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

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0.4<br />

and 75 radionuclides. A summary <strong>of</strong> cumulative dose and percent contribution by nuclide for<br />

each food type is calculated. Radionuclide concentrations in soil, plants, and animal pro-<br />

ducts are also calculated.<br />

D.1.2 Accidental Releases<br />

The dose to individuals exposed to a passing cloud <strong>of</strong> accidentally released radio-<br />

nuclides consists <strong>of</strong> external and internal components. The external radiation doses are<br />

calculated using the computer code SUBDOSA (1975), and the spatial distribution determined<br />

by the methods described in Meteorology and Atomic Energy (Slade 1968) and code XOQDOQ<br />

(Sagendorff and Goll 1977) for a semi-infinite cloud. External exposure results from both<br />

gamma radiation and beta particles emitted from radionuclides while they are airborne and<br />

external to the human receptor. This dose is dependent not only upon the type <strong>of</strong> radiation<br />

(i.e., gamma or beta) but also upon the energy <strong>of</strong> the radiation and the spatial distribution<br />

<strong>of</strong> the airborne radionuclides with respect to the receptor. The type and energy <strong>of</strong> radia-<br />

tion are characteristic <strong>of</strong> each radionuclide.<br />

Because the range <strong>of</strong> beta particles in the air is only a few meters, the air concentra-<br />

tion at ground level is sufficient to calculate the doses resulting from beta-emitting<br />

radionuclides. Ground-level air concentrations are not sufficient, however, for calculating<br />

the dose from gamma radiation. This is due to the relatively large range <strong>of</strong> gamma radiation<br />

in air. This range varies according to gamma energy and can be as long as a few hundred<br />

meters. As a result, the dose from external exposure to gamma radiation during cloud pas-<br />

sage depends upon the air concentration at distances up to a few hundred meters. Thus the<br />

height <strong>of</strong> release has much less effect on gamma dose than it does on beta dose, particularly<br />

at close distances. As before for air submersion doses, both beta and gamma radiations con-<br />

tribute to skin dose; but only gamma radiation contributes to total-body dose (calculated<br />

at 5 cm depth).<br />

Inhalation doses are calculated using the same models and codes used for chronic<br />

release except for increased ventilation rate (0.35 t/sec) (Sagendorff and Goll 1977;.<br />

D.1.3 Dose to Biota Other Than Man<br />

The doses to terrestrial and aquatic animals living within the influence <strong>of</strong> the nuclear<br />

facilities described in this report were not calculated separately. Two recent compre-<br />

hensive reports (NAS-NRC 1971 and Garner 1972) have been concerned with radioactivity in the<br />

environment and pathways to biota other than man. Depending on the pathway being consid-<br />

ered, terrestrial and aquatic organisms will receive either about the same radiation doses<br />

as man or somewhat greater doses. Although no guidelines have been established to set<br />

acceptable limits for radiation exposure to species other than man, it is generally agreed<br />

that the limits established for humans are also conservative for t .se species (Auerbach<br />

1971).<br />

The literature relating to radiation effects on organisms is extensive, but very few<br />

studies have been conducted on the effects <strong>of</strong> continuous low-level exposure to radiation

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