Chop-Leach Dissolution of Commercial Reactor Fuel

The primary goal of the present work was to demonstrate the use of the chop-leach (with nitric acid) process to produce a feed solution for the UREX process

DISSOLUTION OF ZIRCALOY 2 CLAD UO2 COMMERCIAL REACTOR FUEL

The primary goal of this investigation was to evaluate the effectiveness of the chop-leach process, with nitric acid solvent, to produce a nominally 300 g/L [U] and 1 M [H{sup +}] product solution. The results of this study show that this processing technique is appropriate for applications in which a low free acid and moderately high U content are desired. The 7.75 L of product solution, which was over 450 g/L in U, was successfully diluted to produce about 13 L of solvent extraction feed that was 302 g/L in U with a [H{sup +}] in the range 0.8-1.2 M. A secondary goal was to test the effectiveness of this treatment for the removal of actinides from Zircaloy cladding to produce a low-level radioactive waste (LLW) cladding product. Analysis of the cladding shows that actinides are present in the cladding at a concentration of about 5000 {eta}Ci/g, which is about 50 times greater than the acceptable transuranium element limit in low level radioactive waste. It appears that the concentration of nitric acid used for this dissolution study (initial concentration 4 M, with 10 M added as the dissolution proceeded) was inadequate to completely digest the UO{sub 2} present in the spent fuel. The mass of insoluble material collected from the initial treatments with nitric acid, 340 g, was much higher than expected, and analysis of this insoluble residue showed that it contained at least 200 g U

LITERATURE REVIEW: REDUCTION OF NP(V) TO NP (IV)-ALTERNATIVES TO FERROUS SULFAMATE

The baseline approach to control of Np oxidation in UREX and PUREX separation processes is the reduction of Np(V) and Np(VI) to Np(IV) using ferrous sulfamate. Use of this reagent results in increased sulfur and iron concentrations in the liquid waste streams from the process. Presence of these two elements, especially sulfur, increases the complexity of the development of wasteforms for immobilizing these effluents. Investigations are underway to identify reductants that eliminate sulfur and iron from the Np reduction process. While there are a variety of chemical reductants that will reduce Np to Np(IV) in nitric acid media, the reaction rates for most are so slow that the reductants are not be feasible for use in an operating plant process. In an attempt to identify additional alternatives to ferrous sulfamate, a literature search and review was performed. Based on the results of the literature review, it is concluded that photochemical and catalytic processes should also be investigated to test the utility of these two approaches. The catalytic process could be investigated for use in conjunction with chemical oxidants to speed the reaction rates for reductants that react slowly, but would otherwise be appropriate replacements for ferrous sulfamate. The photochemical approach, which has received little attention during the past few decades, also shows promise, especially the photocatalytic approach that includes a catalyst, such as Pt supported on SiC, which can be used in tandem with an oxidant, for Np reduction

Characterization of lung cancer by amide proton transfer (APT) imaging: an in vivo study in an orthotopic mouse model. Plos One

Abstract Amide proton transfer (APT) imaging is one of the chemical exchange saturation transfer (CEST) imaging methods which images the exchange between protons of free tissue water and the amide groups (2NH) of endogenous mobile proteins and peptides. Previous work suggested the ability of APT imaging for characterization of the tumoral grade in the brain tumor. In this study, we tested the feasibility of in-vivo APT imaging of lung tumor and investigated whether the method could differentiate the tumoral types on orthotopic tumor xenografts from two malignant lung cancer cell lines. The results revealed that APT imaging is feasible to quantify lung tumors in the moving lung. The measured APT effect was higher in the tumor which exhibited more active proliferation than the other. The present study demonstrates that APT imaging has the potential to provide a characterization test to differentiate types or grade of lung cancer noninvasively, which may eventually reduce the need invasive needle biopsy or resection for lung cancer

MOISTURE AND SURFACE AREA MEASUREMENTS OF PLUTONIUM-BEARING OXIDES

To ensure safe storage, plutonium-bearing oxides are stabilized at 950 C for at least two hours in an oxidizing atmosphere. Stabilization conditions are expected to decompose organic impurities, convert metals to oxides, and result in moisture content below 0.5 wt%. During stabilization, the specific surface area is reduced, which minimizes readsorption of water onto the oxide surface. Plutonium oxides stabilized according to these criteria were sampled and analyzed to determine moisture content and surface area. In addition, samples were leached in water to identify water-soluble chloride impurity content. Results of these analyses for seven samples showed that the stabilization process produced low moisture materials (< 0.2 wt %) with low surface area ({le} 1 m{sup 2}/g). For relatively pure materials, the amount of water per unit surface area corresponded to 1.5 to 3.5 molecular layers of water. For materials with chloride content > 360 ppm, the calculated amount of water per unit surface area increased with chloride content, indicating hydration of hygroscopic salts present in the impure PuO{sub 2}-containing materials. The low moisture, low surface area materials in this study did not generate detectable hydrogen during storage of four or more years

Paclitaxel Drug-Coated Balloon Angioplasty Suppresses Progression and Inflammation of Experimental Atherosclerosis in Rabbits

Paclitaxel drug-coated balloons (DCBs) reduce restenosis, but their overall safety has recently raised concerns. This study hypothesized that DCBs could lessen inflammation and reduce plaque progression. Using 25 rabbits with cholesterol feeding- and balloon injury-induced lesions, DCB-percutaneous transluminal angioplasty (PTA), plain PTA, or sham-PTA (balloon insertion without inflation) was investigated using serial intravascular near-infrared fluorescence−optical coherence tomography and serial intravascular ultrasound. In these experiments, DCB-PTA reduced inflammation and plaque burden in nonobstructive lesions compared with PTA or sham-PTA. These findings indicated the potential for DCBs to serve safely as regional anti-atherosclerosis therapy

Giant breast tumors: Surgical management of phyllodes tumors, potential for reconstructive surgery and a review of literature

<p>Abstract</p> <p>Background</p> <p>Phyllodes tumors are biphasic fibroepithelial neoplasms of the breast. While the surgical management of these relatively uncommon tumors has been addressed in the literature, few reports have commented on the surgical approach to tumors greater than ten centimeters in diameter – the giant phyllodes tumor.</p> <p>Case presentation</p> <p>We report two cases of giant breast tumors and discuss the techniques utilized for pre-operative diagnosis, tumor removal, and breast reconstruction. A review of the literature on the surgical management of phyllodes tumors was performed.</p> <p>Conclusion</p> <p>Management of the giant phyllodes tumor presents the surgeon with unique challenges. The majority of these tumors can be managed by simple mastectomy. Axillary lymph node metastasis is rare, and dissection should be limited to patients with pathologic evidence of tumor in the lymph nodes.</p