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

Response
77
CONSEQUENCE ANALYSIS
There are "astroblemes" (any scar on the surface of the earth caused by the impact of
cosmic body) that have been recorded in Canada and elsewhere that suggest breach by such a
mechanism is possible, although very unlikely. The meteorite scenario does serve as an
upper bound for the kind of improbable events required to compromise repository containment
and disperse radioactive material over large areas. Damage caused by a meteorite strike to
the surrounding environment (e.g.,nonradiological) are mentioned in the text as being
severe, but no elaborations were made.
Draft pp. 3.1.120-123
Issue
The discussion in GEIS under "routine releases of radioactive materials" does not
address the problem of radionuclide contamination of ground water and run-off water. This
could happen as a result of accidents, clean-up operations in storage rooms, decontamination
operations during the retrieval cycle, etc.
In the section titled "Ecological Effects" seepage and water inflow from overlying
strata for repositories in granite and in shale are discussed. The estimated inflow of
water in a granite repository ranges from 550 to 1550 m3/day. The estimated maximum
inflow during the last stages of operation in shale will range from about 3,800 to 19,000
m3/day (50,000 gpd) (sic). There appear to be two implications by omission from the
discussion:
* No continued water inflow is expected in the repositories in granite and in shale after
the'last stage of operation.
* No water inflow is expected in the repositories in salt and in basalt.
The generic stratigraphy for salt includes possible aquifers overlying the salt bed.
An area of uncertainty in state-of-the-art technology is whether the effects of mining a
repository in salt and of the thermal loading are such as to create fractures that would
connect the aquifer bed to the repository. TM-36/21 (p. C-1) discounts this in assuming
that the permeability for salt remains at zero. No justification is provided. (208-NRC)
Response
With respect to groundwater migration of radionucl.ides, the impact of operational
accidents and normal procedures is negligible compared to the overall repository inventory.
The assumptions are that no flow will occur in any repository after final stage. The.pur-
pose of the Statement is to address the impact if flow does occur after the final stage.