Results from uranium deposition studies for development of a limited frequency-unannounced access inspection strategy for gas centrifuge enrichment plants

Uranium deposition studies were performed on a test loop system designed to simulate process gas flow through the header piping of a gas centrifuge enrichment plant. The objectives of these studies were to investigate the effectiveness of an in-line gaseous cleaning agent in removing uranium in pipe deposits and to analyze long-term deposition growth and isotopic exchange under simulated centrifuge plant operating conditions. The test loop studies are described, the results are reported, and the implications for analyzing actual plant data are discussed. Results indicate that (1) 93% of the uranium deposit is removed within 15 min when a pipe is pressurized with gaseous ClF3, (2) the isotopic abundance of a highly enriched uranium deposit remains unchanged when UF6 of a lower assay is introduced into the pipe, and (3) air inleakage will be the cause of the largest deposits in centrifuge plant process header pipes