ORNL-1771 - Oak Ridge National Laboratory

1. CIRCULAT1NGFUEL AIRCRAFT REACTOR EXPERIMENT
THE EXPERIMENTAL REACTOR SYSTEM
A general revision was found to be necessary
in the ARE in that shadow shielding had to be
installed, at several points where elastomers were
used (belts, diaphragms, etc.),to provide protection
from gamma fields that would have produced pro-
hibitive degrees of radiation damage. At some
points, where shielding was impractical, the compo-
sition diaphragms were replaced by metal dia-
phragms.
The entire ARE system has now been completely
checked out as far as room-temperature preoper-
ational tests are concerned. Both the fuel and the
sodium circuits have been operated simultaneously
with water as the circulated liquid in each circuit.
The moderator volume of the reactor was bypassed
for these tests to keep water away from the be-
ryllium oxide blocks.
The sodium circuit was pressure-filled with
water from the sodium fill tanks, while the fuel
system was vacuum-filled to ensure the elimination
of gas pockets in the fuel system. 90th systems
were found to function quite satisfactorily, and the
filling, circulating, and draining operations were
effected with a lrinimum of difficulty,
During these operational shakedown tests, it was
found that the gas lines to the sump tanks could
not be kept pressure tight because the Swagelok
fittings developed leaks. All these joints have
therefore been silver-soldered to correct this
situation. The pumps performed satisfactorily,
and useful system curves for actual future operation
were obtained.
After the water tests of the system had been
completed, it was necessary to remove all water
from the system. This necessitated heating the
entire system to a temperature of approximately
600°F. This operation provided the first check out
of the electrical heating system. Here again the
performance was gratifying. Such troubles as
arose were corrected rather easily, and, in general,
the heating of the system was effected with very
little difficulty.
A CO, cold trap was incorporated in the off-gas
line while the system was being heated to collect
all moisture that was driven from the system. Dry
E. S. Bettis J. L. Meem
Aircraft Reactor Engi fieeri ng Division
air was admitted to the fill tanks, and both the
fuel and the sodium systems were flushed with
this dry air, the air leaving the system through the
CO, cold trap. When the dew point of the exit air
from this cold trap reached -3OoF, the system was
considered to be dry and the electrical heat was
turned off.
Before the heat was removed from the system,
however, the temperature on the thermal barrier
doors around the heat exchangers was raised to
approximately 1000°F and operation of the doors
was checked. Even though the doors had been
reworked to eliminate sticking, it was found that.
the doors were still binding. When the barrier
doors were removed, it could be seen that the side
guides whichrun the height of the door were binding
in the guide ways of the door frames. This binding
was resulting from the bowing of the guide rails
caused by the thermal gradient which exists in the
door. The door does not require these side guides,
since the door housing provides ample guides for
the normal functioning of the doors. Therefore the
side guide rails are being removed so that there
will be no further binding of the barrier doors.
It was also noted while the system was hot that a
considerable volume of kerosene was being driven
out of the beryllium oxide moderator blocks by the
high temperature. The kerosene had been absorbed
by the blocks during the cutting operations. To
remove the kerosene, a vacuum was pulled on the
moderator volume of the reactor. A CQ, cold trap
was inserted in the vacuum line to the moderator,
and while the reactor was maintained at a temper-
ature of approximately 45OoF, the vacuum pump was
run continuously. This operation wa5 continued
until no more condensate of the kerosenedistillation
was being collected in the cold trap. Approxi-
matesy 2 gal of kerosene was removed by this
procedure. It is possible - in fact, fairly certain -
that some residue was left in the moderator blocks.
It was the consensus of the chemists that this
would not have an adverse effect on the sodium
codant, and therefore nothing further is to be done
amount of tarry residue remaining
in the reactor moderator blocks,
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