,. ,, LA-UR- ~ ~ - Approved forpubllc release; dLstribut/on/s unhked. Title: Author(s): Submitted to: 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 DISCLAIMER This report was,,prepared as an account of work sponsored by an agency of the United States Government. 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Images are produced from the best available original document. ..-...” ,-, ._ .—. . .,. =m, >. “.. ., . ,. .--<= . — - ... > . 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. ,. . -=---- ( @4.CM 1 (4.69) , \ A 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 ‘. 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 . .. . . . ● 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 . . . 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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