ML19332E956

Speech Entitled, Intl Projects in Validating Groundwater Flow & Transport Models, Presented at 880523-26 Validation of Flow & Transport Models for Unsaturated Zone Workshop in Ruidoso,Nm

ML19332E956
Person / Time
Issue date:	05/23/1988
From:	Davis P, Timothy Mccartin, Thomas Nicholson NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES), SANDIA NATIONAL LABORATORIES
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Title:

Validation of Flow and Transport Models far the Unsaturated m

Zone Workshop I

.Ddte & Place:

May 23-26, 1988, Ruidoso, New Mexico (New Mexico State Univ.)

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INTERNATIONAL PROJECT $ IN VAllDATING GROUND-WATER FLOW AND TRANSPORT H3DELS

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Thomas J. Nichalson & Timothy J. McCartin Of fice of Nuclear Regulatory Research US Nuclear Regulatory Commission Washington, DC 20$55 I

Paul A. Davis Sandia National Laboratories Albuquerque, NM 87185 ABSTRACT I

The U.S. Nuclear Regulatory Commission (US NRC) is involved in international projects dealing with develop-ment of validation strategies for ground-water flow (HYDROCOIN) and transport (INTRAVAL) models. The 1

U.S. NRC staf f and their contractors, along with other international participants in the " Hydrologic Code Intercomparison Study," HYDROCOIN, simulated laboratory and field experiments to gain insights into the validation process for hydroDeologic systems. Although true validation was not achieved, this phase of the HYDROC0!N effort provided the following insights on validation of ground-water flow modelst (1) valida-l tion is a site specific and purpose specific issue (i.e., validity depends on both the model, and the correct interpretation and use of site data); (2) comparison of model simulations with a single spatial

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and temporal set of experimental results is likely to result in model calibration rather than validation; (3) more is learned when models are rigorously tested on a v6riety of possible site conditions than when models are tested for simple conditions which can be easily reproduced; and (4) validat:on can best be judged when prior performance measures are established and specific criteria for model acceptance are fully defined.

The " International Transport Validation Study," INTRAVAL, is a direct outcome of the successes and lessons learned in the HYDROCOIN project, for example, the validation studies of HYDROCOIN illustrate the need

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to reexamine the data base and to perform additional experiments to isolate individual processes and phenomena of the conceptual model. Based on this need, the INTRAVAL project is utilizing data bases which are amenable to later testing. Also, scale dependency of the large temporal and spatial considera-tions associated with radioactive waste disposal precludes complete validation. Therefore, the INTRAVAL project will examine natural analogues to radioactive repositories, and use coupled laboratory and large-scale field studies (e.g., Las Cruces Trench study) to analyze scale dependance issues. The original test cases considered for the INTRAVAL project were for saturated flow and transport in fractured and porous media (INTRAVAL Ad Hoc 1987). Unsaturated flow problems relevant to low-level and high-level radioactive repositories have recently been defined for the INTRAVAL project.

INTRODUCTION Validation Issues This paper discusse? the U.S, NRC staff's and The validation issues identified in the ground-contractor's computer modeling efforts as part water flow (HYDROCOIN) (see HYDROCOIN 1987 and of two international cooperative projects for Andersson 1988) and transport (INTRAVAL) studies studying ground water flow modeling strategies (see INTRAVAL 1988 and INTRAVAL Ad Hoc 1987)

(HYDROC0lN) and examining the validation process deal with testing different aspects of con-for geosphere transport models (INTRAVAL) asso-ceptual models and related computer codes used ciated with performance assessment of radio-to simulate them, active waste disposal facilities. Both studies involve member countries of the OECD including The process of model validation can be thought the U.S.A. (both US kRC and US DOE are of as a series of questions to be asked of the participating parties) with the Swedish Nuclear experimental database and the computer models:

Power Inspectorate serving as the managing party.

Numerous publications provide a detailed 1.

What are the relevant processes of the discussion of both the HYDROCOIN (see HYDROCOIN experiment and how does the model 1987) and INTRAVAL (see INTRAVAL 1988 and consider them?

INTRAVAL Ad Hoc 1987) projects' objectives and programmatic structure.

