I A

January 31, 1989

PROGRAM PLAN FOR

MODELING AND VALIDATION EXERCISES

UNDER THE

NMSS/RES MEMORANDUM OF UNDERSTANDING (MOU)

NRC PROJECT TEAM

INTRAVAL RPOJECT

8902060043 89020 1 7

NMSS SBJ CDC l

414.4.1 I 
2

PROGRAM PLAN FOR MODELING AND VALIDATION EXERCISES

UNDER THE NMSS/RES MEMORANDUM OF UNDERSTANDING MOU)

INTRODUCTION

The NRC accepted an invitation from the INTRAVAL Project Secretariat to

participate in INTRAVAL (Letter from E. Beckjord, RES to K. Andersson, SKI

dated Sept. 9, 1987). INTRAVAL is an international endeavor focusing on

validation issues associated with simulating hydrologic flow and radionuclide

transport for radioactive waste reporting sites. This ongoing effort is being

incorporated as Task 1 of the NMSS/RES Memorandum of Understanding (MOU).

Under the MOU, NMSS and RES staff will be developing an in-house flow and

transport modeling expertise for performance assessment modeling. This

expertise will come from evaluating and modeling observed processes at

experimental field sites and in controlled laboratory experiments. The NRC

staff will improve its understanding of the controlling phenomena for flow and

transport in the geosphere. NRC staff participation in INTRAVAL will benefit

the MOU by; 1) comparison and development of validation criteria for different

conceptual models for flow and transport through the different participants

analyses, 2) peer review of NRC analyses and modeling of flow and transport of

radioactive waste, and 3) interaction with and ability to influence

experimental programs in other countries.

NRC participation will focus on test cases which, at this time, are considered

to be most relevant to NRC licensing needs. The test cases initially selected

for analysis are:

1. Apache Leap unsaturated tuff experiments

(University of Arizona - FIN D1662)

2. G-tunnel borehole experiment in unsaturated tuff

(USGS - DOE Funding)

3. Synthetic migration experiment

(Cooperative Effort Among NRC - PNL - NAGRA)

4. Alligator Rivers natural analog experiment

(ANSTO International Cooperative Project)

5. Las Cruces unsaturated flow and transport experiment

(New Mexico State University - FIN B8934)

NRC participation includes fourteen staff members (see Table 2) and a number of

RES contractors (SNL/NRC, MIT, PNL, and UofA) at different levels of

involvement. This program plan structures and defines the staff participation

for the flow and transport modeling exercises and the NRC participation in

INTRAVAL.

BACKGROUND
3

NRC will need to review and accept the validity of DOE's assumptions and

simulations of ground-water flow and radionuclide transport at Yucca Mountain.

The validity of ground-water flow and radionuclide transport models is still an

issue that is being examined in all countries involved in nuclear waste

disposal. A clear explanation of validation needs and goals was presented in

the following excerpt from the INTRAVAL First Progress Report;

"Previous experiences from attempts to validate geosphere transport models have

lead to an increased confidence in the models. They have, however, also lead

to an awareness that model validation is a difficult issue, which cannot be

resolved by simply comparing model results with experimental data. This

procedure will most likely create alternative explanations of the experiments

that cannot be unambigously confirmed or rejected because of insufficient

information.

In order to increase the possibilities to be conclusive in validation, there is

a need to utilise information from different types of experiments on different

temporal and spatial scales. There is also a need to increase the interaction

between modellers and experimentalists in order to gain reassurance that the

experimental data are properly understood and that the experiences of modellers

regarding the type of data needed from the experiments are accounted for.

One must recognise that validation of models is an integrated part of the

scientific process with the necessary components:

- identification of outstanding issues requiring

experimental/technical resolution,

- identification of experimental procedures to address these issues,

- peer evaluation and review.

These different aspects of the model validation process are well suited to be

tackled in an international group. Confrontation of ideas, larger range of

experimental data, as well as contacts between modellers and experimentalists

from several countries should serve as a driving force for progress.

Considering the fact that nuclear waste disposal programmes in many countries

now gradually leave a generic stage and enter a stage of application it is

clear that the need for "validated" models will increase. The detailed

validation strategies will vary between different countries and their

programmes for nuclear waste disposal due to e.g. different time schedules as

well as dissimilar performance measures and criteria for waste repositories.

It is, however, foreseen that the INTRAVAL project will provide a framework for

international co-operation-which can meet important demands in the development

of strategies for geosphere transport model validation."

OBJECTIVES

NMSS and RES (memorandum from R. Browning HLW, NMSS to G. Arlotto, DE, RES

dated May 13,1988) have committed staff involvement to INTRAVAL that will

address; 1) improve understanding of the validity of models for flow and

transport of radionuclides, 2) better understanding limitations of current
4

experimental techniques used in site characterization and parameter estimation,

3) better defining experiments needed to distinquish between different

conceptual models, 4) improving performance assessment capability within NMSS

and RES, and 5) allowing for peer review of NRC staff analyses similar to the

analyses that will be required during the DOE's liscence application.

PROGRAM DESCRIPTION

As described above, the INTRAVAL participation will focus on five test cases.

While staff simulation efforts will concentrate on these test cases, it is

anticipated that additional benefit will be derived from following the efforts

of the other project teams involved in the other test cases (e.g., fracture

flow and transport phenomena). This supplemental effort will consist primarily

of attendance and participation at INTRAVAL Meetings. The MOUJ program work is

limited to the situation exercises related to the five specific test cases

described earlier.

Each validation/simulation exercise may involve different technical issues or

phenomena, however, the steps taken to reach a conclusion will require the

following three programmatic steps:

Step 1: Test Case Definition and Validation Strategy

The staff effort for each test case will begin with a review of the INTRAVAL

test case definition., Based on this review, a strategy will be developed as a

guide for the hypothesis testing and simulation effort to be performed in Step'

2. The strategy will include; 1) clear description of phenomena to be

analysed/validated, 2) initial identification of data needs and uncertainties,

3) identification of performance measures, 4) discussion of relevance to

performance assessment, and 5) initial estimate of goodness-of-fit expected

between experimental and simulation results (as quantitative as possible). The

validation strategy will be documented and reviewed prior to proceeding to the

next step of the test case exercise.

Step 2: Initial Simulations

Based on the validation strategy developed in Step 1, initial simulations will

be performed. The goals of these simulations will be; 1) determine the

adequacy of computer programs to simulate the test case, 2) determine the

appropriateness of the performance measures, 3). better define uncertainties and

data needs, and 4) define a rigorous validation test.

Step 3: Validation Simulation and Conclusions

Based on the previous results, a validation simulation will be designed,

executed and analysed. The results of the simulation will also consider other

INTRAVAL results to support or reject the validity of the model. Regardless of

the the validation finding, the final analyses will involve; 1) technical

rational for the finding, 2) discussion of the results of other conceptual
K>

5.

models used by other INTRAVAL participants, 3) recommendations for future

experiments, and 4) discussion of unresolved issues and possible resolution.

INITIAL TEST CASE EXERCISES

Specific exercises for the five test cases are expected to be:

Apache Leap -

Exercise 001; Fracture and matrix flow will be analysed using field

experimental data. The initial approach will assume a porous media where

fractures may be accounted for as high conductivity zones and/or a bi-modal

characteristic curve. Computer programs such as TOUGH and SUTRA will be used.

Staff equivalent porous media simulations will be compared with discrete

fracture models of other INTRAVAL participants (University of Arizona).

Exercise 002; Two-phase flow and heat transport in a porous media will be

examined using the core experiment data. The computer program TOUGH and a

semi-analytic solution (to be developed in-house) will be used. Staff

two-phase flow simulations will be compared with other two-phase flow models of

other INTRAVAL participants (SNL/NRC and USGS).

Exercise 003; Fracture and matrix flow will be analysed with the laboratory

block experiment data. The initial approach will assume a porous media where

fractures may be accounted for as high conductivity zones and/or a bi-modal

characteristic curve. Computer programs such as TOUGH and SUTRA will be used.

Staff equivalent porous media simulations will be compared with discrete

fracture models of other INTRAVAL participants (University of Arizona and

SNL/NRC).

G-Tunnel -

Exercise 004; The G-tunnel experiment examines the effect of wet and dry

drilling on heat and fluid flow in unsaturated tuff. Analyses will concentrate

on fracture and matrix flow under slightly elevated temperatures. Two-phase

flow will be analysed assuming porous media with fractures accounted for as a

high conductivity zone and a bi-modal characteristic curve. The computer

programs TOUGH and SUTRA will be used. Comparisons will be made with of a

model which includes two phases (TOUGH) and a model which includes a single

phase (SUTRA) for simulating unsaturated flow and heat transport.

Synthetic Migration Experiment -

Exercise 005; The synthetic migration experiment is designed to examine the

uncertainties of performance predictions arising from incomplete knowledge of

the hydrogeologic system. The limitations of current predictive simulation

techniques are to be examined in this test case. Computer models such as SWIFT

II, SUTRA and DPCT could all be used. Comparison of predictive modeling

techniques of the NRC staff with other techniques used by other INTPAVAL

participants.
6

Alligator Rivers Analog -

Exercise 006; The Alligator Rivers analog is focused on the long term (hundreds

of thousands of years) and large scale (hundreds of meters) migration of

radionuclides from an unranium ore body. Analyses will examine dispersive and

retardation mechanisms. Computer programs such as SWIFT II, SUTRA, DPCT and

EQ3/EQ6 will be used. (The significant time involved in detailed geochemical

modeling (i.e., use of EQ3/EQ6) may require that NRC staff follow the work

being done by other contributors to INTRAVAL such as Dimitri Sverjensky from

Johns Hopkins University.) Comparison of various retardation mechanisms (e.g.,

retardation coefficient, Freundlich isotherm, detailed geochemistry) and

examination of dispersion phenomena over long times will be made within the NRC

staff effort and with other INTRAVAL participants.

Las Cruces Trench -

Exercise 007; The Las Cruces trench experiment was designed to examine the

affect of spatial variability on the infilitration and subsequent moisture

redistribution in a porous media. The analyses of this test case will examine

how spatial variability in hydrologic properties affects horizontal and

vertical flow and transport in heterogeneous unsaturated media. It is

anticipated that deterministic models such as TOUGH and SUTRA will be used.

