thermal-hydraulics structures. That indicates how the reactor kinetics is being influenced by the differences in the recorded thermal history, and it shouldn't be neglected even for small deviation. Besides, the constant overestimation of the fuel temperatures implies the need for modelling the heat sink induced by central Zirconium rod in fuel element and investigating its effect. That being said, the code agrees fairly well in many cases corresponding to those changes, when it predicts the peak power and fuel centerline temperature. Moreover, the gap between the experimental and the numerical results for the fuel temperature gets smaller with the increase of the pulsing reactivity. Another promising aspect is that the adapted point kinetics approach shows similar performance, in comparison with the common Cohen's approach used by EUREKA-2/RR, while providing relative simplicity in developing and implementing the TM2-RIA code.