1. NAME AND TITLE

FRCRL2: Calculation of Fission-Product Release in Reactor Accident Analyses.

2. CONTRIBUTOR

Battelle Columbus Laboratories, Columbus, Ohio.

3. CODING LANGUAGE AND COMPUTER

FORTRAN IV; CDC 6400.

4. NATURE OF PROBLEM SOLVED

FRCRL2 calculates the cumulative fractional release of fission products from nuclear reactor fuel under postulated loss-of-coolant accident conditions. The mathematical model for release is based on simple volume diffusion theory and the equivalent-sphere approximation of fuel porosity. Both the operational pre-accident release component and the accident core thermal transient-induced release component are calculated. Detailed core temperature data are needed to make the latter set of computations. In addition, specific core power distribution factors and fission product diffusion parameters must be supplied.

5. METHOD OF SOLUTION

Analytical solutions to the conventional problem of one-dimensional diffusion from a sphere are used. For the pre-accident release component, uniform conditions are assumed over the period of reactor operation. Parabolic radial temperature profiles for the fuel pellets are computed and used to define five radial temperature zones for each core segment. From this, the corresponding set of dimensionless release parameters are calculated for insertion in the analytical solution. For the accident release component, the change in temperature versus time is considered by incrementally modifying the dimensionless release parameters for each of the core segments.

6. RESTRICTIONS OR LIMITATIONS

The calculation is limited to maxima of 12 fission product species, 10 radial core regions, and 11 axial core regions. Also, four separate sets of fission product diffusion parameter values must be supplied for different temperature ranges or assumed atmosphere conditions.

7. TYPICAL RUNNING TIME

Approximately 2 seconds are required per fission product species per accident time step.

8. COMPUTER HARDWARE REQUIREMENTS

FRCRL2 is operable on the CDC 6400 computer.

9. COMPUTER SOFTWARE REQUIREMENTS

A FORTRAN IV compiler is required.

10. REFERENCE

R. L. Ritzman and D. L. Morrison, "FRCRL2A Computer Code for Calculating Fission-Product Release in Reactor Accident Analyses," BMI-1913 (August, 1971).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document and one (1.2MB) DOS diskette which contains the source code and sample problem input.

12. DATE OF ABSTRACT

July 1975; revised October 1982.