(Time commitments of the NRC staff may dictate that participation be limited to

following the stochastic and deterministic modeling being done by NRC

contractors such SNL/NRC, PNL and MIT.) Comparison of stochastic and

determinsitic models-will be performed.

Test case exercise scheduling and staff commitments are presented in Tables

1-7. (Due to NRC participation in INTRAVAL prior to the MOU, progress on the

Apache Leap test case has already been made and is reflected in the Tables.)

Documentation

It is anticipated that due to the complexity of both the validation issues and

test cases, the staff effort will be an iterative process consisting of a

number of simulation excercises which analyse a particular issue. At the

conclusion of each exercise (Steps 1-3), a progress report will be written to

document the results. A notebook for each test case exercise will be

maintained for the duration of the project which will provide a record for the

various simulation activities and the technical findings. The emphasis of the

test case notebooks will be to maintain a clear ongoing technicl documentation

of the work.

Additionally, an annual summary report will be prepared which documents the

important findings from the INTRAVAL project. The objective of this

documentation is to incorporate and document the collective INTRAVAL findings

(i.e., obtained through attendance at meetings and review of INTRAVAL

documentation) as they pertain to individual test cases and to the licensing of
7

an HLW repository in the United States (i.e., scaling of hydrologic and

transport properties for the INTRVAL cases should be directly applicable to

scaling issues at Yucca Mountain).

Meetings

The INTRAVAL Project involves a variety of problems that examine a number of

flow and transport validation issues under a variety of hydrogeologic

conditions and at differing spatial and time scales. The NRC staff and their

contractors do not have the resources to be involved in every test case and

will only be able to try a limited number of modeling exercises for selected

test case. However, through active participation at INTRAVAL Workshops, the

NRC Staff will.be able to maximize this effort by closely following the

simulation analyses of all test cases via the cooperative nature of this

international project.

An integral part for benefiting from the cooperative effort on INTRAVAL is the

participation in workshops and associated field trips. The workshops are the

primary way technical ideas are exchanged and peer review of staff analyses is

accomplished. NRC staff and contractors attending the workshops and field

trips will brief NRC staff and management on their technical findings.

Staff participation will primarily be coordinated through bi-weekly meetings to

be held in OWFN. RES will be responsible for distributing an agenda the Friday

prior to the meeting.

NRC PROGRAM MANAGER

The NRC program manager will coordinate staff simulation work and documentation

on the modeling exercises and be responsible for communication with the NRC

representative to the INTRAVAL Project Secretariat.

Contractor Participation

This program plan describes NRC staff participation, however, it is important

to note that it is dependent on a significant contribution from NRC

contractors. These contractors are responsible for developing an experimental

data base at Apache Leap and Las Cruces Trench sites. RES is also currently

providing partial funding to the multi-national cooperative agreement for the

Alligator Rivers Analog Project. NRC contractors (i.e., MIT, PNL, SNL, and

UofA) will also be using different models for simulating these test cases.
8

REFERENCES:

1. INTRAVAL Ad Hoc Group, June 1987, "Geosphere Transport Model Validation -

A Status Report," SKI 87:4, Swedish Nuclear Power Inspectorate, Stockholm,

Sweden.

2. INTRAVAL Ad Hoc Group, .Luly 1987, " INTRAVAL Project Proposal", SKI 87:3,

Swedish Nuclear Power Inspectorate, Stockholm, Sweden.

UNSATURATED ZONE TEST CASES

3. Evans, D.D. and T. J. Ncholson, 1987, "Flow and Transport Through

Unsaturated Fractured Rock: An Overview", in Flow and Transport

Through Unsaturated Fractured Rock, AGU Geophysical Monograph 42, American

Geophysical Union, Washington, DC, pp.1-10.

4. Evans, D.D., T.C. Rasmussen, and T.J. Nicholson, 1987, "Fracture System

Characterization for Unsaturated Rock", in Proceedings of the Waste

Management 87 at Tucson, Arizona, March 1-5, 1987, Edited by Roy G. Post,

University of Arizona, Tucson, AZ.

5. Nicholson, T.J. and others, "Validation of Stochastic Flow and Transport

Models for Unsaturated Soils: Field Study and Preliminary Results", in

Buxton, B.E., Editor, Proceedings of the Conference on

Geostatistical, Sensitivity, and Uncertainty Methods for Ground-Water

Flow and Radlonuclide Transport Modeling, Battelle Press, Columbus, Ohio,

1989.

6. Polmann, D. J., and others, "Applications of Stochastic Methods to the

Simulation of Large-Scale Unsaturated Flow and Transport," NUREG/CR-5044,

U.S. Nuclear Regulatory Commission, Washington, D.C., September 1988.

7. Rasmussen, T. C. and Evans, D. D., "Unsaturated Flow and Transport Through

Fractured Rock Related to High-Level Waste Repositories," NUREG/CR-4655,

U.S. Nuclear Regulatory Commission, Washington, D.C., May 1987.

8. Wierenga, P. J., and others, "Validation of Stochastic Flow and Transport

Models for Unsaturated Soils: A Comprehensive Field Study,"

NUREG/CR-4622, U.S. Nuclear Regulatory Commission, Washington, D.C.,

August 1986..

9. Yeh, T. C., and others, "Simulation of Liquid and Vapor Movement in

Unsaturated Fractured Rock at the Apache Leap Tuff Site," NUREG/CR-5097,

U.S. Nuclear Regulatory Commission, Washington, D.C., March 1988.

HYDROCOIN COOPERATIVE REPORTS

10. Cole, C.R. and T.J. Nicholson, Co-Chairman, 1986, Proceedings of the

Symposium on Ground-Water Flow and Transport Modeling for Performance

Assessment of Deep Geologic Disposal of Radioactive Waste: A Critical

Evaluation of the State-of the-Art, May 20-21, 1985, Albuquerque, New
-

i * 9

Mexico, NUREG/CP-0079 (PNL-SA-13796, CONF-8505180), U.S. Nuclear

Regulatory Commission, Washington, DC.

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

Learned from the HYDROCOIN Experience", Proceedings of the GEOVAL 87

Symposium on Verification and Validation of Geosphere Performance

Assessments of Models, Swedish Nuclear Power Inspectorate, Stockholm,

Sweden, April 7-9, 1987.

12. Davis, P.A., T.J. McCartin, D. Updegraff, W. Beyeler, R. Miller, and T.J.

Nicholson, 1988, "NRC Model Simulations in Support of the Hydrologic Code

Intercomparison Study (HYDROCOIN): Level 1- Code Verification," 

NUREG-1249, Vol. 1, U.S. Nuclear Regulatory Commission, Washington, DC.

13. Nicholson, T.J., T,J, McCartin, and P.A. Davis, 1988, "International

Projects in Validating Ground-Water Flow and Transport Models", in

Proceedings of International Conference and Workshop on the Validation

of Flow and Transport Models for the Unsaturated Zone, May 22-25, 1988,

Ruidoso, New Mexico, New Mexico State University, Las Cruces, NM.

14. Nicholson, T.J., T.J. McCartin, and P.A. Davis, 1987, "NRC Experiences in

HYDROCOIN: An International Project for Studying Ground-Water Flow

Modeling Strategies", n Proceedings'of the Waste Management 87 at

Tucson, Arizona, March 1-5, 1987, Edited by Roy G. Post, University of

Arizona, Tucson, AZ.
11

Table 2 MOU

TASK

INTRAVAL

Las Cruces

G-Tunnel

Apache Leap

Alligator R.

Synthetic

Migration

Travel

Training

staffing requirements

PES

TN TM GB LK TOTAL

4 4

7 2 2 2 13

5 5 10

10 10 4 5 29

5 6 5 16

4 4

(reported as staff weeks).

RC NE WF JB JV NC DC JH

1

6 7 4

4 4 3

6 16 5

7

2

3

NMSS

KM SC TOTAL

2 3

2 21

1 12

2 32

2 16

17

NRC

TOTAL

7

34

22

61

32

21

10

4

I

14 3

4 4

2 2

8

4

2 2

0

Totals 32 32 12 12 88 16 16 27 19 3 7 5 1 7 2 103 191

TN - Tom Nicholson

TM - Tim McCartin

GB - George Birchard

LK - Linda Kovach

RC - Richard Codell

NE - Nonman Eisenberg

WF - Bill Ford

JB - John Bradbury

JV - John Buckley

NC - Neil Coleman

DC - Don Chery

JH - Joe Holonich

KM - Keith McConnell

SC - Seth Coplan
12

Table 3. Task plan and staff commitments

Apache Leap Test Case.

Jan Feb Mar

EXERCISE 001 (Field Experiment)

Step 1 (Strategy)

Staff Effort - 0 weeks

Step 2 (Simulation)

Staff Effort - 0 weeks

Step 3 (Validation) X XXX

Staff Effort - 4 weeks

Total Exercise Effort - 4 weeks

TM(1), TN(1), WF(1), JB(.5), DC(.5)

EXERCISE 002 (Core Experiment)

Step 1 (Strategy) X X

Staff Effort - 7 weeks

Step 2 (Simulation) X X

Staff Effort - 14 weeks

Step 3 (Validation)

Staff Effort - 5.5 weeks

Total Exercise Effort - 26.5 weeks

WF(6), TM(5), TN(4), NE(3), JB(2),

GB(2), LK(2), DC(1.5), KM(1)

EXERCISE 003 (Block Experiment)

Step 1 (Strategy) X

Staff Effort - 7 weeks

Step 2 (Simulation) X

Staff Effort - 18 weeks

Step 3 (Validation)

Staff Effort - 5 weeks

Total Exercise Effort - 30 weeks

WF(9), TN(5), TM(4), LK(3), JB(3),

NE(2.5), G(2), DC(1.5), KM(1)

(reported in weeks)

FY 1989

Apr May Jun Jul

for the

Aug Sep

X

X X

X X X XXX 

X X X

X X X X X

X X X

XXX - Progress Report Due
13

Table 4. Exercise plan and staff commitments (reported in weeks) for the

G-Tunnel Test Case.

FY 1989

Jan Feb Mar Apr May Jun Jul Aug Sep

EXERCISE 004

Step 1 (Strategy)

Staff Effort - 11 weeks

Step 2 (Simulations)

Staff Effort - 11 weeks

x x x x

x x x x x x

Step 3 (Validation)

Staff Effort - 0 weeks

Total Exercise Effort - 22 weeks

TM(5), TN(5), WF(4), NE(4)j JB(3),

K (I)
14

Table 5. Exercise plan and staff commitments (reported in weeks) for the

Synthetic Migration Test Case.

