NESC0555 PARET-ANL(NESC).

1. NAME OR DESIGNATION OF PROGRAM:  PARET-ANL.

3. DESCRIPTION OF PROBLEM OR FUNCTION

This program is designed for use in predicting the course and consequences of nondestructive reactivity accidents in research and test reactor cores. It can be used for both steady-state and transient analysis.

4. METHOD OF SOLUTION

PARET provides a hydrodynamic and point kinetics capability. The core can be represented by four or fewer regions, each having different power generation, coolant mass flow rate, and hydraulic parameters as represented by a single fuel pin or plate with is associated coolant channel. The heat transfer in each fuel element is computed on the basis of a one-dimensional conduction solution in each of up to a maximum of 21 axial sections. The hydrodynamics solution is also one-dimensional for each channel  at each time node. The heat transfer may take place by natural or forced convection, nucleate, transition, or stable film boiling. The coolant is allowed to range from subcooled liquid, through the two-phase regime, up to and including superheated steam, and coolant flow reversal is allowed. PARET-ANL also has an optional "voiding model" which estimates the voiding produced by subcooled boiling.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

The PARET model is subject to several recognized limitations which may limit the applicability in any specific situation, depending on the nature of  the transient under consideration. The code employs steady-state heat transfer correlations throughout, possibly being unrealistic in certain transient situations. Any complete description of a severe transient must include provision for some sort of thermal or hydraulic crisis. PARET is limited in predicting such a crisis by the fact that it employs only steady-state correlations; no transient correlations with demonstrated reliability was developed.  Accurate description of hydraulic instability depends upon accurate  calculation of transient pressure and flow fluctuations. PARET is limited in this respect because it employs an incompressible model and a simplified void volume generation equation. Also, the magnitude of local pressures predicted to accompany coolant expulsion is strongly affected by the number of axial sections chosen in the computations. As a result,the hydrodynamic output should be interpreted as a qualitative indication of a possible crisis rather than a reliable quantitative prediction.
PARET is not applicable to either destructive excursions or situations in which there is a space-time effect in neutron flux.

6. TYPICAL RUNNING TIME

The sample problem requires less than 18 seconds of CPU time to process 320 time-steps with 2 channels on an  IBM3033.

7. UNUSUAL FEATURES OF THE PROGRAM:

8. RELATED AND AUXILIARY PROGRAMS

This program is an extension of CHIC-KIN (NESC Abstract 473). The original PARET program was developed by P.D. Adolf and C.F. Obenchain at EG&G Idaho.

10. REFERENCES

- J.A. Redfield,
  CHIC-KIN - A FORTRAN Program for Intermediate and Fast Transients
  in a Water-moderated Reactor,
  WAPD-TM-479, January 1965.
- C.J. Smith and W.A. Cody,
ANL DATE Routine, ANL Subroutine Description Q054S, February 1968.

- A. Strecok:
  PARET-ANL Tape Description and Implementation Information.
  NESC Note  85-02  (October 4, 1984)
- W.L. Woodruff:
  The PARET Code and the Analysis of the SPERT I Transients.
  (ANL Paper)
- W.L. Woodruff:
  A User Guide for the Current ANL Version of the PARET Code.
  (ANL Paper)
- C.F. Obenchain:
  PARET - A Program for the Analysis of Reactor Transients.
  IDO-17282  (January 1969)
- Excerpts from NRTS, Environmental Subroutine Manual.
  (December 1972)
- ANL-AMD System/360 Library Subroutine: ANL Q054S Subroutine.
  (August 1, 1973)

11. MACHINE REQUIREMENTS:  240K bytes plus one magnetic tape.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  OS/MVT (IBM370),
MVS (IBM3033).

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

A generalized input processor in IBM assembly language is included.  Auxiliary Fortran routines for processing and editing the summary plot file generated by PARET-ANL and for generating an updated properties library are also included. Subroutine INLK was compiled with the FORTX450 compiler with 450K. The normal compiler could not  process OPT=2 because this routine is too large. The size parameter  of the linkage editor must be set to (300K,24K).

15. NAME AND ESTABLISHMENT OF AUTHOR

      W.L. Woodruff
      Applied Phisics Division
      Argonne National Laboratory
      9700 South Cass Avenue
      Argonne, Illinois 60439

source program   mag tapePROPGENER Source Program (Fortran-IV)      SRCTP
source program   mag tapeCVI,TIMSET,DATE Subroutines Source (BAL)   SRCTP
source program   mag tapePARET Source Program (Fortran-IV)          SRCTP
bin data lib     mag tapeProperties Library (Binary Code)           LBBTP
test-case data   mag tapePARET Sample Problem Input                 DATTP
test-case output mag tapePROPGENER Output                           OUTTP
test-case output mag tapePARET Sample Problem Output                OUTTP
source program   mag tapePLOTPROS Source Program (Fortran-IV)       SRCTP
test-case data   mag tapePLOTPROS Sample Problem Input              DATTP
prog. note               NESC Note 85-02  (October 4, 1984)         NOTPT
paper                    The PARET Code and the Analysis of ...     PAPPT
user's guide             PARET User Guide                           WRKPT
report                   IDO-17282  (January 1969)                  REPPT
paper                    Excerpts from NRTS  (December 1972)        PAPPT
paper                    ANL Q054S Subroutine (August 1, 1973)      PAPPT