NESC0174 FORE2

1. NAME OR DESIGNATION OF PROGRAM:  FORE2

3. DESCRIPTION OF PROBLEM OR FUNCTION

FORE2 is a coupled thermal hydraulics-point kinetics digital computer code designed to calculate significant reactor parameters under steady-state conditions, or as functions of time during transients. The transients may result from a programmed reactivity insertion or a power change. Variable inlet coolant flow rate and temperature are considered. The code calculates the reactor power, the individual reactivity feedbacks, and the temperature of coolant, cladding, fuel, structure, and additional material for up to seven axial positions in three channel types which represent radial zones of the reactor. The heat of fusion, accompanying fuel melting, the liquid metal voiding reactivity, and the spatial and the time variation of  the fuel cladding gap coefficient due to changes in gap size are considered.

4. METHOD OF SOLUTION

FORE2 input consists of property data, geometry, power and flow distribution factors, external time varying functions, experimental coefficients, and termination data. The differential equations for fluid flow, heat transfer, and point neutronics are solved by explicit finite-difference procedures.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

Reactor excursions which can be calculated are restricted to those transients in which  the reactor is not substantially destroyed. As a general rule, changes in reactor geometry and composition during an excursion are  limited to those cases in which the reactivity effects of the changes may be considered as small perturbations of the initial system. Thus, accidents involving large-scale disassembly and bulk meltdown of a core are not covered by FORE2. FORE2 is valid only while the core retains its initial geometry.

6. TYPICAL RUNNING TIME

On a 10 microsecond computer FORE2 running time is on the order of 3.5 seconds per step, for a 1 microsecond computer 0.5 second per step.

7. UNUSUAL FEATURES OF THE PROGRAM

Unusual features of FORE2 include:    (a)  variable clad-fuel gap coefficient model;
   (b)  simulation of liquid metal voiding;
(c) unlimited wrapup and restart capability with changes in         input permitted before restart;
   (d)  determination of maximum stable time-step by code;
(e) separation of power into prompt and total (includes decay         heat);
   (f)  capability to use any single phase coolant;
(g) inclusion of fuel bowing and core deformation due to axial         pressure difference;
(h) ability to handle correctly the variation of coolant flow  rate in channels with orificing during a coastdown accident.

8. RELATED AND AUXILIARY PROGRAMS

The original Philco-2000 version of FORE was prepared by P. Greebler, D.B. Sherer and N.H. Walton of the General Electric Atomic Power Equipment Department, San Jose, California.
   FORE2 consists of three independent codes -
(a) EEEE performs all calculations and gives a condensed or         short edit of the results.
   (b)  FEDIT gives a detailed or long edit of the results.
   (c)  FRCURV performs curve plotting of the output.

10. REFERENCES

- P.Greebler, D.B. Sherer, N.H. Walton:
  FORE, A Computational Program for the Analysis of Fast Reactor
  Excursions
  GEAP-4090 (October 16, 1962) plus Errata and Addenda, EA2,
  (February 10, 1965), EA3 (June 22, 1965), and EA4 (December 22,
  1965).

- J.N. Fox, B.E. Lawler, and H.R. Butz:
  Fore II, A Computational Program for the Analysis of Steady-state
  and Transient Reactor Performance
  GEAP-5273 (September 1966).
- T.J. Heames:
  Adaptation of the General Electric Fast Oxide Reactor Excursion
  Code Number Two, FORE-II, to Operating System 360 Model 50/75
  ANL Reactor Physics Division Memorandum (February 1968).
- FORE2 Subroutine Descriptions including
- Nels J. Anderson, Jr.:
  IDFTAP, A FORTRAN IV Function Subprogram, S6T001, (January 15,
  1965), BITA, L5T001 (December 3, 1964).
- Nels J. Anderson, Jr.:
  FORTRAN IV Subroutine ERRSYS, S4T001 (January 15, 1965), FLEXO,
  J3T001 (January 21, 1965), FLTBCD, L2T006. LISTFORM, S6T002,
  (February 12, 1964), NFXBCD, L2T004, (November 16, 1965).
- C.T. Ehlers:
  NSORT, P5T001, (October 29, 1964).
- John W. Weil:
  PLOTRC, K5T003.
- Walter A. Duncan:
  VAMPIR, K5F009, (April 25, 1966).
- A.E. Scadden:
  ZERO, Division Overflow Modifier, Q4T001.
- LIMRTN, GESJ Note (September 19, 1967).

11. MACHINE REQUIREMENTS:  3 files and 40K memory (GE635).

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  GECOS (GE635), OS/360 (IBM360).

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

FORE2 calls several systems subroutines which are not included with the program. However, writeups of these subroutines are included with the code package.

15. NAME AND ESTABLISHMENT OF AUTHORS

   635           J. N. Fox, B. E. Lawler, and H. R. Butz
                 Advanced Products Operation
                 General Electric Company
                 Sunnyvale, California  94086
   360           T. J. Heames
                 Reactor Analysis and Safety Division
                 Argonne National Laboratory
                 9700 South Cass Avenue
                 Argonne, Illinois  60439

File name	File description	Records
NESC0174_01.001	SOURCE & DATA 360/65	9499
NESC0174_01.002	FRCURV FOR FORE-2	1449
NESC0174_01.003	OUTPUT	1500