Design and Preliminary Evaluation of the Near Real-time Accounting System for a Reprocessing Facility

The near real-time nuclear material accounting system for a spent fuel reprocessing facility was designed and preliminarily evaluated. Based on routine cycle accounting and the method of shortening the traditional accounting cycle，combined with the inventory data of nuclear materials in process equipment or containers，a preliminary real-time accounting analysis model for nuclear materials has been established. This study employed the reference 200 MTHM/a facility and its operating data from the International Atomic Energy Agency’s STR-193，the real-time balance calculation analysis across different time intervals was conducted by using a batch-wise error calculation and synthesized model. Comparative analysis was performed against semi-annual analysis data from routine closed balance calculations. The results indicate that near real-time accounting is feasible and a monthly calculation period is deemed sufficient under this specified balance model. A preliminary investigation of dynamic analysis and Page’s test was conducted using time-correlated dynamic data simulation upon this balance calculation model. The results indicate that both cumulative and Page’s test are effective in detecting significant sudden losses of nuclear materials. Page’s test，particularly in detecting cumulative losses of nuclear materials，especially under conditions with longer accounting periods and approaching detection limits，demonstrates superior anomaly detection capabilities compared to cumulative evaluation，with the ability to control false alarm rate. The near real-time accounting system makes the entire system more effective in anomaly detection and can be used for dynamic trend analysis of nuclear material management in the future，thereby improving the application value of nuclear material accounting management.