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.

235<br />

GEOLOGIC CONSIDERATIONS<br />

activities and patterns that have prevailed for many years; "... is correct because projec-<br />

tion <strong>of</strong> changing stresses on a regional, not local, scale is required." This is where the<br />

plate theory provides insight. (154)<br />

Response<br />

The theory <strong>of</strong> plate tectonics provides a mechanism and cause for such geologic items<br />

as the distribution and occurrence <strong>of</strong> earthquakes on a world-wide basis, volcanism and reg-<br />

ional stress patterns.<br />

Draft pp. 3.1.22 and 3.1.47<br />

Issue<br />

Isotopic date boundaries and provinces may rank second to crustal plate boundaries in<br />

importance to site selection and this should be mentioned. (113-EPA)<br />

Response<br />

Isotopic ratio dating and province boundaries have added considerably to our knowledge.<br />

<strong>of</strong> former mobile zones in the earth's crust, particularly those older than say 400 million<br />

years. However, the question <strong>of</strong> future activity along these zones is not thoroughly<br />

resolved.<br />

Initial strontium ratios (8Sr/87Sr), for example, have been used to partly define<br />

the western limit <strong>of</strong> the North American continent (Armstrong, R. L. et al. 1977 and Peto,<br />

P. and R. L. Armstrong 1976).<br />

At present, because <strong>of</strong> uncertain knowledge <strong>of</strong> the distribution, significance and potential<br />

for affecting a repository, it is believed premature to rank isotopic date boundaries<br />

second only to crustal plate boundaries in importance to site selection. Isotopic ratio<br />

dating has been added to the draft as an item for consideration.<br />

Draft p. 3.1.23<br />

Issue<br />

If regions are to be eliminated because aquifers are present at depth, then the thres-<br />

hold proximity <strong>of</strong> aquifers should be defined. (154)<br />

Response<br />

The text has been changed (see Section B.4 <strong>of</strong> the final Statement).

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

Saved successfully!

Ooh no, something went wrong!