The Waste Isolation Pilot Plant A Potential Solution for the Disposal of Transuranic Waste (1996) / Chapter Skim
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3 SALADO HYDROGEOLOGY, GAS PRESSURE, AND ROOM CLOSURE
3 SALADO HYDROGEOLOGY, GAS PRESSURE, AND ROOM CLOSURE
Pages 37-46
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From page 37... ...
SALADO HYDROGEOLOGY In assessing deep geological disposal as a potential means of isolating radioactive waste from the biosphere and worthy of further research, the National Research Council suggested rock salt as a particularly suitable geological material (NRC, 1957~. The fact that water-soluble formations such as the Salado Formation in New Mexico have remained in place for hundreds of millions of years indicates that, except for slow dissolution at the margins, they are hydrologically inactive.
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From page 38... ...
Brine seepage comes from isolated domains of porosity containing brine that, in the undisturbed state, will be at lithostatic pressure. These domains become interconnected if they are penetrated by the micro and
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From page 39... ...
With appropriate design width and sealing of the entrance drifts to the rooms, it should be possible to minimize extension of the DRZ to the marker beds and avoid connection between the beds and the excavation (see discussion of room seals in Chapter 4~. In conclusion, brine inflow to excavations in the Salado is likely to be significantly less than was thought to be the case several years aground will occur primarily via anhydrite marker beds.
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From page 40... ...
Time Dependence of Bacterial Activity Even if the experimental program eventually succeeds in measuring bacterial gas generation rates, a question will remain about extrapolating short-term, laboratory-derived rates to repository compliance time scales. Linear extrapolation may be appropriate for certain physical and chemical processes, but living organisms are more complex.
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From page 41... ...
and the proximity of marker beds suggest that the DRZ formed around each room (including roof sag, floor uplift, and wall fractures) could, after some time, provide hydrologic contact between the waste-filled rooms and one or more marker beds.
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From page 42... ...
If the gas pressure reaches lithostatic, it would open fractures in the marker beds, greatly increasing the marker bed permeability to outward flow from the rooms. Gas would tend to flow out of the rooms.
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From page 43... ...
` Anhydnte underlain by day seam (anhydnte ~b-) ` 43 0 2, m 1 .79m 1 0.06m 2.12m 2 2m 1 .82m .: 1 .25m O.9Om FIGURE 3.2 Close-up of stratigraphy of the Salado Formation at the repository horizon.
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From page 44... ...
37) , the 1° inclination of the marker beds results in countercurrent flow (i.e., brine flows into the excavation as gas flows out)
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From page 45... ...
The hazard of such "pockets" of pressurized gas is considered by the committee to be negligible because of its small volume and small gas pressure energy. The committee believes that placement of effective room and pane} seals wall reduce greatly the potential for hydrological communication between the individual rooms.
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From page 46... ...
46 expected. Creep closure and gas pressure buildup will serve to limit liquid brine entry.
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