FY 1989

Jan Feb Mar Apr May Jun Jul Aug Sep

EXERCISE 005

Step I (Strategy)

Staff Effort - 7 weeks

Step 2 (Simulations)

Staff Effort - 14 weeks

x x x x x x

x x x x x x

Step 3 (Validation)

Staff Effort - 0 weeks

Total Exercise Effort - 21 weeks

RC(14), (4), JV(3)
15

Table 6. Exercise plan and staff commitments (reported in weeks) for the

Alligator Rivers Analog Test Case.

FY 1989

Jan Feb Mar Apr May Jun Jul Aug Sep

EXERCISE 006

Step 1 (Strategy) x x x x x x

Staff Effort - 15 weeks

Step 2 (Simulations)

Staff Effort - 17 weeks

Step 3 (Validation)

Staff Effort - 0 weeks

Total Exercise Effort - 32 weeks

JB(7), NC(7), GB(6), TM(5), LK(5),

KM(2)

X X X X X X
16

Table 7. Exercise plan and staff commitments (reported in weeks) for the

Las Cruces Trench Test Case.

FY 1989

Jan Feb Mar Apr May Jun Jul Aug Sep

EXERCISE 007

Step 1 (Strategy)

Staff Effort - 14 weeks

Step 2 (Simulations)

Staff Effort - 20 weeks

X X X X X X

x x x x x x

Step 3 (Validation)

Staff Effort - 0 weeks

Total Exercise Effort - 34 weeks

TN(7), WF(7), NE(6), JB(4), TM(2),

LK(2), GB(2), DC(2), KM(2)
/

PROGRAM PLAN FOR TASKS 2 AND 3

OF THE MOU ON PERFORMANCE ASSESSMENT ACTIVITIES

SOURCE TERM AND TOTAL SYSTEM PERFORMANCE MODELING
T &

DETAILED PROGRAM PLAN FOR PERFORMANCE ASSESSMENT ACTIVITIES

UNDER THE NMSS/RES MEMORANDUM OF UNDERSTANDING

JANUARY 31. 1989
TABLE OF CONTENTS

I. Introduction

II. Goal and Scope of Tables 2 & 3

III. Planning Assumptions

IV. Technical Description of Work

V. Work Breakdown Structure

Appendices

A. Major Milestones

B. Gantt Charts

C. Staff Loading Charts

D. Sumwary of Technical Issues to be Considered in Phase I
1

Detailed Program Plan for Performance Assessment Activities

Under the NMSS/RES Memorandum of Understanding

I. Introduction

This detailed program plan describes the first phase of Task 2 and Task 3 of

the performance assessment (PA) activities to be carried out under the

NMSS/RES Memorandum of Understanding (MOU) of September 1. 1988. This plan

expands on the memorandum of December 9, 1988, which implements the MOU. This

plan describes in greater detail the work to be performed under various

subtasks, how the various subtasks relate to each other, the schedule for that

work, and the individuals responsible for the work.

The purpose of Task 3 of the MOU activities is to perform a total system

performance assessment for the proposed Yucca Mountain Repository, and by doing

so, to extend the RC capability to model repository performance pursuant to

the regulatory review of the Yucca Mountain Project. Task 2, the source term

modeling effort, is broken out as a separate activity, but is an essential part

of the overall PA activities in Task 3; therefore, Tasks 2 and 3 will be

treated together except for the purposes of making work breakdown schedules and

personnel assignments.

The September 1, 1988 ?4OU describes the three Tasks comprising the MOU

activities n broad outline. The December 9, 1988 implementing memorandum

describes the various subtasks, persons assigned to various subtasks, and staff

time commitments. This plan provides more detail about these matters and how

the work is envisioned to proceed. An important aspect of the Task 2 and 3 OU

activities, delineated in the September 1, 1988 MOU, is that these Tasks are to

proceed in two phases. Phase 1, to be completed in FY 89, is intended to be

accomplished with a minimum of technical input and interaction with RC

contractors, except for work documented and products delivered (including

computer codes) to the NRC. Phase 2, to be accomplished in FY 90 and beyond,

is intended to incorporate significant products to be delivered by NRC

contractors, most notably the Tuff Performance Assessment Methodology currently

under development by Sandia National Laboratories under FIN-A1266. Phase 1 is

intended to result in a framework for PA modeling,-with the limited resource

allocated to perform this activity, only a rudimentary demonstration of a PA

modeling capability-is anticipated. Phase 2 is intended to provide a more

complete, accurate, sophisticated, and realistic PA modeling capability.

1I. Goal and Scope of Tasks 2 and 3

The primary goal of Phase I of Task 2 is to provide a simplified radionuclide

source term in the form of a table or a computer code, to the overall system

performance activities in Phase I of Task 3. The goal of Phase I of Task 3

is to conduct a preliminary performance assessment of the high level waste

repository at Yucca Mountain, Nevada. As explained in I above, only a

rudimentary performance assessment is Intended for Phase 1 of the MOU, because
2

of limited resources and time and because input from NRC contractors, that

could contribute greatly to the goals of the 140U, is not currently available.

The performance assessment is considered to be comprised of two parts:

(I)quantitative estimation of total system performance through the use of

predictive models and (2)documentation, ncluding detailed subsidiary modelling

where appropriate, to support the assumptions, data, and modelling approaches

used to obtain quantitative estimates of performance. Tasks 2 and 3 of the OU

will nclude both of these activities.

The total system performance measure for a high level waste repository can be

expressed by a complementary cumulative distribution function (CCDF) of

radionuclide releases to the accessible environment, weighted by a factor

approximately proportional to radiotoxicity, integrated over an appropriate

period of time (10,000 years is the current regulatory requirement). This

performance measure is estimated by following the steps outlined in the

information flow diagram (Figure .). These steps are described briefly below

for the Phase I effort:

1. System Description - The repository is broken into its component

parts for the purposes of modeling. These include the source term

model and the flow and transport model. Computer codes are adapted

or written to simulate models of these components. Ranges of

parameter values are chose to bound the expected behavior of the

system models.

2. Scenario Analysis - Scenarios representing alternative futures for

the system and possible future states of the environment are screened

and chosen. Probabilities are assigned to chosen scenarios.

3. Consequence Analysis - The consequence in terms of cumulative release

of radionuclides to the accessible environment over a specified time

period (usually 10,000 or more years) is calculated for each scenario

and usually numerous realizations of possible parameter values. In

addition to being incorporated by way of cumulative releases into the

CCDF (step 4), certain types of consequences might also be considered

separately to compare to standard for maximum doses to individuals

and for maximum concentration in groundwater.

4. Performance Measure Calculation (CCDF) - The consequences for each

scenario, in terms-of normalized cumulative releases of radionuclides

to the environment over a specified period of time, are calculated

and the results are displayed in a curve of consequences versus the

probability that such consequences will not be exceeded. Compliance

with the performance criteria is determined by comparing the curve to

two fixed points, which provide limits the curve must not exced..
si

-e

I- - Mined Geologic Repository

I . System Description mm p mm Waste

Site Package

Description System

I Description

Packing

and Seals

Description

Scenario 0evelopment

-I

I Scenario Screening __ _ _

Consequence Modeling

* Waste Form

* Waste Package System

* Packing Materials and Seals

* Geosphere Transport Releases)

* Biosphere Transport Health

Effects)

___ww~ 4 + MM

I Scenario Probability Estimation I S

Performance Calculation

* Release Rate

- Expected Conditions - Unexpected Conditions

* Cumulative Release

- Expected Conditions - Unexpected Conditions

._ _

F -

Comparison to

Regulatory Standards

and Requirements

* Cumulative Releases

for 10.000 Years

* Containment Period

* Release Rate

* Ground-Water Travel

Time

4-

Providing Reasonable

Assurance 1:

* Model Documentation

* Model and Methods

Poor Review

* Verification and Partial

Validation

* Field and Laboratory

Research

Providing Reasonable

Assurance II:

* Sensitivity Analysis

* Uncertainty Analysis

* Peor Review of

Results 4-

-

FIGURE 1. COMPONENTS OF THE STRATEGY FOR ASSESSING THE POSTCLOSURE

PERFORMANCE OF THE GEOLOGIC REPOSITORY SYSTEM
3

5. Sensitivity and Uncertainty Analysis - Sensitivity analysis

investigates the change in performance measures caused by incremental

changes in the values of input parameters and data. Uncertainty

analysis attempts to quantify the uncertainty in performance

estimates in terms of the major sources of uncertainty, including

uncertainty in input parameters, uncertainty in modeling (both the

conceptual model of the geometry and characterization of the system

and the process model of what physicochemical processes occur and how

they are manifested), and uncertainty about future states-of-nature.

6. Documentation - This is largely self explanatory; however, the most

effective documentation must make the assumptions used in the

analysis, their basis, and the implications of their use explicit and

clear.

Two types of uncertainty-are usually treated explicitly in the generation of

the CCDF: ()uncertainty due to future states of nature and 2)uncertainty in

the values of parameters determining system performance. In a safety analysis

for a more conventional type of system, the response of the system to any

single future state of nature to be considered would be a single-valued

estimate of system performance (in the parlance of the repository system, a

single value of consequence). System performance would then be described by

the plot of consequences versus the likelihood of the future state of nature

(scenario) producing that consequence; such a curve would be the distribution

function. The integral of such a curve over probability would yield a

cumulative distribution function; .e. the likelihood that the consequence

would be at least of a certain magnitude. The complementary cumulative

distribution function would be the curve of the likelihood that the consequence

would be a certain magnitude or less. For the repository system considerable

uncertainty exists concerning the values of parameters used to estimate the

consequences of the repository. Traditionally the uncertainty from this source

is also displayed on the CCDF. This is accomplished by: ()describing some or

all of the parameters used to estimate consequences as distributions of values

rather than point estimates, (2)choosing a value of each parameter required to

describe system performance from these distributions representative of some

portion of the various distributions, (3)estimating performance based on a

given realization of parametric values, (4)noting the conditional parametric

probability, i.e. the joint probability density for the given realization or

region of parameter space (for uncorrelated parameters this would be the

product of the individual parameter probabilities), (5)calculating the CCDF

using the parametric probability multiplied by the probability of the scenario.

