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

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Draft p. 3.6.7<br />

Issue<br />

365<br />

ALTERNATIVE DISPOSAL CONCEPTS<br />

Why would one expect low nuclide concentrations around a waste canister? If the can-<br />

ister failed, one would expect high levels. (113-EPA)<br />

Response<br />

Canisters will be designed so that containment rather than failure will be expected.<br />

In the multiple-barrier concept, there is a waste form inside the canister which, if the<br />

canister failed, would release nuclides very slowly if at all, and therefore one would not<br />

expect high contamination levels.<br />

Draft p. 3.6.7<br />

Issue<br />

Previous reports on the U.S. seabed disposal program have not included the water<br />

column as a design barrier. Is it the program's intention to now identify the water column<br />

as a primary design barrier to radionuclide migraton, or rather to investigate its proper-<br />

ties as a barrier only for unexpected releases? In other words, do the conceptual plans<br />

allow for radionuclides to enter the water column during the period when they may present a<br />

hazard to man or the ecosystem? What is meant by inadvertent release? Scenarios leading<br />

to inadvertent release should be described. (208-NRC)<br />

Response<br />

The water column, which extends from the benthic boundary layer to the surface <strong>of</strong> the<br />

water, would only provide dilutional.mitigation to the release <strong>of</strong> radionuclides. It is not<br />

considered an isolation barrier between the water and the biosphere, but is considered a<br />

barrier in the sense that it impedes man's intrusion into the subseabed repository.<br />

"Inadvertent" means "unintended by man". It is not appropriate at this early stage <strong>of</strong><br />

the program to develop all possible scenarios <strong>of</strong> inadvertency.<br />

Draft p. 3.6.7<br />

Issue<br />

The fourth sentence <strong>of</strong> paragraph 6 appears to overdramatize the potential effect <strong>of</strong><br />

heating and should be more realistically reworded. Also, the "risks" associated with sink-<br />

ing <strong>of</strong> the waste in the sediment should be explained, particularly in light <strong>of</strong> the prefer-<br />

ence for penetrometer emplacement. (58)

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