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What is the geometric and spatial strategies used to analyle the perfomance of j

framcwork of the hydrogeologic system nuclear waste disposal facilities (HYDROCtlN i

and do the modeling assumptions 1987). The study began in May 1984 by the i

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$wedish Nuclear Power Inspectorate. The first !

I workshop was held in October 1984 in Stockholm, '

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_Are the simplifying assumptions Sweden with 19 participating groups (see

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inherent in the model compatible to HYDROCOIN 1987). Because ground-water flow the hydrogeologic, hydraulic, and modeling will be used in conjunction with site

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geochemical components of the system characteritation and for simulation of radio-being modeled and consistent with the nuclide migration to the accessible environment model use?

through dissolution of the waste form and trans*

p port by ground water, the importance of ground-4 Are the model inputs representative of water flow modeling in performance assessment s

l the system?

requires a thorough knowledge of the validity of ground water models and the application of 1

Are the field and laboratory experi-ground-water models in sensitivity and e

i ments detailed enough to provide uncertainty analyses, a

unique sets of databases that characteritt the governing processes?

The HYDROCOIN study was divided into three levels to accomplish the following three basic 6.

Is the measurement scale compatible to technicalobjectives:

the scale of the relevant processes?

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1.

Benchmarking and verifying the numerical 7.

Is there a coherent validation accuracy of codes by code intercomparison strategy that allows for additional and by comparing code results with anal

• data collection and determination of ytical solutions (code verification).

" goodness of fit" criteria for comparison of the simulation results 2.

Evaluating and demonstrating the appli-versus the independent experimental cability of the modcling process for database?-

describing the results of experiments at both the laboratory and field scales (model Performance Assessment of HLW and LLW validation).

The purpose of the NRC staff's involvement in 3.

Investigating and evaluating various methods the HYDROCOIN and INTRAVAL projects is to and approaches for determining the importance g

. prepare for future performance assessments of of different phenomena and parameters I

high-level and low level radioactive waste (sensitivity analysis) and for establishing facilities. Specifically, the NRC staff will be the uncertainties associated with the able to examine the validity of computer Codes performance assessments obtained through that may be used in licensing reviews. These this modeling process for both current and codes are anticipated to be used to simulate future conditions (uncertainty analysis),

radionuclide migration over time periods and in

. hydrogeologic systems relevant to waste disposal.

Code Verification (Level 1)

HYDROCOIN and INTRAVAL are limited to geosphere transport models and do not include waste Seven verification and benchmark problems were leaching or dose assessment models.

selected for the HYDROCOIN Level 1 effort (see Davis 1988 and HYDROCOIN 1987). They include:

HYDROCOIN has examined the validity of ground-water flow models primarily with respect to Case 1

• two-dimensional, transient, radial their impact on site characterization (see flow from a borehole in a fractured-Davisi 1988 and HYDROCOIN 1987). After site permeable medium, characterization, the next step in a performance assessment of a radioactive waste disposal site Case 2 - two-dimensional, steady-state flow is the prediction of performance with respect to in a rock mass intersected by radionuclide migration. Therefore, the INTRAVAL fracture zones.

Project was begun to address the validity of hydrologic transport models to predict repository Case 3 - two dimensional, saturated-I performance over the spatial and temporal scales unsaturated flow in a layered of-interest to radioactive waste disposal sequence of rocks.

(INTRAVAL Ad Hoc 1987).

Case 4 - two dimensional, transient, thermal HYDROCOIN STUDY convection in a saturated permeable i

medium, The

• Hydrologic Code Intercomparison Study."

HYDROCOIN, is an international study designed to Case 5 - two-dimensional, steady-state investigate various ground-water modeling flow and brine transport around a hypothetical salt dome.

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Case 6 - three-dimensional, steady-state C'ese 2 - unsaturated flow in fractured 7 I

flow in a regional aquifer system tuff.

containing bedded salt deposits.

1 Case 3 -. regional ground water flow for a Case 77 two-dimensional. saturated flow bedded salt system (en extension through a shallow land disposal of Level 1, Case 6),

i facility in argillaceous media.

Case 4 *. coupled ground-water flow and

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,The NRC staff and contractors simulated all of brine transport (an extension of the Level I cases which are described in Level 1, Case 5).

