Probability Distribution for Flowing Interval Spacing

Kuzio, S.

United States. Department of Energy. Yucca Mountain Project Office.

关键词: Probability;    Radioactive Waste Facilities;    Boreholes;    Computerized Simulation;    Geologic Fractures;   

DOI  :  10.2172/837138
RP-ID  :  ANL-NBS-MD-000003, REV 00, ICN 02
RP-ID  :  NONE
RP-ID  :  837138

美国|英语

来源: UNT Digital Library

【 摘 要 】

The purpose of this analysis is to develop a probability distribution for flowing interval spacing. A flowing interval is defined as a fractured zone that transmits flow in the Saturated Zone (SZ), as identified through borehole flow meter surveys (Figure 1). This analysis uses the term ''flowing interval spacing'' as opposed to fractured spacing, which is typically used in the literature. The term fracture spacing was not used in this analysis because the data used identify a zone (or a flowing interval) that contains fluid-conducting fractures but does not distinguish how many or which fractures comprise the flowing interval. The flowing interval spacing is measured between the midpoints of each flowing interval. Fracture spacing within the SZ is defined as the spacing between fractures, with no regard to which fractures are carrying flow. The Development Plan associated with this analysis is entitled, ''Probability Distribution for Flowing Interval Spacing'', (CRWMS M&O 2000a). The parameter from this analysis may be used in the TSPA SR/LA Saturated Zone Flow and Transport Work Direction and Planning Documents: (1) ''Abstraction of Matrix Diffusion for SZ Flow and Transport Analyses'' (CRWMS M&O 1999a) and (2) ''Incorporation of Heterogeneity in SZ Flow and Transport Analyses'', (CRWMS M&O 1999b). A limitation of this analysis is that the probability distribution of flowing interval spacing may underestimate the effect of incorporating matrix diffusion processes in the SZ transport model because of the possible overestimation of the flowing interval spacing. Larger flowing interval spacing results in a decrease in the matrix diffusion processes. This analysis may overestimate the flowing interval spacing because the number of fractures that contribute to a flowing interval cannot be determined from the data. Because each flowing interval probably has more than one fracture contributing to a flowing interval, the true flowing interval spacing could be less than the spacing determined in this analysis. Therefore, in terms of repository performance the results of this analysis may underestimate the effect of matrix diffusion processes in SZ transport models. In summary, performance analysis will be conservative if the flowing interval spacing determined by this study is used in the simulation of mass transport in the saturated zone instead of the fracture spacing.