1. NAME AND TITLE
SURF: Conical and Plane Surface Single Scattering Code.
Nuclear Materials and Propulsion Operation, General Electric Company, Cincinnati, Ohio.
3. CODING LANGUAGE AND COMPUTER
FORTRAN IV; IBM 360/75.
4. NATURE OF PROBLEM SOLVED
The code calculates dose rates and flux spectra at unshielded detection points. Radiation at the detection points is composed of direct and once-scattered contributions. The latter component is that scattered from a homogeneous conical shell or slab thin enough so that attenuation and higher order scattering can be neglected. The radiation source can be neutrons or gamma rays. For neutrons, elastic and inelastic scattering is treated. For gamma rays, Klein-Nishina scattering is treated.
Detection points can be located arbitrarily with respect to both the scattering structure and the radiation source. The radiation source can be represented as that escaping from a reactor or shield with an arbitrary energy spectrum. In addition, the source energy range can be divided into three subranges, each governed by a different angular distribution, which the user can arbitrarily specify.
5. METHOD OF SOLUTION
The source distribution is represented in terms of intensities in discrete energy groups and angle intervals. The scattering structure is divided into discrete volume elements. Each volume element contributes to the flux in a certain energy group at a detection point by means of scattering radiation incident on the volume element from a source point. The flux spectrum of scattered radiation at each detection point is then calculated by summing scattering contributions from all volume elements and from all source points. The direct contributions, computed in a straightforward manner, are also added. The dose rate is then computed by multiplying the flux in each energy group by an appropriate conversion factor and summing the results. The user specifies, as input, source point coordinates and intensities for the source energy and angle intervals. Also, the structure configuration and volume element division instructions must be provided.
Neutron elastic scattering is treated as being isotropic in the center-of-mass system, and inelastic scattering is treated as being isotropic in the lab system. The user provides appropriate cross sections. In addition, energy transfer probabilities for inelastic scattering must be provided.
Photon scattering is automatically handled by means of the Compton and Klein-Nishina equations.
6. RESTRICTIONS OR LIMITATIONS
Maximum number of point sources 50
Maximum number of energy groups 30
Maximum number of materials 6
Maximum number of detection points 50
Maximum number of source polar angles for discrete intervals 12
Maximum number of source azimuthal angles for discrete intervals 12
Maximum number of scattering angles for discrete intervals 12
7. TYPICAL RUNNING TIME
Estimated running time of packaged sample problem on the IBM 360/370: 2 minutes.
8. COMPUTER HARDWARE REQUIREMENTS
The code was designed for a 32K GE-625 Computer and was made operable on the IBM 360/75 by RSIC.
9. COMPUTER SOFTWARE REQUIREMENTS
The code is operable on the IBM 360/75 Operating System using OS-360 Fortran H Compiler.
J. E. MacDonald, "Conical and Plane Surface Scattering Program - SURF," GEMP 582 (February 1968).
11. CONTENTS OF CODE PACKAGE
Included are the referenced document and one (1.2MB) DOS diskette which contains the source code and input and output for a sample problem.
12. DATE OF ABSTRACT
May 1969, July 1981.
KEYWORDS: SINGLE SCATTERING; NEUTRON; GAMMA-RAY