Semi-analytical Stochastic Study of Radionuclide Transport in the ...

Title: Semi-analytical Stochastic Study of Radionuclide Transport in the Saturated ZoneBelow Yucca MountainDocument No.: SIP-DRI-016/Rev. 0 Page 1 of 71.0 APPROACHThe complex heterogeneity of the natural media and the uncertainty in data for the saturated zonebelow the Yucca Mountain project (YMP) area preclude using traditional deterministic approachesto model solute transport. To overcome the scale dependence of hydraulic parameters, currentdeterministic numerical methods adopt the concept of macro-parameters (or effective values ofparameters), which comes from stochastic theory, to deal with small scale variations of parameters.This adoption, coupled with the flexibility of numerical methods to complex initial and boundaryconditions, makes the current numerical modeling approach popular in modeling groundwater flowand chemical transport processes. Small-scale variation of parameters, such as hydraulicconductivity, has significant influence on macro-scale flow and transport processes. SandiaNational Laboratory (SNL) has conducted geostatistical studies to investigate parameter variationwithin a single gridblock (500×500×50 meters). Dispersivity at the grid scale has been obtained.However, geostatistical simulations of the hydraulic conductivity and sorption coefficients at thescale of the site-scale model (30×45×0.9 km) have not been conducted. These geostatisticalsimulations are the basis for study of dispersion process and for the uncertainty analysis ofradionuclide transport prediction in the site-scale.Large differences exist between the scale of field measurements and the scale of numericalgridblocks and the scale of macrodispersivity being modeled for the YMP. Currently, a veryimportant issue that needs to be resolved is how to scale-up the parameter values to effective macroscaleparameter values, especially the evaluation of macro-dispersivity from micro-scale variationof hydraulic conductivity.The numerical method, coupled with effective parameter values, is effective to predict mean orexpectation values of flow and chemical plume distributions. However, it is difficult to apply thisnumerical method to analyze the uncertainty of prediction, which is associated with the uncertaintyof input data of parameters. However, because quantification of prediction uncertainty is asimportant as the mean value prediction in engineering design, the prediction uncertainty, or possiblevariation about the expected concentration or solute flux, must be evaluated.2.0 SCOPE AND OBJECTIVESThe study will couple a stochastic perturbation approach with numerical methods to study the roleof heterogeneity, and boundary and initial conditions on chemical transport in natural media. Forgroundwater flow in the media under the YMP area, flow boundaries are finite and the assumptionof spatially stationary flow at the site scale is violated. The method used in this study willovercome the limitations of classical stochastic theory. The study results will provide the mean andvariance of solute plume distribution in complex groundwater flow system below the study site.The method used in this project can be applied to many other sites at the YMP. This study is beingconducted as a part of the efforts documenting the YMP site recommendation. To reach this goal,the following objectives will be achieved:

Title: Semi-analytical Stochastic Study of Radionuclide Transport in the Saturated ZoneBelow Yucca MountainDocument No.: SIP-DRI-016/Rev. 0 Page 2 of 7Objective 1. Construct conductivity and sorption coefficient distributions in the study site usinggeostatistical methods.Objective 2. Estimate the effective value of dispersivity in the scale of site-scale model fromgeostatistical study of hydraulic conductivity in grid-block size. The upscaling results can be usedas input parameter values for future numerical modeling.Objective 3. Predict the means and variances of solute flux through a hypothetical 20-kmcompliance plane using a newly developed semi-analytical stochastic method. This prediction isintended to complement transport predictions made by LANL.3.0 SUBTASKS AND WORK PLANThe proposed study has 5 subtasks to be completed within three funding cycles totaling 28 months:Cycle I: 03/01/00 through 06/30/00;Cycle II: 07/01/00 through 06/30/01;Cycle III: 07/01/01 through 06/30/02.Subtask 1. Quality Assurance (QA)The proposed study includes data collection and numerical code development. This study, underthe cooperative agreement, has been determined by DOE to be quality-affecting. Accordingly, theproposed study will comply with the University and Community College System of Nevada(UCCSN) Quality Assurance (QA) program. The purpose of this Subtask is to ensure that theUCCSN QA program is satisfied. We will prepare Quality Assurance documentation including thisScientific Investigation Plan (SIP), implementing procedures (IP) for testing procedures that will befollowed without variation. The SIP must be complete and approved prior to the start of qualityaffecting work. The numerical codes developed in this study will have QA testing conducted beforethey are used to conduct quality-affecting calculations.The subtask 1 is an ongoing effort for the duration of the 28 months.Subtask 2. Data Collection and EvaluationIntrinsic permeability and related measures of hydrologic behavior such as hydraulic conductivityand transmissivity have been measured at a variety of scales both within the study area and ingeologically similar media proximate to the study area. Supplementing these direct measurementsare observations of lithostratigraphy, fracture orientation and frequency, and geophysicalobservations such as electrical conductivity. These measurements and observations will be collectedalong with the spatial coordinates and used to develop an estimate of the spatial distribution ofintrinsic permeability. Measurements of petrographic composition (XRD, micro-probe, etc.) will becollected and evaluated to refine the estimate of the sorption coefficient spatial distribution. Data

