1. NAME AND TITLE

ACT-ARA: Code System for the Calculation of Changes in Radiological Source Terms with Time

AUXILIARY ROUTINE

RACT: Interactive Input Generation Program

DATA LIBRARIES

IS30; IS50; IS60; IS90; and IS106: Isotopic decay data for isotopes with atomic numbers 1-30, 31-50, 51-60, 61-90, and 91-106, respectively.

2. CONTRIBUTOR

Applied Research Associates, Inc., Albuquerque, New Mexico.

3. CODING LANGUAGE AND COMPUTER

Fortran; Cray.

4. NATURE OF PROBLEM SOLVED

The program calculates the source term activity as a function of time for parent isotopes as well as daughters. Also, at each time, the "probable release" is produced. Finally, the program determines the time integrated probable release for each isotope over the time period of interest.

5. METHOD OF SOLUTION

The ACT-ARA program modifies an initial source term for changes with time due to decay of parents and production of daughters. The calculated activity for each daughter is based on the activity of the chain's parent. Time steps are distributed uniformly on a base 10 logarithmic scale. Decay constants, half-lives, specific activities, identified daughter products and their rate of production are maintained in data files IS30, IS50, IS60, IS90, and IS106. The probable release of the activity is calculated at each time interval based on the fraction released and the probability of intrusion. The fraction released is a step function which changes from an initial release fraction to a final release fraction at a specified time. The probability of release is nonzero following a period of active control and is modelled by a "Wisconsin Regression" function. The integrated probable release for each isotope is obtained by summation of the probable release over the total time.

6. RESTRICTIONS OR LIMITATIONS

The probability of intrusion is modelled by a "Wisconsin Regression" function that is assumed to be able to fit the projected probability data.

7. TYPICAL RUNNING TIME

Large runs with 500 iterations require approximately 12 s.

8. COMPUTER HARDWARE REQUIREMENTS

Tested on a Cray-XMP/2.

9. COMPUTER SOFTWARE REQUIREMENTS

Cray CTSS operating system, Fortran 77 compiler, CFT.

10. REFERENCE

S. W. Woolfolk, "ACT: A Program for Calculation of the Changes in Radiological Source Terms with Time," WIPP/DOE-85-201 (ARA/TSD 5006-0006) (August 1985).

11. CONTENTS OF CODE PACKAGE

Included are the referenced documents and one (1.2MB) DOS diskette which contains the source code, data libraries, and sample problem input and output.

12. DATE OF ABSTRACT

February 1988.

KEYWORDS: ISOTOPE INVENTORY; RADIOACTIVITY RELEASE; TIME DEPENDENT; WASTE MANAGEMENT