**1. NAME AND TITLE**

MORSE-C: Monte Carlo Multigroup Neutron Code System for the Solution of Criticality
Problems. We recommend C00474/ALLCP/02 MORSE-CGA.

**DATA LIBRARY**

N92GRP: 92-group library obtained from the LLNL ENDL compilation existing in November
of 1976.

**2. CONTRIBUTOR**

Lawrence Livermore National Laboratory, Livermore, California.

**3. CODING LANGUAGE AND COMPUTER**

CHAT; CDC-7600.

**4. NATURE OF PROBLEM SOLVED.**

MORSE-C is based on the original ORNL versions of CCC-127/MORSE and CCC-261/MORSE-L
but is restricted to criticality problems. Continued efforts in criticality safety calculations led to the
development of techniques which resulted in improvements in energy resolution of cross sections,
upscatter in the thermal region, and a better cross section library. Only time-independent problems
are treated in the packaged version.

**5. METHOD OF SOLUTION**

Monte Carlo methods are used to solve the Boltzmann neutron transport equation in order to obtain
the eigenvalue when fissionable materials are present. Cross-sections are specified as multigroup,
multi-table values with up to a P_{3} Legendre expansion and 100 energy groups. Upscatter is allowed.
Geometry is specified in a general 3-D package with first and second degree surfaces and allowance
for array specifications. Pictures are drawn and volumes and masses calculated from the input
geometry definitions. Russian roulette and splitting can be utilized. Numerous output plots are made
to assist the user in understanding the physics of the problem being run.

**6. RESTRICTIONS OR LIMITATIONS**

The P_{0} cross-section table must not contain negative values.

**7. TYPICAL RUNNING TIME**

Running time depends upon the physical nature of the problem (the more thermal the system the
longer the running time), the geometrical complexity, and the desired accuracy. Typical problems
have run from 30 seconds to 45 minutes.

**8. COMPUTER HARDWARE REQUIREMENTS**

MORSE-C was written for the CDC-7600 with LLNL graphics devices.

**9. COMPUTER SOFTWARE REQUIREMENTS**

MORSE-C was written in LRLTRAN for a LLNL internal compiler, CHAT.

**10. REFERENCE**

T. P. Wilcox, "MORSE-C, a CDC-7600 program assigned to solve nuclear criticality problems
by using the Monte-Carlo Method," UCID-18993 (January 1981).

**11. CONTENTS OF CODE PACKAGE**

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

**12. DATE OF ABSTRACT**

September 1983.

**KEYWORDS: ** COMPLEX GEOMETRY; CRITICALITY CALCULATIONS; CROSS
SECTION PROCESSING; MONTE CARLO; MULTIGROUP; NEUTRON