**1. NAME AND TITLE**

GENP-2: Generalized Perturbation Theory Code System

**2. CONTRIBUTOR**

Nucleare Italiana Reattori Avanzati, Genova, Italy, through NEA Data Bank, Gif-sur-Yvette Cedex, France.

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN IV; IBM 3090, VAX 8810.

**4. NATURE OF PROBLEM SOLVED**

GENP-2 is a system of programs that use generalized perturbation theory to calculate perturbation of reactor integral characteristics which can be expressed as ratios of linear and bilinear functionals of the real and adjoint fluxes due to cross section perturbations.

**5. METHOD OF SOLUTIONS**

GENP-2 consists of the following codes: DDV, SORCI, CIAP-PMN and GLOBP-2D. DDV calculates the real or adjoint fluxes and power distributions using multigroup diffusion theory in two dimensions. SORCI uses the fluxes from DDV to calculate the real or adjoint general perturbation sources. CIAP-PMN reads the sources from SORCI and uses them in the real or adjoint generalized importance functions calculations in two dimensions. GLOBP-2D uses the importance calculated by CIAP-PMN, and the fluxes calculated by DDV, in generalized perturbation expressions to calculate the perturbation in the quantity of interest.

**6. RESTRICTIONS OR LIMITATIONS**

The maximum number of mesh points and the maximum number of regions cannot exceed 6400. The maximum number of energy groups is 100. If the power distribution is calculated, the product of the number of groups by the number of regions must not exceed 2500.

**7. TYPICAL RUNNING TIME**

The following times were noted at NEA Data Bank. On the IBM 3090 and VAX 8810 and sample input 1 for each program: DDV -- 44s, 77s; SORCI -- 4s, 14s; CIAP -- 37s, 74s; GLOBP -- 4s, 15s. On the IBM 3090 and VAX 8810 and sample input 2 for each program: DDV -- 30s, 64s; SORCI -- 4s, 14s; CIAP -- 34s, 74s; GLOBP -- 4s. In each case, the first CPU time is for the IBM, the second for the VAX.

**8. COMPUTER HARDWARE REQUIREMENTS**

GENP-2 runs on the IBM 3090 and VAX 8810.

**9. COMPUTER SOFTWARE REQUIREMENTS**

The code was written is in FORTRAN IV. On the IBM 3090, the compiler was VS FORTRAN Level 2.1.1 under the MVS/XA operating system; on the VAX 8810, VAX FORTRAN Version 5.0-1 under the VAX/VMS 5.1 operating system was used.

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10. REFERENCE**

**a. Included in the documentation:**

G. Bruna. *Manuale D'Uso Del Programma DDV*, SEC-I-01-03, Nucleare Italiana
Reattori Avanzati, Genova, Italy, September 1975. (In Italian).

A. Boioli, G. Bruna, G. P. Cecchini, N. Meda. *Il Codice GLOBPERT-2D*, SEC-I-01-04,
Nucleare Italiana Reattori Avanzati, Genova, Italy, September 1975. (In Italian).

A. Boioli, G. Bruna, G. P. Cecchini, N. Meda. *Il Codice CIAP-2D*, SEC-I-01-05,
Nucleare Italiana Reattori Avanzati, Genova, Italy, September 1975. (In Italian).

G. Bruna. *Manuale D'Uso Del Programma SORCI*, SEC-I-01-06, Nucleare Italiana
Reattori Avanzati, Genova, Italy, September 1975. (In Italian).

**11. CONTENTS OF CODE PACKAGE**

Included are the referenced documents and one DS/HD 5.25-inch diskette (1.2 MB) which include the source programs and sample input and output.

**12. DATE OF ABSTRACT**

December 1990.

**KEYWORDS: ** ADJOINT; CROSS SECTIONS; DIFFUSION THEORY; NEUTRON;
REACTOR PHYSICS; TWO-DIMENSIONS; PERTURBATION
THEORY