Efficient powder blending in support of plutonium conversion for

Efficient powder blending in support of plutonium conversion for
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Title:
Author(s):
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Los Alamos
NATIONAL
LABORATORY
Efficient Powder Blending [n Support of Plutonium
Conversion For Mixed Oxide Fuel
David K. Dennison
John P. Brucker
Horatio E. Martinez
23” Annual Actinide Separations
Richland, WA
June 7-10,
1999
Conference
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Efficient Powder Blending
In Support of Plutonium Conversion
For Mixed Oxide Fuel
David K. Dennison
John P. Brucker
Horatio E. Martinez
Los Alamos National Laboratory
P.O. BOX 1663, M/S J580
LOS Aki.IIIOS,
NM 87545
Abstract
This paper describes a unique system that is used to mix and blend multiple batches of plutonium
oxide powder of various consistencies into an equivalent number of identical and homogeneously
mixed batches. This system is being designed and built to support the Advanced Recovery and
Integrated Extraction System (ARIES) at the Los Alamos TA-55 Plutonium Facility. The
ARIES program demonstrates dismantlement of nuclear pits, retrieval of the plutonium
components, and conversion of the plutonium into an oxide for eventual use in mixed oxide
(MOX) fuel for nuclear reactors. The purpose of this powder blending work is to assure that
ARTES oxide is converted into an unclassified homogeneous mixture and that consistent feed
material is available for MOX fuel assembly. This blending system is being assembled in a
selected glovebox a TA-55 using an LANL designed split/combine apparatus, a commercial
Turbula blending unit, and several additional supporting hardware components.
Introduction
The HYDOX or Direct Oxidation (DO) module in the ARIES line is used to extract the
plutonium metal from nuclear pits and convert it into an oxide. As the oxide is generated it is
packed and sealed into standard foodpack storage cans. The storage cans specified for use in the
ARIES system are standard #2 1/2 foodpack cans manufactured without any sealing elastomers
on the lids. These cans are 4.065” in diameter and 4.688” high (external dimensions) with 32
gauge walls (.0097”). Total internal volume of each can is approximately 975 cc but they are not
filled to more than 80% of their maximum volume (780 cc). The oxide powder generated in the
ARIES line has been shown to range in density from 1 to 4 gmlcc. Therefore, the net weight of
the product in these foodpack containers can range from 780 to 3,120 grams. Atypical ARIES
oxide powder (foodpack) can is shown without its lid in Figure 1.
Blendirw Seauence
In order to assure that the oxide in all the available foodpack cans is thoroughly and
homogeneously mixed a blending sequence and procedure was determined. The procedure is to
mix the powder from two ARIES foodpack cans into one 2-liter mixing can, blend the oxide in
the mixing can until it is a homogeneous mixture, then split the oxide in half and load it back into
the two foodpack cans. This combine/blend/split sequence is defined as one complete operation.
By rearranging the cans and performing additional operations 2s(where S is any integer from 1
on up) initially available foodpack cans can be blended into an equal number of cans all
containing identical homogeneous powder mixtures. An example, assuming four initial oxide
cans, is illustrated in Table 1.
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Figure 1
Table 1
Typical ARIES oxide can (foodpack can) with lid removed
Typical Sequence Used To Homogeneously Blend 4 Initial Cans of Oxide
Operation 1
Initial cans
Combine &Blend
Split
Operation 2
A
A+B
A12i-B12
B
f~:
AJ2i-B12
c
C+D
C12+D/2
Operation 3
Swap Cans
Combine &Blend
Split (Blended material)
D
“:
“..
C/2+D/2
Operation 4
A12+B12
C/2+D/2
A12+B12
C/2+D/2
. .....&..2f.
A12+B/2+u2+D/2 [.’,’--- ;
A.12+B12+C12+D12-“:-. :’:+<.j’!<,yr
A14+B14+CL4+D14 A/4i-B14+u4+D/4
A14+B14+C14+D14 A/4+B/4+c/4+D/4
The total number of combine/blend./split operations required to produce theoretically identical
blends of powder in each final foodpack can is dependent on the initial number of cans available
for blending. The dependency is shown in the following equation and demonstrated in Table 2.
The more initial cans of powder to be homogenized the more operations required.
