The Role of 
Digital Computers 
in Nuclear Design 
High-speed digital computers are essential 
to the modern nuclear reactor designer. 
The many programs coded for nuclear problems 
illuminate questions of application and cost 
By WARD C. SANGREN 
John Jay Hopkins Laboratory for Pure and Applied Science 
General Atomic Division, General Dynamics Corp., San Diego, California 
NEUTRON FLUX plot in two dimensions for Belgian Engineering Test Reactor 
typifies computer use in nuclear design. Central axis of reactor core is at top 
of figure and outer surface of water-shield annulus is at bottom. Top and 
bottom core-support plates are at right and left. Calculation by Nuclear 
Development Corporation of America using Datatron and new R-Z reactor code 
THE USEFULNESS OF digital computers 
for nuclear calculations was appreciated 
early by scientists and engineers con- 
nected with atomic laboratories. In- 
deed, some individuals, such as John 
von Neumann, played major roles in 
the early development of both high- 
speed digital computers and nuclear 
energy. Calculating punch-card ma- 
chines, such as IBM 602, 604, and 
Card-Programmed Calculator, were 
used for reactor calculations in the late 
1940’s. Oak Ridge National Labora- 
tory, Los Alamos Scientific Laboratory, 
and Knolls Atomic Power Laboratory 
can be singled out for their early inter- 
est in such calculations. 
There is little question today that 
nuclear reactor calculations on high- 
speed digital computers are vital, and 
will become more so, in furthering the 
design of nuclear reactors. Computing 
and mathematics groups are becoming 
a more essential part of the scientific or 
engineering installation. The recent 
establishment of these groups as major 
divisions at Brookhaven and Argonne 
National Laboratories emphasizes this 
trend. 
Problems and Codes 
Nuclear reactor calculations that 
have been programmed for digital com- 
puters are already so numerous and 
diverse that classification and catalogu- 
ing of the existing digital codes is not a 
trivial undertaking. In fact today 
this is equivalent to classifying nuclear 
reactors and all the problems involved 
in their design. Among the possible 
classification systems are those based 
upon the particular mathematical or 
numerical technique that is used; the 
number of independent variables, such 
as space dimensions; the aspect of the 
reactor that is being calculated; and the 
scientific or nuclear field from which 
the calculation arose. 
Radkowsky and Brodsky (1) have 
listed and classified the digital machine 
codes used for reactor calculations that 
existed up to October, 1955. In this 
bibliography, reactor codes are classi- 
fied under reactor physics, reactor sur- 
vey, shielding, reactor kinetics, reactor 
burn-out, reactor engineering, or mis- 
cellaneous. The Newsletters of the 
Nuclear Codes Group (2, 3) have con- 
tinued with the classification system of 
Radkowsky and Brodsky. 
The classification below closely fol- 
lows that of Radkowsky and Brodsky. 
A few comments have been added to 
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