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Proceedings ArticleDOI

Performance of an Annular Linear Induction Pump with Applications to Space Nuclear Power Systems

About: The article was published on 2010-07-25 and is currently open access. It has received 1 citations till now. The article focuses on the topics: Nuclear power & Space (mathematics).

Summary (2 min read)

I. Introduction

  • F ISSION surface power (FSP) systems could be used to provide power on the surface of the Moon, Mars, or other planets and moons of their solar system.
  • Fission-based systems also offer the potential for outposts, crew, and science instruments to operate in a power-rich environment.
  • The major effort in the FSP technology project has been focused on a reference mission and concept.
  • An annular linear induction pump (ALIP) is used to pump the liquid-metal coolant in the system.
  • Electromagnetic pumps do not contain moving parts that can mechanically wear over the lifetime of the reactor system.

II. Experimental Apparatus and Test Setup

  • The ATC apparatus, shown schematically and photographically in Fig. 1 , was fabricated to allow for performance testing of liquid-metal induction pumps.
  • The present test circuit consists of the ALIP, an induction heater, a throttling valve, an electromagnetic flowmeter, and a gaseous nitrogen-(GN 2 -) to-NaK heat exchanger.
  • A large pipe size (3-in, schedule 10, stainless steel) was employed to minimize the viscous flow losses throughout the loop.

A. Annular Linear Induction Pump

  • The design and development of the ALIP was performed by Idaho National Laboratory (INL) and is discussed in a companion report.
  • This magnetic wave induces currents in the liquid metal, which subsequently interact with the magnetic field to produce a Lorentz body force on the fluid, pushing it through the system.
  • In the present experiment, an Allen Bradley PowerFlex 400 variable frequency drive (VFD) with a sine wave filter was employed to set the frequency of the power delivered to the pump to an arbitrary value from zero to 60 Hz.
  • The VFD employs pulse width modulation (using a 4-kHz carrier wave frequency) to produce an approximately sinusoidal current at these arbitrary frequency levels.
  • By adjusting the variac, the voltage and commensurate power to the pump could be controlled to an arbitrary level.

B. Addtional Test Circuit Hardware

  • An in-house custom designed valve was used to control the flow impedance in the system.
  • A gate valve design was selected to produce the smallest pressure drop across the valve, making use of a welded bellows to provide actuation and hermetic sealing of the valve.
  • The high-temperature NaK required stainless steel (SS) or similar materials for all wetted surfaces.
  • The NaK was heated using the radio frequency (RF) inductive heater coil shown in figure 8 .
  • A gas-to-NaK counterflow concentric tube heat exchanger was used to provide cooling and temperature control for the loop.

C. Instumentation

  • The pressure transducers are manufactured by Delta Metrics, Worthington, OH.
  • The transducer P-01 measures the absolute pressure of the NaK upstream of the ALIP, while the transducer P-02 performs the same measurement downstream of the ALIP.
  • An electromagnetic (EM) flowmeter was used to measure the volumetric flow rate of NaK in the system.
  • It consisted of two neodymium-iron-boron magnets opposing each other on opposite sides of the pipe containing the flowing NaK.
  • The apparatus was calibrated to provide a data correction factor at low power that was dependent on the frequency of the three-phase power fed to the pump.

III. Pump Performance Measurements

  • Presented in this section are performance measurements obtained during the course of testing.
  • The Cu coil windings were thicker than expected, so fewer coil turns were possible, leading to a magnetic field strength at a given applied current level that was lower than the design value.
  • The data presented in Fig. 2a,b were analyzed and are presented as pump performance curves in Fig. 2c,d .
  • Data are plotted in Fig. 4 showing efficiency contours as a function of real power and flow rate at constant temperature.
  • As expected, the data obtained while operating at 60 Hz exhibit significantly lower performance than the other data sets.

IV. Electromagnetic Field Mapping

  • A custom-fabricated, two-axis Hall probe was used to map the time-varying magnetic field inside the ALIP annular flow channel.
  • The magnetic field plots have been accurately scaled to the ALIP drawing shown at the top of the figure, providing full spatial and temporal representation of the field variation throughout the course of one cycle of the phase current.
  • When installed in the ATC, the NaK flow through the pump is right to left , indicating that wires for two of the phases were swapped when performing the field mapping exercise.
  • It was found during testing that the phase current was not equal in all three phases of the pump, which seems to manifest in the difference in peak value of B r at the different locations of the pump during the course of a cycle.

