**1. NAME AND TITLE**

TDT: Generalized One-Dimensional Multigroup Time-Dependent Transport and Diffusion
Kinetic Code System.

TDT is based on CCC-184/TASK.

**2. CONTRIBUTORS**

Nuclear Engineering Department, University of Tennessee, Knoxville, Tennessee.

Neutron Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee.

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN IV; IBM 360/370.

**4. NATURE OF PROBLEM SOLVED**

TDT solves the one-dimensional multigroup form of the time-dependent reactor kinetics
equations, allowing an arbitrary number of delayed neutron groups. It can also solve standard static
problems such as eigenvalue problems (transport only), distributed source problems, and boundary
source problems using either diffusion theory or transport theory. Convergence problems associated with highly multiplicative media are circumvented, and such problems are readily calculable.

**5. METHOD OF SOLUTION**

TDT employs a combination scattering and transfer matrix method to solve the transport
equation in the spatial domain and a predictor-corrector method to obtain solutions in the temporal
domain.

**6. RESTRICTIONS OR LIMITATIONS**

The principal restrictions are available storage and computational time. Since the code is
flexibly dimensioned, there are no internal restrictions on group structure, quadrature, and number
of coordinates. The code contains an option whereby it will calculate the most efficient time mesh.
The cylindrical geometry option is not operational in this version.

**7. TYPICAL RUNNING TIME**

A 10-second rod-drop transient in a 7-region, 5-group, S4 problem requires 5 minutes on the
IBM 360/91 computer. The packaged sample problem ran in 1.6 minutes. A point kinetics
approximation is available which significantly reduces the computational time.

**8. COMPUTER HARDWARE REQUIREMENTS**

TDT runs on the IBM 360/370 computers, requiring 178 K of storage plus data block storage,
a total of 244 K. One tape is required to utilize the flux tape option.

**9. COMPUTER SOFTWARE REQUIREMENTS**

A FORTRAN IV compiler is required.

**10. REFERENCE**

E. T. Tomlinson, H. L. Dodds, R. A. Lillie, and J. C. Robinson, "A User's Manual for TDT
(Time Dependent Task)," ORNL-TM-4869 (June 1975).

**11. CONTENTS OF CODE PACKAGE**

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

**12. DATE OF ABSTRACT**

September 1975; revised January 1983.

**KEYWORDS: ** TRANSPORT DIFFUSION; MULTIGROUP; KINETICS; ONE-DIMENSION