ORNL-2106 - the Molten Salt Energy Technologies Web Site

ANP PROJECT PROGRESS REPORT
2.0 to-'
4.8
4.6 x 40-'
4.4 x
I
{ t.zX4o-7
Q
(3
z
% 4.0 x 40-'
w I
5
a
I
a
I 8.0 x 4 6 '
I
a W
6.0 x 4 6 '
4.0 x 4 6 '
2.0 x 40-8
a 0 2
DISTANCE FROM REACTOR AXIS (in.)
ecmu-
ORNL-LR-DWG 14448
Fig. 4.4.1. Radial Distribution of Gamma-Ray Heating in the Compact-Cae ReflectorModemted-
Reactor Critical Assembly.
Fast-Neutron Leakage
Relative measurements of the fast-neutron leak-
age at points on the outer surface of the reflector
were made with a Hornyak button, 2 in. in diameter
and in. thick, mounted on a Du Mont 6292 photo-
multiplier tube. The button had the same compo-
sition, 0.15 g of powdered ZnS in 1.0 g of Lucite,
as a similar button described by Hornyak.' By
proper choice of a discriminator bias it was
possible to detect neutrons with energies above
7W. F. Hornyak, Rev, Sci. Instr. 23, 264 (1952).
256
0.5 MeV against the gamma-ray background of the
reactor.
A polar plot of the fast-neutron leakage distribu-
tion observed in a longitudinal traverse over the
top of one end of the reactor is presented in
Fig. 4.4.3. The observed counting rates, nor-
malized to the counting rate at point 19, near the
axis of the assembly, have been plotted on the
polar radii drawn through points on the reflector
surface where measurements were made. For this
traverse, the reflector thickness was approximately
11 Y2 in., and the top layer of beryllium was 28%
22
w .
.
c