23.04.2013 Views

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

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

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

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

323<br />

ALTERNATIVE DISPOSAL CONCEPTS<br />

See a prior response in this section (General comment-Letter 208) for discussion <strong>of</strong><br />

current status <strong>of</strong> knowledge <strong>of</strong> alternative concepts and the mined repository concept.<br />

Draft p. 3.3.7<br />

Issue<br />

Although fractures may be only a few meters long, they are <strong>of</strong>ten interconnected with<br />

others making a continouous flow network; therefore, the statement in paragraph 2, lines 7<br />

and 8 in the report is misleading. (218-DOI)<br />

Response<br />

It is agreed that fractures are <strong>of</strong>ten interconnected; measuring/assessing this inter-<br />

connection is an important problem <strong>of</strong> hydrology in fractured media and is the subject <strong>of</strong><br />

several ongoing studies. The size and degree.<strong>of</strong> interconnection <strong>of</strong> fractures is quite var-<br />

iable and may account for as much as 12 orders <strong>of</strong> magnitude variation in measured hydraulic<br />

conductivities.<br />

Draft p. 3.3.7<br />

Issue<br />

Fracture porosity should not be discounted. Fracture traces are systematically used<br />

in the exploration <strong>of</strong> oil and gas to at least 3 km. In areas <strong>of</strong> the crystalline shield,<br />

water well drilling commonly uses the concept <strong>of</strong> fracture traces to develop high capacity<br />

water wells. (43)<br />

Response<br />

DOE is in agreement with the comment that fracture porosity is very important,<br />

although to some extent the reviewer might be misinterpreting fracture porosity to mean<br />

fracture permeability. The latter was discussed in the subsequent paragraph on page 3.3.7<br />

<strong>of</strong> the draft Statement. Deep resistivity measurements reflect only on interconnected poros-<br />

ity, which is quite low compared to the bulk porosity <strong>of</strong> crystalline rocks as measured in<br />

the laboratory. The difference in the two porosities is quite important to waste disposal;<br />

if water in the rocks is flowing so slowly that diffusion is important, then the entire<br />

interconnected porosity will provide large surface area for sorption/reaction. If the<br />

water is flowing rapidly, then only the small volumes <strong>of</strong> the fractures are <strong>of</strong> first-order<br />

importance.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!