1. NAME AND TITLE

HARAD: Calculation of Daughter Concentrations in Air Following the Atmospheric Release of a Parent Radionuclide.

2. CONTRIBUTOR

Oak Ridge National Laboratory, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER

Fortran IV; IBM 360/370/3033.

4. NATURE OF PROBLEM SOLVED

HARAD calculates concentrations of radioactive daughters in air following the atmospheric release of a parent radionuclide under a variety of meteorological conditions. It can be applied most profitably to the assessment of doses to man from the noble gases such as ²²²Rn, ²²⁰Rn, and Xe and Kr isotopes. These gases can produce significant quantities of short-lived particulate daughters in an airborne plume, which are the major contributors to dose from these chains with gaseous parent radionuclides.

5. METHOD OF SOLUTION

The simultaneous processes of radioactive decay, buildup, and environmental losses through wet and dry deposition on ground surfaces are calculated for a daughter chain in an airborne plume as it is dispersed downwind from a point of release of a parent. The program employs exact solutions of the differential equations describing the above processes over successive discrete segments of downwind distance. Average values for the dry deposition coefficients of the chain members over each of these distance segments are treated as constants in the equations.

HARAD can be used as a subroutine in other code systems such as CCC-357/AIRDOS-EPA which is designed to estimate the radiological impact of atmospheric releases of radionuclides.

6. RESTRICTIONS OR LIMITATIONS

None noted.

7. TYPICAL RUNNING TIME

The sample problem executes in 45 seconds on the IBM 360/91. Typical ²²²Rn calculations require only 0.12 second on the IBM 370/3033.

8. COMPUTER HARDWARE REQUIREMENTS

HARAD is operable on the IBM 360/370/3033 computers. 44 K of core storage is required.

9. COMPUTER SOFTWARE REQUIREMENTS

A Fortran H compiler is required.

10. REFERENCE

R. E. Moore, "HARAD: A Computer Code for Calculating Daughter Concentrations in Air Following the Atmospheric Release of a Parent Radionuclide," ORNL-5634 (May 1980).

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 and output.

12. DATE OF ABSTRACT

February 1982; revised February 1983.