A summary of the models used for the mechanical response of disposal rooms in the Waste Isolation Pilot Plant with regard to compliance with 40 CFR 191, Subpart B

Butcher, B.M.; Mendenhall, F.T.

doi:10.2172/10189369

Cited by 7 publications

(9 citation statements)

References 4 publications

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“…1997) Table 6: Elastic and Drucker-Prager constants for anhydrite (Butcher. 1997) (Butcher and Mendenhall, 1993) …”

Section: List Of Tablesmentioning

confidence: 99%

Structural evaluation of WIPP disposal room raised to Clay Seam G.

Park¹,

Holland²

2004

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This report summarizes a series of structural calculations that examine effects of raising the Waste Isolation Pilot Plant repository horizon from the original design level upward 2.43 meters. These calculations allow evaluation of various features incorporated in conceptual models used for performance assessment. Material presented in this report supports the regulatory compliance re-certification, and therefore begins by replicating the calculations used in the initial compliance certification application. Calculations are then repeated for grid changes appropriate for the new horizon raised to Clay Seam G. Results are presented in three main areas: 1. Disposal room porosity, 2. Disturbed rock zone characteristics, and 3. Anhydrite marker bed failure. No change to the porosity surface for the compliance re-certification application is necessary to account for raising the repository horizon, because the new porosity surface is essentially identical. The disturbed rock zone evolution and devolution are charted in terms of a stress invariant criterion over the regulatory period. This model shows that the damage zone does not extend upward to MB 138, but does reach MB 139 below the repository. Damaged salt would be expected to heal in nominally 100 years. The anhydrite marker beds sustain states of stress that promote failure and substantial marker bed deformation into the room assures fractured anhydrite will sustain in the proximity of the disposal rooms.

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“…1997) Table 6: Elastic and Drucker-Prager constants for anhydrite (Butcher. 1997) (Butcher and Mendenhall, 1993) …”

Section: List Of Tablesmentioning

confidence: 99%

Structural evaluation of WIPP disposal room raised to Clay Seam G.

Park¹,

Holland²

2004

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“…By correlating simulated pressure-time or molestime conditions in the disposal room with a specified porosity function, a corresponding porosity for the simulated room was determined. The original concept for a moles-time-porosity function based on the SANCHO f-series room closure results was developed by Butcher and Mendenhall (1993). Three different porosity functions were investigated for this application: moles-timeporosity surface interpolation (Section 2.3.1. l), moles-time-porosity line interpolation (Section 2.3.1.2), and pressure-time-porosity line interpolation (Section 2.3.1.3).…”

Section: Porosity Function Approachmentioning

confidence: 99%

A summary of methods for approximating salt creep and disposal room closure in numerical models of multiphase flow

Freeze¹,

Larson²,

Davies³

1995

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Section: Pressure-time-porosity Line Interpolationmentioning

confidence: 99%

“…Fracturing and dilation in response to excavation is expected to create a zone of enhanced permeability, porosity, and interconnectivity that decreases with distance from the excavation (Stormont, 1990), However, fractures in the DRZ are expected to close and heal as room closure and consolidation reach their maximum extent, returning the zone to its original, undisturbed state (Butcher and Mendenhall, 1993). The DRZ conceptual model assesses the impact of these changes in the rock properties in the halite near the room.…”

Section: Disturbed Rock Zonementioning

confidence: 99%

“…By correlating simulated pressure-time conditions in the disposal room with a specified pressure-time-porosity relationship, a corresponding porosity for the simulated room was determined. The original concept for a porosity relationship based on the SANCHO f-series room closure results was developed by Butcher and Mendenhall (1993).A pressure-time-porosity line was calculated from each of the five SANCHO f-series simulations performed by Stone (1995a) based on the room porosity vs. time and gas pressure in the room vs. time results. To mitigate possible adverse effects of numerical oscillations apparent in the original SANCHO results, sections of the data were smoothed.…”

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confidence: 99%

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Coupled multiphase flow and closure analysis of repository response to waste-generated gas at the Waste Isolation Pilot Plant (WIPP)

Freeze¹,

Larson²,

Davies³

1995

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A long-term assessment of the Waste Isolation Pilot Plant (WIPP) repository performance must consider the impact of gas generation resulting from the corrosion and microbial degradation of the emplaced waste. A multiphase fluid flow code, TOUGH2/EOS8, was adapted to model the processes of gas generation, disposal room creep closure, and multiphase (brine and gas) fluid flow, as well as the coupling between the three processes. System response to gas generation was simulated with a single, isolated disposal room surrounded by homogeneous halite containing two anhydrite interbeds, one above and one below the room. The interbeds were assumed to have flow connections to the room through high-permeability, excavation-induced fractures.System behavior was evaluated by tracking four performance measures: (1) peak room pressure; (2) maximum brine volume in the room; (3) total mass of gas expelled from the room; and (4) the maximum gas migration distance in an interbed. A deterministic approach, including baseline and sensitivity simulations, was used. Baseline simulations used current best estimates of system parameters, selected through an evaluation of available data, to predict system response to gas generation under best-estimate conditions. Sensitivity simulations quantified the effects of parameter uncertainty by evaluating the change in the performance measures in response to parameter variations. In the sensitivity simulations, a single parameter value was varied to its minimum and maximum values, representative of the extreme expected values, with all other parameters held at best-estimate values.Simulation results indicated that (1) in the absence of interbed fracturing, disposal room pressures will exceed, lithostatic, even at gas-generation rates representative of vapor-limited conditions, (2) under best-estimate conditions, brine availability was insufficient to fully exhaust the brine-dependent gas-generation potential, (3) the mass of gas expelled from the room and the gas migration distance are much more sensitive to the total mass of gas generated than to the gas-generation rate, and (4) the halite properties are important to gas migration because gas movement in the interbeds is limited by the displacement of interbed brine into the surrounding halite.Sensitivity simulations identified the following parameters as important to gas expulsion and migration away from a disposal room: interbed porosity; interbed permeability; gas-generation potential; halite permeability; and interbed threshold pressure. The uncertainty in multiphase flow parameters was not adequately characterized because of the lack of WIPP-specific data. Simulations also showed that the inclusion of interbed fracturing and a disturbed rock zone had a significant impact on system performance.The TOUGH2/EOS8 deterministic simulation and sensitivity results were similar to stochastic results obtained by WIPP Performance Assessment from a repository-scale model. Because the deterministic approach allows conceptual models to be quanti...

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A summary of the models used for the mechanical response of disposal rooms in the Waste Isolation Pilot Plant with regard to compliance with 40 CFR 191, Subpart B

Cited by 7 publications

References 4 publications

Structural evaluation of WIPP disposal room raised to Clay Seam G.

Structural evaluation of WIPP disposal room raised to Clay Seam G.

A summary of methods for approximating salt creep and disposal room closure in numerical models of multiphase flow

Coupled multiphase flow and closure analysis of repository response to waste-generated gas at the Waste Isolation Pilot Plant (WIPP)

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