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

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Response<br />

325<br />

ALTERNATIVE DISPOSAL CONCEPTS<br />

The measurement <strong>of</strong> fracture permeability is recognized as a difficult problem and addi-<br />

tional research will be needed to resolve remaining problems in its expermental determina-<br />

tion for situations where it is an important factor. It is recognized from experience and<br />

has been experimentally shown that increasing compressive force or stress in a rock mass<br />

will decrease its permeability, including that contributed by fractures. At depths <strong>of</strong><br />

10,000 m the forces on the rock are substantial and the total permeability is expected to<br />

be extremely low. In view <strong>of</strong> lack <strong>of</strong> experience, experimental evaluation <strong>of</strong> this fact will<br />

be required before a final conclusion can be drawn.<br />

Draft 3.3.11-13<br />

Issue<br />

It appears that in the context <strong>of</strong> the duration <strong>of</strong> periods under consideration in repos-<br />

itory planning, the discussion <strong>of</strong> rock strength needs to include at least in a general way<br />

changes in rock strength and characteristics that may occur with increasing time and their<br />

effects on permeability. (218-DOI)<br />

Response<br />

Section 6.1.1.4 (Issues and R&D Requirements) <strong>of</strong> the final Statement contains a discus-<br />

sion <strong>of</strong> thermomechanical and thermochemical factors relavant to the deep hole disposal con-<br />

cept. It notes that one <strong>of</strong> the area where additional study is needed is in permeability<br />

changes caused by a rock mass being heated.<br />

Draft p. 3.3.13<br />

Issue<br />

The possibility that oxygen introduced with the waste will change the reducing con-<br />

ditions should be considered. (113-EPA)<br />

Response<br />

A discussion <strong>of</strong> the effects <strong>of</strong> waste heat and chemistry on the host rock is presented<br />

in the final Statement, Section 6.1.1.3, Status <strong>of</strong> Technical Development and R&D Needs,<br />

under the sub-heading Heat Transfer (Thermomechanical and Thermochemical Factors).

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