-- ANSI/ANS-8.15, Nuclear Criticality Control of Special Actinide Elements (ANSI,
1981). This standard provides the single nuclear criticality control parameter limits for
the unique aspects of the special actinides (e.g., certain neptunium, plutonium,
americium, and curium isotopes).
-- ANSI/ANS-8.19, Administrative Practices for Nuclear Criticality Safety (ANSI, 1984).
This standard provides the elements of an acceptable nuclear criticality safety program
for operations outside of reactors.
Additional Standards of interest that are not required by DOE Order 420.1A include:
-- ANSI/ANS-8.20, Nuclear Criticality Safety Training (ANSI, 1991). This standard
(referenced in DOE Order 5480.20A) provides the criteria for the administration of a
nuclear criticality safety training program for personnel who manage, work in or near
facilities, or work outside of reactors, where the potential exists for nuclear criticality
-- ANSI/ANS-10.3, Documentation of Computer Software (ANSI, 1986b). This standard
presents guidelines for documenting computer codes (i.e., user documentation) for
engineering and scientific applications.
-- ANSI/ANS-10.4, Guidelines for the Verification and Validation of Scientific and
Engineering Computer Programs for the Nuclear Industry (ANSI, 1987a). The
objective of this standard is to identify processes that will enhance the reliability of
computer codes used in the nuclear industry and reduce the risk of incorrect
CRITICALITY CONTROL FACTORS
For a criticality accident to occur, there must be a critical mass of fissionable material. As
noted in ANSI/ANS-8.1 (ANSI, 1983b), the critical mass is a function of the radionuclides
in the material as well as its density, chemical and physical form, shape, and surroundings
through the control over both the quantity and distribution of fissile materials and other
materials capable of sustaining a chain reaction as well as the control of the quantities,
distributions, and nuclear properties of all other materials with which fissile materials are
associated. For new facilities, DOE requires that design considerations for the establishing
types, and nuclear poisons (neutron absorbers). The use of administrative controls is to be
minimized (DOE, 2002a).
Nuclear criticality control factors can be classified as technical (e.g., geometry controls and
mass limitation controls) or administrative (e.g., operating procedures).