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.NUklG 1249 Vol. 1 (Davis 1988).

i Case $ - crystalline rock case with two Model Validation (Level 2) alternatives; (a) Chalk River (an extension of Level 2 Case L

Five experimental data sets were selected for 3),(b)Fjaeliveden, Sweden, use in the Level 2 (validation) effort KBS 3 site.

(Andersson 1985 and HYDROCOIN 1987). They include:

Case 6 - three dimensional ground-water

-flow in low permeable media (an Case 1

• a field heat transfer experiment extersion of Level 2 Case 4).

(Cornwall, England) involving thermal convection and Case 7 - particle tracking sensitivity

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conduction.

study.

Case 2 - variable density fluid flow based The NRC-staff and contractors are presently on a laboratory experiment with completing simulation studies of cases 1, 2, 3, thermal convection (Elder 6 and 7, and were the pilot groups for experiment).

formulating and initially modeling cases 6 and 7 (Nicholson 1987 and HYDROC0!N 1987).

Case 3 + a small ground-water flow system in fractured montonitic gneiss HYDROCOIN Products (Chalk River Ontario,- Canada).

Twenty-five project teams representing 11 Case 4 - three dimensional, regional, countries have participated in HYDROCOIN through i.

ground-water flow in low the simulation and analysis of the test cases r7 permeability rocks (Piceance (see HYDROCOIN 1987)..The experiences of the Basin, Colorado USA).

various project teams resulted in a number of r

recommendations or " lessons learned" related to Case 5 - unsaturated tone, soil water the validation and use of hydrogeologic models redistribution near the surface (see Cole 1987 and Nicholson 1987). In this at a field site (Central Valley, report " lessons" is used in the more generic California, USA).

sense to mean the variety of quantitative and i

qualitative findings (e.g., numerical tech-While none of these data sets were felt to be niques, particle tracking algorithms, and totally adequate for validation, it was belie'ved problem formulations) that have resulted from that the exercise of simulating these field and this effort. Lessons include newly identified laboratory experiments provided valuable informa-findings as well as confirmation of the O

tion about the codes and the modeling strategies, importance of previously identified findings.

Tt-NRC Staff and contractors have simulated Many of the lessons are drawn from direct i

cases 1, 4 and 5 and were the pilot groups that experiences with numerical simulations of both formulated and initially modeled cases 4 and 5 saturated and unsaturated flow problems dealing (see Andersson 1988, HYDROCOIN 1987, and with various geologic media (e.g., fractured

~ Nicholson 1987).

Crystalline rock, clay, bedded salt, tuf f) for both high-and low level waste disposal Uncertainty and Sensitivity Analysis settings. They relate directly to the codes, (Level 3) numerical techniques, and details regarding the way the codes were applied, as well as-the-The Level 3 ef fort' includes the use of tools and methods and approaches for interpreting the data techniques for. Sensitivity and uncertainty sets. Other validation lessons developed

analysis in conjunction witt, ground water flow directly from the interactions and discussions models. Seven Level 3 problems and data sets at the HYDROC0!N workshops and at specially' (see HYDROCOIN 1987) have been defined, and convened symposia (Cole 1987. HYDROC0lN 1987 and these include

Tsang 1986), and from the process of code and Case 1 - near-surface disposal in argillaceous media (an extension Work on Level 1, model verification, has been of Level 1, Case 7),

completed and published (see Davis 1988,and 3

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l Nicholson 1987). Work on Levels 2 model ante measure calculations to identify the most validation, and 3. model uncertainty and important parameters for the performance assess-sensitivity analysis, has been completed and ment. Uncertainty analysis is used to evaluate will be published soon.

the effect limitations in site characterization and incomplete understanding of the hydrogeologic Lessons Related to Validation system have on the simulation results. In this regard, uncertainty analysis provides a In the coni, ext of waste management it has been quantitative measure of the reliability of the

. suggested that validation applies to both the model. Data for characteriging and understanding code and conceptual model (IAEA definition (IAEA a hydrogeologic system is primarily obtained 1982)):

through the drilling of wells and subsequent 4

testing using the well field. A site conceptual "A conceptual model and the computer code model implicitly and explicitly contains many derived from it are " validated" when it is simplifications of the natural system based on p

confirmed that the conceptual model and the extrapolations and interpolations of the data-derived computer code provide a good base. Sensitivity and uncertainty analyses are representation of the actual processes important to understanding simulation limita-i occurring in the real system. Validation tions of a hydrogeologic system. Therefore, the is thus carried out by comparison of calcu-application of sensitivity and uncertainty anal-lations with observations and experimental yses in support of hydrogeologic investigations h-measurements."

were examined in the final phase of HYDROC0!N.