V. Conclusions

  • A dedicated test apparatus, the ATC, was fabricated expressly for this purpose.
  • The results of the testing lead to the following conclusions: .
  • The test setup was well suited to quantifying the performance of the ALIP, allowing for accurate measurement of the various pump input parameters and resulting in narrow, well-defined uncertainties on the data set.
  • The pump was fed at 60 Hz using both the VFD and ac power drawn straight from the electrical grid.
  • The maximum efficiency measured during testing was slightly greater than 6%. Efficiency decreased as the temperature in the loop increased.

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American Institute of Aeronautics and Astronautics
PerformanceofanAnnularLinearInductionPumpwithApplications
toSpaceNuclearPowerSystems
Kurt A. Polzin
*
, Michael Schoenfeld, J. Boise Pearson, Kenneth Webster, Thomas Godfroy
NASA-Marshall Space Flight Center, Huntsville, AL 35812
Harold E. Adkins, Jr.
Pacific Northwest National Laboratory, Richland, WA 99352
James E. Werner
Idaho National Laboratory, Idaho Falls, ID 83415
The Early Flight Fission – Test Facility (EFF-TF) was established by the Marshall Space Flight Center to provide a
capability for performing hardware-directed activities to support multiple in-space nuclear reactor concepts by using
a non-nuclear test methodology. [1,2] This includes fabrication and testing at both the module/component level and
near prototypic reactor configurations. The EFF-TF is currently supporting an effort to develop an affordable fission
surface power (AFSP) system that could be deployed on the Lunar surface. [3] The AFSP system is presently based
on a pumped liquid metal-cooled (Sodium-Potassium eutectic, NaK-78) reactor design. [4,5] This design was
derived from the only fission system that the United States has deployed for space operation, the Systems for
Nuclear Auxiliary Power (SNAP) 10A reactor, which was launched in 1965. [6]
An important component for this system is the pump that drives the liquid metal through the system. In the present
AFSP system, that pump is an annular linear induction pump (ALIP). The pump duct has no moving parts and no
direct electrical connections to the liquid metal containing components. Pressure is developed by the interaction of
the magnetic field produced by the stator and the current which flows as a result of the voltage induced in the liquid
metal contained in the pump duct. Flow may be controlled by variation of the voltage supplied to the pump
windings. Three-phase power is provided to the pump through an electrical power system that uses pulse-width
modulation to produce current waveforms at an arbitrary frequency, with the overall phase-to-phase voltage on the
pump set by a variac on the modulated output of the power system.
A NaK flow loop (see Fig. 1) has been fabricated to allow for testing of this pump and others like it, allowing for the
development of pump performance curves over a variety of flow conditions. The loop consists of the ALIP, a
variable throttling orifice, a flow meter, an induction heater, and a NaK-to-gas heat exchanger. The temperature is
varied using the heater and heat exchanger, and the flow is controlled by adjusting the amount of power provided to
the pump and the flow restriction introduced by the throttling orifice.
Under steady-state conditions, pump performance is measured for flow rates from 0.5 – 4.3 kg/s. The pressure rise
developed by the pump to support these flow rates is roughly 5 – 65 kPa. The RMS input voltage (phase-to-phase
voltage) ranges from 5 – 120 V, while the frequency can be varied arbitrarily up to 60 Hz. Performance is
quantified at different loop temperature levels from 50 C up to 650 C, which is the peak operating temperature of the
proposed AFSP reactor. The transient response of the pump is also evaluated to determine its behavior during start-
up and shut-down procedures.

*
Propulsion Research Engineer, Propulsion Research and Technology Applications Branch, Propulsion Systems Department.
SeniorMemberAIAA.
MaximumTechnologyCorporation,Huntsville,AL,35814.

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American Institute of Aeronautics and Astronautics
REFERENCES
[1] T.J. Godfroy, M. Van Dyke, and R. Dickens, “Realistic Development and Testing of Fission Systems at a Non-
Nuclear Testing Facility,” Space Technologies and Applications International Forum (STAIF-2000), AIP,
504:1208 (2000).
[2] M. Van Dyke, T.J. Godfroy, M. Houts, et al., “Results of a First Generation Least Expensive Approach to
Fission Module Tests: Non-Nuclear Testing of a Fission System,” Space Technologies and Applications
International Forum (STAIF-2000), AIP, 504:1211 (2000).
[3] M. Houts, S. Gaddis, R. Porter, et al., “Options for Affordable Fission Surface Power Systems,” Proceedings of
the 2006 International Congress on Advances in Power Plants (ICAPP), ANS, paper 6370 (2006).
[4] D.D. Dixon, M. Hiatt, D.I. Poston, et al., “Design of a 25-kWe Surface Reactor System Based on SNAP
Reactor Technologies,” Space Technology and Applications International Forum (STAIF-2006), AIP, 813:932
(2006).
[5] D.I. Poston, R.J. Kapernick, D.D. Dixon, et al., “Reference Reactor Module for the Affordable Fission Surface
Power System,” Space Technology and Applications International Forum (STAIF-2008), AIP, 969:277 (2008).
[6] J.A. Angelo and D. Buden, Space Nuclear Power, Orbit Book Company, Malabar, FL (1985).
Fig. 1: Rendering showing the components in the flow loop. NaK flow through the loop is clockwise.

