A new power mapping method based on ordinary kriging and determination of optimal detector location strategy

• A new power mapping method based on Ordinary Kriging (OK) is proposed.
• Measurements from DayaBay Unit 1 PWR are used to verify the OK method.
• The OK method performs better than the CECOR method.
• An optimal neutron detector location strategy based on ordinary kriging and simulated annealing is proposed.

The Ordinary Kriging (OK) method is presented that is designed for a core power mapping calculation of pressurized water reactors (PWRs). Measurements from DayaBay Unit 1 PWR are used to verify the accuracy of the OK method. The root mean square (RMS) reconstruction errors are kept at less than 0.35%, and the maximum reconstruction relative errors (RE) are kept at less than 1.02% for the entire operating cycle. The reconstructed assembly power distribution results show that the OK method is fit for core power distribution monitoring. The quality of power distribution obtained by the OK method is partly determined by the neutron detector locations, and the OK method is also applied to solve the optimal neutron detector location problem. The spatially averaged ordinary kriging variance (AOKV) is minimized using simulated annealing, and then, the optimal in-core neutron detector locations are obtained. The result shows that the current neutron detector location of DayaBay Unit 1 reactor is near-optimal.