Comprehensive databases sufficient for valida-The use of sensitivity and uncertainty analysis tion of complex ground water flow models are not.

requires: (1) determination or selection of available at present (INTRAVAL Ad Hoc 198/ and performance measure (s) (quantitative measure (s)

Nicholson 1987), lhis was confirmed by that relates simulation results to the purpose extensive literature searches and technical of the investigation); (2) hydtDgeologic simula*

inquiries that were undertaken to find data sets tions which investigate sensitisities and for Level 2.

Numerical simulations using the uncertainties of the hydrogeologic system; and Level 2 data bases, initially thought to be (3) identification of important 'entures or-complete, tevealed that the test case data were sensitivities of the hydrogeologic system not sufficient for validation purposes. Earlier through the analysis of the results of the INTRACOIN project efforts indicated that for performance measure (s) calculations.

many field situations, especially at larger scalesi there are too many degrees of problem Simulations, in support of the sensitivity

' f reedom to allow validation in the traditional analysis of HYOR0 COIN, were comprised of varia-O sense. As a result at least two espects of tion of a single model parameter (single validation must be addressed. One aspect parametric variation) and simultaneous variation involves selecting sufficiently complete data of all model parameters (global sensitivity).

sets and well-defined experiments (at either the For the single parametric variation technique the lab or field scale) to validate, in the tradi*

analyst uses his tnowledge of the hydrogeologic

.tional sense, our mathematical description of system to select certain parameters and modeling the physical processes involved in ground water assumptions to vary to better understand system

' hydrology. A second aspect involves building behavior. Analysis results can be biased by an confidence in the ground water modeling process, incomplete or erroneous understanding of the 3.

' Confidence in the way data are interpreted and system. Another class of sensitivity analysis, codes are applied to assess performance is global sensitivity analysis, attempts to remove generated by the application of codes to this bias by varying parametric values simul

• understand and interpret hydrologic experiments taneously via a statistical sampling scheme such having different levels of detail in databases, as Latin Hypercube Sampling. No significant Patrict Goblet (Ecole des Mines, Fontainbleau, differences in results using the two dif ferent France) summarized at the 4th HYOROCOIN types of sensitivity and analysis were observed workshop some of the aspects of validation when in the HYDROC0lN test cases. The primary reason he stated, "We need to validate the applicabil-for the similar results was that the simplicity ity of our characterization methods, ability to of the test cases presented little of the inter-Interpret, understand and model in low permeabil-pretational dif ficulty and multiple processes ity deep hydrologic systems."

encountered for field investigations, it would be expected that as site complexity increases Uncertainty and Sensitivity Analysis and understanding the hydrogeologic system becomes more difficult the benefit of a global Level 3 of HYDROColN was concerned with the sensitivity analysis would increase, application of sensitivity and uncertainty analysis techniques to hydrologic models in the Performance Measures for Validation context of radioactive waste disposal. Sensitiv-ity analysis is used to evaluate the effect of The HYOR000!N group also recognited that the changes in model parameters and modeling assump-selection of an appropriate performance measure tions have on the simulation results or perform-j l

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U is an integral part of valit*ation. One must Based'on this need, the INTRAVAL projEt is'

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select a performance measure suited to the utilizing data bases which are amenable to later modeling purpose. This issue in code validation testing. Also, scale dependency of the large.