0=?4XCXS
(Equation 1)
S = Number of equal powder splits per can
C = Number of initial cans (= 2s)
O = Total number of combine/blend/split operations
Page 3 of 7
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Table 2
Number of Initial Cans vs. Total Required Blending Operations to Get
Complete Homogeneous Mixtures in Each Can
Cans
Powder Splits per Initial
Can
2
4
8
16
32
64
128
Number of Required
Operations
1
1
2
3
4
5
6
7
4
12
32
80
192
448
Hardware Required
Atypical blending operation utilizes two major pieces of equipment. In order to combine and
split the powder into the various cans without creating a significant dusting problem a specially
designed combiner/splitter was developed. A cutaway sketch of the combiner/splitter device
with the foodpack cans and 2-liter can attached is shown in Figure 2. The heart of this device is
the central chamber which is designed to allow powder to flow equally from one large chute into
two smaller chutes and vice versa without significant hang up in the apparatus or on any of the
transition locations. The system utilizes a vibrator to assure that all powder is transferred with
minimal hang-up.
r
2-liter
mixing
can
Splitter/
Combiner
device
/
ARIEs
oxide
foodpack
cans
Figure 2
Combiner/Splitter
Page 4 of 7
‘.
The next major piece of hardware required for this process is a Turbula style blender. This type
of blender as shown in Figure 3 is well suited for use in a glovebox environment. The physical
dimensions of the Model 2TF Turbula blender are 20” wide, c24” deep, and 16” high. The
required overhead height needed to accommodate apparatus with the safety cover open is 30”.
The unit weighs about 85 lbs. The 2TF unit will handle a 2-liter container, which is adequate for
this prototype system. The Turbula achieves a uniform blend of powder materials in a much
shorter time than other types of blending apparatus such as the V-blender, double cone blender,
or the drum roller. Also, the addition of other materials to enhance the blending (ball mill,
rotary paddles, ribbon blending devices, etc.) is not required thereby reducing the chance that
impurities will be added to the oxide. There are several Turbula blenders currently being utilized
at TA-55 today for other programs.
●
●
●
Figure 3
Turbula Blender
All hardware including the Turbula blender and the combiner/splitter apparatus were designed
and configured within a standard glovebox at TA-55 to allow possible incorporation of
automationhobotic handling at a future date. Other hardware required to support this operation
is listed below:
. Conventional can opener is used to remove lids from the ARIES foodpack cans.
. Standard lid crimper is used to clamp and seal the lids onto the foodpack cans at the end
of the process.
Page 5 of 7
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..
.
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●
A scale is used to weigh cans and oxides at various stages of the process.
A 2-liter stainless steel mixing can with easily removable lid is used to hold the powder
from the foodpack cans and contain it while being blended on the Turbula mixer. (See
Figure 4).
Temporary lids me used to cover the foodpack cans while waiting further processing
during the blending operations.
Other miscellaneous tools are used to support the processing.
Figure 4
2-Liter Mixing Can and Lid
Tvpical Blending Operation
A typical blending operation uses the combiner/splitter apparatus and the Turbula blender to
homogeneously blend the oxide from two foodpack cans at a time. The two cans (containing the
oxide) are opened and then securely mounted side by side on one end of the combiner/splitter
apparatus. The 2-liter stainless steel mixing can is fastened upside down to the other end of the
combiner/splitter. Then the apparatus is flipped 180°to allow the powder from the two foodpack
cans to flow into the 2-liter can. After waiting for the dust to subside the mixing can is removed
from the combiner/splitter, a temporary lid is attached, and it is inserted into the Turbula blender.
After the powders have been thoroughly blended (optimum blending times will be determined
during both surrogate and plutonium oxide powder tests) the mixing can is removed from the
Turbula blender, the lid removed, and the can reinserted into the combiner/splitter. The
combiner/splitter is again rotated 180° and the powder is split and flows back into the two
foodpack cans. Again, after waiting a fixed amount of time to allow all powder dust to settle, the
two foodpack cans are removed from the combiner/splitter apparatus. Then temporary lids are
attached and the blended foodpack cans are stored in the glovebox until needed for the next
required blending operation. Once all operations are complete and all the foodpack cans contain
Page 6 of 7
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identical homogeneous mixtures then permanent sealed lids are installed onto the foodpack cans
for storage, handling, and subsequent packaging into DOE-STD-3013-96 certified outer
containers.
Conclusion
This paper has described a system for mixing and blending multiple batches of plutonium oxide
powder of various consistencies into an equivalent number of homogeneously mixed batches.
This system is being designed and built to support the Advanced Recovery and Integrated
Extraction System (ARIES) at the Los Alamos TA-55 Plutonium Facility. The work is being
done to assure that ARIES oxide is converted into an unclassified homogeneous consistent feed
material available for MOX fuel assembly.
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