Controlled PuO/sub 2/ particle size from Pu(III) oxalate precipitation

Burney, G.A.; Smith, P.K.

doi:10.2172/6141411

Cited by 6 publications

(6 citation statements)

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“…An increase in particle size with increasing nitric acid concentration during Pu(III) oxalate precipitation has been previously reported. [8][9] In the earlier of the two reports, analysis of 44 precipitations with 239 Pu and 238 Pu was reported to show the mass mode size of the calcined PuO 2 depended on the variables affecting final solubility of Pu(III) oxalate. 8 The particle size was observed to increase with increasing precipitation temperature, increasing nitric acid concentration in the feed, decreasing Pu concentration in the feed, and decreasing oxalic acid concentration.…”

Section: Particle Size Analysismentioning

confidence: 99%

Determination of filter pore size for use in HB line phase II production of plutonium oxide

Shehee

Crowder

Rudisill

2014

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H-Canyon and HB-Line are tasked with the production of plutonium oxide (PuO 2) from a feed of plutonium (Pu) metal. The PuO 2 will provide feed material for the Mixed Oxide (MOX) Fuel Fabrication Facility. After dissolution of the Pu metal in H-Canyon, plans are to transfer the solution to HB-Line for purification by anion exchange. Anion exchange will be followed by plutonium(IV) oxalate precipitation, filtration, and calcination to form PuO 2. The filtrate solutions, remaining after precipitation, contain low levels of Pu ions, oxalate ions, and may include solids. These solutions are transferred to H-Canyon for disposition. To mitigate the criticality concern of Pu solids in a Canyon tank, past processes have used oxalate destruction or have pre-filled the Canyon tank with a neutron poison. The installation of a filter on the process lines from the HB-Line filtrate tanks to H-Canyon Tank 9.6 is proposed to remove plutonium oxalate solids. This report describes SRNL's efforts to determine the appropriate pore size for the filters needed to perform this function. Information provided in this report aids in developing the control strategies for solids in the process. The tests performed during this effort report the following results.  Percent losses to the filtrate were < 1% for four of five tests and 1.5% for one test.  Sub-micron particle sizes are retained by initial filtration using a 10 μm filter. The filter cake aids in the filtration of the smaller particles.  The mean particle size increases with an increase in the initial acid concentration.  Larger mean particle sizes were observed when changing from a nitric acid/oxalic acid flush to nitric acid alone.  The size of Pu oxalate particles in HB-Line filtrate solutions averages 2.0 ± 0.4 μm in range of precipitation conditions tested. Further development of the "filter the filtrate" strategy must be geared to retain particles of the 2 μm size range.

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Section: Particle Size Analysismentioning

confidence: 99%

Determination of filter pore size for use in HB line phase II production of plutonium oxide

Shehee

Crowder

Rudisill

2014

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“…Although several facilities around the world have produced PuO 2 , almost none have performed designed experiments for forensics applications. One exception is , who described a 53‐run experiment for three factors (HNO 3 in moles, Pu in g/L, and temperature in °C); we refer to these factors as x 1 , x 2 , and x 3 . Five particle morphology responses were observed: mode in μ m, agglomeration index in weight percent, length in μ m, width in μ m, and thickness in μ m; we refer to these responses as y 1 ,…, y 5 .…”

Section: Motivating Examplementioning

confidence: 99%

“…To model the relationship between each of the responses and the three input factors, reference used quadratic models that included a three‐factor interaction with the following form:

\begin{matrix} alignleft \\ align-1 y_{i} & align-2 = β_{i 0} + β_{i 1} x_{1} + β_{i 2} x_{2} + β_{i 3} x_{3} + β_{i 12} x_{1} x_{2} + β_{i 13} x_{1} x_{3} \\ align-1 & align-2 + β_{i 23} x_{2} x_{3} + β_{i 123} x_{1} x_{2} x_{3} + β_{i 11} x_{1}^{2} \\ align-1 & align-2 + β_{i 22} x_{2}^{2} + β_{i 33} x_{3}^{2} + ε_{i}, \end{matrix}

with

\begin{matrix} ε_{i} \sim Normal (0, σ_{i}^{2}) . \end{matrix}

…”

Section: Motivating Examplementioning

confidence: 99%

See 1 more Smart Citation

Statistical analysis for nuclear forensics experiments

Anderson‐Cook

Burr

Hamada

et al. 2015

Statistical Analysis

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As with any type of forensics, nuclear forensics seeks to infer historical information using models and data. This article connects nuclear forensics and calibration. We present statistical analyses of a calibration experiment that connect several responses to the associated set of input values and then 'make a measurement' using the calibration model. Previous and upcoming real experiments involving production of PuO 2 powder motivate this article. Both frequentist and Bayesian approaches are considered, and we report findings from a simulation study that compares different analysis methods for different underlying responses between inputs and responses, different numbers of responses, different amounts of natural variability, and replicated or non-replicated calibration experiments and new measurements. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

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“…In the past decades, some ways have been found to control actinide oxalate size, structure, and morphology. − Increasing crystallization temperature of tetravalent actinides An(C 2 O 4 ) 2 ·6H 2 O (An = Pu or Np) has, for example, a significant influence on particle size and shape. − Considering the strong correlation between the particle shape and the crystal structure, another way to influence the final morphology of the oxalate is to target its crystal structure by varying chemical conditions of crystallization. − Few studies were dedicated to the influence of additives on actinide oxalate structure and morphology. However, influence of some additives on oxalic precipitation was studied on other systems as calcium oxalate, primary constituent of human kidney stones, or copper oxalate, which permits to obtain copper oxide, used for bulk and thin film applications.…”

Section: Introductionmentioning

confidence: 99%