University of Idaho
Department of Mechanical Engineering
Daniel Powers on behalf of Team VECCTR
Senior Mechanical Engineering
vecctr@uidaho.edu
December 12, 2008
Dr. Akira Tokuhiro
Assistant Professor, Mechanical Engineering
University of Idaho
tokuhiro@uidaho.edu
Dr. Tokuhiro:
I submit herewith the design report for the sodium flow Cold Trap and Test Section Project for
your approval. This should serve as an update on the current status of the project and the plan for
next semester.
Questions or comments regarding our project can be directed to any member of team VECCTR
(vecctr@uidaho.edu).
Your review of this document is greatly appreciated.
Sincerely,
Daniel Powers
Enclosed: VECCTR Design Report
Cc: Dr. Jay McCormack
VECCTR Design Report
Team VECCTR:
Dan Powers
Jason Cyr
Jeff Haines
Rob Richardson
VECCTR@uidaho.edu
Executive Summary
Because of sodium’s high chemical reactivity and its clear color, there are limited
methods for measuring the fluid dynamic properties while the sodium is in service. One such
method is the use of acoustics to measure the velocity profile of sodium, and is being researched
by Dr. Akira Tokuhiro using an ultrasonic transducer. He has asked for the development of a test
section to accommodate the transducer as well as an active cold trap able to remove and relese
impurities in the sodium flow.
Background
Sodium is being used as coolant in nuclear reactors; this is primarily due to its excellent
thermal properties. But sodium reacts violently if it contacts either air or water, this makes taking
flow measurements difficult. The sensor options are very limited for sodium. In order to take
these measurements, Dr. Akira Tokuhiro is exploring the use of acoustics in measuring the
velocity profile.
By measuring the Doppler shift of impurities in th flow with an acoustic trasducer, the
sodium flow rate can be calculated. Sound from a ultrasonic transducer is sent through the
sodium flow were it is bounce is off the impurities in the flow. Dr. Tokuhiro will test this method
at the Argonne Nation Laboratory (ANL) using their sodium test loop. In order to conduct this
experiment, Dr. Tokuhiro requested that team VECCTR design and build the test section to
acuminate the transducer and an active cold trap fir the loop.
Problem Definition
Test Section
The test section will be designed to accommodate the ultrasonic transducer and give it the
largest possible cross section together data. It must be able to maintain and control the sodium’s
temperature with out human inter action. Further more the test section must integrate with the
sodium loop at ANL and meet all of ANL’s safety standards.
During the fall semester, the test section was fully design with all the heaters and the
controllers specified. The material is going to be order over winter break and the section will be
complete and test for proof of concept in spring semester.
Active Cold Trap
A standard cold trap operates by reduce the sodium’s temperature to around its melting
point and then filtering out the impurities which start to drop out of the flow. Because the
ultrasonic transducer needs the impurities to bounces its signal off of, the active cold trap must
be able to reintroduce enough impurities to get a good signal into the flow. The ability to
rerelease impurities is why the cold trap in question is referred to as active. Again the cold trap
must be able to integrate into the existing ANL sodium loop and meet ANL standards.
By the end of the fall semester, we gained an understanding on how current passive cold traps
operate. Furthermore 3 concepts on how these passive cold traps could be made to be active were
developed. Fully design and fabrication of an active cold trap will be done during the spring
semester.
Project Plan
The fall semester was primarily dedicated to project research and designing the test
section. The spring semester will be primarily focused on the development of the cold trap and
the construction and testing of the test section. Below is a tentative schedule of the team’s goals
for next semester.
Spring Semester Schedule (tentative)






January 30
o Complete construction of test section
February 27
o Perform tests with test section
March 13
o Order cold trap
April 3
o Construct cold trap
April 17
o Test cold trap
May 8
o Final product and report
Team Responsibilities

