ORNL-1771 - Oak Ridge National Laboratory

After irradiation each belt was used in the cold
shakedown test stand to drive a pump rotary ele-
ment at 1600 rpm with no pump load. After 90 hr
of operation, the B-105 belt showed no visible
damage and was returned io ARE personnel. After
75 hr of operation, the 8-103 belt showed no visible
damage and was transferred to the pump in the
reactor component test loop pump to transmit 3 hp
at 800 rprn. This belt, which has naw been in
service for more than 900 hr, has increased in
length approximately 1 in. Failure of the belt
does not appear to be imminent, and pump operation
has not been affected. An idler pulley is used to
maintain tension.
On the basis of these tests, it was decided to
use the cotton-corded, rubber-matrix V-belts on
the fuel and the sodium pumps in the ARE. As an
additional safeguard, the belt on the fuel pump
drive will be shielded with lead.
Radiation Damage to Shaft Seal
W. G. Cobb J. M. Trummel
Aircraft Reactor Engineering Division
W. W. Parkinson
Solid State Division
The rotary subassembly of the ARE pump con-
tains six Buna-N O-ring static seals which will
receive radiation during reactor operation. To get
information on the expected life of these seals,
an O-ring sealing arrangement similar to two of
the pump seals was constructed and was placed in
the LlTR flux. The test assembly included six
radial O-ring seals and three gasket O-ring seals.
One side of the seals was supplied with oil at
75-psig pressure, and the other side was vented to
the reactor off-gas system through bubblers and a
catch tank so that it was possible to detect any
appreciable leakage by the seals. Since the seals
PERIOD ENDING SEPTEMBER 70, 1954
were vented in four groups, it WQS possible to get
some information on variations in seal life. Differ-
ences in the following might produce such vari-
ations: (1) flux density over test assembly,
(2) twisting and rolling of the rings during assembly
for testing, (3) the O-rings, and (4) the machined
parts.
The gamma radiation intensity at the test lo-
cation in the LlTR was estimated by extrapolation
from data taken on the Bulk Shielding Facilitys7
The neutron flux was negligible. The results are
reported in Table 1.2, which gives time of irradi-
ation to first observed leakage and the total esti-
mated dose to first leakage. Examination of the
0-r i ngs after irradiation revealed substantia I
hardening. No appreciable elastic recovery of the
rings occurred upon removal from the container.
The O-rings to be used in the ARE will not be
in sohigh a flux asthat used for these experiments,
and they will be under much lower pressures.
Since it is not essential in the ARE application
that the O-rings retain their resiliency, the results
of these experiments do not have immediate signifi-
cance. It is evident from these tests, however,
that O-rings cannot be used successfully in future
hi g h-power reactor app I i cat i on s,
Motor Test
W. G. Cobb A. 6. Grindell
Aircraft Reactor Engineering Division
A test of an ARE-type d-c motor operating in dry
helium Qt 130 to 14OOF was terminated after 4000
hr of uneventful operation. Examination of the
si Iver-impregnated graphite brushes used during
the test indicated that total wear was limited to
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'1-1. E. Hungerford, The Skyshzne Enperzrnrnts ut the
Bulk Sbzeldzng Reactor, ORNL-1611, p 24 (July 2,
1954).
TABLE 1.2. RESULTS OF RADIATION DAMAGE TESTS OF RUBBER O-RING SEAL5
Two radial ring seals on bottom piston 128
Time to Leakage Dose to Leakage
(hr) (rep)
5 x 108
Two radial ring seals on middle piston 167
6.7 x lo8
One radial ring on top piston 259 1 lo9
Three gasket seal rings 259 1 x 109
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