ORNL-4191 - the Molten Salt Energy Technologies Web Site

about 500 mm Hg at the test operating temperature
(1200°F), it will be necessary to maintain an over-
pressure of BF3 in the pump bowl vapor space to
avoid a loss of BF3 from the salt with the resultant
increase in salt liquidus temperature. The cover
gas system is being revised to include the neces-
sary equipment for handling and controlling the
EF3. 'This system, shown schematically in Fig.
'7.4, includes some of the features of the cover
gas system used with the MSRE coolant salt, and
the information developed in the test will be useful
in planning the revisions which will be necessary
to prepare for testing of NaBF4 in the MSRE
coolant system.
'The operating conditions for the loop are:
Temperature 1200°F
Flow rate 800 gpm
Pump head 120 ft
Pump speed 1800 rpm
The tendency of BF to induce polymerization of
organic materials could cause problems in the
pump lubrication system and in the off-gas line.
The heliuiii purge to the shaft annulus will be
adjusted to minimize diffusion of BF, into the
pump bearing chamber, and filters are provided
in the off-gas line to protect the pump tank pressure
control valve. The BF3 flow required will be
dictated by the total pump bowl pressure, the
desired BF3 partial pressure, and the required
heliuiii purge flow.
It is planned to operate the loop isothermally
for a period of about six months. The objective
will be to uncover any problems associated with
the circulation of NaBF4 and to devise and test
suitable solutions or corrective measures.
7.4 MSBR PUMPS
A. G. Grindell
P. G. Smith L. V. Wilson
Survey of Pump Experience Circulating Liquid
Metals and MOltell SlaIt5
A survcy of experience with pumps for liquid
metals and molten salt was made, and a report1
'P. G. Smith, Experience with High-Temperature
Centrifugal Punips in Nuclear Reactors arid Their
Application to Molten-Salt Thermal Breeder Reactors,
ORNL-'1'M-1993 (September 1967).
96
was issued relating pump descriptions, operating
hours, and the problems encountered during oper-
ation.
Introduction of MSBW Pump Program
The objectives of the salt pump program for the
MSBR include the production of suitable and reliable
pumps for the fuel, blanket, and coolant salt
circuits of the Molten-Salt Breeder Experiment
(MSRE) and its nonnuclear prototype, the Engineering
Test Unit (ETU). Table 7.2 presents the
pump requirements as they are presently envisioned.
A single conditional objective requires
that the pumps developed for the MSBE should be
capable of flow capacity scale-up by a factor of
approximately 4 to the 550-Mw (thermal) MSBR
with little or no additional development work.
Our approach is to invite the strong participation
of U.S. pump industry in the design, development,
and production of these pumps. We will
prepare pump specifications along with a preliininary
pump assembly drawing, pertinent rotordynamic
and heat transfer analyses, and the results
of a survey of fabrication methods for suhmission
to pump manufacturers. The pump maiiufacturers
would be asked to make an independent
analysis of the pump specifications arid supporting
material and to define all the changes and improvements
they believe necessary. Parenthetically,
it may prove necessary to pay for several
independent analyses. The pump inaiiufacturers
would then be asked to bid on the production of
the detailed pump design and shop drawings, the
fabrication and assembly for shop inspection of
the required quantities of sa1.t pumps, and the
shipment of disassembled pumps to ORNL for
further testing.
Two important implicit requirements are provided
in this approach. The individual pump
configurations are matched to the various MSRE
systems requirements by and at ORNL, and the
responsibility for approval of the final pump design
and the detailed drawings rests with ORNL.
The principal pump components requiring development
effort are the molten-salt bearing, if
used, the shaft seal, and a full-scale rotor-dynamic
simulator, if supercritical operation of a salt pump
is required, that is, operation of the pump at
speeds above the first critical shaft speed. The
pump manufacturers would be invited to participate
in this and other development work they may