LABORATORY DEVELOPMENT OF A TRIBUTYL PHOSPHATE SOLVENT EXTRACTION PROCESS FOR PROCESSING 20% ENRICHED URANIUM ALLOY FUEL

A preliminary chemical flowsheet was developed on a laboratory scale for the preparation of feed and two solvent extraction cycles for the processing of Si-containing Al--U alloy, 20% enriched, fuel elements. Major process steps include dissolution of the fuel assembly in Hg-catalyzed ritric acid, removal of silica by coagulation during feed clarification, and recovery of U and pu by extraction with a tributyl phosphate solvent and selective stripping. Criticality control in existing process equipment is maintained by the use of internal neutron poisons and concentration control throughout the process. (auth

Recommendations to encourage participation of individuals from diverse backgrounds in psychiatric genetic studies

We present innovative research practices in psychiatric genetic studies to ensure representation of individuals from diverse ancestry, sex assigned at birth, gender identity, age, body shape and size, and socioeconomic backgrounds. Due to histories of inappropriate and harmful practices against marginalized groups in both psychiatry and genetics, people of certain identities may be hesitant to participate in research studies. Yet their participation is essential to ensure diverse representation, as it is incorrect to assume that the same genetic and environmental factors influence the risk for various psychiatric disorders across all demographic groups. We present approaches developed as part of the Eating Disorders Genetics Initiative (EDGI), a study that required tailored approaches to recruit diverse populations across many countries. Considerations include research priorities and design, recruitment and study branding, transparency, and community investment and ownership. Ensuring representation in participants is costly and funders need to provide adequate support to achieve diversity in recruitment in prime awards, not just as supplemental afterthoughts. The need for diverse samples in genetic studies is critical to minimize the risk of perpetuating health disparities in psychiatry and other health research. Although the EDGI strategies were designed specifically to attract and enroll individuals with eating disorders, our approach is broadly applicable across psychiatry and other fields

Solar Intranetwork Magnetic Elements: bipolar flux appearance

The current study aims to quantify characteristic features of bipolar flux appearance of solar intranetwork (IN) magnetic elements. To attack such a problem, we use the Narrow-band Filter Imager (NFI) magnetograms from the Solar Optical Telescope (SOT) on board \emph{Hinode}; these data are from quiet and an enhanced network areas. Cluster emergence of mixed polarities and IN ephemeral regions (ERs) are the most conspicuous forms of bipolar flux appearance within the network. Each of the clusters is characterized by a few well-developed ERs that are partially or fully co-aligned in magnetic axis orientation. On average, the sampled IN ERs have total maximum unsigned flux of several 10^{17} Mx, separation of 3-4 arcsec, and a lifetime of 10-15 minutes. The smallest IN ERs have a maximum unsigned flux of several 10^{16} Mx, separations less than 1 arcsec, and lifetimes as short as 5 minutes. Most IN ERs exhibit a rotation of their magnetic axis of more than 10 degrees during flux emergence. Peculiar flux appearance, e.g., bipole shrinkage followed by growth or the reverse, is not unusual. A few examples show repeated shrinkage-growth or growth-shrinkage, like magnetic floats in the dynamic photosphere. The observed bipolar behavior seems to carry rich information on magneto-convection in the sub-photospheric layer.Comment: 26 pages, 14 figure

Voloxidation and dissolution of irradiated (Th,U)O/sub 2/

Exploratory hot-cell tests were made to determine the amounts of fission products released by high-temperature oxidation (voloxidation) of irradiated fuel, initially (Th/sub 0/ /sub 96/U/sub 0/ /sub 04/)O/sub 2/, and whether the treatment would affect the subsequent dissolution of the oxide. Fifteen-year-decayed fuel rods were sheared to dislodge the (Th,U)O/sub 2/ from its cladding, sieved to determine the size range, and an aliquot was oxidized in flowing air at 600/sup 0/C for approx. 2 h while tumbling at 12 rpm. The voloxidation released only 0.2% of the /sup 85/Kr and 6% of the /sup 3/H contained in the (Th,U)O/sub 2/. The oxidized and unoxidized portions were leached three times in a 95/sup 0/C Thorex reagent to dissolve the fuel. The voloxidation apparently had no effect on the dissolution of the mixed oxide. The presence of cladding slowed the dissolution by limiting the amount of fuel exposed to the acid

DAREX PROCESS: BATCH DISSOLUTION AND CHLORIDE REMOVAL STEPS FOR YANKEE ATOMIC FUEL

In laboratory scale experiments dilution of a Darex dissolver product from the integral dissolution of Yankee Atomic fuel specimens with at least an equal volume of 15.8M HNO/sub 3/, followed by distillation, produced a solvent extraction feed containing less than 50 ppm of chloride. Properly designed chloride stripping and nitric acid rectification columns are capable of conserving acids for recycle to the dissolver and chloride removal still. In initial experiments about 87% of the nitric acid and 36% of the hydrochloric acid were recovered. (auth

HOT CELL DEMONSTRATION OF ZIRFLEX AND SULFEX PROCESSES. Report No. 2

Twelve Zircaloy-2 clad UO/sub 2/ specimens, irradiated in the NRK to about 15,500 Mwd/t and decayed about 9 months, were declad and core dissolutions completed. The pellets were fractured brt were essentially intact (i.e. had not fallen apart) when declad. The U losses ramged from 0.03 to 0.09%, due to solubility of U(IV) in the Zinflex reagent, and the U losses from 0.01 to 0.04%. The core pellets were 99.5% dlssolved in 4 M HNO/sub 3/-0.1M Al(NO/sub 3/)/sub 3/ in 5 hr, which was slightly faster than the rate of unirradiated pellets. (auth

Characterization of insoluble residues from the dissolution of irradiated (U,Pu)O{sub 2}

Hot-cell tests were conducted using (U,Pu)O{sub 2} fuels that had been irradiated to about 5.2 TJ/kg (U + Pu) [60 MWd/kg (U + Pu)] in an effort to characterize the insoluble residues that remained after the fuel pellets had been dissolved in HNO{sub 3} and in HNO{sub 3}-KF. The composition, particle size range, and density of the material were determined by newer analytical techniques, including spark-source mass spectrometry, neutron activation, scanning electron microscopy, and x-ray fluorescence, combined with older methods such as sedimentation and powder density by water displacement

Head-end reprocessing studies with H.B. Robinson-2 fuel

A series of exploratory hot-cell tests was made to determine the effects of voloxidation on tritium, fission product removal, and on subsequent steps of the light water reactor fuel cycle. The 100-g scale experiments indicated that >99% of the tritium, 50% of the {sup 14}C, 6% of the {sup 85}Kr, and smaller amounts of other elements were volatilized and collected when the UO{sub 2} was roasted in air at 480{sup 0}C for {similar_to} h. There was little effect on the solubility of the uranium and plutonium in HNO{sub 3}. The experiments indicated that the first 2-h leach usually dissolved >99.9% of the uranium and plutonium, and varying amounts of fission products, in voloxidized or unvoloxidized fuel. Two additional HNO{sub 3} leaches on the unvoloxidized fuel dissolved all but 0.004% of the plutonium; the additional leaches on the voloxidized material left {similar_to}.02% of the plutonium. (28 figs., 21 tables