Construct test section to specifications

Creating specifications for cold trap

Construct cold trap to specifications

Deliver a working final product

Interfacing with client, vendors, mentors and other concerned parties
Concepts Considered
Design Constraints
When our team started to formulate ideas for the test section, we already had an existing
approved design from Argonne Labs that we needed to redesign for our application, see
Appendix 1.1. The design constraints for the test section included minimum internal dimensions,
a desired overall length, a heating rate, and Swagelok fittings to interface with the existing
system. The inner dimensions of the test section needed to be a rectangular cross section that is a
minimum of 40 x 60 mm (1.54 x 2.36 in) so that the ultrasonic transducer could get a proper
reading across the entire length of the test section. The overall length of the test section needed to
be 922.1 mm (36.3 in) in length so that it could interface securely with the existing system.
The four main design considerations that needed to be addressed were intake/exit design,
center section assembly, heating options, and how to mount the transducer.
Intake / Exit Design
Initially when we began formulating ideas for the test section, the team assumed that the
flow into the test section needed to be as close to laminar as possible. To achieve laminar flow, a
nozzle design for the intake and the exit was used.
Figure 1: Test Section Nozzle Concept
The idea behind the nozzle was to disperse the incoming sodium flow from the jet stream
through the fittings, to a more even flow across the test section. Although the nozzle design does
help to create a laminar flow, the sodium was still not achieving a laminar state. To help with
laminar flow, the team decided to use a simple diffuser to disrupt the flow of the sodium.
Figure 2: Diffuser Concept
Our initial design of the diffuser was a simple perforated plate with smaller holes in the
middle and gradually getting bigger toward the edges, such as the one in Figure 2. The plate was
to be mounted in between the end of the intake nozzle and the beginning of the center section.
The exit end nozzle of the test section was to be the same as the intake nozzle but instead
of the flow exiting at the center, the nozzle exit was moved down so that it was bottom side was
flat instead of tapered. This made sure that at the end of each testing session the sodium in the
test section would drain completely. A more detailed drawing of the test section nozzles and
diffuser can be seen in Appendix 1.2.
Center Section Assembly
Designing the center part of the test section was a straight forward process. Since the
internal dimensions and the material were given as a design constraint, the only design
considerations were the thickness of the material and how to achieve a rectangular cross section.
The first idea for a rectangular cross section was to use two pieces of sheet metal and bend them
to form the desired cross section. The sheet metal would then be welded along the butted seams
to form the center section, such as what is shown in the drawing in Appendix 2. This design
would work but due to the volatile nature of liquid sodium, the welded seams did not meet safety
standards. The second idea was to use a fully formed steel tube. This design met Argonne’s
safety standards but the desired inner cross section would be difficult to find because it was not a
standard size. However, a McMasters-Carr stainless steel tube was found with the exact inner
dimensions. The vender data is available in Appendix 3.1.
Heating
As a design constraint, the test section would require a heater and controllers to keep the
sodium from dropping below 100 °C where it begins to solidify. After researching different types
of heaters, it was determined that the best and least expensive heater would be a “wrap” style
heater. This style of heater allowed for the most uniform heat transfer throughout the test section.
The heater is displayed in vender data in Appendix 3.2. The heat transfer calculations can also be
seen in Appendix 2.1.
Transducer Mounting
As part of the design constraints, the test section needed to incorporate both invasive and
an external mounting option for the ultrasonic transducer. The transducer that is being used for
testing cannot exceed 250 °C, therefore a cooling system needed to be designed. As a side
project, the cooling system for the transducer was designed by Peter Britanyak who is a graduate
student in the Mechanical Engineering Department. The first idea on mounting the transducer
was to mount it on the intake end of the test section. However, due to the size of the cooling
design the transducer was mounted on the right side of the test section center piece as seen in
Figure 3.
Figure 3: Transducer Mounting
Concept Selection
Final Design Selection
The final design of the test section incorporated many of the same designs as our initial
concept. The center section of the test section uses the steel tube outlined in Appendix 3.1. The
major change to the test section design was the intake and exit ends. Initially, it was assumed that
the flow of the sodium needs to be as close to laminar as possible. After phone conferencing with
our client, Dr. Akira Tokuhiro, it was determined that laminar flow was not a high priority.
Therefore, the ends can be assumed to be flat plates with the entrance and exit Swagelok fittings
