On-line monitoring analysis of BEAVRS benchmark using NECP-ONION

摘要

On-line monitoring analysis has been carried out for BEAVRS benchmark using NECP-ONION, which is a 3D power distribution on-line monitoring system developed by NECP lab. Harmonics expansion method is employed to obtain the spatially continuous 3D on-line power distribution based on detector measurements in this system. Krylov subspace method is used to solve harmonics from diffusion equation. Traditional two-step method calculation has been used to afford initial predicted flux and power distributions to monitoring system. CASMO4E and NECP-SIMME have been chosen as the assembly/reflector few-group constants solution and the core fuel management solution. Boron letdown curve was calculated with HFP-ARO condition, while the detector responses with the simplified power history. Errors of boron concentration to measured values are small. Detector response differences between monitoring results and measurements are within the acceptable limits. The monitoring system has excellent accuracy.