Development of a Predictor-Corrector Quasi-Static Transient Fission Matrix combination method for the neutronics transient simulation

The Transient Fission Matrix (TFM) method was introduced as a hybrid approach for conducting 3D whole-core kinetic calculations with reduced computational expense. While more efficient than direct Monte Carlo simulations, the efficiency of TFM transient simulations is primarily constrained by the TFM creation and source iteration process. This paper proposes a Predictor-Corrector Quasi-Static method (PCQM) based transient fission matrix combination method aimed at achieving highly efficient kinetic simulations. The innovative fission matrix combination theory is further developed for transient scenarios to rapidly estimate the whole-core TFM when system changes occur. In the predictor step, a temporal-collapsed TFM is initially employed to compute a source shape function. This information is then integrated with the original TFM in the corrector step to determine dynamic parameters and solve the point-kinetics equation, yielding the amplitude function. The efficacy of the algorithm is validated using a PWR-based control rod drop transient problem. The results demonstrate strong agreement with direct Monte Carlo results, yet the computations can be completed within minutes.