1. NAME AND TITLE

AMC: Monte Carlo Albedo Code for Neutron and Capture Gamma-Ray Distributions in Rectangular Concrete Ducts.

2. CONTRIBUTOR

Engineering Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee.

3. CODING LANGUAGE AND COMPUTER

FORTRAN IV and MAP; IBM 360/75/91.

4. NATURE OF PROBLEM SOLVED

AMC calculates neutron and associated capture gamma-ray transmission through concrete-walled rectangular ducts of varying complexity to establish design criteria for entryway shielding against initial weapons radiation.

5. METHOD OF SOLUTION

AMC can be used to calculate the fluxes and dose rates inside large rectangular ducts constructed of concrete walls and arising from neutrons of all energies incident upon the duct mouth. An option in the code allows a simultaneous calculation of the secondary gamma-ray dose rates arising from wall capture as well. The code treats duct transmission by employing the albedo concept in conjunction with a Monte Carlo treatment of history generation.

In its present form the code can calculate the fast-neutron dose rates, epicadmium differential energy fluxes, thermal fluxes, and wall-capture secondary gamma-ray dose rates arising from an arbitrary incident neutron source for the following concrete-walled rectangular structures:

a. a completely enclosed room,

b. an open straight duct or a straight duct closed at one end,

c. an open or closed two-legged duct with one right-angled bend,

d. an open or closed three-legged duct with two right-angled bends,

e. a three-legged duct open or closed at the mouth, but opening into a room at the end of the third leg, with two right-angled bends,

f. any of geometries c through e above with the first leg sloping downward, the mouth and the remaining legs being horizontal.

In geometries a through e the mouth is vertical and the legs horizontal.

6. RESTRICTIONS OR LIMITATIONS

The structure considered must have dimensions of a foot or greater, a limitation imposed by the albedo model.

The present description is limited to six distinct types of rectangular duct geometries but includes ducts having up to three legs with two right-angle bends.

7. TYPICAL RUNNING TIME

Estimated running time for packaged sample problem: 10 minutes.

8. COMPUTER HARDWARE REQUIREMENTS

The code was designed for the IBM 360/75/91 with standard I-O and one tape unit.

9. COMPUTER SOFTWARE REQUIREMENTS

The code is written in FORTRAN IV with the exception of two function subprograms written in MAP. It is operable on the IBM 360/75/91 Operating System using OS-360 Fortran H Compiler.

A file of epicadmium data or fast-neutron data is input on logical 3 or 4 respectively, according to value of the mode-determining option.

10. REFERENCE

R. E. Maerker and V. R. Cain, "AMC: A Monte Carlo Code Utilizing the Albedo Approach for Calculating Neutron and Capture Gamma-Ray Distributions in Rectangular Concrete Ducts," ORNL-3964 (August 1967).

11. CONTENTS OF CODE PACKAGE

Included are the referenced document and one (1.2MB) DOS diskette which contains two libraries of data, the source codes, and input and output for two sample problems.

12. DATE OF ABSTRACT

May 1969; updated July 1981.