Simulation of over-power transients in tank-in-pool type research reactors

A tank-in-pool type Research Reactor Simulator (TPR2) has been developed which models the core neutronics using the point kinetics equations along with the Doppler and moderator reactivity feedbacks. For thermalhydraulic calculations, it uses a lumped parameters, multizone model based correlation which has been verified by physical mockup of the reactor assembly. The coupled set of dynamics equations has been solved by the semi-implicit method utilizing Richardsonʹs extrapolation scheme. The computer implementation includes adaptive time step control which enables the simulations to be carried out in real-time and even faster. The predictions of the TPR2 simulator have been compared with the experimental data obtained for transient over power (TOP) tests carried out at the Pakistan Research Reactor-2 (PARR-2). The TPR2 computed values of the reactor power and the coolant temperatures at the core outlet were found in good agreement with the corresponding experimental data throughout various positive reactivity induced transients.