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ANP PROJECT PROGRESS REPORT
Auxiliary NaK Pump Development Tests
H. C. Young J. G. Teague
M. E. Lackey
Water tests were conducted on the auxiliary NaK
pump (model PK-A). The volute used for these
tests consisted of two brass volute halves bolted
together. The volute flow passage was accurately
milled in each volute half. The test impeller was
fabricated of brass, with vanes silver-soldered to
the hub and soft-soldered to the inlet shroud.
The pump assembly was tested in the test loop
used for the water tests of the primary NaK pump.9
A 60-hp d-c drive motor was used. No changes
were necessary in the instrumentation, except
that a new orifice was installed to measure the
lower flow rates.
Performance and cavitation data were obtained
for as wide a flow range as possible within the
practical limits of volute hydraulic unbalance, and
the final head vs flow curves are presented in
Fig. 1.4.5. A plot of pump shaft horsepower versus
flow for some head and flow conditions is shown in
Fig. 1.486. The volute hydraulic unbalanceoverthe
design range was found to be quite satisfactory,
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450
400
350
300
E 250
0
a
y 200
450
400
50
a
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ORNL-LR-OW644957
0 400 200 300 400 500 600 700 000
FLOW (gpml
Fig. 1.4.5. ART Auxiliary NaK Pump (Model
PK-A) Performance Curves of Head vs Flow Show-
ing Efficiency and Volute Pressure Balance Lines.
54
and therefore this pump will be satisfactory for
use as the special NaK pump for cooling the ART
fuel fill-and-drain tank. This pump requires 300-gpm
flow at a 275-ft head. The impeller diameter, the
dynamic seal vanes, and the top labyrinth seal are
the same as those for the primary NaK pump, and
the speed ranges of both pumps are the same.
Therefore the radial and axial clearances determined
by the primary pump tests were used for the auxiliary
pump. The pump showed satisfactory degassing
characteristics with these clearances.
After the initial performance tests were com-
pleted, a 0.023-in. spacer was installed between
the volute halves, and tests were conducted to
determine whether the addition of the spacer would
change the volute hydraulic unbalance. The pur-
pose of these tests was to ascertain the allowable
tolerances for use in welding the Inconel volute
halves together.
The volute hydraulic unbalance was measured
during these tests by eight static pressure taps
equally spaced in the volute near the periphery of
the impeller. The static pressure readings at any
of the eight taps, for a given discharge head and a
set flow rate, did not change over 1 psi from the
measurements taken without the spacer.
In general, the water tests indicate that the pump
will meet the head and flow conditions required for
use in the ART, both for the auxiliary and the
special NaK pumps, The design conditions are in
the range of minimum volute hydraulic unbalance.
Cavitation characteristics of the pump, based on
extrapolations from water to NaK, indicate that a
pump tank gas pressure of 14.4 psia, or -0.3 psig,
should be sufficient to suppress cavitation at
design flow for a NaK temperature of 1282OF, as
compared with a required pressure of 6 psig for the
primary NaK pump at the same NaK temperature.
Primary and Auxiliary NaK Pump lest Stands
H. C. Young J. G. Teague
Fabrication of all parts for two primary and two
auxiliary NaK pump high-temperature test loops is
under way. At present, the pump volutes are the
most critical delivery item. A method of profile-
machining the volute halves from a pattern is being
used. Several primary pump volute halves have
been received, and the vendor is now setting up for
profile-machining of the first auxiliary pump volute
halves.
A series of welding tests were conducted to
determine the joint preparation and the welding
w
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