ABSTRACTION OF DRIFT SEEPAGE
Drift seepage refers to flow of liquid water into repository emplacement drifts, where it can potentially contribute to degradation of the engineered systems and release and transport of radionuclides within the drifts. Because of these important effects, seepage into emplacement drifts is listed as a ''principal factor for the postclosure safety case'' in the screening criteria for grading of data in Attachment 1 of AP-3.15Q, Rev. 2, ''Managing Technical Product Inputs''. Abstraction refers to distillation of the essential components of a process model into a form suitable for use in total-system performance assessment (TSPA). Thus, the purpose of this analysis/model is to put the information generated by the seepage process modeling in a form appropriate for use in the TSPA for the Site Recommendation. This report also supports the Unsaturated-Zone Flow and Transport Process Model Report. The scope of the work is discussed below. This analysis/model is governed by the ''Technical Work Plan for Unsaturated Zone Flow and Transport Process Model Report'' (CRWMS M&O 2000a). Details of this activity are in Addendum A of the technical work plan. The original Work Direction and Planning Document is included as Attachment 7 of Addendum A. Note that the Work Direction and Planning Document contains tasks identified for both Performance Assessment Operations (PAO) and Natural Environment Program Operations (NEPO). Only the PAO tasks are documented here. The planning for the NEPO activities is now in Addendum D of the same technical work plan and the work is documented in a separate report (CRWMS M&O 2000b). The Project has been reorganized since the document was written. The responsible organizations in the new structure are the Performance Assessment Department and the Unsaturated Zone Department, respectively. The work plan for the seepage abstraction calls for determining an appropriate abstraction methodology, determining uncertainties in seepage, and providing probability distributions of seepage. These are all discussed in detail in this report. In addition, the work plan calls for evaluation of effects of episodic flow and thermal-hydrologic-chemical alteration of hydrologic properties. As discussed in Section 5, these effects are not addressed in detail in this report because they can be argued to be insignificant. Effects of thermal-mechanical alteration of hydrologic properties are also not addressed in detail in this report because suitable process-model results are not available at this time. If these effects are found to be important, they should be included in the seepage abstraction in a future revision.
- Research Organization:
- Office of Scientific and Technical Information (OSTI), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 875321
- Report Number(s):
- ANL-NBS-MD-000005; TRN: US0600921
- Country of Publication:
- United States
- Language:
- English
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