**1. NAME AND TITLE**

PADLOC: A One-Dimensional, Time-Dependent Program for Calculating Coolant and Plateout
Fission Product Concentrations in a Network of Pipes.

**2. CONTRIBUTOR**

General Atomic Company, San Diego, California.

**3. CODING LANGUAGE AND COMPUTER**

Fortran IV; UNIVAC.

**4. NATURE OF PROBLEM SOLVED**

The one-dimensional computer program PADLOC is designed to analyze steady-state and time-dependent plateout of fission products in an arbitrary network of pipes. The problem solved is one of
mass transport of impurities in a fluid, including the effects of sources in the fluid and in the plateout
surfaces, convection along the flow paths, decay, adsorption on surfaces (plateout), and desorption
from surfaces. These phenomena are governed by a system of coupled, nonlinear partial differential
equations.

**5. METHOD OF SOLUTION**

The solution is achieved by a) linearizing the equations about an approximate solution, employing
a Newton-Raphson iteration technique, b) employing a finite-difference solution method with an
implicit time integration, and c) employing a substructuring technique to logically organize the systems
of equations for an arbitrary flow network.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

No study has been made by RSIC of typical running times for PADLOC.

**8. COMPUTER HARDWARE REQUIREMENTS**

The code is operable on the UNIVAC computer.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A Fortran IV compiler is required.

**10. REFERENCE**

W. W. Hudritsch and P. D. Smith, "PADLOC, A One-Dimensional Computer Program for
Calculating Coolant and Plateout Fission Product Concentrations," GA-A1401 (November 1977).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced document and one (1.2MB) DOS diskette which contains the source
code.

**12. DATE OF ABSTRACT**

January 1982.

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