Computer program calculates neutron or gamma ray first order scattering from a plane or cylindrical surface to a detector point. The SAP Codes, G-SAP and N-SAP, constitute a multiple scatter albedo model shield analysis

Sapovchak, B. J.

Stephenson, L. D.

English

NASA Technical Reports Server

December 1967	 Brief 67-10536 
•	
.AEC-NASA TECH BRIEF 
TH
AEC-NASA Tech Briefs describe innovations resulting from the research and development program 
of the U.S. AEC or from AEC-NASA interagency efforts. They are issued to encourage commercial 
application. Tech Briefs are published by NASA and may be purchased, at 15 cents each, from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
N-SAP and G-SAP Neutron and Gamma Ray Albedo Model

Scatter Shield Analysis Program 
The problem: 
To devise a computer program to calculate neutron 
or gamma ray first order scattering from a plane or 
cylindrical surface to a detector point. Previously, 
calculations of scattered radiation required tedious 
and time consuming hand calculations. Also, inclusion 
of an opaque shielding plane by hand calculation was 
an almost impossible task involving the construction 
of a physical three-dimensional model. 
The solution: 
The SAP Codes, G-SAP and N-SAP, which con-
stitute a multiple scatter albedoo, model shield analysis. 
How it's done: 
Fast neutron scattering is calculated in the N-SAP 
Code by the use of a formula for concrete scattering 
developed by French and Wells. Optionally a fast 
neutron (E 2.0 Mev) scattering model developed for 
water may be used. The gamma ray scattering form'ormula 
used in the G-SAP Code is of thè form shown by 
T. Rockwell. Semi-opaque or completely opaque ef-
fectiveness of from 0 to 100 percent may be included 
to approximate shielding encountered by the reflected 
radiation. Scattering surfaces may be plane or cylin-
drical. 
Two operations must be performed to provide input 
data to the program: (1) subdivide the scattering 
region into incremental scattering areas, and (2) 
determine either by experimental or analytical means, 
the neutron or gamma dose rate incident on each of 
these incremental scattering areas. 
Using the input values of the incident dose rate, 
coordinates and areas associated with the incremental 
scattering areas, coordinates of the effective point 
source and receiver points, and energy dependent 
albedo terms, the program calculates the scattered 
This document was prepared under the sponsorship of the Atomic 
Energy Commission and/or the National Aeronautics and Space 
Administration. Neither the United States Government nor any per-
son acting on behalf of the United States Government assumes any
dose from all incremental scattering areas at a re-
ceiver point. If the straight line segment between 
an incremental scattering area and a receiver point 
intersects one or more semi-opaque surfaces, the dose 
is reduced by the reduction factors assigned to the 
surfaces intersected. 
Notes: 
1. Additional information may be found in: 
(a) R. L. French and M. B. Wells, An Angle De-
pendent Albedo for Fast Neutron Reflection 
Calculations, Nuclear Science and Engineering, 
19,441 (1964). 
(b) T. Rockwell, Reactor Shielding Design Manual, 
D. Von Nostrand, Princeton (1956), page 335. 
2. This program is written in Fortran IV for use on 
the IBM 7094 computer. 
3. The analysis may be useful in the study of sta-
tionary commercial nuclear power plants, isotopic 
x-ray sources as applied in medical diagnosis, 
"shielding window" designs for remote handling 
facilities, and fallout shelter designs. 
4. Inquiries concerning this program may be made 
to:	 COSMIC 
Computer Center 
University of Georgia 
Athens, Georgia 30601 
Patent status:	 Reference: B67-10536 
No patent action is contemplated by AEC or 
NASA.
Source: L. D. Stephenson and B. J. Sappvchak 
of Westinghouse Astronuclear Laboratory 
under contract to

AEC—NASA Space Nuclear Propulsion Office 
(NUC-10126)
Cateorv 06 
liability resulting from the use of the information contained in this 
document, or warrants that the use of any information, apparatus, 
method, or process disclosed in this document may not infringe pri-
vately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19670000535 2020-03-11T21:00:22+00:00Z


N-SAP and G-SAP neutron and gamma ray albedo model scatter shield analysis program

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