TRACKING INTERNATIONAL OBLIGATIONS IN URANIUM ACCOUNTING \"POOL\"

Both Euratom and the United States are using a system of codes to track and report foreign obligated nuclear material. Fungibility, equivalence, and proportionality principles regulate this tracking. In the case of uranium in accounting \"pools\", blending or enrichment can lead to discrepancies if the proportionality principle is applied without care. We present the types of discrepancies that occur in these pools. We argue that proportions should be calculated using the mass of special fissile material as a reference and that the element mass should then be calculated as a function of the average enrichment in order to correct discrepancies.