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

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Draft p. 3.3.33<br />

Issue<br />

328<br />

ALTERNATIVE DISPOSAL CONCEPTS<br />

The section on thermomechanical behavior <strong>of</strong> rocks does not acknowledge that a signifi-<br />

cant body <strong>of</strong> information has been published on studies <strong>of</strong> hydrothermal alteration <strong>of</strong> natural<br />

rock bodies. The time, temperature, and the nature <strong>of</strong> ion migration in hydrothermally<br />

altered rocks has been studied for years by igneous/metamorphic petrographers, geochemists<br />

and mining companies. (208-NRC)<br />

Response<br />

The DOE acknowledges the existence <strong>of</strong> the significant body <strong>of</strong> information referenced<br />

by the commenter. However, this information pertains to much shallower depths than those<br />

envisioned for a very deep hole. The question <strong>of</strong> depth and its concomitant increasing pres-<br />

sure is the principal reason that significant information on the thermomechanical behavior<br />

<strong>of</strong> rocks is not available to support the concept. The information concerning hydrothermal<br />

alteration mentioned in the comment is available for rocks at depths where the total impact<br />

<strong>of</strong> the altering forces are less than that expected in very deep holes.<br />

Draft p. 3.3.34<br />

Issue<br />

Note $500,000,000 just to drill the first hole; $760,000,000 for R&D. Simple back-<strong>of</strong>-<br />

envelope cost estimates surely would show the costs <strong>of</strong> this system, even if it were possible<br />

to work out all the problems, to be prohibitive. (154)<br />

Response<br />

The cost <strong>of</strong> implementing a disposal option is a significant point <strong>of</strong> concern. Cost<br />

estimates that are accurate are dependent on the availability <strong>of</strong> thorough conceptual<br />

designs and a detailed understanding <strong>of</strong> the technical developments that must be completed.<br />

Although deep hole is an interesting concept and has a number <strong>of</strong> attractive advantages,<br />

detailed design studies or a thorough evaluation <strong>of</strong> technology requirements has not been<br />

undertaken. The comment that the cost may be unacceptably high may be correct. It will<br />

not be possible, however, to support this conclusion until these studies are completed.<br />

Draft p. 3.3.36<br />

Issues<br />

Is not borehole sealing covered under the shallow geological repository program? (35).<br />

It should be reemphasized here that satisfactory backfilling-sealing techniques have<br />

not yet been developed and proven. (218-DOI)

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