Improving Operations and Long-Term Safety of the Waste Isolation Pilot Plant Final Report (2001) / Chapter Skim
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2. Repository Performance Confirmation
2. Repository Performance Confirmation
Pages 20-32
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From page 20... ...
Quoting from that report, "The panel emphasizes that it supports the notion of underground testing with TRU wastes, provided that the underground location does not prevent important tests from being carried out (e.g., the measurement of brine compositions in contact with real waste or progression of gas generation experiments without purging) , and that the tests can be continued for sufficient time to provide useful information." 20
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From page 21... ...
The committee's proposed performance confirmation monitoring plan is very similar to the DOE's monitoring program. The significant difference between the DOE monitoring program and the committee proposal is that the committee's recommended plan includes monitoring rooms and panels after sealing of the panels and extends until closure of the repository and sealing of the shafts.
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From page 22... ...
A concern is the possible failure of a well casing or cement outside the casing during an injection operation and fluid leaking into overlying formations and flowing laterally along one of the several anhydrite layers in the Salado Formation. A previous NRC committee analyzed the brine accumulation issue and concluded that "the formation of an abundant mobile fluid in a repository at the WIPP site .
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From page 23... ...
The committee recommends that the results of the on-site monitoring program be used to improve the performance assessment for recertification purposes. Gas Generation in the Repository Gas generation within the WIPP is one of the issues for consideration in the overall performance of the repository.
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From page 24... ...
Observation should continue at least until the repository shafts are sealed and longer if possible. The results of the gas generation monitoring program should be used to improve the performance assessment for recertification purposes.
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From page 25... ...
As mentioned in the previous section, there are uncertainties concerning assumption 1 about the presence of a significant amount of brine in the rooms. Since assumption 2 relies on microbial generation of CO2 under repository conditions, it is also affected by uncertainties (see previous section)
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From page 26... ...
Salt Healing and Disturbed Rock Zone Integrity The period between placement of waste and closure of the repository provides a window of opportunity to monitor significant deformation of the salt and self-healing of the DRZ. The DRZ is the zone around an excavation in the host rock salt where the stress field has been modified sufficiently to cause the formation of microfractures in the rock salt.
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From page 27... ...
However, if the drilling intersects a pressurized brine reservoir before the borehole casing is placed, and if the pressure in the formation is unexpectedly higher than the pressure exerted by the drilling fluid, the high-pressure formation fluids could flow into the wellbore and cause an underground blowout into the Culebra. Drillers would use a blowout preventer to contain any immediate surface release of brine from the repository horizon.
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From page 28... ...
Extraction activities can be divided into drilling activities and mining activities. Drilling Activities Two scenarios related to drilling activities are of particular interest to the WIPP site: the Hartman scenario and the intersection of a pressurized brine reservoir.
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From page 29... ...
The committee's opinion is that there are considerable uncertainties concerning both the mechanism of the Hartman scenario and its likelihood to develop at the WIPP site. For instance, if the hypothesis of a hydraulically induced fracture were valid, and the fracture would indeed extend directly below or above the repository, a surge of brine would be expected only when the drillbit penetrates the brinefilled fracture.
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From page 30... ...
In case of drilling, precautionary methods, such as directional drilling, should be taken to prevent brine from entering the repository. Recommendation: The committee recommends the utilization of seismic survey techniques to detect the presence of a large brine reservoir below the repository.8 In case a brine reservoir were ~ The committee recognizes that small brine reservoirs, including brine occurring as a saturated continuum, could not be detected by seismic surveys, or other noninvasive remote sensing techniques.
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From page 31... ...
the potential Impact of potash mlmng on WAIF performance Is not considered significant, but it is important that the DOE monitor during the operational phase all mining activities in close proximity of the area addressed in the LWA to ensure that the WIPP repository performance is not affected. After reviewing the analyses performed for the human intrusion scenarios as a part of the performance assessment and given the reasons mentioned above, the committee finds that oil, gas, and mineral activities will not unduly threaten the integrity of the repository.
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From page 32... ...
The committee supports and encourages the pursuit of this initiative. Recommendation: The committee recommends that the DOE continue the implementation of its plan to sample oil-field brines, petroleum, and solids associated with current and future hydrocarbon production, as necessary to assess the magnitude and variability of NORM in the vicinity of the WIPP site for baselining purposes.9 9 On March 12, 2001 the DOE-Carlsbad Field Office informed the committee that the efforts to collect data on NORM have received little support from oil companies and that cooperation seems unlikely.
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