This process is complicated further when consideration of different scenarios

make it s necessary to (1)vary the consequence models for different scenarios,

(2)vary the distributions of parameters (either the range of parameters, the

magnitude of the parameters, or the shape of the distribution) depending on the

scenarios.

Because of the complexity of the calculation of the CCDF it is likely, but not

absolutely necessary that the generation of the CCDF be performed by a computer

code. At a minimum such a code would need to: ()sequence through all the
'a.

4

scenarios to be considered, (2)choose the consequence models and parametric

distributions corresponding to the scenario being analyzed, (3)sample the

parameter space appropriate to the given scenario, (4)estinate consequences

based on the models and parameter values for the scenario, (5)combine the

parametric and scenario probabilities and the calculated consequences to

generate a CCDF.

III. Planning Assumptions

The NRC staff will carry out Phase I. However, resources allocated by NRC

management appear to be insufficient.

Other than existing reports and papers and computer code packages already

delivered, there will be no contractor input available for Phase 1.

CNWRA involvement in Phase 1 will be primarily as an observer, but will

become more active as the CNWRA PA capability expands.

All work will be conducted under the NQA-1 Category III. J. Holonich is

responsible for managing QA for these activities.

IV. Technical Description of the Work

This section states our current view of the mechanisms that appear to control

the performance of the Yucca Mountain repository. In many cases, the

mechanisms are poorly understood, requiring further research and more

sophistication than can reasonably be expected in the Phase I effort. The

processes are nevertheless listed here with the understanding that they will be

considered to the extent possible in the Phase I study. In some cases, we may

simply choose to ignore a mechanism entirely, if such an assumption leads to a

conservative estimate of performance. In many cases, we will rely only on

reported ranges of parameters governing these phenomena rather than a truly

independent estimate.

Task 2 - Source Term Modeling

The engineered barrier for inhibiting releases of radionuclides consists of

multiple layers of protection. The release rate model will consider at least

the following mechanisms:

1. Waste Package Lifetime - The estimate of the loss of waste package

integrity will consider such factors as corrosion and mechanical

damage; exactly what factors will be used in the computation of an

estimate of performance s yet to be determined. Corrosion will be

caused by contact of the canister with liquid water, either by

immersion, dripping, or by direct contact with the rock. We will

consider various mechanism that lead to the presence of liquid water

and to increased concentrations of corrosive minerals in the water.

We will investigate the likelihood of pitting and other types of

corrosion as opposed to simple corrosion. While a very conservative
5

assumption would be that all waste packages fail instantaneously,

such an assumption might lead to an unrealistically high importance

given to highly radioactive, but relatively short-lived

radionuclides, and would not further the understanding of performance

assessment at the Yucca Mountain site. We might however consider the

instantaneous loss of all waste package integrity as a highly

unlikely, very severe scenario in the Phase I study.

2. Oxidation of UO - We will investigate the conditions that might be

present and whiih lead to the exposure of the uranium dioxide fuel to

dry oxidizing conditions. Oxidation of fuel could be caused by

exposure to atmospheric oxygen, to groundwater with high oxygen

potential, and possibly from exposure to dissociated water vapor.

Some of the fuel might have been converted to a higher valence state

before being placed in the canisters. The oxidation state of the

fuel is important, because the oxidized fuel is much more soluble

than the unoxidized fuel, which could lead to increased release rates

if and when the fuel is exposed to liquid water at a later time. For

the Phase I study, we might consider as a bounding case that all fuelhas been instantaneously converted to the most soluble state.

3. Dissolution of radionuclides - We will investigate how water comes in

contact with the fuel following canister failure. Part of the

problem will focus on mechanisms outside of the engineered barrier

leading to large enough quantities of liquid water to allow direct

contact between the waste package and the water (e.g., increased

quantities of infiltration because of climate change, non-uniform

percolation from the earth's surface to the repository level,

perching of water along horizontal rock structure). Part of the

analysis will focus on repository-related changes such as the

evaporation of water by the heat generated within the waste, with

subsequent condensation at some distance away and flow-back through

fractures.

Given that there will be a source of liquid water, we will explore

ways that the water can get inside of the canisters and come in

contact with the clad and exposed fuel. We-will consider estimating,

most likely with highly simplified models, the approximate time span

during which heat generated by radioactive decay might keep any water

infiltrating the canisters from remaining in liquid form.

For those conditions for which liquid water does come in contact with

the waste, it is important to consider the mechanisms of release of

radionuclides from the intergranular boundaries and cladding gap, and

the dissolution of the waste matrix. For the last mechanism, we will

investigate the ramifications of the reprecipitation of radionuclides

less soluble than the uranium oxide matrix. This consideration will

take into account conceptual models for transport away from the fuel

(e.g., canisters filled with water, water dripping onto the waste),

the fraction of the fuel converted through oxidation to a more

soluble state, and the accessibility of the fuel to the water through
is

6

the failed or partially intact claddin. We will also consider the

possibility that the oxidation state of the liquid water will be

diminished because of sacrificial corrosion of the canister and

associated metal structure. For Phase I we may choose to consider as

a very conseravative case probably producing maximum releases of

radionuclides, that liquid water comes directly in contact with the

bare fuel almost instantaneously, and that the water is in its most

corrosive, oxidizing state.

Task 3 - Overall System Performance Assessment

Phase I of Task 3 will consider only simplified models of transport of

radionuclides from the engineered barrier to the accessible environment. The

emphasis of this task will be on calculating the cumulative release of

radionuclides at the accessible environment for a period of at least 10,000

years, in terms of their compliance with the regulatory standards of 40 CFR 191

as incorporated in 1OCFR60.112. We may also consider the maximum exposures to

individuals to determine compliance with the individual protection limits of

these rules (although the standard for the time being has been remanded). We

will pay no particular attention to the performance measures for radionuclide

release rate at the engineered barrier, waste package lifetime, or groundwater

travel time in the Phase I exercise.

The main modeling effort in Task 3 is centered on the flow and transport model.

The model should consider the following phenomena to the degree that can be

handled under the constraints of Phase I work:

1. Infiltration of precipitation at the land surface.

2. Flow through the unsaturated zone, both in the matrix and in

fractures. The conceptual model should consider the possibility

of perched water on interfaces.

3. Flow through the saturated zone. This model should consider

both matrix diffusion and fracture flow.

4. Retardation mechanisms. This model should take into account the

physical and chemical effects on the migration of dissolved

substances in the rock; e.g., matrix diffusion, chemical

sorption.

5. Decay of radionuclides, especially chains. This model should

take into account different retardation factors for parent and

daughter radionuclides in the same chain.

Other phenomena such as convection and vapor phase transport might be

considered in more detail in-the Phase II study.

Appendix D contains a summary of technical issues to be addressed during Phase

I. Also included is a discussion of the various issues. These issues will be

addressed primarily by considering the results of work done previously and.

reported in the open literature. In some cases particular issues may be

addressed by incorporating particular phenomena, processes, or features n the

models used to compute repository performance. In other cases we may, as time

and resources permit, perform subsidiary calculations to treat particular
7

issues, so that even though the issue is not treated explicitly in the

calculation of performance, we will be able to evaluate the effect of such

issues on our estimates of performance.

V. Work Breakdown Structure

Task 2 - Preliminary Source Term Modeling

Subtask 2.0 - Technical Management

1. Purpose and Scope

The purpose of this subtask Is to provide a means for first-line

technical management of the source term activity.

2. Expected Products

The products of this subtask will be interaction with line and

project management, the MOU coordinators, and the technical

staff working on tasks 2 and 3.

3. Relationship to other Subtasks

This subtask provides leadership and coordination of all the

other subtasks of Task 2 of the MOU.

4. Scheduling Considerations

This subtask is active during the entire duration of Task 2,

Phase 1.

5. Methods anticipated to perform work

Meeting and consultation with affected persons.

6. Staff

R. Codell

Subtask 2.1 - Problem Definition

1. Purpose and Scope

The purpose of this subtask is to determine, by reaching a

common understanding among the involved staff: ()what the

objectives of Task 2 are, (2)what the technical issues are,

(3)what potential technical approaches might work, (4)who does

what and when it is needed, (5)what products are required.

2. Expected Products

The detailed program plan for the conduct of Task 2 is the

primary product.

3. Relationship to other Subtasks

This subtask sets the stage for accomplishing all the other

subsequent work.

4. Scheduling Considerations

The detailed program plan is required by the end of January

1989.

5. Methods anticipated to perform work

The planning and documentation activities required to accomplish

this subtask will be performed primarily by the Task Leader for

Task 2. However, in order that the planning be effective, it is

essential that all nvolved staff provide technical and planning

input and provide comments on the detailed program plan.
8

6. Staff

All

Subtask 2.2 - Background Literature Review

1. Purpose and Scope

The purpose of the background literature review is: ()to

determine what facts are known and published that have a bearing

on determining an approach to modeling the source term for a HL

repository at Yucca Mountain, (2)to determine what computational

methods and tools are available for this purpose, (3)to

determine what data on site parameters needed to model the

source term are available, (4)to become familiar with the

modeling approaches used by others for the same or similar

problems. Information specific to Yucca Mountain is of the

highest priority; as time permits, auxiliary information on

modeling approaches, codes not specifically adaptable to Yucca

Mountain, related parametric data, etc. should be evaluated.

2. Expected Products - See above

3. Relationship to other subtasks

We expect that the models used in the Phase I study will come

principly from the literature, especially previous performance

assessments for Yucca Mountain and other High and Low-level

repository studies.

4. Scheduling Considerations

The background literature review will commence as early as

possible. The limitations of staff resources and a short

schedule for delivering a product dictate that we must rely

heavily on previously published reports to extract useful models

of processes important to the source term. While the literature

review will continue throughout the Phase I effort, it will be

important to glean useful models and parameter ranges by April

to complete the Modeling Requirements subtask.

5. Methods anticipated to perform work

No special guidance is necessary, except perhaps to point out

that there are several indices of references relating to the

Yucca Mountain site n general and performance assessment in

particular.

