abnormal situation: Unplanned event or condition that adversely affects, potentially affects, or indicates degradation in
the safety, security, environmental, or health protection performance or operation of a facility.
accountable sealed radioactive source: A sealed radioactive source having a half-life equal to or greater than 30 days
and an isotopic activity equal to or greater than the corresponding value provided in Appendix 4A of this Standard [see
activation: Process of producing a radioactive material by bombardment with neutrons, protons, or other nuclear
administrative control level: A numerical occupational dose constraint established at a level below the occupational
dose limits provided in Chapter 2 to administratively control and help reduce individual and collective dose.
airborne radioactivity: Radioactive material dispersed in the air in the form of dusts, fumes, particulates, mists, vapors,
or gases [see 835.2(a)].
airborne radioactivity area: Any area, accessible to individuals, where:
a. the concentration of airborne radioactivity, above natural background, exceeds or is likely to exceed the
derived air concentration (DAC) values listed in appendix A or Appendix C of 10 CFR 835; or
b. an individual present in the are without respiratory protection could receive an intake exceeding 12 DAC-
hours in a week [see 835.2(a)].
annual limit on intake (ALI): The derived limit for the amount of radioactive material taken into the body of an adult
worker by inhalation or ingestion in a year. ALI is the smaller value of intake of a given radionuclide in a year by the
reference man (ICRP Publication 23) that would result in a committed effective dose equivalent of 5 rems (0.05 sievert)
or a committed dose equivalent of 50 rems (0.5 sievert) to any individual organ or tissue [see 835.2(a)].
As Low As is Reasonably Achievable (ALARA): The approach to radiation protection to manage and control
exposures (both individual and collective) to the work force and to the general public to as low as is reasonable, taking
into account social, technical, economic, practical, and public policy considerations. As used in this Standard, ALARA
is not a dose limit but a process that has the objective of attaining doses as far below the applicable controlling limits as
is reasonably achievable [see 835.2(a)].
ALARA Committee: Multi-disciplined forum that reviews and advises management on improving progress toward
assessment: Evaluation or appraisal of a process, program, or activity to estimate its acceptability.
background radiation: Radiation from:
(1) Naturally occurring radioactive materials which have not been technologically enhanced;
(2) Cosmic sources;
(3) Global fallout as it exists in the environment (such as from the testing of nuclear explosive devices);
(4) Radon and its progeny in concentrations or levels existing in buildings or the environment which have not
been elevated as a result of current or prior activities; and
(5) Consumer products containing nominal amounts of radioactive material or producing nominal amounts of
radiation [see 835.2(a)].
becquerel (Bq): The International System (SI) unit for activity of radioactive material. One becquerel is that quantity of
radioactive material in which one atom is transformed per second or undergoes one disintegration per second.