Title: Semi-analytical Stochastic Study of Radionuclide Transport in the Saturated ZoneBelow Yucca MountainDocument No.: SIP-DRI-016/Rev. 0 Page 3 of 7used will be qualified, obtained from the Technical Data Management System, and identified by adata tracking number.The subtask 2 is conducted during two periods: May 1, 2000 to December 31, 2000 for collection ofpermeability data, and October 1, 2001 to December 31, 2001 for collection of sorption coefficientdata.Subtask 3. Acquisition of Analytical ToolsEstimation of spatially heterogeneous parameters, such as intrinsic permeability or the sorptioncoefficient, entails identifying the boundaries of distinct populations and the nature of distributionwithin those boundaries. In this study, the discrete deterministic layers in the existing anddeveloping saturated zone (SZ) model are being used as boundaries, and only the variation withinthose boundaries is being addressed. No uncertainty in the location of contacts between the layers isbeing considered. Because of differences in grid spacing between the existing SZ model and thework being done in this study, a coarser grid will be contoured using Surfer software. If a morecurrent model of the SZ surfaces can be obtained in time, those surfaces will be used, however atpresent an older, currently available version is being used.Heterogeneity within the deterministic layers will be simulated using software from GSLIB, 2 ndedition. These programs require the estimation of semivariograms, as well as means and variances.The output from these programs will be composited such that the SZ model contacts will behonored. The final maps of intrinsic permeability and sorption coefficient will reflect heterogeneitydue to the geometry of deterministic layers as well as heterogeneity within the layers. The softwareused in this subtask has already been through QA. The generated permeability data will be recordedon CDROMS and managed according to QAP-3.6.This subtask will be conducted during October 1, 2000 to March 30, 2001.Subtask 4. Numerical Code DevelopmentIn this study, we will develop a 3-D numerical code to calculate solute flux mean and variance inthe nonstationary flow field. The developed code will be sent to DOE Yucca Mountain office forQA checking before use in quality-affecting calculations. The code will be written in FORTRANlanguage. The code development will be conducted under QAP-3.2.This subtask will be conducted during two periods: October 1 2000 to June 30, 2001 forconservative chemical transport, and October 1, 2001 to December 31, 2001 for reactive chemicaltransport.Subtask 5. AnalysisThe codes developed in subtask 3 and 4 will be used to conduct numerical calculation forconductivity distribution and solute transport prediction in accordance with QAP-3.3, “Analysis and