L is also a problem with real site analysis. The temporal and spatial considerations associated type of performance measure used to gent "te with radioactive waste disposal precludes true r!-

confidence in the model's results must be validation. Therefore,theINTRAVALproject carefully selected to be a true measure of the will examine natural analogues to radioactive model's adequacy for use in performance assess

• repositories and use coupled laboratory and j <'

ments, for example, in ground water simulations large-scale field studies (e.g., Las Cruces of the Piceance Basin (Level 2, Case 4), the Trench study) to analyze scale dependence ability of the model to match the measured heads

issues, was dependent on whether en arithmetic mean, a root mean square error, or a kriged weighted The original test cases considered for the I' '

erro* was used.in the comparison. The selection INTRAVALprojectwerefor$tturatedflowand of the most appropriate performance measure must transport in fractured and porous media be resolved in order to decide which of the (INTRAVAL Ad Hoc 1987). Unsaturated flow various simulations provides an adequate problems which are relevant to low-level and I

description of the flow fleid for the purpose of high+1evel radioactive repositories have since the modeling exercise, been defined for the INTRAVAL project. The US NRC staff and contractors have prepared test The performance measure (s) used to evaluate case descriptions for both the experimental LF system behavior were found to have a significant studies and the associated modeling activities effect on the analysis results. For example, for both porous and fractured unsaturated media, for test case 1 of Level 3 (concrete encep-sulated waste disposed of near the surface (see The purpose of INTRAVAL is to increase the HYDPOCOIN 1987)) the properties of the concrete understanding of how various processes and were found to be important to the calculation of hydrogeological structures of importance for the one performance measure (volumetric flux through transport of radionuclides from a repository to the concrete) and not the other (shortest travel the accessible environment can be properly tire from the concrete to a boundary). The described by mathematical models, end how models volumetric flux performance measure is a developed for this purpose can adequately quantitative measure of the amount of ground simulate radionuclide transport during short as water available for leaching nuclides from the well as very long time periods (INTRAVAL 1988),

E concrete blocks while the travel time perform-Additional benefits from the INTRAVAL project ante measure is a conservative measure of the involvement are active interchange between g-containment ability of the geologic site. The experimentalists and modelers on state cf the-use of multiple performance measures allow the art experiments for validating geosphere flow total system to be divided into subsystems each and transport models for radioactive waste with its own performance criteria (e.g.,

disposal. Discussions on improvements to these volumetric flux for the concrete). This experiments and suggested new experiments also increased reliability in the interpretation of will be pursued.

results was clearly demonstrated in validation test case 1 of Level 2 (see HYDROCOIN 1987).

INTRAVAL Cases o

for this test case (heater experiment in granite), project teams were able to fit either The study cases adopted and assigned " Pilot of two performance measures but not both with Group Leaders" by the Co-ordinating Group in

' comparabic accuracy. - Validation was not April 1988 for Part I and Part 11 were:

achieved and the accuracy of the experimental procedure was called into question based on the Part I simulation results for both performance measures. The multiple performance measures Case la Radionuclide migration in intact rock promoted the consideration of alternative and clay samples by diffusion and conceptual models and yielded more focused advection based on laboratory measures of system performance, experiments performed at Harwell, U.K.

Pilot Group Leader: David Lever, INTRAVAL STUDY Harwell.

W The " International Transport Validation Study,"

Case Ib Uranium migration in crystalline bore INTRAVAL, which formally began in Stockholm, cores based on laboratory experiments

' Sweden in October 1987.. is a direct outcome of performed at ElR, Switzerland.

the successes and lessons learned in the Pilot Group Leader: Jorg HYDROC0!N project. For example, the validation Hadermann, ElR.

Studies of HYDROCOIN illustrate the need to reexamine the database and assumptions used to Case 2 Radionuclide migration in single I

develop the model input and to perform addi-natural fis:ures in granite based on tional experiments to isolate individual pro-cesses and phenoment of the conceptual model.

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laboratory experiments performed at on varying moisture content and KTH, $weden, temperature gradients

f-Pilot Group Leader: Tryggve Pilot Group Leader: Dwight Eriksen, KTH.

Hoxie, US Geological Survey Case 3 Tracer tests in a deep basalt flow top NRC Activities in INTRAVAL performed at the Hanford reservation, O

Washington, USA.

NRC staf f involvement in thin project is extremely L

' Pilot Group Leader: Charles beneficial to the waste management program for Cole, PNL.

two reasons. First, a number of issues relevant to assessing the adequacy of a license applica-Part 11 tion will be addressed, such as: the validity of hydrogeologic models, hydrogeologic charac-Case 4 Flow and tracer experiments in-terization of a field site, extrapolation of crystalline rock based on the Stripa laboratory measurements to field experiments, 3 D experiment performed within the and extrapolation of short-term test (e.g.,.

international 5tripaproject.

days to months) data to long term (e.g.,

Pilot Group Leader: Ivars thousands of years) performance assessments.

