THE USE OF PROCESS INFORMATION FOR VERIFICATION OF INVENTORYIN SOLVENT EXTRACTION CONTACTORS IN NEAR-REAL-TIME ACCOUNTING FOR REPROCESSING PLANTS*

Near-real—time accounting is being studied as a technique for improving the timeliness of accounting in nuclear fuel reprocessing plants. A major criticism of near-real-time accounting is perceived disclosure of proprietary data for IAEA verification, particularly in verifying the inven- tory of solvent extraction contactors. This study indicates that the contribution of uncertainties in estimating the inventory of pulsed columns or mixer settlers may be insignificant compared to uncertainties in measured throughput and measur- able inventory for most reprocessing plants, and verification may not be a serious problem. Veri- fication can become a problem for plants with low throughput and low inventory in tanks if contactor inventory variations or uncertainties are greater than ~25%. Each plant must be evaluated with respect to its specific inventory and throughput characteristics.