6. Staff - ALL

Subtask 2.3 - Review/expand system definition and Scenario Analysis

Subtask 2.4 - Define Modeling Strategy

Subtask 2.5 - Code Selection and testing

(These tasks will be considered together in this program plan)
K>

9

1. Purpose and Scope

Based on the literature review, the assigned staff will develop

a system definition of-the Yucca Mountain repository source

term, and the range of scenarios which will be applied to the

performance analysis. The assigned staff will define the

modeling which must be performed on the expanded system

definition and range of scenarios which will lead to a

reasonable source term to be used in the overall performance analysis. This modeling strategy will take into account the

following:

a. Phenomena important to modeling the source term and

availability of models of the phenomena

b. Probability that model can be tested in allowable time for

inclusion into the total systems performance model.

Based on their conclusions, the staff will either use presently

existing computer programs or write a new one for expressing the

source term for the overall performance assessment model.

2. Expected Products - We expect to develop a computer program

to be included in the overall system performance model, that

implements a model of the source term.

3. Relationship to other Subtasks - The model will be coupled

directly to the overall system performance model in Task 3.

4. Scheduling Considerations - The model must be completed

before the total systems performance analysis can be completed.

5. Methods anticipated to perform work - We could develop empirical

models based on reported behavior of canisters and fuel and

analytical approximations to heat transfer in rock. The most

sophisticated modeling is likely to be analyses with geochemical

reaction path and speciation codes for examining chemical states of

water in the very near field, including reactions inside the

canisters with spent fuel. e may occasionally resort to using

multiphase heat transfer codes such as TOUGH for near field

environmental determinations.

6. Staff - R.Codell, .Randall, K.Chang, J. Bradbury, T. o

Subtask 2.6 - Document Results

Staff - All
V

10

Task 3 - Preliminary total system performance assessment

Subtask 3.0 - Technical Management.

1. Purpose and Scope

The purpose of this subtask is to provide a means for first-line

technical management of the total system performance assessment

actlvity

2. Expected Products

The products of this subtask will be interaction with line and

project management, the MOU Coordinators, and the technical staff

working on Tasks 2 and 3.

3. Relationship to other Subtasks

This subtask provides leadership and coordination of all the other

subtasks of Task 3 of the MOU. This subtask is also intended to

assure that the activities and products of Task 2 are thoroughly

coordinated with those of Task 3.

4. Scheduling Considerations

This subtask is active during the entire duration of Task 3, Phase 1.

5. Methods Anticipated to Perform Work.

Meetings and consultation with affected persons. 6. Staff - N.

Eisenberg, R. Codell, J. Randall.

Subtask 3.1 - Program definitions and program planning

1. Purpose and Scope

The purpose of this subtask is to reach a common understanding

among the involved staff as to: ()what the objectives of Task 3

are, (2)what the technical issues are, (3)what potential

technical approaches might work, (4)who does what and when it is

needed, (5)what products are required.

2. Expected Products

The detailed program plan for the conduct of Task 3 is the

primary product.

3. Relationship to other Subtasks

This subtask sets the stage for accomplishing all the other

subsequent work.

4. Scheduling Considerations

The detailed program plan is required by the end of January

1989.

5. Methods anticipated to perform work

The planning and documentation activities required to accomplish

this subtask will be performed primarily by the Task Leader for

Task 3. However, in order that the planning be effective, it is

essential that all involved staff provide technical and planning

input and provide comments on the detailed program plan.

6. Staff - All
K)

11

Subtask 3.2 - Background literature review

1. Purpose and Scope

The purpose of the background literature review is: (1)to determine

what facts are known and published that have a bearing on determining

an approach to modeling repository performance at Yucca Mountain,

(2)to determine what computational methods and tools are available

for this purpose, (3)to determine what data on site parameters needed

to model the performance assessment are available, (4)to become

familiar with the modeling approaches used by others for the same or

similar problems. Information specific to Yucca Mountain is of the

highest priority* as time permits auxiliary information on modeling

approaches, modeis not specifically adaptable to Yucca Mountain,

related parametric data, etc. should be evaluated.

2. Expected Products - see Purpose and Scope above

3. Relationship to other subtasks

The background literature review forms the basis for the remaining

work in Task 3. The system definition, scenario analysis, and

determination of modeling approach all are based on information in

the literature. The literature review will provide the basis for

decisions about computations, as well as providing the basis for

putting the modeling into technical and regulatory perspective. We

expect that the models used in the Phase 1 study will come

principally from the literature, especially previous performance

assessments for Yucca Mountain and other High and Low-level

repository studies.

4. Scheduling Considerations

The background literature review will commence as early as possible.

The limitations of staff resources and a short schedule for

delivering a product dictate that we must rely heavily on previously

published reports to extract useful models of processes important to

the source term. While the literature review will continue

throughout the Phase 1 effort, it will be important to glean useful

models and parameter ranges by July to complete the Total System

Modeling subtask.

5. Methods anticipated to perform work

No special guidance is necessary, except perhaps to point out that

there are many references relating to performance assessment in

general and the performance assessment of Yucca Mountain in

particular.

6. Staff - ALL

Subtask 3.3 - System Definition

1. Purpose and scope

The purpose of the System Definition subtask is twofold: ()to

provide a description of the proposed repository at Yucca Mountain in
4.

12

physicochemical terms sufficient to enable us to simulate its performance

and (2)to provide a summary of the scientific information known about the

behavior of the proposed Yucca Mountain repository to enable placing

estimates of performance in technical and regulatory context. At a

minimum the system description must consider the geologic, hydrologic, and

geochemical processes and systems operating at Yucca Mountain so that

transport of radionuclides through the geosphere can be estimated

quantitatively. The natural systems must be described in sufficient

detail so that the scenario analysis can be performed.

2. Expected Products

(1)an integrated, mechanistic description of the physicochemical

systems at Yucca Mountain influencing waste isolation and, especially,

transport of radionuclides through the geosphere; (2)parameter values and

distributions of parameter values important for estimating radionuclide

transport and other aspects of repository performance; (3)a summary of

factors not included in the system description used to calculate

performance and an estimate of the significance of such omissions on the

estimates of performance.

3. Relationship to other subtasks

The subtask is based on subtask 3.2 Background Literature Review. It

provides the basis for the analyses in subtasks 3.4, 3.5, and 3.6. 4.

Scheduling considerations

This subtask should begin in January, based on the early part of the

Literature Review, and should be complete by the end of February, so that

the subsequent, dependent analyses can commence.

5. Methods anticipated to perform work

Analysis and synthesis of scientific information about Yucca ountain

and the proposed repository there. Abstraction of the essential elements

to be included in the system description must be derived from careful

evaluation of the information available.

6. Staff - All, but Codell.

Subtask 3.4 - Scenario Analysis

1. Purpose and scope

The purpose of this subtask s to provide information on potential

scenarios at the Yucca Mountain repository to guide the modeling of total

system performance and to provide the probabilities to be incorporated in

the CCDF.

2. Expected Products

(1)A list of processes and events or a list of scenarios that should

be considered in an analysis of performance, (2)a screening of these to

determine the most important, (3)estimates of probability of occurrence.

In addition the scenario analysts will confer with the system modeler,

flow and transport modeler, and Task leader to determine which scenario

classes to treat explicitly in the computational models and which to defer

to Phase 2. Scenario analysts will also confer on what features,
13

processes and parameters should be incorporated in consequence models to effectively treat various scenario classes.

3. Relationship to other subtasks

This subtask derives from subtasks 3.2 and 3.3. It is a prerequisite to defining the modeling requirements (subtask 3.5). Synthesized data on

scenario class probability will be used in the computations of total

system performance (subtasks 3.7 and 3.8). Insights into the treatment of

scenarios and scenarios omitted from the estimation of performance will be

documented in subtask 3.9.

4. Schedulin considerations

This subtask must be largely complete by the end of March so that

subtask 3.5 can commence.

5. Methods anticipated to perform work

(1)evaluation of scenario literature for the Yucca Mountain

repository, (2)synthesis of a coherent set of scenarios or scenario

classes, (3)estimation of probabilities of basic events and processes based on the geologic record or historical record (other methods as

appropriate), (4)combinatorial analyses to estimate probabilities of scenarios used for the performance computation.

6. Staff - J. Trapp, D. Fehringer, other staff as needed.

Subtask 3.5 - Determination of Modeling Requirements 1. Purpose and scope

The purpose of this subtask is to synthesize the knowledge gained in

subtasks 3.2, 3.3, and 3.4 to articulate the nature of the modeling to be

conducted for the remainder of Task 3.

2. Expected Products

This subtask will produce a major product the Modeling Requirements

Document', which will articulate the type of modeling to be pursued for

the remainder of Task 3 and, more important, the rationale for such an

approach.

3. Relationship to other subtasks

This subtask depends on the information and analysis conducted in

subtasks 3.2 - 3.4. The Modeling Requirements Document is a means to

reach general agreement on the modeling approaches to be used in subtasks

3.6 - 3.8. It is anticipated that a substantial amount of the reasoning documented in the Modeling Requirements Document will be incorporated into

the Final Report for Task 3, Phase 1.

4. Scheduling considerations

This subtask requires substantial completion of subtasks 3.2 - 3.4.

It is scheduled to be completed in April 1989. Completion of this subtask

is required before total system modeling and subsequent subtasks can begin in earnest (subtasks 3.6 - 3.8).
14

5. Methods anticipated to perform work

Key staff will evaluate what modeling approaches to adopt based on:

(1)the importance of various processes features, and scenarios as

disclosed by the literature review (25the existence of available and

adaptable quantitative methods; (35the practical constraints of limited

time and personnel, as well as the limitations of the available computer

environments. A determination will also be made as to what type of

computation will be included in the direct calculation of the performance

measure(s), which modeling will be conducted as analyses supporting the

calculation of the performance measures, and which modeling will be

deferred to Phase 2.

6. Staff - N. Eisenberg, J. Randall, J. Pohle.

Subtask 3.6 - Total System Modeling

1. Purpose and scope

The purpose of subtask 3.6 is to assemble the computational tools to

enable computation of the performance measure(s) for the repository at

Yucca Mountain. Important components of this activity include:

(1)computerization of parametric distribution and other data bases

required to obtain performance estimates, including information related to

scenarios; (2)testing and selection of codes to calculate consequences

(e.g. codes calculating geosphere transport of radionuclides); (3)coding

of an executive program to exercise the consequence models with the

appropriate data bases or adoption/adaptation of an existing executive

code for calculating CCDF's and other total system performance measures.

In addition, testing and selection of codes and assembly of data bases

required to perform analyses supporting the estimation of performance will

be accomplished under this subtask.

