1. NAME AND TITLE

PLACID: Monte Carlo Simulation of Gamma Streaming Through Straight Cylindrical Ducts.

2. CONTRIBUTOR

Reactor Research Centre, Kalpakkam, Tamil Nadu, India.

3. CODING LANGUAGE AND COMPUTER

Fortran IV and Assembler language; IBM 370 and 3033.

4. NATURE OF PROBLEM SOLVED

PLACID simulates gamma streaming through straight cylindrical ducts in shields using the Monte Carlo Method.

5. METHOD OF SOLUTION

Monte Carlo simulation is employed with variance reduction devices such as Russian Roulette and cutoff weight for history termination. Photon point total cross sections are used. Klein Nishina formulae are used for differential scattering cross section. The Kahn double rejection technique is used for sampling the scattered photon energy and the scattering angle. Next event estimation is used for scoring the streaming flux.

6. RESTRICTIONS OR LIMITATIONS

Only straight cylindrical ducts in shields are simulated.

7. TYPICAL RUNNING TIME

Simulation of Cs-137 photon streaming through a cylindrical duct of 100 cm length and 5 cm radius takes 76 milliseconds per history. About 6400 histories give the total dose at the duct exit within a 10% statistical error. The sample problem included in the package required 63.93 cpu seconds to compile and execute on the IBM 3033 computer.

8. COMPUTER HARDWARE REQUIREMENTS

PLACID was developed on the IBM 370/55-II computer and modified to run on the IBM 3033 computer.

9. COMPUTER SOFTWARE REQUIREMENTS

The IBM 370 computer on which PLACID was developed runs IBM OS/VS and the IBM 3033 used for testing runs IBM OS/VS2. At RSIC, PLACID was compiled using the IBM Fortran H Extended Enhanced compiler.

10. REFERENCE

R. Indira and K. P. N. Murthy, "Monte Carlo Simulation of Gamma Streaming Through Straight Cylindrical Ducts," FRG/01100/RP-219 (January 1982).

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

March 1984.