**1. NAME AND TITLE**

SAMCEP: Monte Carlo Code System Correlated to the Simultaneous Solution of Multiple, Perturbed, Time-Dependent Neutron Transport Problems in Complex Three-Dimensional Geometry.

**AUXILIARY ROUTINES**

ENDTS: Cross Section (ENDF/B) Data Generator (CDC 6600).

SAMX: Neutron Element Data Generator (IBM 360).

SAMCEP is an extension of the SAM-F forward Monte Carlo neutron transport code, which is a component of the MAGI SAM-CE general purpose three-dimensional Monte Carlo radiation transport code system.

**2. CONTRIBUTORS**

Mathematical Applications Group, Inc. (MAGI), Elmsford, New York.

U.S. Army Ballistic Research Laboratories, Aberdeen Proving Ground, Maryland.

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN IV; CDC 6600.

**4. NATURE OF PROBLEM SOLVED**

SAMCEP is a system of codes designed for the simultaneous solution of multiple, perturbed, time-dependent neutron transport problems in complex three-dimensional geometry using correlated Monte Carlo. It is designed to calculate differences in neutron fluxes, and in flux derived quantities such as dose, as functions of differences in cross section data. Source spectral changes can also be considered.

Several correlated neutron transport problems in complex three-dimensional geometries can be handled at the same time. Up to 10 correlated problems, involving up to 100 perturbations of composition, neutron cross sections, angular or energy distributions, and/or source spectra, can be run simultaneously. Individual problem fluxes or doses (region-, energy-, and (on option) time-dependent), as well as the differences between those of any or all pairs of problems, are available.

SAMCEP retains essentially all the features of its predecessor code, SAMCE, including the use of basic neutron data in the latest ENDF/B format.

**5. METHOD OF SOLUTION**

SAMCEP is capable of running several similar Monte Carlo problems simultaneously. The mathematical basis of this capability is the simultaneous use, in several correlated problems, of the same Monte Carlo histories, taking account of the effects of the cross section differences via a series of problem-dependent weights associated with each history.

Using SAMCEP, flux differences due to small cross section variations can be calculated much more rapidly and accurately. It is a practical tool that can provide information permitting one to direct cross-section research toward obtaining more accurate data in those areas where the lack of precision leads to the greatest uncertainty in the transport calculation.

A perturbation is a specific change in some portion of the neutron source or changes in the nuclear data for any or all of the elements that make up a medium in a neutron transport problem. SAMCEP can handle, in a single calculation, up to ten correlated problems, each correlated problem including a combination of up to ten perturbations. The number of allowed perturbations is, therefore, one hundred. Perturbation types include: composition (i.e., concentration perturbation); the complete set of cross section data of an element (i.e., an alternate set of cross section data of a specific element); change of microscopic total cross sections; change of microscopic scattering cross sections; change of microscopic inelastic scattering cross sections; change in angular distribution of elastic scattering; change in secondary energy distribution in continuum inelastic scattering; excitation; change in angular distribution of discrete level inelastic scattering; and change in source spectrum.

**6. RESTRICTIONS OR LIMITATIONS**

Up to 10 correlated problems, involving up to 100 perturbations of composition, neutron cross sections, angular and secondary energy distributions, and source spectra, can be run simultaneously.

**7. TYPICAL RUNNING TIME**

The running time for SAMCEP is highly problem dependent.

**8. COMPUTER HARDWARE REQUIREMENTS**

SAMCEP is operable on the CDC 6600 computer and requires 300K core with seven external storage devices and a printer. The clock is sampled.

**9. COMPUTER SOFTWARE REQUIREMENTS**

SAMCEP currently operates under SCOPE 3.2.0 on a FORTRAN IV compiler.

**10. REFERENCE**

S. Hui, D. Spielberg, H. Steinberg, E. S. Troubetzkoy, and M. Kalos, "SAMCEP: An Application of Correlated Monte Carlo to the Simultaneous Solution of Multiple, Perturbed, Time-Dependent Neutron Transport Problems in Complex Three-Dimensional Geometry," MR-7020(P-7007) (January 1972).

**11. CONTENTS OF CODE PACKAGE**

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

**12. DATE OF ABSTRACT**

October 1972; updated September 1975.

**KEYWORDS:** NEUTRON; MONTE CARLO; COMPLEX GEOMETRY; TIME-DEPENDENT;
COMBINATORIAL GEOMETRY; SENSITIVITY ANALYSIS