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

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102<br />

CONSEQUENCE ANALYSIS<br />

in addition to the releases used in accident number 6.2.8. The probability <strong>of</strong> accidents<br />

occurring where several release mechanisms operate is less than the probability associated<br />

with accidents where only a few release mechanisms operate. Thus the risk may be greater<br />

for the latter accident than the one involving many release mechanisms. Recommend the GEIS<br />

address these accidents that involve several release mechanisms and show that either the<br />

risks involved are less than those <strong>of</strong> accident number 6.2.8 or if the risks are greater,<br />

this more severe accident should be used as the umbrella source term for severe accidents.<br />

(208-NRC)<br />

Response<br />

An Assessment <strong>of</strong> the Risk <strong>of</strong> Transporting Spent Nuclear Fuel by Truck (PNL-2588, Elder<br />

et al. 1978 in reference list) was not available at the time <strong>of</strong> the writing <strong>of</strong> DOE/ET-0028.<br />

Available literature at the time, primarily WASH-1238 (AEC 1972), stated that a vaporization<br />

,release <strong>of</strong> cesium was the most likely mechanism for the release <strong>of</strong> radionuclides from a<br />

spent fuel accident <strong>of</strong> the type considered in this EIS. Other mechanisms for radionuclide<br />

release may exist, but they are either small compared to those used in the present Statement<br />

or require cask failures in excess <strong>of</strong> the design basis accident spectrum. PNL-2588 (Elder<br />

et al. 1978) and DOE/ET-0028 agree that cesium is the largest contributor to consequences<br />

from accidents involving overheated fuel with a small breech <strong>of</strong> the cask wall or<br />

penetration.<br />

Draft p. N.4<br />

Issue<br />

Although the radiation dose to the maximum individual from postulated accidents are<br />

given, the total population dose to persons in the vicinity <strong>of</strong> the accident is not given.<br />

Since this is an important environmental impact, it should be included in the GEIS in<br />

context with accident frequencies.<br />

The actual value for this population dose can be found on p. 4.1.10 <strong>of</strong> DOE/ET-0029.<br />

The 70-year dose commitment is given as 140 man-rem. Although the analysis uses a popula-<br />

tion density <strong>of</strong> 90 persons per square km for routine radiological impacts, the population<br />

density used for the accident analysis is 130 person per square km. Note that population<br />

densities in suburban or urban areas can be at least an order <strong>of</strong> magnitude higher than this<br />

population density. A severe accident occurring in a suburban or urban area would, there-<br />

fore, have a substantially greater environmental impact than the accident consequences pre-<br />

sented in the GEIS. In order that all relevant impacts be included in the GEIS, recommend<br />

including the consequences <strong>of</strong> severe accidents in high population density areas.<br />

The largest accident dose reported in the GEIS results from a severe accident involving<br />

a rail shipment <strong>of</strong> spent fuel. The resulting whole-body dose to the maximum individual is<br />

given as 120 rem for a one year period following the accident. The dose is based on the

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