ORNL-4191 - the Molten Salt Energy Technologies Web Site

800 and 930 rpm and makes it appear advisable to
separate the inner and outer casing frequencies by
suitable changes in the wall thicknesses and
diameters of the two casings.
A preliminary undamped torsional critical-speed
analysis has been made for the pump system, and
the results indicate that the two torsional critical
speeds that might affect pump operation can be
strongly dependent upon the electromagnetic
torsional stiffness of the drive motor. We believe
that by changing some of the component dimensions
and accounting for inherent system damping, the
pump will operate satisfactorily between the first
and second torsional critical speeds.
Fabrication Methods Survey. - Based on the
preliminary layout of the MSBK fuel salt pump, the
shaft and inner and outer casings were detailed,
and a survey is being made of potential fabrication
methods to identify fabrication problems. For the
shaft, it is important to determine the straightness
and concentricity tolerances that can be supplied.
These tolerances have considerable effect on the
provisions that must be made for the dynamic
balancing of the shaft, which must be done rather
precisely when the pump is to operate above the
first shaft critical speed. A manufacturer was
found who could fabricate shafts in the range 7 to
10 in. outside diameter with a wall thickness as
small as '4 in., and who would guarantee the
straightness from end to end to 0.005 total indi-
cator reading (TIR) and the outside diameter-
inside diameter concentricity to 0.005 in., but at
considerable expense. As these two tolerances
are relaxed, more manufacturing capability is
available, and the fabrication costs are reduced;
however, dynamic balancing of the shaft becomes
a more important portion of the fabrication process.
10 1
An investigation is under way to determine the
relationship between shaft precision and total
shaft cost (fabrication plus dynamic balancing) as
well as its effect on pump design.
Several manufacturers have been found who are
capable of fabricating the inner and outer casings
to the tolerances shown on the preliminary layout,
but also at considerable expense. The effects on
pump design of relaxing the preliminary values of
the tolerances are being studied.
Other Molten-Salt Pumps
Fuel Pump High-Temperature Endurance Test
Facility. - The facility,3 including the salt pump,
gas systems, instrumentation, and handling equip-
ment, is being prepared for operation with sodium
fluoroborate (WaBF,). The new drive motor, rated
200 lip at 1800 rpm, was delivered, and the existing
motor support was modified to suit the new motor.
Also, the pump rotary element was retnoved
from the facility, disassembled, cleaned, and
reassembled.
Molten-Salt B'earing Pump Endurance Test
Facility. - A new salt bearing constructed of
Wastelloy N was installed on this pump.4 The
gimbals support for the bearing was modified to
reduce the possibility of the support becoming
disassembled during operation. The bearing and
gimbals arrangement was satisfactorily tested
with oil iis the pumped fluid at room temperature.
3
MSK Program Semiann. Pro&. Rept. Feh. 28, 1967,
ORNL-41 19, p. 66.
'MSR Program Semianti. [Jrogr. f?cpt. ~ u g 31, . 1966,
OHNL-4037, p. 82.