Developing a Tool for Simulating the Behavior of Axial Flux Difference During Power Reduction for Maanshan Pressurized Water Reactor Units

A tool, AFDCONTROL, is developed to help the operators of pressurized water reactors predict axial flux difference (AFD) and find the control rod positions for power maneuvers. AFDCONTROL has used an off-line procedure to simulate AFD.

After adopting a long-cycle strategy as the fuel management policy of Maanshan nuclear power plant (MNPP), AFD control during the power reduction near end of cycle (EOC) becomes more difficult than before. In this study, we have used AFDCONTROL to simulate this trend. AFDCONTROL suggests that AFD (even at higher burnup conditions) can be controlled by extending the power reduction rate. After implantation of the AFDCONTROL tool in MNPP, the operators of MNPP units have used AFDCONTROL to find the control rod sequences and positions under certain power reduction rates to control AFD without violating limits, especially at EOC of the high-burnup cycle.