NESC0317 GAPOTKIN

1. NAME OR DESIGNATION OF PROGRAM:  GAPOTKIN

3. DESCRIPTION OF PROBLEM OR FUNCTION

GAPOTKIN is  a point-kinetics
code that  solves the space-independent  kinetics equations  for a
very general form of the reactivity function.

4. METHOD OF SOLUTION

The form  of the  kinetics equations  used is
the reactivity-lifetime formulation.  The  reactivity is specified
in terms of step, linear, and quadratic coefficients proportionate
to the reactor  power and/or total energy  release.  The numerical
method for the integration of  the kinetics equations is discussed
in detail  by Hansen,  Koen, and  Little (see  reference 3).   The
operating life of  the system is divided into  various time zones,
each with its  own set of parameters, in order  to treat sequences
of events for which the system properties change.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

GAPOTKIN      will
handle up to  20 time zones and will allow  for 50 power-dependent
or  energy-dependent  reactivity  coefficients per  time  zone  if
tables are used.  General data are stored for up to 500 time-steps
and time delay data are stored for 10,000 time-steps.

6. TYPICAL RUNNING TIME

For  a problem  with  two  time zones,  the
first with a  60-second maximum operating time and  no time delay,
the second continuing  to 160 seconds and with no  time delay, the
running time is  about 20 seconds.  With delay times  for zone one
of 0.1 second and 0.4 second,  the running times are approximately
3.5 minutes and 5 minutes, respectively.

7. UNUSUAL FEATURES OF THE PROGRAM

A unique  feature of  the energy
feedback is the option of including time delays in the reactivity.
There  is  also  provision  for  including  time-varying  external
sources.   The overall  versatility  of the  code  allows for  the
handling of complex  sequences of events such as a  sudden loss of
coolant  followed by  a control  rod drop  and delayed  reactivity
insertions due to  energy buildup.  Built-in data  for U233, U235,
and Pu239 are from ANL-5800 (reference 4).

8. RELATED AND AUXILIARY PROGRAMS:

10. REFERENCES

K.  F.  Hansen and  P.  K.  Koch, GAPOTKIN,  A  Point
Kinetics Code for the UNIVAC 1108, GA-8204, October 25, 1967.
             G. R. Keepin,  Physics of Nuclear  Kinetics, Addison-
Wesley Publishing Company, Inc., Reading, Massachusetts, 1965.
             K. F.  Hansen, B.  V. Koen,  and W.  W. Little,  Jr.,
Stable  Numerical  Solution  of the  Reactor  Kinetics  Equations,
Nuclear Science and Engineering, Vol. 22, No. 1, p. 51, 1965.
             Reactor Physics Constants,  Second Edition, ANL-5800,
1963.

11. MACHINE REQUIREMENTS

GAPOTKIN requires  4100 storage  locations.
The data storage requirement is roughly 33,000 locations.  Two I/O
devices are required  for reading and printing  and one additional
I/O device is necessary if the program is loaded from tape.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:   EXEC2, GAX29.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

   The
dimensions  of  most of  the  arrays  are handled  with  parameter
statements.  Adaptation to a particular  machine with a FORTRAN IV
compiler can be made easily by  either adjusting the parameters to
allow for  available memory or  by eliminating the  parameters and
using explicit dimensions.

15. NAME AND ESTABLISHMENT OF AUTHOR

                 P. K. Koch
                 General Atomic Company
                 P. O. Box 81608
                 San Diego, California  92138

File name	File description	Records
NESC0317_01.001	SOURCE & DATA IBM 360	1495
NESC0317_01.002	OUTPUT	281