RSICC CODE PACKAGE PSR-476

1. NAME AND TITLE

SPIRT: Code System to Calculate Stress-Strains from Transient Pressures.

2. CONTRIBUTORS

EG and G Idaho, Inc., Idaho Falls, Idaho through the Energy Science and Technology Software Center, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER

FORTRAN IV; CDC CYBER76 (P00476C760000).

4. NATURE OF PROBLEM SOLVED

The SPIRT (Stress-strains from Pressures Instigated by Reactor Transients) program was developed to predict the pressure generated by the rapid dispersal of molten UO2 from power-reactor-type fuel rods into the coolant water. This rapid dispersal of molten fuel results from very high-power excursions initiated by the rapid insertion of reactivity. SPIRT was used in the safety analyses of the ATR and ETR. The program can analyze the response of one-dimensional plane, cylindrical, and spherical geometric configurations to pressure-generating heat sources with free-surface or fixed-surface boundary conditions. SPIRT can calculate the response of systems to the dispersal of hot fuel particles as a function of the following variables: enthalpy of fuel at time of dispersal, rate at which fuel is dispersed, size of dispersed fuel droplets, dispersal density of fuel (grams of fuel dispersed per cc of water), quality of water at time of fuel dispersal, enthalpy of water at time of fuel dispersal, system pressure at time of fuel dispersal, and the size and constituency of the medium enveloping the dispersed fuel. By holding all but one of the listed variables constant, and varying that one, the program computes the relative effect of that variable upon the response of systems to the dispersal of hot fuel. SPIRT exists as two releases one, written for UO2 fuel is called SPIRTU; the second, for uranium-aluminide fuel is identified as SPIRTA.

5. METHOD OF SOLUTION

Both SPIRTU and SPIRTA predict the pressure histories which might be expected when fuel rods fail and calculate the strain responses on both the capsule and the capsule hold down system.

6. RESTRICTIONS OR LIMITATIONS

None noted.

7. TYPICAL RUNNING TIME

Typical running time is two to three minutes. In NESC testing of the sample problem, SPIRTU required approximately 87 CPU seconds for execution, including creation of the plot file on a CYBER175; SPIRTA required approximately 93 seconds.

8. COMPUTER HARDWARE REQUIREMENTS

SPIRTU and SPIRTA required approximately 173K (octal) words for execution under NOS 1.3 on CDC or CYBER.

9. COMPUTER SOFTWARE REQUIREMENTS

SPIRT ran under SCOPE 2.1 (CDC CYBER76); or NOS 1.3 (CDC CYBER175) and required a FORTRAN IV compiler.

10. REFERENCES

a) Included in document:

L. J. Siefken, "Spirt Computer Program Stress-Strains from Pressures Instigated by Reactor Transients," RE-A-78-189 (October 1978).

L. Reed, "SPIRT, NESC No. 927, SPIRT Tape Description, Implementation Information, and Excerpts from ANCR-NUREG-1335, Volume II," NESC Note 82-83 (August 12, 1982).

b) Background information:

"RELAP4/MOD5, A Computer Program for Transient Thermal-hydraulic Analysis of Nuclear Reactors and Related Systems, User's Manual, Volume II: Program Implementation," ANCR-NUREG-1335 (September 1976).

M. L. Wilkins, "Calculation of Elastic-Plastic Flow," Methods in Computational Physics, Vol. 3, 211-263 (1964).

11. CONTENTS OF CODE PACKAGE

Included in the package are the referenced documents in (10.a) and a DOS-formatted 3.5" diskette which includes source, sample problems, and library auxiliary information.

12. DATE OF ABSTRACT

April 2000.

KEYWORDS: RISK ASSESSMENT; HEAT TRANSFER; PWR