2. Expected Products

An integrated methodology in the form of a computer code and the data

bases required for it to operate. The integrated methodology would, at a

minimum, calculate a CCDF for Yucca Mountain. This integrated methodology

will be described in "Total System Performance Assessment Methodology

Report,' which is a major deliverable (it is anticipated that much of this

documentation will be incorporated in the Final Report).

3. Relationship to other subtasks

This is the most important aspect of the OU Tasks 2 & ; this central

activity Incorporates and focuses all previous work and is the basis for

all subsequent work.

4. Scheduling considerations

This subtask can begin in March and must be completed in July.

5. Methods anticipated to perform work

Data bases will be encoded; formats will be selected to be compatible

with a broad range of codes and uses. Consequence codes will be tested

and compared to each other in terms of accuracy, ease of use, running
15

time, and other relevant attributes. Tote system performance assessment

codes and approaches will be tested and evaluated. Choices on codes will

be made based on testing results.

6. Staff - N. Eisenberg, J. Randall, R. Codell, J. Pohle, W. Ford, K.

McConnell, J. Bradbury.

Subtask 3.7 Total System Code Test and Debug

1. Purpose and scope

Test and debug the methodology assembled in subtask 3.6.

2. Expected Products

A tested computer code to compute the CCDF and tested codes to

perform supporting analyses, f any.

3. Relationship to other subtasks

Must follow completion of subtask 3.6.

4. Scheduling considerations

Start in May and finish in July.

5. Methods anticipated to perform work

Run the computer code and evaluate results.

6. Staff

N. Eisenberg, J. Randall, J. Pohle.

Subtask 3.8 - Final Run to generate Preliminary CCDF

1. Purpose and scope

Generate performance estimates for Yucca Mountain repository.

2. Expected Products

CCDF's, perhaps other performance measures.

3. Relationship to other subtasks

Must follow subtask 3.7.

4. Scheduling considerations

Start and finish in August.

5. Methods anticipated to perform work

Run the code(s); assemble the results.

6. Staff - N. Eisenberg, J. Randall, R. Codell, J.Pohle

Subtask 3.9 - Document Results

1. Purpose and scope

Self evident.

2. Expected Products

The Final Report - the major deliverable for the Phase 1 activity.
16

3. Relationship to other subtasks

Reports on all the others.

4. Scheduling considerations

Begin n June and terminate In September.

5. Methods anticipated to perform work

Analyze results of modeling and write up.

6. Staff - all.
17

Schedules and Resource Allocations

Appendix A. Major Milestones

Appendix B. Gantt Charts

Appendix C. Staff-Loading Charts
APPENDIX A

Major FY89 Mlestones

Task 2. Source Term

2.1 January 1989

2.2 April 1989

2.5 April 1989

2.3 May 1989

2.4 September 1989

2.6 September 1989

Task 3. Preliminary

3.1 January 1989

3.2 April 1989

3.5 April 1989

3.3 July 1989

3.4 September 1989

3.6 Septenber 1989

Detailed Program Plan

Modeling Requirements for Source Term

N~d-Term Briefing for NRC Management

Source Term Subroutine Delivery to Task 3

First Annual Scurce Term Report'

End-of-Year Briefing for NRC Management

Total System Performance Assessment

Detailed Program Plan

Modeling Requirements Document

Mid-Term Briefing for NRC anagement

Total Systems Performance Assessment ethodology Report

First Annual Report for Performance Assessment Modeling

End-of-Year Briefing for RC Management
APPENDIX B

.,

TASK 2 - SOURCE TERM

TASK

1. Program Definition and

Program Planning

2. Background Lit. Review

3. Review/Expand System

Defin. Scenario

Analysis

4. Define Modeling Strategy

5. Code Selection/Writing 

Test Data Requirements

6. Obtain Results

7. Document

NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV

a

C

(

Management Meetings

Reports C

Subroutine

Briefings

NOV DEC JAN

X ( X

X

(2.1)

FEB MAR

X I

APR MAY JUN JUL AUG

X X X X X

X

(2.2) 0

X

(2.3)

SEP

m

X

(2.4)

OCT NOV

(

( X

(2.5)

X

(2.6)

Note: Numbered milestones are keyed to listing on Enclosure A.
APPENDIX B

TASK 3 - PRELIMINARY TOTAL SYSTEM PERFORMANCE ASSESSMENT

TASK NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV

1. Program Definition and

Program Planning

2. Background Lit. Review C

3. System Definition

4. Scenario Analysis .

5. Model Requirements -

6. Total System Modeling

(Parameter dist., code dev.,

executive code)

7. Total System Code Test &

Debug

8. Final Run/CCDF

9. Document ResuTts - (

OV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV 

Management Meetings X X X X X X X X X X X

Reports X X X X

(3.1) (3.2) (3.3) (3.4)

Briefings X X

(3.5) (3.6)

Note: Numbered milestones are keyed to listing on Enclosure A.
lASK 2 - SOURCE TERM

o TEfHXICAL MANAGEMENT

1. PROBLEV DEFINIPROGRAM MANAGING

2. BACKGROUND LIT. REV.

3. REVIEVIEPAHD SYSTEM DEF.

4. DEFINE MODELING STRATEGY

5. CODE SELECTIQ!WRITIN I

TOTAL SSTEM MODELING

. OBTAIN RESULTS

7. DOCUMENT

IL ANAL GE MY

2.4

0.8 1.0 0.4 0.4

1.2 3.0 0.9 0.1

0.4 1.0 0.0 0.0

0.9 2.0 0.4 0.4

O.E 4.0 0.0 0.0

0.0 - 0.0 0.0 0.0

4.0 4.0 0.4 0.4

1.2 2.0 p.0 0.0

11.6 17.0 2.0 2.0

APPENDIX C

RN CE WPA TOTAL

.9.4 2.4

0.4 0.4 0.4 3.e

0.4 0.4 0.4 7.0

0.0 0.0 0.4 1.9

0.4 0.4 0.8 5.2

0.0 0.0 0.4 5.2

0.0 0.0 0.0 0.0

0.4 0.4 0.4 10.0

o.o 0.0 0.4 3.6

!.6 i.6 3.2 39.0

TASK 2 KEr

TL - iASK LEADER. R. CODELL

ANAL - SYSTEM ANALYSI. J. RANDALL

SE - 6EOCHEMISTRY. T.Mo

M - HYDROLOSY. . FORD

RH - ROCK MECHANICS, . BUC LEr

MPA - UASTE PACKAGE ANALYST. K. CHANG

TASK 3 - TOTAL SSTEN PA IL SN ST FT

0 TECHNICAL MANASEMENT 4.0 0.0 2.4 0.0

1. PROBLEM DEFINITIONlfROGRAN PLANNI 0.8 2.0 0.0 0.4

2. BACKGROUND LIT. REV. 0.e 4.0 0.0 0.8

3. SYSTEM DEFINITION 0.8 4.0 0.0 0.8

4. SCENARIO ANALYSIS 0.4 3.0 0.0 0.9

S. MODEL REQUIRE. TOTAL SYSTEMS ODE 0.4 3.0 4.0 0.9

h. REQUIREMENTS FROM: 0.8 9.0 1.a 2.4

A. PARAMETER OISTRIGUTIONS 0.0 0.0 0.0 0.0

D. CODE SELECTIONITESTINS 0.0 0.0 0.0 0.0

C. ElECUTIVE SIRUCTURE CODING 0.0 0.0 0.0 0.0

7. TOTAL SYSTEM CODE TEST & DEBUG 0.0 3.0 0.0 0.8

S. FINAL RUNICCDF 0.4 2.0 0.8 0.4

9. DOCUMENT RESULTS 1.2 4.0 1.2 1.2

TOTAL 10.4 33.0 6.0 8.4

SE NY 6E

0.0 0.0 0.0

0.4 0.4 0.4

0.8 0.9 0.8

0.8 0.9 0.9

1.2 0.4 0.4

0.0 0.0 0.0

0.0 1.2 0.4

0.0 0.0 0.0

0.0 0.0 0.0

0.0 0.0 0.0

0.0 0.0 0.0

0.0 0.0 0.0

1.2 0.4 0.4

4.4 4.0 3.2

Sc

0.0

0.4

0.8

0.9

0.4

0.0

0.4

0.0

O.0

0.0

0.0

0.0

0.4

3.2

TOTAL

1.4

4.8

8.8

9.8

6.6

4.2

14.9

0.0

0.0

0.0

4.6

3.6

10.0

72.&

TASK 3 KEY

TL - TASK LEADER. N. EISEHBER6

SM - TOTAL SYSTEM INTESRATION AND MODELINS. J. RANDALL

St - SOURCE TERN INTEGRATION. R. CODELL

FT - FLOW L TRANSPORT MODELING. J.Pohle/W.Ford

SC - SCENARIO ANALYSIS. J. TRAPP, 0. FEHRINKER

HY - HYDROLOGY. V. FORD

GE - GEOLOGY. K. fteONNELL

SC - GEOCHEMISrRv, J.Bradbury

APPENDIX C - STAFF LOADING
1

Appendix D. Summary of Technical Issues to be considered in Phase I

The following is a summary of technical issues and some discussion of them

where appropriate. These are listed because the literature reviews, modeling

activities, and analyses conducted by the staff for Phase I should attempt to

resolve these issues by providing a concrete, rational basis for decisions. In

Phase I of this effort, it may be appropriate to simply ignore an issure for

the sake of expediency or conservatism. In most cases, we pose the question of

whether we can neglect the mechanism a priori, or if it is necessary to

connence the work taking it into account, at least initially.

1. Should we consider that the waste package protects the nuclear waste, or

for Phase should we simply ignore this protection and presume that the

fuel is unprotected and directly exposed to adverse forces in the

repository?

Discussion

The waste packages should remain intact for many years. Neglecting this

protection places a heavy emphasis on highly radioactive and dangerous,

but short-lived nuclides such as Cs-134, Cs-137, Sr-89, Sr-90 and -3,

which probably would not be of much concern if a realistic treatment of

the waste package were used. We therefore could inappropriately divert

attention from the more serious problem of treating long-lived

radionuclides such as transuranics and actinides.

2. Should we explicitly model the releases of gaseous radionuclides to the

atmosphere in calculating repository performance for Phase I?

