NESC0606 GAPER1D

1. NAME OR DESIGNATION OF PROGRAM:  GAPER1D

3. DESCRIPTION OF PROBLEM OR FUNCTION

Reactivity coefficients are computed using first-order transport perturbation theory for one- dimensional multi-region reactor assemblies. The number of spatial mesh-points and energy groups is arbitrary. An elementary synthesis  scheme is employed for treatment of two- and three-dimensional problems. The contributions to the change in inverse multiplication  factor, delta(1/k), from perturbations in the individual capture, net fission, total scattering, (n,2n), inelastic scattering, and leakage cross sections are computed. A multi-dimensional prompt neutron lifetime calculation is also available.

4. METHOD OF SOLUTION

Broad group cross sections for the core and perturbing or sample materials are required as input. Scalar neutron fluxes and currents, as computed by SN transport calculations, are then utilized to solve the first-order transport perturbation theory equations. A synthesis scheme is used, along with independent SN calculations in two or three dimensions, to treat a multi- dimensional assembly. Spherical harmonics expansions of the angular  fluxes and scattering source terms are used with leakage and anisotropic scattering treated in a P1 approximation. The angular integrations in the perturbation theory equations are performed analytically. Various reactivity coefficients and material worths are then easily computed at specified positions in the assembly.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

The formulation of the synthesis scheme used for two- and three-dimensional problems assumes that the fluxes and currents were computed by the DTF4 code  (NESC Abstract 209). Therefore, fluxes and currents from two- or three-dimensional transport or diffusion theory codes cannot be used.

6. TYPICAL RUNNING TIME

A three-dimensional, 11-group series of eight problems with eight regions defined for a 9x9x9 interval mesh requires 12 seconds. A one-dimensional, 20-group series of 6 problems with 5 regions defined for a 50-interval mesh requires 22 seconds.

7. UNUSUAL FEATURES OF THE PROGRAM

Problems involving calculations for different assemblies can be run consecutively, if desired.

8. RELATED AND AUXILIARY PROGRAMS

GAPER and GAPER2D (NESC Abstract 471). GAPER1D is an updated version of the GAPER code.

10. REFERENCES

D. A. Sargis, GAPER - A Transport Perturbation Theory
Program, GA-8667, April 26, 1968.
                 K.  Lathrop, DTF-IV,  A  FORTRAN  IV Program  for
Solving  the   Multigroup  Transport  Equation   with  Anisotropic
Scattering, LA-3373, July 15, 1965.
             R. J. Archibald  and D. A.  Sargis, GAPER-2D,  A Two-
dimensional Transport Perturbation Theory Program, GA-10103, April
29, 1970.
             GAPER-1D Sample Problem Description, Gulf Note, 1973.
             P.   Koch,   GAPER-1D  Description,   Gulf   Internal
Memorandum, July 11, 1973.

- D. A. Sargis;
  GAPER - A Transport Permutation Theory Program
  GA-8667 (April 26, 1968).
- D. Koch;
  GULF Internal Memo FMA:099:PK:73 (July 11, 1973).

11. MACHINE REQUIREMENTS

One I/O device for reading input and printing results and one tape drive to read the code from tape. Core storage  requirements are variable.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:   EXEC8.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

GAPER1D is core-contained. Parameter statements are used to set dimension limits on the arrays.

15. NAME AND ESTABLISHMENT OF AUTHOR

                 P. K. Koch
                 General Atomic Company
                 P. O. Box 81608
                 San Diego, California  92138

File name	File description	Records
NESC0606_01.001	SOURCE PROGRAM (F4) + SAMPLE INPUT DATA	2386
NESC0606_01.002	SAMPLE PROBLEM PRINTED OUTPUT	1210