Material surveillance and verification programme at a uranium enriching plant

A licence for a nuclear facility in the United States of America is approved only after a licencee demonstrates by procedure or practice that an adequate material control system exists. A licence can specify acceptable material control practices. Therefore, processors in the United States receiving uranium hexafluoride (UF6) from a United States Government-owned enriching plant can accept shipper's values for nuclear material accounting purposes if: (1) there is surveillance during withdrawal of the UF6; (2) an independent sample is obtained; and (3) certain measurement verification is subsequently performed by the receiver or the receiver's agent. Because of the high equipment and operating costs, essentially all UF6 processors have adopted a surveillance and verification programme. A resident observer is employed to perform surveillance, obtain samples, and make the shipping cylinders tamper-safe. Samples are analysed by the receiver or by an independent laboratory. The observer determines by surveillance that withdrawals, or transfers of material, weighings, and sampling are accomplished in accordance with accepted procedures. Surveillance of the withdrawals includes observing the transfer of UF6 from the enriching plant cylinder to the shipping cylinder(s) and the withdrawal of samples. In addition, it includes observing the weighing of all cylinders associated with a sample lot of UF6. Following the surveillance of withdrawals, weighings, and sampling, the cylinders are made tamper-safe by the application of tamper-indicating devices. Statistics for the verification programme have shown shipper and receiver measurements to be within the limits acceptable for adequate material control. (author)