摘要
Core axial power distribution is an essential topic in pressurized water reactor(PWR)reactivity control.Traditional PWRs limit stability against axial core power oscillations at a high-cycle burnup.Because the‘‘camel’’peak power shape typically occurs with increasing depletion,the approaches used for the axial power control deserve special attention.This study aims to investigate the performance of different gadolinium rod design schemes in core axial power control during power operation based on the reactivity balance strategy,and to propose new multiconcentration gadolinium rod design schemes.In the new design schemes,low-concentration gadolinium pellets are filled in the axial hump part of the gadolinium rod,and high-concentration gadolinium pellets are filled in the other parts.The impact of different gadolinium rod design schemes on the main core characteristics was evaluated using the nuclear design code package PCM developed by CGN.The results show that the new gadolinium rod design significantly impacts the core axial power shape.The new design schemes can efficiently improve the core axial power distribution along the entire cycle by reducing the core axial power peak at the end of a cycle,enhancing the reactor operation stability,and achieving a better core safety margin,revealing a sizeable potential application.
