scope:

Introduction

The American National Standard for Nuclear Criticality Safety in Operations with Fissionable Materials Outside Reactors, N16.1-}975 (AN8-S.1)(1]^l. provides single parameter limits for operations with ²³³U, ²³⁵U. and ²³⁹Pu. The principal interest in criticality safety is in these isotopes of uranium and plutonium since they are the most abundant. but there are also other isotopes of these nuclides and other elements within the actinide group that are capable of supporting a chain reaction and that may be encountered in sufficient quantities to cause concern. It has been speculated that potential requirements for certain of the synthetic actinide elements could lead to their production in large. possibly ton. quantities.^2,3

¹ Numbers in brackets refer to corresponding numbers in Section 7, IUferences,

² See Reference Al in the BiblWgraphy.

³ The phySical characteristics of the principsl actinide elements of interest are given in Appendiz B.