NESC0301 FREVAP6

1. NAME OR DESIGNATION OF PROGRAM:  FREVAP6.

3. DESCRIPTION OF PROBLEM OR FUNCTION

The FREVAP type of code for estimating the release of longer-lived metallic fission products from HTGR fuel elements has been developed to take into account the combined effects of the retention of metallic fission products by fuel particles and the rather strong absorption of these fission products by the graphite of the fuel elements. Release calculations are made on the basis that the loss of fission product nuclides such as strontium, cesium, and barium is determined by their evaporation from the graphite surfaces and their transpiration induced by the flowing helium coolant. The code is devised so that changes of fission rate (fuel element power), fuel temperature, and graphite temperature may be incorporated into the calculation. Temperature is quite important in determining release because, in general, both release from fuel particles and loss by evaporation (transpiration) vary exponentially with the reciprocal of the absolute temperature.

THIS VERSION DIFFERS FROM THE PREVIOUS ONE IN THE FOLLOWING POINTS:
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The source and output files were converted from BCD to ASCII coding.

4. METHOD OF SOLUTION

A problem is defined as having a one-dimensional segment made up of three parts - (1) the fission product source (fuel particles) in series with, (2) a non-source and absorption part (element graphite) and (3) a surface for evaporation to the coolant (graphite-helium interface). More than one segment may be connected (possibly segments stacked axially) by way of the coolant. At any given segment, a continuity equation is solved assuming equilibrium between the source term, absorption term, evaporation at coolant interface and the partial pressure of the fission product isotope in the coolant.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

Maxima of -
    5 isotopes
   10 time intervals for time-dependent variable
   49 segments (times number of isotopes)
    5 different output print time-steps

6. TYPICAL RUNNING TIME:  15 minutes are required.

7. UNUSUAL FEATURES OF THE PROGRAM:

8. RELATED AND AUXILIARY PROGRAMS:

- L. R. Zumwalt, V. H. Pierce, and M. J. Gerber:
FREVAP-6 Code for Estimating Metallic Fission Product Release, GAMD-7656,
January 12, 1967.

11. MACHINE REQUIREMENTS:  64K memory with 2 tapes (I/O).

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:   EXEC2, GAX27.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

The RKGA subroutine provides the solution of the derivative equation by the Runge-Kutta-Gill method to use as the starting HAMDE value. The HAMDE subroutine is then used for the solution of the derivative equation using the Milne-Hamming method.

15. NAME AND ESTABLISHMENT OF AUTHOR

                 V. H. Pierce
                 General Atomic Company
                 P. O. Box 81608
                 San Diego, California  92138, USA

Information file
NESC0301_02.001 SOURCE PROG.+OVERLAY CARDS+INPUT DATA 1205 records
NESC0301_02.002 PRINTED OUTPUT 2870 records
NESC_301_02.pdf Reference Report