MUF, or "material unaccounted for," is a term commonly used in the nuclear processing industry. It refers to the difference between the amount of nuclear material that is supposed to be present in a facility and the amount that is actually measured. This discrepancy can arise from various factors, including inherent process losses, measurement uncertainties, and, in some cases, diversion of material.[^1] At the [[Nuclear Materials and Equipment Corporation|NUMEC]] plant, MUF became a significant issue, with over two hundred pounds of enriched uranium unaccounted for. The [[Atomic Energy Commission|AEC]] eventually worked out complicated rules for accounting for MUF, enabling private firms to estimate how much missing but accountable uranium was believed to be in a plant's air filtration system or buried in its waste pits. The AEC accepted these estimates as realistic and deferred assessments of penalties, assuming that no reprocessing firm would divert or steal uranium if it resulted in a stiff fine.[^1] ### Footnotes [^1]: Hersh, Seymour M. *The Samson Option: Israel's Nuclear Arsenal and American Foreign Policy*. Random House, 1991. Chapter 18.