Discussion

Radionuclides such as 1-129 and C-14 may be released in gaseous form, and

would be present in the in the air-filled pores and fractures of

unsaturated rock. This raises two issues regarding transport of these

radionuclides. First, the gaseous releases would partially equilibrate

with the water phase in the unsaturated zone, and probably end up

partially as water-borne contaminants. Second, it isn't clear that the

regulatory agencies will actually end up including any atmospherically

released radionuclides in the cumulative release totals or, f included,

how. DOE is petitioning EPA for such an exemption, and to reinstate a

separate table for atmospheric pathways, which would allow much greater

releases than allowed for the water pathway. Given this regulatory

uncertainty, should we include gaseous releases in models used to generate

the CCDF for Phase I? The release of these radionuclides is not expected

to produce significant health effects; this is a further reason for

delaying calculation of such releases to a later Phase.

3. Should we assume that the repository is saturated, or at least that water

comes in contact with the waste package immediately?
2

Discussion

In many respects, this would be a worst-case assumption, and probably

should be considered as an extreme case for Phase I. Yucca Mountain was

chosen partially on the basis that it is a relatively dry site, and is

likely to remain that way for a very long time. We could consider the

site unsaturated, but examine conditions which lead to saturation under

low probability conditions. Even under unsaturated conditions, there may be ways that water could come into contact with the waste package, either

by contact with water in the rock pores or fractures. We could consider

the extent to which the waste packages would be subjected to this water,

and what mechanisms either increase or diminish this contact.

4. Should we consider that the uranium in the spent fuel is in its most

soluble state?

Discussion

The oxidation state of the uranium largely determines its solubility.

Under reducing conditions, solubility is likely to be low. When oxidized,

the solubility could be much greater. Ground water at YMP is oxidizing,

but there are several factors protecting the uranium from oxidation: - The fuel is stored in a canister, probably filled with an inert gas. - The fuel is clad in highly corrosion-resistant zircaloy or stainless

steel. - The oxygen in the water, even if it were to come in contact with the

canister, might be consumed by corrosion of the metal in the waste

package, cladding and auxiliary structure (e.g., tubes and racks).

The fuel could be oxidized under dry, hot conditions if canister integrity

is lost. In fact, the oxidation of the fuel through small cladding

imperfections is likely to cause total failure of the cladding because the

uranium dioxide swells. If the fuel then is saturated with water at a

later time, it might already be in a very soluble state. Which of these

possible concepts should be implemented in the calculation of performance

in the Phase I study?

5. How should we consider unsaturated conditions for flow and transport in

the calculation of performance?

Discussion

We must consider unsaturated flow, but it ay not be necessary to

incorporate very complicated models into our performance assessment. For

example, we may want to explore with a complicated model the phenomena

leading to saturated flow along discontinuities in the rock in order to

place boundaries on the length and flowrate through fast pathways to the

accessible environment. Once we have chosen the pathway, however, we

could use a simple one dimensional model with constant flux and no other

hydraulics.
3

6. What kinds of models should we use for retardation along the geological

pathways and what is an acceptable treatment of the chemical behavior of

radionuclides in the geosphere?

Discussion

Tie use of retardation coefficients in calculating radionuclide migration

has frequently been criticized. As a practical atter what alternatives

are available for calculating transport? Can the error in estimates of

radionuclide releases to the accessible environment be quantified? To

what degree? Can subsidiary geochemical calculations be useful in

quantifying the uncertainties in using simplified chemical models? How

important is the fact that the medium is unsaturated and how does the

degree of saturation affect conclusions about the appropriateness of a

given chemical modeling approach? Should the model of the saturated zone

include matrix diffusion? Could retardation be completely neglected in

Phase I?

7. Over what length of time should we calculate the performance of the

repository?

Discussion

For a realistic treatment of the repository performance, the cumulative

radionuclide releases may be zero or insignificant during the regulatory

period of 10,000 years. Should we extend the period of consideration to

determine how the repository might realistically release radionuclides to

the environment? If so, how long should we extend the period of

consideration?

8. The remanded EPA standard requires calculation of three performance

measures: (1)CCDF of cumulative radionuclide releases to the accessible

environment over 10,000 years; (2)concentration of radionuclides in

certain groundwater at 1000 years; (3)dose to maximally exposed

individuals at 1000 years. Which of these performance measures should we

aim toward calculating in Phase 1?

Discussion

If doses are calculated, what models of usage should we have concerning

the doses to people living close to the repository and consuming food and

water impacted by radioactive releases from it?

9. For what set of scenarios should we calculate performance in Phase 1?

Discussion

Should we calculate performance for only the base case' scenario or

should we include disruptive scenarios? If so, which disruptive

scenarios? Do consequence models exist to treat important classes of

disruptive scenarios?
4

10. What form of sensitivity and uncertainty analysis, if any, should be

performed in Phase 1?

Discussion

SiMeFlsTivy and uncertainty analyses can be very resource intensive tasks.

However, these are very important parts of the performance assessment.

For the Phase 1 activities what approach to these analyses is appropriate?

Can we conceptualize some scaled-down version that would be doable and

meaningful ith the scarce resources allowed?

11. What form of waste should be assumed for the Phase 1 analysis?

Discussion

Spent reactor fuel, and to a smaller extent, vitrified high-level

radioactive waste, will be stored in the repository. Since nearly all of

the waste will be in the form of spent fuel, should only this waste form

be considered in Phase 1 of this study?

12. What design for the engineered barrier system should be assumed for the

Phase 1 analysis and, in particular, what type of canister material should

be assumed?

Discussion

The spent fuel waste form will consist mainly of zirconium alloy or

stainless-steel clad UO§, some of which will be stored in racks, and put

into metal canisters. The canisters will probably be constructed of

stainless steel, although other alloys are also being considered. For the

present study, should we consider only stainless steel canisters? Should

we assume for Phase I that there are neither canisters nor cladding

present (see issue 1)? The canisters will be stored in the repository

rock either horizontally or vertically, probably in lined holes with an

air gap between the canister wall and the rock. Should only the vertical

orientation with the air gap present be studied in the present work?

13. How should the modeling of the repository treat the spatial distribution

of waste packages and the likely temporal (and therefore spatial)

distribution of waste package failure?

Discussion

Although t is attractive in many situations to consider point sources as

the origin of groundwater pollution, some essential behavior of the

repository may be lost by making such an assumption. Further, t may be

difficult to argue that conservative estimates of performance are obtained

for all performance measures. Some models (e.g. the AREST code) have

considered the temporal distribution of waste package failure and found

that it has a pronounced effect on performance. What is the appropriate

level of detail for the treatment of these facets of the model of

repository performance for Phase 1.
5

14. Should doses to ndividuals and populations be calculated as a

consequence in Phase I or should this complication and refinement of the

consequence modeling be deferred to later?

Discussion

Although several standard codes are available to calculate doses and the

resulting health effects, such modeling does complicate the treatment of

consequences and adds to the already large burden of work to be done. In

addition, considerable contention might develop around the assumptions

used regarding future population densities, land use, and ecology at the

site

15. What is the appropriate degree of sensitivity and uncertainty analysis

for this effort? How should these analyses differ between Phase I and

Phase II? WIhat methods should be used to perform these analyses?

Several methods are available for performing sensitivity and uncertainty

analysis, including Monte Carlo methods, stratified sampling methods

(e.g. Latin Ijypercube), and the adjoint method to investigate sensitivity

to parameters determining performance. Methods for uncertainty analysis

are less well developed, especially for quantification of conceptual model

uncertainty. Given the limited resources available for the Phase I

effort it is unlikely that a substantial amount of quantitative

sensitivity and uncertainty analysis is possible; however qualitativie

analyses should be undertaken to the extent feasible. Also it may be

possible to perform semiquantitative analyses by using extreme values of

parameters to remove the effects of certain processes from equations used

to predict performance (e.g. velocity equal to zero to remove the effect

of advection on radionuclide migration).
4I

ENCLOSURE B - 1 -

ENCLOSURE B

The following is a compilation of statements prepared by the staff members

participating in Phase 1 of the MOU Task 2 and 3 modeling activities. The

requested information was:

"Prepare a short paragraph (3-5 sentences) summarizing the work you intend

to perform as part of the MOU acitivities. This should state (succintly)

the purpose, scope, content, planned approach, and key products and/or

milestones for the work."
MU Phase 1 Task Description for

Richard Codell

R. Codell is the Task Leader for Task 3, Source Tenm Modeling, of the MOW

activities. Responsibilities include first line technical management of the

work, coordination of the various technical activities, communication with NRC

management, participation in the drafting of deliverable documents as one of

the principal authors, and technical analysis as appropriate and required.

The Task Leader will participate in decisions regarding modeling approaches to

be used to calculate the source term, subsidiary analyses to support modeling

approaches, analysis of data for input to the models, descriptions of the

modeling results and their implications. Key technical issues in which the

Task Leader is expected to be involved include:

- Evaluation of the literature dealing with performance of the whole and

the component parts of the engineered barrier.

- Selection of the model for barriers to release of radionuclides from

the waste to the edge of the engineered barrier.

- Adapting currently existing computer programs of source term models or

alternatively creating ad hoc computer programs for the present task

- Selection of scenarios that affect the release of radionuclides at the

edge of the engineered barrier.

- Integration of the source term model with the total system performance

model to assure it is compatible, philosophically and computationally

with Task 3.

- Limited technical management of the overall system performance model

effort

- Limited computer programming of the overall system performance model

computer program.

- One of the principal authors of the Detailed Program Plan and Modeling

Requirements Document.

- Responsible for interim and end-of-year briefings of NRC management on

progress of Task 2 and 3 studies.

