PLATFORM SCALE TESTING TO SUBSTANTIATE LOAD CELL MONITORING FOR NUCLEAR SAFEGUARDS

摘要

The International Safeguards Group at the Oak Ridge National Laboratory installed and commissioned a Platform Scale Testing Center designed to investigate the accuracy and performance capabilities of a variety of load cell weighing systems which mimic the size, capacity, and function of weighing systems used in a UF_6 product withdrawal station. Measuring the weight of UF_6 cylinders is a primary measurement method used for nuclear material accountancy, process control and safety. Use of continuous, unattended monitoring of process load cells in feed and withdrawal stations can significantly improve capabilities for detecting credible diversion and undeclared production scenarios. If process load cell data are used to reach safeguards conclusions, the accuracy of these scales could directly influence the inspection schedule and activities. Early performance tests showed that when operated and calibrated according to weighing industry standards, platform scales perform well within the expected accuracies. These tests also demonstrated that, in general, the scales are robust against improper loading scenarios. Alternative calibration procedures were also tested and revealed that the alternative calibration approaches are susceptible to errors that could result in observed material inventory differences that may be greater than a significant quantity of material. The presented research shows that if the safeguards community ensures that the scales are properly calibrated and maintained, feed and withdrawal process scales are generally robust and meet the accuracy required to provide a viable safeguards measure.