welded to them. However, the design still needed to incorporate a diffuser of some kind so the
ends were extruded slightly. The ends are modeled in Figure 4 or see Appendix 1.3 for the full
test section drawing.
Figure 4: Test Section Fittings
System Architecture
Test Section
Tube
The test section will be constructed using 304 stainless steel tube. The dimensions of the
test section need to be 60 mm x 40 mm x 922 mm long. These dimensions are specified to
accommodate the acoustic transducer. The surface of the acoustic transducer has a surface area
of 8 mm in diameter. In order to measure an accurate velocity profile the cross section must be 7
times the width of the transducer and 5 times the height. The test section tubing will be ordered
from McMaster-Carr, part number 89825K999. The tubing has a wall thickness of 2mm and has
outer dimensions of 60 mm x 40 mm x 6 ft long. The test section will have squared ends.
Interface
The test section must interface with the loop so the fittings must be identical to the ones
employed currently. The connections at each end are Swagelok VCR fittings, part number SS-8-
VRC-1. These are ½ in. female face seal fittings made from 316 stainless steel. The fittings are
connected to Swagelok VAR VCR ½ in. short tube butt weld glands made from 316 stainless
steel, part number 6LV-8-VCR-3S-8TB7. The fittings are connected at each end of the tube. At
the exit end of the tube, the fittings are connected below the center of the tube in order to limit
the amount of sodium pooling when the system is drained.
Heaters
The test section must maintain and raise the temperature of the liquid sodium in the loop
as desired. In order to accomplish this, the test section will be wrapped in insulation and fitted
with a ribbon heater. The insulation selected will be made of alumina-silicate because of its high
thermal resistance and use in high temperature industrial applications. The heaters will provide
sufficient power to maintain the temperature of liquid sodium at 500 C as well as increase the
temperature of the sodium from 350 C to 500 C.
Control
Accurate temperature measurements of the test section are required for safety purposes. The
temperature of the test section will be monitored by 3 Omega brand type K thermocouples, part
number XCIB-K-4-1-10. The heaters will be controlled by an Omega brand process controller
based upon feedback from the thermocouples. The test section will have 2 independent limit
controllers in order to adhere to Argonne National Laboratory safety standards. The limit
controllers will be 2 identical Omega brand limit controllers.
Active Cold Trap
The cold trap acts as way to regulate the size and quantity of impurities in the sodium
flow. This is done so that the acoustic transducer measures accurate data about the velocity
profile in the test section. Ideally, the cold trap should regulate particulate flow so that the size
of the impurities is roughly 50 microns. A cold trap operates as a filter and a heat exchanger;
reducing the temperature of the sodium so the particulates and impurities solidify and drop out of
solution, then collect them in a filter.
Achieving “Active”
In order to make the cold trap active, the device must increase the temperature of the
sodium and release the impurities from the trap by some mechanical method. The methods being
considered to mechanically release the impurities are vibration, agitation, and surface-to-surface
scraping. By using vibrations to shake the cold trap, it may be possible to loose the particles
from the cold trap and reintroduce them to the flow. The vibrations may be generated by an
ultrasonic tool, or by an unbalanced cam driven by a motor. By agitating the fluid, the
particulate can be re-released into the flow. This may be achieved by using some kind of blade
or impellor or fluid jet that increases the turbulence of the flow through the cold trap. Lastly,
surface to surface scraping might allow the impurities caught by the filter to be reintroduced into
the flow. This method is much like a flour sifter used in a kitchen.
Future Work
By the end of next semester we will prototype and test the test section, integrate the
acoustic transducer, design and construct the active cold trap, and deliver the products to Dr.
Tokuhiro. Adapting the transducer to integrate with the test section is being done at this time.
Additionally, resizing the ribbon heaters to provide sufficient power input to the flow will be
worked on due to revised design requirements. To collect flow data for the test section, we will
construct a loop using water and aluminum powder to simulate the ANL sodium loop. The
initial test section prototype construction will be completed by the beginning of next semester.
Appendix 1.1: Previously Approved Test Section Design
Appendix 1.2: First Test Section Design
Appendix 1.3: Second Test Section Design
Appendix 2.1: Heater Calculations
Appendix 2.2: Heat need to bring sodium to 500ºC
Appendix 3.1: McMaster-Carr Steel Tubing Quote
Your Quotation from McMaster-Carr
From:
la.sales@mcmaster.com
Sent: Tue 11/11/08 2:19 PM
To: VECCTR@UIDAHO.EDU
Hi Peter,
This is the closest tube we have to the size you requested. This material can ship in 2 weeks.
Line Part
Description
Quantity Unit Cost
1
Type 304 Stainless Steel Rectangular Tube
60mm X 40mm Od, 2mm Wall, 6 Ft Length
1
89825K999
Amanda
$245.13 Each
Appendix 3.2: Omega.com Ribbon Heater Vendor Information