Performance of an Annular Linear Induction Pump with
Applications to Space Nuclear Power Systems
Kurt A. Polzin
, Michael Schoenfeld, J. Boise Pearson,
Kenneth Webster, Thomas Godfroy
, and John Bossard
NASA-Marshall Space Flight Center, Huntsville, AL 35812
Harold E. Adkins, Jr.
Pacific Northwest National Laboratory, Richland, WA 99352
James E. Werner
Idaho National Laboratory, Idaho Falls, ID 83415
Results of performance testing of an annular linear induction pump are presented. The pump electromag-
netically pumpsliquid metal through a circuit specially designed to allow for quantification of the performance.
Testing was conducted over a range of conditions, including frequencies of 33, 36, 39, and 60 Hz, liquid metal
temperatures from 125 to 525
C, and input voltages from 5 to 120 V. Pump performance spanned a range of
flow rates from roughly 0.16 to 5.7 L/s (2.5 to 90 gpm), and pressure head <1to90kPa(<0.145 to 13 psi). The
maximum efficiency measured during testing was slightly greater than6%. The efficiency was fairly insensitive
to input frequency from 33 to 39 Hz, and was markedly lower at 60 Hz. In addition, the efficiency decreased
as the NaK temperature was raised. The performance of the pump operating on a variable frequency drive
providing 60 Hz power compared favorably with the same pump operating on 60 Hz power drawn directly
from the electrical grid.
Nomenclature
B
r
radial magnetic field , T p change in pressure, Pa
B
z
axial magnetic field , T V signal voltage, V
b calibration constant, L/s ˙v volumetric flow rate, L/s
m calibration constant, (L/s)/mV η efficiency, %
P
IN
pump input power, W
I. Introduction
F
ISSION surface power (FSP) systems could be used to provide power on the surface of the Moon, Mars, or other
planets and moons of our solar system. Fission power systems could provide excellentperformance at any location,
including those near the poles or other permanently shaded regions, and offer the capability to provide on-demand
power at any time, even at long distances from the Sun. Fission-based systems also offer the potential for outposts,
crew, and science instruments to operate in a power-rich environment.
Under the NASA Exploration Technology Development program, NASA and the Department of Energy have
begun long-lead technology development for potentially supporting future integrated FSP systems. The major effort in
the FSP technology project has been focused on a reference mission and concept. The reference mission is to provide
40 kW
e
power to habitats on the lunar surface over a design life of 8 years. Although many options exist, NASAs
Propulsion Research Engineer, Propulsion Research and Technology Applications Branch, Propulsion Systems Department. Senior Member
AIAA.
Maximum Technology Corporation, Huntsville, AL.
BSRD, LLC/Yetispace, Inc., Huntsville, AL.
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American Institute of Aeronautics and Astronautics

