Management of Commercially Generated Radioactive Waste - U.S. ...

C.3
C.1 "AS LOW AS REASONABLY ACHIEVABLE" APPLICATION
The degree of risk to people from very low radiation doses is not apt to be answered
by actual observations, now or in the future, because of the indicated low probability
(ERDA 1975) of any observable health effect in individuals and the nonspecific nature of
some effects. Although the ICRP and NCRP have previously recognized as working hypotheses
the presumably conservative assumptions that all radiation effects would be linear with
dose, have a zero threshold, and be independent of dose rate, the NCRP has reiterated its
stand (1975) against using these assumptions for deriving numerical values for risk-benefit
calculations. More recently, the ICRP (1977) has attempted to distinguish between certain
somatic effects for which a threshold dose seems applicable and other somatic (primarily
neoplasms) and genetic effects for which the zero threshold, linear hypotheses still should
be applied. In any case, the basic principle of radiation protection is still that all
radiation exposures of people should be kept to the lowest levels technically and economi-
cally practicable.
The Nuclear Regulatory Commission's 10 CFR 50 Appendix I (1975) defines "as low as
reasonably achievable" (ALARA) population dose limits for light-water-cooled nuclear reac-
tor effluents, primarily for design guidance, but also as an action level for operational
control. Other nuclear facilities are not specifically covered. The NRC in the published
summary of its formal opinion has adopted the use of the phrase "as low as is reasonably
achievable" (as recommended by the ICRP in 1973) as a substitute for "as low as practi-
cable," because ALARA is a more precise definition of the intention of this regulation.
The numerical values of limits assigned by the NRC, for design guidance for each light-
water reactor, are that whole-body doses to any individual shall not exceed 3 mrem per year
from liquid effluents or 5 mrem per year from external radiation resulting from gaseous
effluents.
At present, the dose limits cited in Section 2.2.1 still prescribe upper boundaries for
permissible doses to people. Some fractions of these limits (or the corresponding Concentration
Guides) are generally understood to be "as low as reasonably achievable" for routine
waste management operations. Whether those should be 0.1, 0.01, or some other fractions of
the dose limits can be evaluated for each facility and effluent stream only on a case-bycase
basis by considering the effluent treatments and controls available and the costs of
providing such treatment or controls.