SOC-DS Code /Shield Optimization Code-Direc Search/, selects a nuclear shield material of optimum volume, weight, or cost to meet the requirments of a given radiation dose rate or energy transmission constraint. It is applicable to evaluating neutron and gamma ray shields for all nuclear reactors

Disney, R. K.

Ricks, L. O.

English

NASA Technical Reports Server

December 1967
	
Brief 67-10537 
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AEC-NASA TECH BRIEF 
rES
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. 
SOC-DS Computer Code Provides Tool for Design Evaluation of Homogeneous
Two-Material Nuclear Shield 
The problem: 
To develop a simple and inexpensive method to se-
lect a nuclear shield material of optimum volume, 
weight, or cost to meet the requirements of a given 
radiation dose rate or energy transmission constraint. 
Selection of shield materials previously required 
costly computer runs, using transport, point kernel, or 
other applicable codes. Plotting and data reduction 
from such codes were tedious and time consuming 
operations. 
The solution: 
The SOC-DS Code (Shield Optimization Code—
Direct Search), which is applicable to evaluating 
neutron and gamma ray shields for fixed station, 
mobile, or space reactors. 
How it's done: 
A shielding-materials comparison and optimization 
method has been developed which determines the 
amount or thickness of any two materials that will 
result in a minimum shield weight, volume, or cost. 
The method has been automated in the SOC-DS that 
provides an economical survey tool for finding the 
optimum volume fraction for minimum we vol-
ume, or cost for a homogeneous two-material shield 
to meet a given radiation dose rate or energy trans-
mission constraint. The code considers the attenua-
tion of fast and thermal neutrons and gamma rays 
incident on the shield as well as leakage of neutrons 
slowed down and secondary gamma rays produced in 
the shield. 
The radiation attenuation model is basically ex-
ponential for the incident neutrons and gamma rays 
with a simplified age approximation for determining
the slowed-down neutron component. Secondary 
gamma rays produced in the shield by incident ther-
mal and slowed-down neutrons are treated in two 
groups. The optimization method employed is an 
alternating pattern and exploratory search routine 
which contains simple acceleration and deceleration 
parameters for performing search moves. 
The optimization code finds the optimum volume 
fractions for minimum weight of a homogenized 
mixture of neutron and gamma ray shielding mate-
rials. The code may be constrained in emergent dose 
rate, energy, or volume fraction and will find a mini-
mum mass, volume, or material cost to satisfy the 
constraint. If both dose rates and volume fraction 
are constrained, the code will find the required 
thickness or volume. This output may be automati-
cally plotted as well as printed. 
This method has been used to compare over 50 
combinations of shielding materials as an aid in se-
lecting lightweight shields for detail evaluation. When 
compared to more rigorous neutron and photon S 
transport analysis, which included a coupled routine 
for generating secondary gamma ray sources, SOC-DS 
(I) correctly predicted the order of the various ma-
terials when arranged by weight for a given attenua-
tion and (2) found the optimum volume fraction of 
the two materials. These computations generally re-
sulted in a conservative (overestimated) shield 
thickness. 
Some of the important features of the method are: 
1. consideration of shield secondary gamma rays, 
2. consideration of neutron slowing down in the 
shield, 
3. allowance to adjust for potential energy release 
of neutrons escaping the shield, 
An(continued overleaf) 
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
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=19670000536 2020-03-11T21:00:29+00:00Z
4. plot of data for evaluation of off-optimum 
volume fractions, and 
5. very little computer time. 
NOtes: 
1. This program is written in Fortran IV and MAP 
for use on the IBM 7094 computer. 
2. Inquiries concerning this program may be made 
to:
COSMIC 
Computer Center 
University of Georgia 
Athens, Georgia 30601 
Reference: B67-10537
Patent status: 
No patent action is contemplated by AEC or 
NASA.
Source: L. 0. Ricks and R. K. Disney 
of Westinghouse Astronuclear Laboratory
under contract to

AEC—NASA Space Nuclear Propulsion Office 
(NUC-10142) 
Brief 67-10537	 Category 06


SOC-DS computer code provides tool for design evaluation of homogeneous two-material nuclear shield

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