ANSI/ANS-8.12-1987(R93): Criticality control of plutonium-uranium mixtures

American National Standards Institute/American Nuclear Society (ANSI/ANS)-8.12-1987(R93) was approved for use on September 11, 1987. The first version of this standard, which only included subcritical limits on homogeneous plutonium-uranium fuel mixtures, was approved July 17, 1978. The current version was revised to include limits on heterogeneous systems as well. This paper provides additional information on the limits presented in the standard. As stated in its forward, the standard open-quotes ... provides guidance for the prevention of criticality accidents in the handling, storing, processing, and transporting of plutonium-uranium fuel mixtures outside reactors and is applicable to all operations involving mixtures of plutonium and natural uranium.close quotes It constitutes an extension of the American National Standard for Nuclear Criticality Safety in Operations with Fissionable Materials Outside Reactors, ANSI/ANS-8.1-1983. The standard includes subcritical limits for both homogeneous mixtures and heterogeneous lattices of plutonium and uranium. The uranium is assumed to be natural or depleted