**1. NAME AND TITLE**

MORSE: A General Purpose Monte Carlo Multigroup Neutron and Gamma-Ray Transport Code System. We recommend C00474/ALLCP/02 MORSE-CGA.

**AUXILIARY ROUTINES**

SAMBO: Collision Analysis Code.

PICTURE: GEOM Input Diagnostic Code.

XCHECKR: Multigroup Cross Section Editor.

Non-standard Code Library.

Random Number Generators.

Spherical Geometry.

Slab Geometry.

Cylindrical Geometry.

General Geometry.

MORSE was originally programmed for the CDC 1604 (1970) and was later modified and
extended for the IBM 360 and the CDC 6600. Proliferation led to separate packages:
CCC-203/MORSE-CG (SAI, MAGI, ORNL), CCC-258/MORSE-E (ESIS, NEA DB),
CCC-261/MORSE-L (LLNL), CCC-277/MORSE-SGC (UCC-CSD), CCC-368/MORSE-B (UK
Univ. of Birmingham) and CCC-431/MORSE-C (LLNL). This package contains an early ANSI-Standard version prepared by G. P. Lahti while at NASA/LRC. It is an archived package for
possible reference and is no longer recommended for routine use.

**2. CONTRIBUTORS**

Oak Ridge National Laboratory, Oak Ridge, Tennessee.

NASA Lewis Research Center, Cleveland, Ohio (ANSI-Std version).

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN IV, Assembly Language and FORTRAN IV (ANSI Std); IBM 360/75/91.

**4. NATURE OF PROBLEM SOLVED**

MORSE is a multipurpose neutron and gamma-ray transport Monte Carlo code system. It has
been designed as a tool for solving most shielding problems. Through the use of multigroup cross
sections, the solution of neutron, gamma-ray, or coupled neutron-gamma-ray problems may be
obtained in either the forward or adjoint mode. Time dependence for both shielding and criticality
problems is provided. General three-dimensional geometry, as well as specialized one-dimensional
geometry descriptions, may be used with an albedo option available at any material surface.
Isotropic or anisotropic scattering up to a P16 expansion of the angular distribution is allowed.

**5. METHOD OF SOLUTION**

Monte Carlo methods are used to solve the forward and the adjoint transport equations. Quantities of interest are then obtained by summing the contributions over all collisions, and frequently over most of phase space.

Standard multigroup cross sections such as those used in discrete ordinates codes may be used as input. Anisotropic scattering is treated for each group-to-group transfer by utilizing a generalized Gaussian quadrature technique.

MORSE is organized into functional modules with simplified interfaces such that new modules may be incorporated with reasonable ease. The modules are (1) random walk, (2) cross section, (3) geometry, (4) analysis, and (5) diagnostic.

While basic MORSE assumes the analysis module is user-written, a general analysis package,
SAMBO, handles most of the drudgery associated with the analysis of random walks and minimizes
the amount of user-written coding. An arbitrary number of detectors, energy-dependent response
functions, energy bins, time bins, and angle bins are allowed. Analysis is divided for each detector
as follows: uncollided and total response, fluence versus energy, time-dependent response, fluence
versus time and energy, and fluence versus angle and energy. Each of these quantities is listed as
output. The diagnostic module provides an easy means of printing out, in useful form, the
information in the various labeled COMMON and any part of blank COMMON. This module is
very useful to debug a problem and to gain further insight into the physics of the random walk.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

No effort has been made to estimate typical running time for MORSE.

Estimated running times for the packaged sample problems on the IBM 360/91: 1) 0.42 minutes
and 2) 1.16 minutes.

**8. COMPUTER HARDWARE REQUIREMENTS**

MORSE was originally designed for the CDC 1604 and was converted to the IBM 360 and
revised considerably. Standard hardware equipment is used in each version with standard I-O
devices required.

**9. COMPUTER SOFTWARE REQUIREMENTS**

Standard software for the IBM 360 may be used. Any non-standard library routines which
were used have been included in the code package, or a full description is given for the user's
information. The OS-360 FORTRAN H compiler was used. In the GO Step: problem 1 used 300
K and problem 2 used 306 K of storage.

**10. REFERENCES**

C. E. Burgart, "Additions, Improvements, and Corrections to MORSE-SAMBO Code Package Implemented in the IBM 360 Version," Informal Notes (February 1972).

E. A. Straker, P. N. Stevens, D. C. Irving, and V. R. Cain, "The MORSE Code - A Multigroup Neutron and Gamma-Ray Monte Carlo Transport Code," ORNL-4585 (September 1970).

V. R. Cain, "SAMBO, A Collision Analysis Package for Monte Carlo Doses," ORNL-TM-3203 (September 1970).

D. C. Irving and G. W. Morrison, "PICTURE: An Aid in Debugging GEOM Input Data," ORNL-TM-2892 (May 1970).

Sandia Notes, "MORSE-SAMBO," Informal Notes.

E. A. Straker and M. B. Emmett, "MORSEC: A Revised Cross-Section Module for the MORSE Multigroup Monte Carlo Code," ORNL-4716 (August 1971).

C. E. Burgart, "MORSE-GEOM-MORSEC-SAMBO Input Instructions," ORNL-TM-3632 (1971).

C. E. Burgart and E. A. Straker, "XCHECKR: A Multigroup Cross-Section Editing and Checking Code," ORNL-TM-3518 (August 1971).

D. C. Irving, "The Adjoint Boltzmann Equation and Its Simulation by Monte Carlo," ORNL-TM-2879 (May 1970).

**11. CONTENTS OF CODE PACKAGE**

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

**12. DATE OF ABSTRACT**

August 1971; revised December 1984, and September 1991.

**KEYWORDS: ** MONTE CARLO; MULTIGROUP; COMPLEX GEOMETRY; NEUTRON;
GAMMA-RAY; ADJOINT; TIME-DEPENDENT; COMBINATORIAL
GEOMETRY