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

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compiled (Jenks 1975). It is desirable, at this point, to conduct in-situ tests to deter-
mine the effects of radiation of interactions between the host rock and the waste package
and to ascertain whether deleterious reactions occur due to synergism among the heat, radia-
tion, and chemical interactions with the package (Carter 1979).
5.2.3.4 Repository Penetration
In general, the penetration of host rock by shafts and boreholes will be expected to
have small environmental or safety consequences. Consideration of final sealing will
require the evaluation of excavation techniques, the effect of excavation on the host rock
(fracturing), and changes in rock stresses. Testing of plugging technology for shafts and
bore-holes is in progress. Studies planned or under way addressing this matter are listed
in Appendix L.
5.2.4 Summary
The following summarizes the present status of technology and R&D in support of improv-
ing the reliability of a mined geologic repository.
* The general criteria that have been proposed for repository site qualification
have been identified in the "NWTS Criteria for the Geologic Disposal of Nuclear
Wastes: Site - Qualification Criteria (ONWI-33(2), 1980)."."
* Studies of the natural geological system, development of the man-made waste pack-
age, and repository system analysis will all combine to lead to repository designs
that utilize multiple barriers to their maximum efficiency in a repository.
* Regional geologic conditions in the U.S are well known and have been extensively
described; geologic forecasting is being accomplished by extrapolating past
geologic-event data into the future and weighing results against deterministic
tectonic models.
* Ground water as the principal agent for transport of radionuclides to the bio-
sphere has received extensive study and research; the principles that govern its
occurrence and movement are well established. Additional studies are being con-
ducted, using accepted techniques, to define regional and local ground-water flow
systems.
* Sorption capacities of candidate rock media in contact with radionuclides are
being determined in the laboratory. These data are designed to permit estimation
of long-term migration of the radionuclides in repository host media.
* Continued development of the waste package is expected; studies with candidate
materials for the waste package development will proceed in a logical sequence and
scale of complexity.
* The repository system performance will be affected by excavation and underground
development, thermal effects, radiation effects, and repository penetrations.
These effects are being evaluated individually and synergistically for effects in
overall repository performance.