Neretnieks, KTH.

Second, the staff analysis performed to evalu-ate a hydrogeologic data base will be,similar.

Case 5 Tracer experiments in a fracture zone regardless of whether the purpose is to judge at the Finnsjon research area, Sweden.

the adequacy of (1) an INTRAVAL database to Pilot Group Leader: Peter support a hydrogeologic hypothesis, or (2) a Andersson, Swedish Geological Co.

licensee's database in support of his applica-tion. Therefore, involvement in INTRAVAL will Case 6 Withdrawn.

afford staff " hands-on" experience with some of the analysis work which will be required Case 7 Natural Analogue studies at the Pocos during license reviews. A further benefit of de Caldas site, Minas Gerais Brazil.

INTRAVAL involvement is the interaction with Pilot Group Leader: Nell experts from around the world with the NRC sssff Chapman, BG$.

analysing the same waste management issues.

Case O Natural Analogue studies at the Specifically, NRC staff evaluations will entail:

Koongarra site in the Alligator Rivers (1) analysis of the collected data to construct

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area of the Northern Territory, a conceptual model(s); (2) simulation of the Australia, experiment, based on the constructed conceptual Pilot Group Leader: Peter

.model(s), with an available NRC computer program; Duerden, ANSTO.

(3) evaluation of the simulation.results to validate the conceptual model(s) and/or suggest Case 9 Radionuclide migration in a block of further testing / characterization needed to prove crystalline rock based on laboratory and/or disprove the various conceptual model(s);

experiments performed at AECL.

and (4) revision and reevaluation of these p

Whiteshell, Canada, in cooperation conceptual model(s) and the need for additional with the U.S. 00[.

data. These analyses will be reported through Pilot Group Leader: To be the INTRAVAL Project workshops and reports. 'The appointed by Norman [isenberg, NRC staff will be further assisted by the review USDOE.

and recommendations provided by INTRAVAL participants on the NRC staff analyses.

Case 10 Unsaturated flow and transport in porous media at the Las Cruces Trench The INTRAVAL project structure is based on a Experiment with emphasis on assessing participating organization having one or more spatial variability.

project team (s) performing the technic!tl work.

Pilot Group Leader: Thomas J.

Presently there are nine INTRAVAL test cases Nicholson, USNRC with more being proposed, Although it would benefit the NRC to follow the work performed by Case 11 Unsaturated flow and transport in

-all participants as it relates to generic issues fractured tuf f at the Apache Leap Tuf f (i.e., time and spatial scale issues, extrapola-Site with emphasis on assessing tion of laboratory data), the most important matrix fractured flow systems.

INTRAVAL test cases which the NRC staff and Pilot Group Leader: Thomas J.

contractors will simulate first are:

L Nicholson, USNRC.

case 10 Las Cruces Trench Study (New Mexico Case 12 Unsaturated flow and transport in State University /PNL/MIT)

Infiltration and solute transport i

fractured welded tuff at the G Tunnel.

Nevada Test Site, Nevada with emphasis under variably-saturated condi-tions for heterogeneous porous media in the near surface; 6

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1 Case 11 Apache' Leap Tuf f Study (University of -

assess' ment. These experiments must be" 1

,,L Arizona) formulated and developed by both laboratory and p

jfluid flow and solute transport field experimentalists to provide the compre*

experiments in unsaturated hensive database for validation. Efforts must e

U fractured tuff at both the provide a better understanding of the limita-laboratory and field scales; tions that incomplete system characterization-

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poses in terms of hydrogeologic system inter

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Case 12 Borehole Experiment in G Tunnel, pretation and conceptual model development. The F

Nevada Test Site (USGS) validation process will involve iteration Fluid flow and solute transport between experimentation and simulation wherein at elevated temperatures and the database is reexamined and additional date J

various moisture contents in the is collected.. Additionally, we must be able to' L

. vicinity of boreholes in demonstrate what effect incomplete characteriza*

fractured tuff; tion has on model validation and performance assessment uncertainty.

