Research of Dynamic Rod Worth Measurement Technique Based on the Pin-by-pin Response Function

•The DRWM technique with the pin-by-pin response function has been proposed.•The three-dimensional pin-by-pin response function of the ex-core detector is obtained by the adjoint method with the Hydra code.•The pin-power reconstruction based on source-expansion method has been adopted to provide the pin-by-pin power distribution under steady and transient calculation. The dynamic rod worth measurement (DRWM) technique is widely applied in PWR engineering. In DRWM, the response function of the ex-core detector is very significant to calculate the spatial-correction factors which are introduced to eliminate the spatial effects due to the rapid movement of control rods. Theoretically, the peripheral pins of the peripheral fuel assemblies close to the ex-core detector have large contributions to the ex-core detector signal. However, the conventional DRWM technique only uses the nodal response function, which can’t consider the pin-level contribution. Therefore, the DRWM technique based on the pin-by-pin response function has been proposed in this study. This proposed technique has been applied and verified with the measurement data of commercial PWRs operated in China. The engineering verification showed that this technique could provide accurate spatial-correction factors, and the measured control-rod worth satisfies the engineering acceptance criteria.