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Title: Development of numerical Grids for UZ Flow and Transport Modeling

Abstract

This report describes the methods used to develop numerical grids of the unsaturated hydrogeologic system beneath Yucca Mountain, Nevada. Numerical grid generation is an integral part of the development of the unsaturated zone (UZ) flow and transport model, a complex, three-dimensional (3-D) model of Yucca Mountain. This revision contains changes made to improve the clarity of the description of grid generation. The numerical grids, developed using current geologic, hydrogeologic, and mineralogic data, provide the necessary framework to: (1) develop calibrated hydrogeologic property sets and flow fields, (2) test conceptual hypotheses of flow and transport, and (3) predict flow and transport behavior under a variety of climatic and thermal-loading conditions. The technical scope, content, and management for the current revision of this report are described in the planning document ''Technical Work Plan for: Unsaturated Zone Flow Analysis and Model Report Integration'' (BSC 2004 [DIRS 169654], Section 2). Grids generated and documented in this report supersede those documented in Revision 00 of this report, ''Development of Numerical Grids for UZ Flow and Transport Modeling'' (BSC 2001 [DIRS 159356]). The grids presented in this report are the same as those developed in Revision 01 (BSC 2003 [DIRS 160109]); however, the documentation of themore » development of the grids in Revision 02 has been updated to address technical inconsistencies and achieve greater transparency, readability, and traceability. The constraints, assumptions, and limitations associated with this report are discussed in the appropriate sections that follow.« less

Authors:
Publication Date:
Research Org.:
Yucca Mountain Project, Las Vegas, Nevada (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
837556
Report Number(s):
ANL-NBS-HS-000015, REV 02
DOC.20040901.0001, DC 38119; TRN: US0502711
DOE Contract Number:
AC28-01RW12101
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 31 Aug 2004
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; DOCUMENTATION; MANAGEMENT; PLANNING; SIMULATION; TRANSPORT; YUCCA MOUNTAIN

Citation Formats

P. Dobson. Development of numerical Grids for UZ Flow and Transport Modeling. United States: N. p., 2004. Web. doi:10.2172/837556.
P. Dobson. Development of numerical Grids for UZ Flow and Transport Modeling. United States. doi:10.2172/837556.
P. Dobson. 2004. "Development of numerical Grids for UZ Flow and Transport Modeling". United States. doi:10.2172/837556. https://www.osti.gov/servlets/purl/837556.
@article{osti_837556,
title = {Development of numerical Grids for UZ Flow and Transport Modeling},
author = {P. Dobson},
abstractNote = {This report describes the methods used to develop numerical grids of the unsaturated hydrogeologic system beneath Yucca Mountain, Nevada. Numerical grid generation is an integral part of the development of the unsaturated zone (UZ) flow and transport model, a complex, three-dimensional (3-D) model of Yucca Mountain. This revision contains changes made to improve the clarity of the description of grid generation. The numerical grids, developed using current geologic, hydrogeologic, and mineralogic data, provide the necessary framework to: (1) develop calibrated hydrogeologic property sets and flow fields, (2) test conceptual hypotheses of flow and transport, and (3) predict flow and transport behavior under a variety of climatic and thermal-loading conditions. The technical scope, content, and management for the current revision of this report are described in the planning document ''Technical Work Plan for: Unsaturated Zone Flow Analysis and Model Report Integration'' (BSC 2004 [DIRS 169654], Section 2). Grids generated and documented in this report supersede those documented in Revision 00 of this report, ''Development of Numerical Grids for UZ Flow and Transport Modeling'' (BSC 2001 [DIRS 159356]). The grids presented in this report are the same as those developed in Revision 01 (BSC 2003 [DIRS 160109]); however, the documentation of the development of the grids in Revision 02 has been updated to address technical inconsistencies and achieve greater transparency, readability, and traceability. The constraints, assumptions, and limitations associated with this report are discussed in the appropriate sections that follow.},
doi = {10.2172/837556},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2004,
month = 8
}

Technical Report:

