Thermal Oxidative Stability of Heat-Stabilised Polyamide 66 by Differential Scanning Calorimetry

The thermal stability of heat-stabilised polyamide 66 in an oxidative environment is evaluated by DSC. The oxidative stability of the polyamide decreases as a result of repeated injection moulding. The results also indicate that the presence of glass fibres in the polyamide has a negative influence on the oxidative stability. Both isothermal and dynamic DSC measurements seem to be useful tools for assessing the stability of polyamides and there is a relationship between data determined using both procedures. This revised version was published online in July 2006 with corrections to the Cover Date.     

Gamma-Radiolyse von Dimethylglyoxim

Die Strahlenresistenz von reinem und an Aktivkohle sorbiertem Dimethylglyoxim (DMG), das für die selektive Abtrennung von Palladium aus Abfallösungen der Kernbrennstoffwiederaufarbeitung geeignet ist, wurde untersucht. Die Bestrahlung erfolgte bei 20–40 °C mit einer ⁶⁰Co-γ-Bestrahlungsanlage mit Dosisleistungen von 0,6 bis 1,7 Gy/s in einem Dosisbereich von 2 kGy bis 5 MGy. Die Radiolyseprodukte wurden mit verschiedenen Methoden analysiert und die G-werte bestimmt. Es wurde gezeigt, daβ DMG bis zu Dosen von etwa 110 kGy relativ strahlenresistent ist. Bei höheren Dosen werden die reaktiven NOH-Gruppen des DMG teilweise zerstört, so daβ sie nicht mit Palladium reagieren können. In Verfahren zur Abtrennung von Palladium aus radioaktiven Abfallösungen werden diese Dosen jedoch nicht erreicht. Auf eine unzureichende Strahlenresistenz von DMG zurückzuführende Komplikationen können deshalb ausgeschlossen werden.     

Accomplishing Equilibrium in ALSEP: Demonstrations of Modified Process Chemistry on 3-D Printed Enhanced Annular Centrifugal Contactors

The major components of the modified ALSEP process have been demonstrated on a modified 2-cm annular centrifugal contactor with an enhanced mixing zone using stable fission products and radiotracers. The results show that by decreasing the pH of the minor actinide stripping solution, using HEDTA instead of DTPA, and increasing contact time, the process is very effective in separating americium from the lanthanides and the fission products.     

纳米材料与纳米技术在先进核能系统中的应用前瞻

随着人类对核能需求的快速增长,为应对核能发展的挑战,世界主要核能国家已经开始了先进核能系统的研发。新材料与新技术被认为将在未来先进核能系统中发挥重要作用,其中纳米材料与纳米技术显示了在未来核能中广泛的潜在应用前景。纳米材料是近年来受到广泛重视的一种新型功能材料,本文综述了纳米材料与纳米技术在先进核燃料制造、乏燃料后处理、核废物处置以及核环境修复等核燃料循环领域的应用基础研究现状,并对纳米材料技术在未来先进核能系统中的应用发展趋势进行了展望。     

氯化物熔盐体系中铀的化学种态研究进展

乏燃料后处理是未来先进核燃料循环体系的中心环节, 基于高温熔盐电解的干法后处理技术具有一定优势. 该技术通常在高温氯化物熔盐体系中进行, 采用电化学技术回收锕系元素, 并实现其与镧系元素的电解分离. 其中铀的分离回收是研究的重点之一. 为更好实现铀在熔盐中的分离与回收, 需要深入理解铀的电化学性质与其在熔盐中的配位化学性质的联系. 因此, 开展铀在氯盐体系中的化学种态研究至关重要. 本Review对国际上氯化物熔盐体系中针对铀化学种态的研究进展进行了总结归纳和提炼, 并对未来锕系元素在高温熔盐介质中的化学种态研究进行了展望.     

类玻璃高分子的再加工

类玻璃高分子(vitrimer)是一类含有动态共价键的共价交联聚合物网络, 结合了热固性聚合物和热塑性聚合物的优点. 在外界刺激作用下, 类玻璃高分子的动态共价键能够可逆断裂及形成, 而交联密度不会发生变化, 这种独特的性质使其能在保持三维交联网络结构的同时, 实现再加工、回收再利用、焊接和愈合等功能. 因此, 类玻璃高分子有望解决传统热固性聚合物无法进行再加工和回收再利用等问题, 推进资源的循环利用和社会可持续发展. 重点介绍了类玻璃高分子不同的再加工方式, 包括热加工、光热加工、电热加工和小分子辅助加工, 并对各个加工方式的原理、特点和应用进行总结. 最后, 对类玻璃高分子再加工的发展进行了展望.     

Evaluation of Treatments to Attain Isotopic Equilibration of Plutonium Preceding the Resin Bead Technique for Mass Spectrometric Assay Analysis of Spent Reactor Fuel

Abstract

Ten chemical treatments are evaluated for the attainment of isotopic equilibration of plutonium prior to its sorption on resin beads for assay of dissolved reactor fuel by isotope-dilution mass spectrometry. The one consistently reliable treatment is reduction to Pu(III) with heated ferrous sulfamate followed by oxidation to Pu(IV) with heated sodium nitrite.     

Key Experimental Results of the PYROSMANI Project

The presented key results were obtained in the course of experiments carried out within the PYROSMANI (PYROchemical processes Study for Minor ActiNIdes recycling in molten salt chlorides and fluorides) Project supported by Rosatom. The individual and joint solubility of UF₄, PuF₃ and CeF₃ in ternary LiF–NaF–KF and LiF- ThF₄-UF₄ melts was measured by method of isothermal saturation for the temperature range 550-800°C. The solubility measurement technique based on isothermal saturation was verified in LiF–NaF–KF eutectics for praseodymium trifluoride by the reflectance spectroscopy. The process under investigation was the extraction of lanthanum, neodymium, europium and samarium trifluorides from 73LiF-27BeF₂ melt (mole %) into liquid bismuth at 600-610°C. There were defined temperature dependences of kinematic viscosity and melting temperatures for molten 46.5LiF–11.5NaF–42KF; 73LiF-27BeF₂; 85LiF-15AlF₃ and 43.5LiF–24.3NaF–32.2UF₄ salt mixtures from liquidus temperature to 840°C.     

The Gas Chromatographic Determination of the Decomposition Products of Tributyl Phosphate

Abstract

The products formed from tributyl phosphate in different diluents have been quantitatively analyzed for components by gas chromatography. Methylation yields and limits of detection of di butyl phosphate are given.     

Analytische Fern- und Laborkontrolle bei der Wideraufarbeitung von Brennelementen aus KKW

The activity of Ni–Cr₂O₃ catalyst for the deuterium exchange reactions between hydrogen and ammonia, as well as for hydrogen and water vapor has been measured in dependence on the reaction temperature and on partial pressure of ammonia and water vapor, respectively. In both cases the activity in dependence on the partial pressure shows a maximum; the maximum of activity for H₂–NH₃ exchange is situated between partial pressures of 0.05 and 0.25, and for H₂–H₂O reaction between 0.25 and 0.5. The Ni–Cr₂O₃ catalyst is about 2.4 more active for the exchange reaction H₂–H₂O than for H₂–NH₃. For both reactions, chromia has a strong promoting effect, enhancing the activity per gram of catalyst of about three orders of magnitude in comparison with that of the Nickel black.