1. NAME AND TITLE

BLT-FEMWATER: Code System to Solve for Release and Transport of Contaminants through Saturated/Unsaturated Media.

AUXILIARY ROUTINES:

FEMWATER - two-dimensional finite-element program that calculates unsaturated/saturated water flow in subsurface media. This program was developed at Oak Ridge National Laboratory. Only minor modifications to permit the code to run under DOS instead of a VMS system were performed on this code.

GRAFBLT - graphics post-processor to view code output

REDIMGRD - program to take the larger grid domain used to calculate water flow and recalculate a new smaller grid used for examining the source term region in detail

Note: BLT is an extension of the code FEMWASTE originally developed at Oak Ridge National Laboratory and available from RSIC as CCC-451. BLT uses the contaminant transport routines supplied by FEMWASTE and has extended capabilities to model container and waste form performance.

2. CONTRIBUTOR

Brookhaven National Laboratory, Upton, NY.

3. CODING LANGUAGE and COMPUTER

FORTRAN 77; IBM PC 386/486 compatibles (C00633/PC386/00).

4. NATURE OF PROBLEM SOLVED

The BLT code solves for release and transport of contaminants from containerized wastes. Each container may have unique properties (i.e., time to failure or localized failure, e.g. pitting) and each waste form may have unique release properties. Release from the waste form is limited by one of four physical or chemical constraints: solubility, diffusion, dissolution, and surface wash-off with partitioning. The release from the waste form acts as a source for transport in the advection/dispersion equation. Transport is modeled in two-dimensions through the groundwater pathway from subsurface disposal.

5. METHOD OF SOLUTION

The advection/dispersion transport equation with spatially varying sources (waste forms) is solved in two-dimensions using the method of finite elements. Advancement in time is controlled by user supplied input. It is recommended to use the fully implicit backward Euler scheme. However, Crank-Nicolson and explicit time step algorithms are provided. Radioactive decay and sorption processes are included in the model. Container performance is calculated through empirical correlations and user supplied input data. Waste form release characteristics are simulated with geometry dependent (rectangular or cylindrical waste forms) analytical solutions to the diffusion equation. Dissolution is modeled through an input value specifying the dissolution rate. Rinse release with partitioning is simulated with user supplied values. In all cases, checks are made to prevent solubility limits from being exceeded.

6. RESTRICTIONS or LIMITATIONS

Two-dimensional.

Maximum problem size is 500 time steps and 400 computational points. These can be readjusted by redimensioning the code.

Maximum number of waste containers and waste forms is 100.

Maximum number of materials is 10 (i.e., number of regions with different transport properties).

Maximum number of different container and waste form types is 20.

Simulates only a single-species.

Changes in chemistry over time are not modeled.

7. TYPICAL RUNNING TIME

For a problem with 120 computational points and 100 time steps, run time is approximately 50 seconds on a 486/50.

8. COMPUTER HARDWARE REQUIREMENTS

An IBM PC or compatible with a minimum of a 386 processor. 500K of available conventional memory is required for execution. Approximately 4MB of disk space is required for installation. A color monitor is recommended for better contour differentiation.

9. COMPUTER SOFTWARE REQUIREMENTS

Lahey Fortran 5.0 was used to create the executable included in the package which were tested at RSIC both in a DOS window of Windows 95 and under MS-DOS 6.22. The graphics program, GRAFBLT, was compiled using the LAHEY FORTRAN version 5.0 graphics library. The program should automatically detect the graphics capability of the monitor. It has been tested on color monitors (SVGA) and black and white monitors (Hercules graphics card). However, the contour plotting routines in GRAFBLT rely on color to differentiate between contours. Other routines work acceptably on black and white monitors.

10. REFERENCES

Included in document:

T.M. Sullivan and C.J. Suen, "Low-Level Waste Shallow Land Disposal Source Term Model: Data Input Guides," NUREG/CR-5387, BNL-NUREG-52206 (July 1989).

Background information:

G. T. Yeh and D. S. Ward, "FEMWASTE: A Finite Element Model of Waste Transport through Saturated-Unsaturated Porous Media," ORNL-5601 (April 1981).

G. T. Yeh and D. S. Ward, "FEMWATER: A Finite Element Model of Water Flow through Saturated-Unsaturated Porous Media," ORNL-5567 (October 1980).

C.J Suen and T.M. Sullivan, "Sensitivity Analysis and Benchmarking of the BLT Low-Level Waste Source Term Code," NUREG/CR-5943, BNL-NUREG-52346 (1993).

T.M. Sullivan and C.J. Suen, "Low-Level Waste Source Term Model Development and Testing," NUREG/CR-5681, BNL-NUREG-52280 (May 1991).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document in 10.a and one 3.5-in. DS/HD (1.44 MB) diskette written in self-extracting compressed DOS files. Source code, the author's executables, and sample input/output are included.

12. DATE OF ABSTRACT

May 1996.