current reference FSP system uses a fast spectrum, pumped liquid, sodium-potassium- (NaK-) cooled reactor coupled
to a Stirling power conversion subsystem. An annular linear induction pump (ALIP) is used to pump the liquid-metal
coolant in the system. The reference system uses technology with significant terrestrial heritage that can perform at
any location on the surface of the Moon or Mars. Detailed development of the FSP concept and the reference mission
are documented in various other reports.
1–4
The Early Flight Fission-Test Facility was established by MSFC to provide a capability for performing hardware-
directed activities to support multiple in-space nuclear reactor concepts by using a nonnuclear test methodology.
5,6
This includes fabrication and testing at both the module/component level and near prototypic reactor components and
configurations, allowing for realistic thermal-hydraulic evaluations of systems.
The reference FSP system uses an ALIP because it can operate at moderate to elevated temperatures for extended
periods of time and it is typically one of the more efficient inductive electromagnetic molten metal conveyance tech-
nologies. Electromagnetic pumps do not contain moving parts that can mechanically wear over the lifetime of the
reactor system. Consequently, these pumps require no bearings, seals or associated maintenance. Futhermore, unlike
DC electromagnetic pumps that experience higher Ohmic losses in the power lines due to the required combination of
high-current/low-voltagepower, an ALIP draws 3-phase AC power at moderate and manageable currents and voltages.
In the present testing, the ALIP test circuit (ATC) was fabricated to provide the capability to measure the perfor-
mance of induction pumps over a wide range of input conditions and environments. The system is described in detail
in section II, followed by measured performance results on the present ALIP. Greater detail on the system and testing
can be found in a report by Polzin et al.
7
II. Experimental Apparatus and Test Setup
The ATC apparatus, shown schematically and photographically in Fig. 1, was fabricated to allow for performance
testing of liquid-metal induction pumps. The present test circuit consists of the ALIP, an induction heater, a throttling
valve, an electromagnetic flowmeter, and a gaseous nitrogen- (GN
2
-) to-NaK heat exchanger. A large pipe size (3-in,
schedule 10, stainless steel) was employed to minimize the viscous flow losses throughout the loop. A description of
the major hardware and instrumentation components of the system is presented in the remainder of this section.
A. Annular Linear Induction Pump
The design and development of the ALIP was performed by Idaho National Laboratory (INL) and is discussed in a
companion report.
8
Three-phase power is applied to the pump to produce an axially-traveling magnetic wave. This
magnetic wave induces currents in the liquid metal, which subsequently interact with the magnetic field to produce a
Lorentz body force on the fluid, pushing it through the system.
In the present experiment, an Allen Bradley PowerFlex 400 variable frequency drive (VFD) with a sine wave filter
was employed to set the frequency of the power delivered to the pump to an arbitrary value from zero to 60 Hz. The
VFD employs pulse width modulation (using a 4-kHz carrier wave frequency) to produce an approximately sinusoidal
current at these arbitrary frequency levels. The filtered VFD output was passed through a variac transformer to control
the voltage. By adjusting the variac, the voltage and commensurate power to the pump could be controlled to an
arbitrary level.
B. Addtional Test Circuit Hardware
An in-house custom designed valve was used to control the flow impedance in the system. A gate valve design was
selected to produce the smallest pressure drop across the valve, making use of a welded bellows to provide actuation
and hermetic sealing of the valve. The high-temperature NaK required stainless steel (SS) or similar materials for
all wetted surfaces. The gate itself was constructed of Inconel
R
. This material was selected because it has a lower
coefficient of thermal expansion than the SS grade 304 that comprised the rest of the valve body, and also to prevent
galling between the valve body and the gate. The bellows was sized to provide3 in of travelcorresponding to the height
of the duct. The valve was translated by a vacuum-rated motor that was connected through a worm-drive gearbox to
the top plate of the bellows.
The NaK was heated using the radio frequency (RF) inductive heater coil shown in figure 8. The coil was manu-
factured by Fluxtrol, Inc., Auburn Hills, MI, and was powered using a Toccotron 400, 12.5-kW, inductive heater power
supply. Four graphite heaters were added to the ATC during testing to provide additional heat and allow for reaching
the target maximum circuit temperature. The design involved clamping four tubes to the sides of the ATC pipe wall
and sliding the heaters inside these tubes. A gas-to-NaK counterflow concentric tube heat exchanger was used to
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American Institute of Aeronautics and Astronautics

a)
b)
Accumlator
ALIP
Inlet Pressure (P-01)
Outlet Pressure (P-02)
Throttling
Valve
Heat Exchanger
RF Heater Coil
Electromagnetic
Flowmeter
Flow Direction
Flow Direction
NaK Temperature
Inlet Pressure (P-01)
ALIP
Outlet Pressure (P-02)
Flow Direction
Flow Direction
Electromagnetic
Flowmeter
RF Heater Coil
Heat Exchanger
Throttling
Valve
Figure 1. a) Schematic and b) photograph of the ALIP test circuit.
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American Institute of Aeronautics and Astronautics

Citations
More filters
Journal ArticleDOI
TL;DR: In this article, the design variables of an annular linear induction electromagnetic pump (ALIP) for SFR thermal hydraulic experimental loop were analyzed magnetohydrodynamically and the developed pressure was found to be a function of design variables, including pump core length, inner core diameter and flow gap.

14 citations

References
More filters
Proceedings ArticleDOI
21 Feb 2001
TL;DR: The use of resistance heaters to simulate heat from fission allows extensive development of fission systems to be performed in non-nuclear test facilities, saving time and money as mentioned in this paper.
Abstract: The use of resistance heaters to simulate heat from fission allows extensive development of fission systems to be performed in non-nuclear test facilities, saving time and money. Resistance heated tests on the Module Unfueled Thermal-hydraulic Test (MUTT) article has been performed at the Marshall Space Flight Center. This paper discusses the results of these experiments to date, and describes the additional testing that will be performed. Recommendations related to the design of testable space fission power and propulsion systems are made.

13 citations

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Q1. What are the contributions in this paper?

The Early Flight Fission – Test Facility ( EFF-TF ) was established by the Marshall Space Flight Center to provide a capability for performing hardware-directed activities to support multiple in-space nuclear reactor concepts by using a non-nuclear test methodology. [ 1,2 ]