1. NAME AND TITLE
THERMOS-OTA: Multigroup Integral Transport Code System for Thermal Lattice
Calculations using Collision Probability Method for Slabs and Cylinders.
AUXILIARY ROUTINE
ETOTO: A program to process data from ENDF/B to THERMOS-OTA and FACEL.
THERMOS-OTA is based on the THERMOS code which was developed at Brookhaven
National Laboratory, Upton, New York. It is, to a large extent, a reprogrammed
version of THERMOS including the dynamic storage allocation facility. Thus, the
range of program applicability has been greatly increased.
2. CONTRIBUTOR
Technical Research Centre of Finland, Nuclear Engineering Laboratory,
Helsinki, Finland, through the OECD NEA Data Bank, Gif-sur-Yvette, France.
3. CODING LANGUAGE AND COMPUTER
Fortran IV, UNIVAC-1108 (A); Fortran V, CYBER 173 (B); Fortran 77, CYBER 740
(C).
4. NATURE OF PROBLEM SOLVED
THERMOS-OTA solves the integral transport equation for the thermal neutron
density in slab or cylindrical geometry. It allows condensed cross section sets
to be obtained for various nuclides and mixtures and they can be stored in mass
storage as pseudo material libraries.
5. METHOD OF SOLUTION
The method used in THERMOS for solving the multigroup integral transport
theory Boltzmann equation by collision probability approach is kept unchanged in
THERMOS-OTA with a few small exceptions. These include treatment of vacuum
regions and making transport correction to the cross sections. THERMOS-OTA uses
successive overrelaxation, renormalization, and extrapolation.
6. RESTRICTIONS OR LIMITATIONS
Due to the use of dynamic storage allocation, it is difficult to specify
limits for the problem size. However, as a rule of thumb, the product of the
number of groups and the number of space points should be less than about 600 if
40,000 words are used for dynamic storage. The amount of storage space reserved
by the program can be changed.
7. TYPICAL RUNNING TIME
For a small system, such as a fuel rod cell, the running time on a UNIVAC
1108 is typically about 1 minute without the transport correction and perhaps 2
minutes with it. For large systems such as 50 mean free paths in radius with
many groups, convergence is poor leading to running times on the order of 20
minutes. On the CDC 740, THERMOS-OTA runs in 70 CPU seconds.
8. COMPUTER HARDWARE REQUIREMENTS
THERMOS-OTA is operable on the UNIVAC 1108 computer (A) or the CYBER 740
computer (B). On the UNIVAC 1108, with 46,000 words used for dynamic storage, 64
K of core storage will suffice. THERMOS-OTA uses 2 auxiliary storage files of
arbitrary type. The CYBER 740 main storage was 170,000 octal words.
9. COMPUTER SOFTWARE REQUIREMENTS
A Fortran IV compiler is required (A). A Fortran 77 compiler is required for
version (B).
10. REFERENCES
J. Saastamoinen and F. Wasastjerna, "THERMOS-OTA, A Revised Version of the THERMOS Program for Thermal Lattice Calculations with the Auxiliary Programs THEPSL and THECOM," Nuclear Engineering Laboratory, Report 10 (January 1974).
E. Patrakka, ETOTO, "A Program to Process Data from ENDF/B to THERMOS-OTA and FACEL," Nuclear Engineering Laboratory, Report 7 (September 1973).
E. Patrakka, "A 48 Group THERMOS-OTA Library," Nuclear Engineering Laboratory
(From YDI 1974 Memo 3).
11. CONTENTS OF CODE PACKAGE
Included are the referenced documents and one (1.2MB) DOS diskette which
contains the source code and sample problem input and the THERMOS-OTA Library.
12. DATE OF ABSTRACT
March 1984; reviewed May 1984, updated September 1985, August 1986.
KEYWORDS: MULTIGROUP CROSS SECTION PROCESSING; NEUTRON CROSS SECTION PROCESSING