Case 8 Alligator Rivers Analogue (Australia Nuclear Science & Technology

' REFERENCES Organization)

Solute transport in a reducing Andersson, K., B. Grunfelt D.' Lindbom, and l

and oxidizing environment over C.P. Jackson. 1988. HYDROC0!N level 2

• L extremely long time scales Final Reportt Validation of Ground-Water (thousands of years) relevant for Flow Models With Respect To Assessment of waste management performance Radioactive Waste Disposal, Draft Report, assessments.

Swedish Nuclear Power Inspectorate, o.

Stockholm, Sweden.

~t Additional cases will be simulated as time and resources permit.

Cole, C.R., T.J. Nicholson, P.A. Davis, and T.J. McCartin. 1987. " Lessons Learned.

CONCLUSIONS from The HYDRJCOIN Experience," Proceed *

'3 inos of the Gf0 vat 87 Symposium on The most significant conclusions taken from the Verification and Validation of Geosphere HYDROCOIN study weret-Performance Assessment of Models, Swedish-huclear Power Inspectorate, 5tockholm, r

(1) validation is a site specific issue (i.e.,

Sweden, April 7 9, 1987.

g p'

validity depends on both the model and the correct interpretation and use of site Davis, P.A. and others, 1988. "NRC Hodel data);-

Simulations in Support of the Hydrologic CoJe Intercomparison Study"(HYDROCOIN) -

-(2) comparison of model simulations with a tevel 1 Code Verification, NUREG 1249 Vol.

single spatial and temporal. set of

1. U.S. Nuclear Regulatory Commission, experimental results is likely to result in Washington, D.C.~

model calibration rather than validation; HYDROCOIN Secretariat. 1987. "HYDROCOIN (3)h a variety of conceptual models should be Progress Report 6. April 1987 - September examined when evaluating hydrogeologic site 1987," Swedish Nuclear Power Inspectorate, conditions to determine if simplifyir.;;.

Stockholm, Sweden.

l assumptions are valid; IAEA. 1982. Radioactive Waste Management

~(4) with respect to_ validation, more is learned

-Glossary, IAEA TECDOC-264, InternalTonal when models are rigorously tested on a Atomic Energy Agency,-Vienna, Austria, g

variety of possible site conditions than when models are tested for simple condi-INTRAVAL Ad Hoc. 1987. "Geosphere Transport tions which can be easily reproduced; Model Validation - A Status Report " SKI 87:4, Swedish Nuclear Power Inspectorate,.

~($) validationcanbestbejudgedwhenprior Stockholm, Sweden.

performance measures are established and specific criteria for model acceptance are INTRAVAL Secretariat. 1988. "INTRAVAL Progress L

fully defined.

Report 1, October 1987 - January 1988,"

Swedish Nuclear Power Inspectorate,

?The'HRC staff and' contractors will be involved Stockholm, Sweden.

in the INTRAVAL study to fully address model

. validation. Future efforts will involve both Nicholson, T.J., T.J. McCartin, P.A. Davis, and I

field and laboratory experimentalists and W. Beyeler. 1987. "NRC Experiences in modelers. These efforts will require experi-hYDROCOIN: An International Project for ments specifically designed to eddress model-Studying Ground-Water Flow Modeling validation issues in the context performance Strategies," in Proceedings of the Waste 7

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' Management 87 at Tucson Arizona March 1*5.

Performance Assessmen','of Doop'Geolocic

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G,

' lpj l. Edited by Roy G.-Post University of Disposal of Radionuc1' de Was'Le: A J

Ar zone,' Tucson, Arizona.

Critical Eve' ua', ion'oF the 5'Lete of the 1

Art May 20 2:

,955 Al pueuereue. New Mexico',

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,Tsang.. Chin Fui '1986. Lessons Learned in the -

.C.R. Cole and T.J. Nic)olson, Co-Chairman,

' verification, Validation and Application of.

NUREG/CP-0079 (PNL*$A 13796 CONF-850$180).

. y.

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, a Coupled Heat and Fluid flow Code,'.' in U.$.' Nuclear Regulatory Commission.f

-c Proceedinos of the Symposium on Ground--

Washington, D.C.

Water Flow and Trans_ port Modelino for

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