CCC-0179 ATR.

1. NAME OR DESIGNATION OF PROGRAM:  ATR.
Models of Radiation Transport in Air.

3. DESCRIPTION OF PROBLEM OR FUNCTION

ATR is a user-oriented code for calculating quickly and simply radiation environment problems at all altitudes in the atmosphere. The code is based on parametric models  of a comprehensive data base of air transport results which were generated using discrete ordinates transport techniques for infinite homogeneous air. The effects of air-ground interface and non-uniform air density are treated as perturbation corrections on homogeneous air results. ATR includes parametric models for neutrons and secondary gamma rays as a function of space, energy and source- target angle out to angles of 550 g/cm2 of air.
ATR contains parameterizations of infinite medium air transport of neutrons and secondary gamma rays and correction factors for the air-ground interface and high altitude exponential air. It responds  to a series of user-oriented commands which specify the source, geometry and print options to output a variety of useful air transport information, including energy-angle dependent fluence, dose, current, and isodose ranges.

4. METHOD OF SOLUTION

The version 3 differs from earlier versions in  that version 3 contains the parameterization of the new neutron and  secondary gamma rays data base that was calculated using the latest  DNA approved cross sections for air. Other improvements to the ATR code include: parameterization and inclusion into ATR of new air- over-ground correction factors, low energy x-rays calculations, new  fission source, and new convenience options.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

ATR takes approximately 36,000 decimal words of storage. This can be lessened  by overlaying different parts of the code.

6. TYPICAL RUNNING TIME

Typical running time on the UNIVAC 1108 is on the order of seconds where a problem is defined as a typical response calculation starting with the specification of an energy dependent source and complete source-target geometry configuration.  The sample problem ran 2 minutes on the IBM 360/91 and 20 sec on the IBM 370/195.

7. UNUSUAL FEATURES OF THE PROGRAM:

8. RELATED AND AUXILIARY PROGRAMS:

10. REFERENCES:

- "Version 3 of Air Transport of Radiation (ATR)"
  DNA 3819F (July 1975).
- L. Huszar, L.J. Nesseler, W.A. Woolson:
  "User's Guide to Version 2 of ATR (Air Transport of Radiation)"
  DNA 3144Z (April 1973).
- R.J. Harris, Jr., J.A. Lonergan, L. Huszar:
  "Models of Radiation Transport in Air - The ATR Code"
  DNA 28031 (May 1972).

11. MACHINE REQUIREMENTS

ATR is fully self contained and machine independent. It required 32K decimal storage on the UNIVAC 1108. It  requires no auxiliary storage and uses standard channel configuration on IBM 370 330k bytes of core memory are required.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED

All routines are in FORTRAN IV and independent of machine. No special operating system or machine dependent routines are required.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:

15. NAME AND ESTABLISHMENT OF AUTHOR:
Science Applications, Inc,
La Jolla, California

File name	File description	Records
CCC0179_01.001	ATR SOURCE (F4)	9411
CCC0179_01.002	ATR SAMPLE PROBLEM INPUT	67
CCC0179_01.003	ATR SAMPLE PROBLEM OUTPUT	512
CCC0179_01.004	JCL	52