NESC0756 TIMEX

1. NAME OR DESIGNATION OF PROGRAM:  TIMEX

3. DESCRIPTION OF PROBLEM OR FUNCTION

TIMEX solves    the     time-
dependent,  one-dimensional  multigroup  transport  equation  with
delayed neutrons  in plane, cylindrical, spherical,  and two-angle
plane  geometries.  Both  regular and  adjoint, inhomogeneous  and
homogeneous  problems  subject to  vacuum,  reflective,  periodic,
white,  albedo  or  inhomogeneous  boundary  flux  conditions  are
solved.  General anisotropic scattering is allowed and anisotropic
inhomogeneous sources are permitted.

4. METHOD OF SOLUTION

The discrete ordinates  approximation for the
angular variable  is used  with the  diamond (central)  difference
approximation for the angular  extrapolation in curved geometries.
A  linear  discontinuous  finite element  representation  for  the
angular flux in  each spatial mesh cell is  used.  Negative fluxes
are eliminated by a local  set-to-zero and correct algorithm.  The
time  variable is  differenced by  an explicit  technique that  is
unconditionally stable so that arbitrarily large time-steps can be
taken.  Two  acceleration methods,  exponential extrapolation  and
rebalance,  are  utilized to  improve  the  accuracy of  the  time
differencing scheme.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

           Variable
dimensioning is used so that any combination of problem parameters
leading to a container array less than MAXCOR can be accommodated.
In addition,  the CDC  version permits  the use  of extended  core
storage less than MAXECS.

6. TYPICAL RUNNING TIME

The  running  time  for   TIMEX  is  highly
problem-dependent,  but  varies  almost linearly  with  the  total
number of unknowns and time-steps.   A 16-group, 30-interval mesh,
S2, 6  delayed neutron group calculation  of the decay of  a point
burst  in  a  Pu-Be  sphere  requires  about  14  minutes  on  the
IBM370/195 or 4 minutes on the CDC7600 for 200 time-steps.

NEA-DB executed test cases 1 + 2 on CDC 7600 in 207 CP seconds.

7. UNUSUAL FEATURES OF THE PROGRAM

Provision is  made for  creation
of standard interface output  files for angular fluxes  and angle-
integrated  fluxes.    Standard  interface  input  files   for  SN
constants,  inhomogeneous  sources, cross  sections,  and  initial
angular  fluxes may  be  read.  A  special  angular  flux file  is
available to provide exact initial conditions.

8. RELATED AND AUXILIARY PROGRAMS

The   ONETRAN  program   may   be
utilized to provide  compatible initial conditions to  TIMEX.  The
ANISN  FIDO format  may be  utilized to  provide compatible  input
cross section data.

10. REFERENCES

- T. R. Hill and Wm.  H. Reed, TIMEX:
  A Time-Dependent Explicit Discrete Ordinates Program for the
  Solution of Multigroup Transport Equations with Delayed Neutrons,
  LA-6201-MS, February 1976.
- T. R. Hill, ONETRAN:
  A  Discrete Ordinates Finite Element Code for the Solution of
  the One-dimensional Multigroup Transport Equation, LA-5990-MS,
  June 1975.
- B. M. Carmichael:
  Standard Interface Files and Procedures for Reactor Physics
  Codes, Version III, LA-5486-MS, February 1974.
- W. W. Engle, Jr.:
  A User's  Guide Manual for ANISN, A One-dimensional Discrete
  Ordinates Transport Code with Anisotropic Scattering, K-1693,
  March 1967.
- R. M. Frank:
  J506A Basic SC4020 Film Display Subroutines, LASL Program
  Library Description, 1967.
- A. Solem:
  J506B Utility Film Subroutines, LASL Program Library Description,
  November 19, 1976.
- T. R. Hill:
  TIMEX Test Problem Set, LASL TIMEX Memorandum, January 1976.
- R. Douglas O'Dell and Raymond E. Alcouffe:
  Transport Calculations for Nuclear Analyses: Theory and
  Guidelines for Effective Use of Transport Codes
  LA-10983-MS and UC-32 (September 1987)

11. MACHINE REQUIREMENTS

Use of a container array of 50,000 requires
500K bytes of IBM storage for execution.  Five interface units may
be required (use  is optional), 2 system input/output  units and 5
output units are required for the IBM version.  Use of a container
array of 16,000 and 16,000 words  of ECS requires 164K total words
of CDC storage  for execution.  Two system  input/output units and
11 additional input/output files are defined in the CDC version.

Test case execution on CDC 7600 required 132,000 octal  words.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:       OS/360,370
(IBM360,370), SCOPE 2.1.3 (CDC7600).

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

   The
frequency factors calculated in  the exponential extrapolation are
extremely sensitive to the machine  precision and LOGF subroutine.
When the  frequencies are  small, this  may result  in significant
differences from the  results given in the  test problem execution
of the TIMEX transmittal package.   In addition, two LASL specific
subroutines DATE1 and SECOND have been supplied as dummy routines.
DATE1 must be provided  by the user to return the  current date as
an  A8 word.   SECOND  provides the  floating-point  value of  the
current time in seconds and an alternate local routine is required
in order for the periodic and time limit options to work.

15. NAME AND ESTABLISHMENT OF AUTHORS

                 T. R. Hill* and W. H. Reed
                 Los Alamos Scientific Laboratory
                 P. O. Box 1663
                 Los Alamos, New Mexico  87545
* Contact

File name	File description	Records
NESC0756_01.002	TIMEX INFORMATION	39
NESC0756_01.003	TIMEX SOURCE PROGRAM CARD IMAGES FTN-4	5788
NESC0756_01.004	TIMEX INPUT FOR TEST CASES 1 + 2	351
NESC0756_01.005	TIMEX TIMEX INPUT FOR TEST CASES 3 + 4 + 5	265
NESC0756_01.006	TIMEX CRITICAL RADIUS FOR CASES 3 + 4	71
NESC0756_01.007	TIMEX OUTPUT OF TEST CASES 1 + 2	4173
NESC0756_01.008	TIMEX JCL FOR TEST CASES	17

File name	File description	Records
NESC0756_02.001	INFORMATION & JCL	155
NESC0756_02.002	SOURCE	6116
NESC0756_02.003	INPUT DATA FOR EXAMPLE	59
NESC0756_02.004	INPUT DATA S.P.1	104
NESC0756_02.005	INPUT DATA S.P.2	188
NESC0756_02.006	INPUT DATA S.P.3	95
NESC0756_02.007	INPUT DATA S.P.4	91
NESC0756_02.008	INPUT DATA S.P.5	79
NESC0756_02.009	INPUT DATA FOR ONETRAN	71
NESC0756_02.010	OUTPUT OF EXAMPLE	822
NESC0756_02.011	OUTPUT OF S.P.1	1525
NESC0756_02.012	OUTPUT OF S.P.2	1836
NESC0756_02.013	OUTPUT OF S.P.3	1906
NESC0756_02.014	OUTPUT OF S.P.4	2314
NESC0756_02.015	OUTPUT OF S.P.5	1642
NESC0756_02.016	OUTPUT OF S.P.3 (DOUBLE PRECISION)	1906
NESC0756_02.017	OUTPUT OF ONETRAN (DOUBLE PRECISION)	984