1. NAME AND TITLE
MARC-PN: A Neutron Diffusion Code System with Spherical Harmonics Option.
AUXILIARY ROUTINES:
FD5: Routine to read card image data and write it out in variable length records.
DECIN: Free format data reading package.
DATA LIBRARY:
FD5: 37-group fast reactor cross section set.
The MARC diffusion theory code developed from CRAM.
2. CONTRIBUTOR
United Kingdom Atomic Energy Authority, Risley, Warrington, England, through
the OECD Nuclear Energy Agency Data Bank, Gif-sur-Yvette Cedex, France.
3. CODING LANGUAGE AND COMPUTER
FORTRAN IV and Assembler language; ICL 2982, IBM 3081 (A); FORTRAN 77, VAX
8810.
4. NATURE OF PROBLEM SOLVED
MARC-PN solves the multigroup diffusion or neutron transport equation in most
geometries of interest. The code has a finite element option so that irregular
problems can be accommodated. Input may be taken from various cross section
libraries such as FD5 (developed by UKAEA for fast reactor studies), those in
the SCALE package or the shielding sets CASK and EURLIB. A comprehensive set of
post edits is available including perturbation calculations, reaction rate
evaluations and burn-up changes for fuel management.
5. METHOD OF SOLUTION
In MARC-PN, the flux is expanded as a series of unnormalized spherical
harmonics terminated at some odd order N and the approximation denoted by PN. A
set of linked first order differential equations results for the coefficients of
the series and, by eliminating odd terms, this yields a second order system,
which may be solved by a mesh centered difference technique or a finite element
approach.
6. RESTRICTIONS OR LIMITATIONS
For the VAX 8810 version (B), using the CRAM method, the variable
(12+NDSCAT)*NG*JMAX must be less than 30000. For the PDQ method,
(6+NDSCAT)*JMAX*IMAX must be less than 30000. NG is the number of groups; NDSCAT
is the number of down scatters; IMAX and JMAX are the number of points in x and
y directions.
7. TYPICAL RUNNING TIME
No study has been made by RSIC of typical running times for MARC-PN. The test
case for the VAX 8810 version took 113 seconds of CPU time at NEA Data Bank.
8. COMPUTER HARDWARE REQUIREMENTS
The code is operable on the ICL 2982 or the IBM 3081 computers and also the
VAX 8810.
9. COMPUTER SOFTWARE REQUIREMENTS
Special library type routines are furnished in FORTRAN IV and Assembler
languages (A). On the VAX 8810, the FORTRAN 77 compiler was used under the
VAX/VMS Version 5.1-1 operating system.
10. REFERENCES
a. Included in the documentation:
J. K. Fletcher, "A User's Guide to the MARC and PN Computer Codes," TRG Report 2911(R), The Reactor Group, United Kingdom Atomic Energy Authority (September 1976).
J. K. Fletcher, "A Finite Element Option for the MARC Transport/Diffusion Theory Computer Code, Northern Division Report," United Kingdom Atomic Energy Authority, ND-R-560(R) (January 1981).
J. K. Fletcher, "CTD: A Computer Program to Solve the Three-Dimensional Multigroup Diffusion Equation to XYZ and Triangular-Z Geometries," TRG Report 2344(R) (1973). J. K. Fletcher, ``The Solution of the Multigroup Neutron Transport Equation Using Spherical Harmonics,'' TRG Report 2547(R) (1974).
J. K. Fletcher, "Further Work on the Solution of the Static Multi-Group
Neutron Transport Equation Using Spherical Harmonics," TRG Report 2849(R)
(1976).
b. Background information:
J. K. Fletcher, "The Solution of the Multigroup Neutron Transport Equation
Using Spherical Harmonics," Nucl. Sci. Eng. 84, 33-46 (1983).
11. CONTENTS OF CODE PACKAGE
Included are the referenced document (10.a) and one (1.2MB) DOS diskette
which contains the source code, data library, and sample problem input and
output.
12. DATE OF ABSTRACT
December 1981; revised February 1983; updated October 1983 and December 1990.
KEYWORDS: DIFFUSION THEORY; MULTIGROUP; NEUTRON; SLAB; CYLINDRICAL GEOMETRY; SPHERICAL GEOMETRY; SPHERICAL HARMONICS; COMPLEX GEOMETRY