- A principal author of the "Total System Performance Assessment

Methodology Report"

- A principal author of the "First Annual Report for Performance

Assessment Modeling"
MOU WORK SUMMARY FOR NAE

MOU Phase 1 Task Description

for

Norman A. Eisenberg

N. A. Esenberg is the Task Leader for Task 3, Total System Performance

Assessment, of the MOU activities. Responsibilities include first-line

technical management of the work, coordination of the various technical

activities, communication with NRC management, participation in the drafting

of deliverable documents (one of the principal authors), and technical analysis

as appropriate and required. The Task Leader will participate in decisions

regarding: modeling approaches to be used to calculate performance, subsidiary

analyses to support modeling approaches, data sets to be employed,

descriptions of the modeling results and their implications. Key technical

issues in which the Task Leader is expected to be involved include:

(M)selection of the model for geosphere transport of radionuclides (the heart

of the consequence portion of the total system model); (2)selection of

scenarios, estimation of their probabilities, and adaptation of consequence

modeling to properly reflect the scenario; (3)interpretation of the CCDF and

Intermediate results; (4)integration of the source term work conducted under

Task 2 to assure it is compatible, philosophically and computationally, with

Task 3. In addition to being a principal author of this "Detailed Program

Plan," the Task Leader will be a principal author of the-'Modeling Requirements

Document,' which will provide the documentation and rationale for the modeling

approach chosen, he will be a principal in the April "Briefing for NRC

Management" and will coordinate the presentations of other participants, he

will be a principal author of the "Total System Performance Assessment

Methodology Report,* which will describe the modeling approach executed for

Phase 1, he will be a principal author of the First Annual Report for

Performance Assessment Modeling,' which will contain an updated version of the

information contained in the two previous written deliverables, and he will

play the same role for the End-of-Year Briefing for NRC Management' as for the

mid-year briefing.
INDIVIDUAL PROGRAM PLAN FOR

CONTRIBUTIONS TO THE MODELING ACTIVITIES SUPPORTING

THE MEMORANDUM OF UNDERSTANDING ON

HLW PERFORMANCE ASSESSMENT ACTIVITIES BY THE NRC STAFF

John D. Randall, RES/DE/WMB

The performance of repositories of high-level radioactive waste (HLW) is

influenced by many individual process and by interactions among those process.

Under the subject MOU, the NRC staff will be developing capabilities for

selecting and using models of those processes.

My duties in this effort involve the integration of individual process

models (of waste package failure, radionuclide release from the waste package,

transport of radionuclides through the geosphere to the accessible

environment, and possibly biosphere transport of radionuclides to man and dose

to man) to insure that the models are physically reasonable and that they are

compatible, both physically and mathematically, with each other. In doing

this work, I plan to prepare a software package that provides a means of data

communication among selected computer programs that implement the individual

process models, that provides a means of specifying data needed by the

Individual programs, and that processes data produced by the programs in such

a way that the NRC staff can interpret the data easily.

One of the outputs of this integrating software package will be a

cumulative complementary distribution function (CCDF) that will summarize

comparisons of estimates of cumulative radionuclide releases from a repository

of HLW to the accessible environment with limits on these releases set by 40

CFR 191, the overall HLW performance standard set by EPA. If time permits,

the integrated software package also will be designed to present comparisons

of predicted and EPA-specified doses to individuals.

In preparing the integrating software package, I first plan to examine

existing software packages that have been developed for the same purpose.

Examples of such packages are Sandia's code coupler (used under NRC's HLW

research project, FIN A1266) SYVAC (from Canada), AREST and PANDORA (developed

for DOE), CONVO (developed for EBS evaluations for NRC), LISA (developed by

CEC), and CNWRA's fast probabilistic methodology (recently proposed to NRC).

If none of these packages proves to be suitable for the purposes of the MOU, I

will develop a new one.

As I carry out my duties of integrating HLW process models into a

methodology that will be useful to the NRC staff in its performance assessment

activities, I plan to work closely with other NRC staff involved with the

MOU's Tasks 2 and 3. This interaction will provide me with the information

that I will need to have in order to decide what needs to be done in order to

prepare that integrates individual process models in such a way that the

integrated results will provide meaningful estimates of repository

performance.
K>

MOU/KM

NOTE FOR: NORM EISENBERG

FROM: KEITH MCCONNELL X

SUBJECT: WORK RELATED TO MOU

I visualize my role in work related to the MOU on performance assessment

modeling to be basically a support role providing input into the various

subtasks outlined in the program plan. Principally, I see my largest input

coming in the System Definition subtask helping to provide basic information

about structural features that may be significant factors in the modeling

effort proposed. Specifically, I am currently doing a literature search on

emplacement hole stability and fracture networks in association with fault

zones. An additional area that I may be able to provide, through John Trapp, a

limited amount of information is in the identification of important scenarios.

In the total system modeling effort, my role, as I see it, is to attempt to

interrelate three-dimensional geologic models used in repository definition and

numerical models of total system performance.

cc: Phil Justus

John Trapp
' K>

MOU Phase 1 Task Description

For

William H. Ford

William Ford will provide ground water support to Tasks 2 and 3 of the MOU

activities. Responsibilities will include the compilation of site ground water

data, compilation of available computer codes, development of modeling

approaches, and setting up and running models. William Ford will contribute to

written reports as necessary.
p

NOTE TO: Norman Eisenbera

FROM: John Bradbury

SUBJECT: MY MOU CTIVITIES

I am presently involved in getting Bill Murphy from the

Center to hold a workshop on EQ3/6. It is intended that

this workshop will be held at NRC headquarters and that it

will involve only NRC staff interested in using the code.

Present plans are for a half day presentation on the

capabilities of the code, and input and output requirements.

Following this presentation there will be a couple of days

of hands on modeling directed/assisted by Bill. It appears

that this workshop might be held in February.

After getting the instruction in the Use of E3/6, I plan to

start applying it to the various subtasks planned. The

version of EQ3/6 that Bill will supply us may not have all

the capabilities that I might require in this effort. For

example, I am interested in subroutine that handles stable

isotope geochemistry. I may have to produce this subroutine

myself or get it elsewhere.

We have in house computer programs (MINTEQ and HYDRAQL)

which handle speciation and sorption. I plan to get familar

with these codes and apply them to portions of the tasks.
NOTE TO: Norman Eisenberg 1-31-89

SPSHLGPHLWM

FROM: Tin Mo

HTS,HLGPHLWM

SUBJECT; My MOU Activities

MAJOR ACTIVITIES:

I am the Project Manager for the Technical Assistance Contract (FIN

A-1756), "Geochemical Sensitivity Analysis for Performance Assessment",

with the Sandia National Laboratory (SNL). In this capacity, I am presently

coordinating with David Brooks,(CNWRA Program Element Manager for the

Geologic Setting), to hold a workshop on Geochemistry Sorption Sensitivity

Analysis. The CNWRA staff will lead the workshop and the NRC and SNL staff

will participate . As part of the workshop proceedings, the SNL staff will

conduct technology transfer sessions for the tools and methodologies for

geochemical sorption sensitivity analysis.

As part of the contract deliverables, I have received a geochemical

computer code on speciation HYDRAOL) along with other codes. I intend to

get familiar with all these codes that are now available in-house with

particular emphasis on HYDRAOL.

The metabolism and dosimetry, health effects and risks to the members of

the general public due to the HLW radionuclides released to the accessible

environment may vary widely depending upon the physicochemical forms of the

bioavailable radionuclides released. I will coordinate and provide the

critical linkage between the geochemical transport (release source terms) /

speciation codes/models (e.g. HYDRAQL) via the radiation exposure

pathways codes (e.g. PATH 1) and the dose and health effects codes

such as BIOPATH, DOSHEM, PABLM or other national and international

codes and models used in the HLW management communities of the world.

I now have available in-house the PATH and DOSHEM codes. I will

evaluate the capabilities of these codes and if suitable apply them

to portions of the MOU tasks 2 and 3. I may need to update the DOSHEM

code so that the dose conversion factors, algorithms and subroutines

used are consistent with the most recent recomendations of the

International Commission on Radiological Protection (ICRP) Publications

26/30 concerning the Annual Limits of Intake (ALI's) for the HLW

radionuclides and other guidance on radiation protection for radioactive

waste disposal in the ICRP publication #46.

The EPA Biosphere model and the other models/codes currently used in

assessing the risks from proposed HLW repositories and performance

assessment do not properly account for the long term accumulation

of radionuclides in different parts of the biosphere as these models and

codes are designed originally to assess the environmental impacts of

routine or accidental releases of radionuclides from nuclear power plants

or fuel cycle facilities. These releases are typically of short duration

(tens of years) compared to those of a much longer duration (tens of

thousands of years) that can be expected from a geologic repository. I will
MOUANDBS

NOTE FOR: orm

FROM: John T.

SUBJECT: MOU and other stuff

For Year 1. o Review scenario reports--basic work already done.

o Provide list of conditions with stipulated probabilities for external

processes and events as surrogate scenarios initiation processes and

events.

O Suggest combinations for analysis.

o Review and comment on other stuff going on.
I>

MOUANDBS - 2 -

Suggest consideration of the following base cases.

whole series of scenarios. At same time ignore gas

These would encompass a

and drilling.

1. "Expected" system conditions assuming

a. .1 m/year flux

b. 1 mm year flux

c. 10 m year flux

2. Uniform

a .

b.

c.

3. Assumed

a.

b.

change

.1 to 1 mm/year over 10,000 years

.1 to 10 m/year over 10,000 years

1 to 10 mi/year over 10,000 years

waste package failure

All at 1000 years

All at 5000 years

4. Tectonic effects--total failure and crushing / smearing of 1 waste

packages

a. @ 100 years

b. @ 1000 years

c. @ 5000 years

5. Distributed flux

a. 95X flux in

6. Repository temperature

a. See attached

5X of area
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JBUCKLEY

Work to be Performed Under Task 2 of the MOU by J. Buckley

The only area which requires rock echanics/design input as presented in the

MOU is Source Term Modeling (waste package lifetime). RM/D input may include:

1. Determine mechanical load on waste package.
7;?

* Z. 

KCHANG/1/31/89 - 1 -

MOU Phase I Task Description for K. Chang

Purpose: To provide a waste package performance assessment code capable of

estimating a conservative bound on performance of DOE's waste package

design.

Scope: The work scope will include a brief literature review of existing

codes being used by DOE and others for waste package performance

analyses and formulation of a simple code which may be used by NRC to

check whether DOE's waste package design can satisfy NRC's regulatory

requirements.

Content: The literature review will summarize the capabilities of the

various codes being used by DOE and others and recommend if any of

these codes may be used for NRC's purpose. The code to be used by

NRC would probably be able to address only the most probable failure

modes expected of the waste packages.

Planned Approach: The code to be developed likely be a simplified version of

a more elaborate code in existence. Simplifications can be

made by imposing additional assumptions on existing

models/codes such that less calculation is required to

arrive at more conservative approximated solutions.

Complex phenomena such as interaction between failed

packages and failed packages and geochemistry will not be

addressed.

1. Review report on existing codes

2. A PC code for source term

Key Products: