1. NAME AND TITLE

DASH-FP: A One-Dimensional Analytic-Numerical Solution to the Problem of Multicomponent Time-Dependent Diffusion of Fission Products.

2. CONTRIBUTOR

Los Alamos National Laboratory, Los Alamos, New Mexico.

3. CODING LANGUAGE AND COMPUTER

Fortran IV, COMPASS; CDC.

4. NATURE OF PROBLEM SOLVED

DASH-FP solves the multicomponent time-dependent diffusion with radioactive decay problem which arises in the study of high-temperature gas-cooled reactors' fission product migration.

5. METHOD OF SOLUTION

DASH-FP provides a one-dimensional analytic-numerical solution of the diffusion problem. The diffusion operator is numerically approximated by a spatial finite-difference representation. The resulting time-dependent problem is solved analytically using a matrix operator method. Comparisons to a number of known one-dimensional analytic solutions have been made. These comparison problems include the one species and two species, two material slab, cylinder, and sphere cases.

The method used produces a correct analytic solution of the equations for isotopes of any possible decay constants. For a given geometry, the error varies inversely as the square of the number of calculational cells.

6. RESTRICTIONS OR LIMITATIONS

None noted.

7. TYPICAL RUNNING TIME

no. of no. of no. of no. of running

isotopes cells materials time steps time

DATA1DM 1 24 4 1 2.6 sec

DATA2DM 2 24 4 1 14.4 sec

DATA3DM 3 24 4 1 46.9 sec

DATAESY 2 4 2 1 1.0 sec

DATA 2 24 3 5 6.4 sec.

8. COMPUTER HARDWARE REQUIREMENTS

The code is operable on the CDC computers. It requires approximately 60 K words of small core storage and 400 K words of large core storage.

9. COMPUTER SOFTWARE REQUIREMENTS

A Fortran IV compiler is required. Subroutine SEARCH is coded in COMPASS. There is an option for plotting, set up for the DISSPLA plot routines. The plotting is done as a postprocessor.

10. REFERENCES

L. M. Carruthers, "DASH Abstract" (April 1981).

C. E. Apperson, Jr., C. E. Lee, and L. M. Carruthers, "DASH: A Multicomponent Time-Dependent Concentration Diffusion with Radioactive Decay Program," NUREG/CR-0776, LA-7793-MS (April 1979).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document and one (1.2MB) DOS diskette which contains the source codes and sample problem input and output.

12. DATE OF ABSTRACT

February 1982.

KEYWORDS: FISSION PRODUCTS; DIFFUSION THEORY; NUCLIDE TRANSPORT; ONE-DIMENSION; TIME-DEPENDENT