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

C.1
APPENDIX C
RADIOLOGICAL STANDARDS
Numerical values of annual dose limits have been set by the Nuclear Regulatory Commis-
sion (NRC) and Department of Energy (DOE). These limits and the Concentration Guides (10
CFR 20) derived from them are based on limits for occupationally exposed workers recommended
by the National Committee on Radiation Protection and Measurements (NCRP 1957, 1959) and
the International Commission on Radiological Protection (ICRP 1958, 1959).. Minor modifica-
tions were made as a result of Federal Radiation Council (FRC) recommendations (1960) and
more recent NCRP recommendations (1971). A review of the known biological effects of ion-
izing radiation by the National Academy of Sciences-National Research Council (NAS-NRC 1972)
confirmed an earlier recommendation for limiting genetic exposure of the population, which
corresponded to that of the NCRP. All these scientific bodies considered available data on
both immediate and delayed effects:
* medical data on effects following therapeutic use of external radiation sources
such as X-rays, and of radionuclides such as radium and iodine.
* occupational accident data on exposure of radiologists, X-ray and cyclotron work-
ers, and workers in nuclear industry
* observations on population groups such as atomic bomb survivors and those irra-
diated by heavy nuclear weapons test fallout near the Marshall Islands.
Delayed effects, observable only years after exposure, were inferred from consideration
of data from animal experimentation, from available epidemiological statistics, and from a
limited number of case observations from medicine and industry (most notably a group of
radium dial painters). The potential effects considered were 1) genetic effects and
2) somatic effects, including leukemia, skin changes, neoplasms, cataracts, changes in life
span, and effects on growth and development. The delayed effects produced by ionizing
radiation in an individual are not unique to radiation. For the most part they are indis-
tinguishable from conditions normally present in the population, which may be induced by
other causes.
In deriving the 10 CFR 20 Concentration Guides, a uniform exposure period of 50 years
for adults was used. When dealing with intakes of radionuclides with effective half-lives
in the body of less than 90 days, or where calculating doses directly from air.and water
concentrations by ratio to the appropriate Concentration Guides, the number of years of
exposure makes little difference in the dose calculations. However, problems arise for non-
uniform exposures to radionuclides with longer effective half-lives, especially when dealing
with several exposure pathways and a heterogeneous population of varying ages and local
residence periods. Although ICRP publications (1968, 1971) aid in making dose calculations,
proper application of annual dose limits in such instances is controversial. The implied
method is to calculate a total dose to an organ for a "standard man" for 50 years including