Title: Semi-analytical Stochastic Study of Radionuclide Transport in the Saturated ZoneBelow Yucca MountainDocument No.: SIP-DRI-016/Rev. 0 Page 5 of 7final technical report. Data resulting from this study will be submitted to the Technical DataManagement System in accordance with QAP-3.6. SIP must be complete and approved beforestarting the relevant quality-affecting work.8.0 VERIFICATION AND REVIEWSInternal verification of all data will be performed to check compliance to procedures and to verifythe accuracy of data reduction. Internal technical review will be performed and documented asdata, scientific notebooks and deliverables generated in this task. Any report of generated datawithout full internal verification will be labeled as preliminary data. Technical reports and otherproducts will be reviewed in accordance with QAP-3.5, “Technical Product Review.” Scientificnotebooks will be reviewed in accordance with QAP-3.0, “Scientific Investigation Control.” Anypublications, presentations, etc., that will provide data or technical information to the public will bereviewed in accordance with IPLV-025, “Publication Review, Approval, and Distribution.”9.0 SOFTWAREOne numerical code for chemical transport prediction will be developed in this task. The softwaredevelopment and implement will be conducted in accordance with QAP-3.2, “SoftwareManagement.” The software packages that may be used in this study include:• Microsoft Word: preparing documents and reports• Microsoft Power Point: preparing presentations• Microsoft Excel: tabulation, figure drafting and analysis of data*• Tecplot, version 7.5: Graphic display of quantitative data• Compaq Visual Fortran, versions 6.0, 6.1, 6.5: compilation of Fortran source code• Surfer, version 7.0: interpolation of model surfaces between existing model points, graphicdisplay• GSLIB, 2 nd Edition: Geostatistical library written in Fortran 77• MathCad, version 8.0: analysis of data**any developed macros will be qualified as a routine in accordance with QAP-3.210.0 INTERFACE CONTROLSThe personnel involved in this task are listed below:Internal InterfacesPI: Xiaolong (Bill) Hu, PH.DInvestigator: Roko Andricevic, Ph.DInvestigator: Craig Shirley, M.S.

Title: Semi-analytical Stochastic Study of Radionuclide Transport in the Saturated ZoneBelow Yucca MountainDocument No.: SIP-DRI-016/Rev. 0 Page 6 of 7Investigator: Jichun Wu, Ph.DTechnical: Tammy KluesnerExternal InterfacesYucca Mountain Cooperative Agreement Technical Contact: Max PowellDOE Technical Task Representative: Drew ColemanSandia National Laboratories: Sean A. McKenna, Ph.D, Technical contact regarding previoushydrogeological characterization work.Los Alamos National Laboratories: George A. Zyvoloski, Ph.D, Coordination to ensurecompatibility with ongoing LANL modeling efforts.Los Alamos National Laboratories: Dongxiao Zhang, Ph.D, Collaborator on theoreticaldevelopment.11.0 OTHER REQUIREMENTSCollaboration with Dr. Xian-Huan Wen of Chevron Research Laboratories on theoreticaldevelopment and enhancement of a currently unqualified two dimensional research code toqualified three dimensional code is anticipated contingent upon approval of funding. A subcontractwith Dr. Wen will be developed after funding approval, and at that time he will be scheduled forQAP training.All data being used as input in the study consists of measurements previously made by otherinvestigators and either have been accepted into the site technical database or published in peerreviewed journals. No samples are being taken or used in this study. The sources of all data whichwill be used in the study will be recorded in the scientific notebook and described in the final report.It is being assumed that data from the site technical database is correct; confirmation of theaccuracy, precision and representativeness of these measurements is outside of the scope of thisstudy.A suite of verification test exercises, for which analytical solutions are known, will be used toconfirm the accuracy of the numerical method as implemented in the source code being developed.Any deviations from the analytical solutions will be evaluated and described. All study activitiesand results, including input, parameter selection and computational results will be entered into thescientific notebook. Due to the large volume of numeric output anticipated in a study of this type,much of the output and results will take the form of electronic media (CDROM’s) which will becited in the scientific notebook.

Title: Semi-analytical Stochastic Study of Radionuclide Transport in the Saturated ZoneBelow Yucca MountainDocument No.: SIP-DRI-016/Rev. 0 Page 7 of 712.0 REFERENCESQAP-2.0, “Quality Assurance Program-Preparation, Approval, and Revision of Procedures.”QAP-3.0 “Scientific Investigation Control.”QAP-3.2, “Software Management.”QAP-3.3, “Analyses and Models.”QAP-3.4, “Technical Product Review.”QAP-3.5, “Technical Product Review.”QAP-3.6, “Submittal of Data to the Technical Data Management System”QAP-17.0, “Quality Assurance Records.”IPLV-025, “Publication Review, Approval, and Distribution”