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  • This Scientific Analysis report describes the methods used to develop numerical grids of the unsaturated hydrogeologic system beneath Yucca Mountain. Numerical grid generation is an integral part of the development of the Unsaturated Zone Flow and Transport Model (UZ Model), a complex, three-dimensional (3-D) model of Yucca Mountain. This revision incorporates changes made to both the geologic framework model and the proposed repository layout. The resulting numerical grids, developed using current geologic, hydrogeologic, and mineralogic data, provide the necessary framework to: (1) develop calibrated hydrogeologic property sets and flow fields, (2) test conceptual hypotheses of flow and transport, and (3)more » predict flow and transport behavior under a variety of climatic and thermal-loading conditions. The technical scope, content, and management of this Scientific Analysis report was initially controlled by the planning document, ''Technical Work Plan (TWP) for: Unsaturated Zone Sections of License Application Chapters 8 and 12'' (BSC 2002 [159051], Section 1.6.4). This TWP was later superseded by ''Technical Work Plan for: Performance Assessment Unsaturated Zone'' (BSC 2002 [160819]), which contains the Data Qualification Plan used to qualify the DTN: MO0212GWLSSPAX.000 [161271] (See Attachment IV). Grids generated and documented in this report supersede those documented in previous versions of this report (BSC 2001 [159356]). The constraints, assumptions, and limitations associated with this report are discussed in the appropriate sections that follow. There were no deviations from the TWP scope of work in this report. Two software packages not listed in Table IV-2 of the TWP (BSC 2002 [159051]), ARCINFO V7.2.1 (CRWMS M&O 2000 [157019]; USGS 2000 [148304]) and 2kgrid8.for V1.0 (LBNL 2002 [154787]), were utilized in the development of the numerical grids; the use of additional software is accounted for in the TWP (BSC 2002 [159051], Section 13). The use of these software packages is discussed in Sections 3 and 6.1.1. The steps involved in numerical grid development include: (1) defining the location of important calibration features, (2) determining model grid layers and fault geometry based on the Geologic Framework Model (GFM), the Integrated Site Model (ISM), and definition of HGUs, (3) analyzing and extracting GFM and ISM data pertaining to layer contacts and property distributions, (4) discretizing and refining the two-dimensional (2-D), plan-view numerical grid, (5) generating the 3-D grid, with finer resolution at the proposed repository horizon and within the Paintbrush nonwelded (PTn) and ch1 (Uppermost Calico Hills Formation (Table 11)) hydrogeologic units, and (6) formulating the dual-permeability mesh. The products of grid development include a set of one-dimensional (1-D) vertical columns of gridblocks for hydrogeologic-property-set inversions, a 2-D UZ Model vertical cross-sectional grid for fault hydrogeologic-property calibrations, and a 3-D UZ Model grid for additional model calibrations and generating flow fields for Performance Assessment (PA).« less
  • This Analysis/Model Report (AMR) describes the methods used to develop numerical grids of the unsaturated hydrogeologic system beneath Yucca Mountain. Numerical grid generation is an integral part of the development of a complex, three-dimensional (3-D) model, such as the Unsaturated-Zone Flow and Transport Model (UZ Model) of Yucca Mountain. The resulting numerical grids, developed using current geologic, hydrogeologic, and mineralogic data, provide the necessary framework to: (1) develop calibrated hydrogeologic property sets and flow fields, (2) test conceptual hypotheses of flow and transport, and (3) predict flow and transport behavior under a variety of climatic and thermal loading conditions. Revisionmore » 00 of the work described herein follows the planning and work direction outlined in the ''Development of Numerical Grids for UZ Flow and Transport Modeling'' (CRWMS M&O 1999c). The technical scope, content, and management of ICN 01 of this AMR is currently controlled by the planning document, ''Technical Work Plan for Unsaturated Zone (UZ) Flow and Transport Process Model Report'' (BSC 2001a). The scope for the TBV resolution actions in this ICN is described in the ''Technical Work Plan for: Integrated Management of Technical Product Input Department'' (BSC 2001 b, Addendum B, Section 4.1). The steps involved in numerical grid development include: (1) defining the location of important calibration features, (2) determining model grid layers and fault geometry based on the Geologic Framework Model (GFM), the Integrated Site Model (ISM), and definition of hydrogeologic units (HGUs), (3) analyzing and extracting GFM and ISM data pertaining to layer contacts and property distributions, (4) discretizing and refining the two-dimensional (2-D), plan-view numerical grid, (5) generating the 3-D grid with finer resolution at the repository horizon and within the Calico Hills nonwelded (CHn) hydrogeologic unit, and (6) formulating the dual-permeability mesh. The products of grid development include a set of one-dimensional (1-D) vertical columns of gridblocks for hydrogeologic property set inversions, a 2-D UZ Model vertical cross-sectional grid for fault hydrogeologic property calibrations, a 3-D UZ Model grid for additional model calibrations, and a 3-D UZ Model grid for generating flow fields for Performance Assessment (PA).« less
  • Public domain computer programs were used to attempt an improved model of the tritium plume observed during Macrodispersion Experiment 2 (MADE-2), a field scale natural gradient experiment conducted at Columbus Air Force Base, Mississippi. The finite difference program MODFLOW was used to simulate the flow of groundwater through a 330 m x 105 m computational domain. Solutions for the 468 day experiment were obtained using a Sun Sparcstation 2 for several choices of convergence and storage parameters. The simulations had small mass balance errors and were consistent with continuous head observations. Tritium plume simulations used the mixed Lagrangian-Eulerian finite differencemore » program MT3D to solve the contaminant transport equation using the MODFLOW-predicted flow field. Thirteen runs were made using various advection algorithms and dispersivities, but none was successful.« less
  • Previous performance analyses conducted by BWIP generally have been carried out in a deterministic framework, whereby a single model prediction was made and nothing was known about the likelihood of that prediction. As the size of the data base used for repository performance analyses increases, BWIP will progressively move toward a stochastic approach to performance studies. The main advantages of a stochastic approach are that: (1) the likelihood of model predictions can be quantified, and (2) information can be gained about how to reduce the uncertainty in these predictions. PORSTAT solves the stochastic groundwater flow equation coupled with the deterministicmore » heat transfer and mass transport equations. An integrated finite-difference numerical scheme is used in PORSTAT to solve the governing equations. The stochastic groundwater flow equation is approximated by means of a second-order uncertainty analysis technique. Stochastic variables input to PORSTAT may be hydraulic conductivity, specific storage, boundary conditions, and initial conditions. The output from PORSTAT consists of the expected values and covariances of hydraulic heads and Darcian velocities. PORSTAT will be used by BWIP to stochastically model groundwater flow in the thermally influenced zone around the repository. In order to make a preliminary evaluation, the results from two test cases run by PORSTAT and BWIP's Monte Carlo groundwater flow computer code (MAGNUM-MC) are compared. The initial comparison indicates that PORSTAT tends to overestimate the uncertainty in hydraulic head predictions, and thus from a risk analysis viewpoint, produces conservative results. Additional testing is being conducted to determine the limitations and capabilities of PORSTAT. 41 references.« less