the Molten Salt Energy Technologies Web Site

z
11
t-
o
a
LT
LL
1 .O
0.8
5 0.6
-
r
n
3
0.4
0.2
0
----
PERIOD ENDING DECEMBER 10, 1952
DGG 174:
--BERYLLIUM ---BERYLLIUM I ------.--- I GRAPHITE---
REACTOR RADIUS (in )
Fig. 5.5. Cadmium Fraction (from Indium-Foil Activity) vs. Radial Fraction.
reports,(') consisied of ReO as re-
flector and moderator with a packed
powder mixture of UF,, Zr02, c, and
NaFas fuel. It was first made critical
with a loading of 5.8 kg of U235 con-
tained in 61 of the 70 fuel tubes
available e Subsequent mea suremen ts
showed that adding fuel to the remain-
ing nine tubes would resul t in $2.70
exc'ess reactivity. ($1.00 is the
reactivity change corresponding to the
effective delayed-neutron fraction. )
T t was found, in an attempt to
evaluate the reflecting effect of the
pressure shell, that a cylinder of
("D. Scott, ANP Quar. Prog. Rep. June 10. 1952,
ORNL-1294, p. 38; D. Scott and C. B. Mills, ANP
Quar. Prog. Rep. Sept. 10, 2952, ORNL-1375, p. 43.
mild steel, 4% in. long and 1/4 in.
thick, surrounding the Re0 blocks,
increased the reactivity 34.5 cents.
A second 1/4-in.-thick layer raised
the reactivity an additional 21 cents,
to a t,otal of 55.5 cent,s. The shell
did not extend over the ends of the
reactor.
In another experiment, an evaluation
was made of the reactivity value of a
tube of fuel at various radial positions.
In Fig. 5.7 is shown the increase in
reactivity as a stainless steel tube,
filled with fuel, is placed in a void
at different points along a reactor
radius, .Also shown are the corres-
ponding values resulting from the
53