Relationship between Extremal and Sum Processes Generated by the same Point Process

2000 Mathematics Subject Classification: Primary 60G51, secondary 60G70, 60F17.We discuss weak limit theorems for a uniformly negligible triangular array (u.n.t.a.) in Z = [0, ∞) × [0, ∞)^d as well as for the associated with it sum and extremal processes on an open subset S . The complement of S turns out to be the explosion area of the limit Poisson point process. In order to prove our criterion for weak convergence of the sum processes we introduce and study sum processes over explosion area. Finally we generalize the model of u.n.t.a. to random sample size processes

Upper and Lower Bounds for Ruin Probability

In this note we discuss upper and lower bound for the ruin probability in an insurance model with very heavy-tailed claims and interarrival times

Lanthanum Activity in La–U–Ga–X Systems (X = Al or In)

Lanthanum activity was determined for the first time in La–U–Ga–X (X = Al or In) alloys. Ga–In and Ga–Al alloys were taken in the eutectic composition (21.8 wt.% In and 1.6 wt.% Al, respectively). Measurements were performed between 573 and 1073 K employing the e.m.f. method. Keywords: Lanthanum; Uranium; Gallium-Indium Eutectic; Gallium-Aluminium Eutectic; Activity; Thermodynamics

The effect of fission product elements on the behavior of uranyl species in alkali chloride melts: A contribution towards reprocessing spent oxide fuels

The reactions of uranyl(VI) containing chloride melts with molybdenum, niobium, zirconium and palladium were studied using high temperature electronic absorption spectroscopy. Depending on the nature of the added element uranium is reduced to uranyl(V) and uranium(IV) chloro-species and UO2. Palladium, niobium and zirconium can all be removed from a uranyl(VI)-containing melt using molybdenum metal and the melt can then be purified from Mo(III) ions by bubbling Cl2 gas. Such approach can be employed for removal a number of fission product elements from molten chloride baths during reprocessing spent oxide fuels. ©The Electrochemical Society.Physical and Analytical Electrochemistry;Electrodeposition;Energy Technolog

Speciation of rhenium in chloride melts: Spectroscopic and electrochemical study

Speciation of rhenium in high-temperature alkali chloride-based melts was studied using electronic absorption and IR spectroscopy of molten salts and diffuse reflectance spectroscopy of quenched melts. Rhenium was added to the melts by anodic dissolution of the metal (at anodic current densities of 0.005-0.05 A/cm2), by reacting Re and ReO2 with Cl 2 and HCl, and by dissolving K2[ReCl6]. The melts included 3LiCl-2KCl and NaCl-2CsCl eutectics, an NaCl-KCl equimolar mixture, and pure NaCl, KCl and CsCl between 450 and 850 °C. Rhenium was present in the melts as Re(IV) hexachloro-ions, [ReCl6]2-; no evidence of species containing rhenium in oxidation states below four was obtained. The kinetics of [ReCl6]2- disproportionation in molten alkali chlorides were investigated, and the IR spectra of [ReO 4]- ions in molten CsCl-CsI and CsI were measured for the first time. © 2008 Verlag der Zeitschrift für Naturforschung, Tübingen

On the formation of uranium(V) species in alkali chloride melts

Uranyl(V) species are normally unstable in solutions but are here shown to be stable in high-temperature chloride melts. Reactions leading to the formation of UO2Cl4 3- ions were studied, including thermal decomposition and chemical reduction of uranyl(VI) chlorospecies in various alkali chloride melts (LiCl, 3LiCl-2KCl, NaCl-KCl, and NaCl-2CsCl) at 550-850 °C. Decomposition of UO2Cl4 2- species under reduced pressure, with inert gas bubbling through the melt or using zirconium getter in the atmosphere results in the formation of UO 2Cl4 3- and UO2. Elemental tellurium, palladium, silver, molybdenum, niobium, zirconium, and hydrogen, as well as niobium and zirconium ions were tested as the reducing agents. The outcome of the reaction depends on the reductant used and its electrochemical properties: uranyl(VI) species can be reduced to uranyl(V) and uranium(IV) ions, and to uranium dioxide. © 2010 IUPAC

Behaviour of rare earth elements in molten salts in relation to pyrochemical reprocessing of spent nuclear fuels

The kinetics of chlorination of lanthanide oxides (by Cl2 and HCl) and precipitation of lanthanide phosphates was studied by in situ electronic absorption spectroscopy in 3LiC1-2KC1 and NaCl-KCl melts at 400-750°C Products of the chlorination are the corresponding hexachlorospecies, LnCl63-, and the rate of chlorination increases with increasing temperature. Composition of the precipitated phosphates depends on the melt composition and 1.5-5 fold excess of phosphate, depending on the nature of lanthanide, is needed for the complete removal of the lanthanides from the melt. Over three hours are required for completing the reaction of phosphate precipitation. copyright The Electrochemical Society.Electrochemical Society, Phys. Anal. Electrochem. Div.;Electrochemical Society, Electrodeposition Division;Electrochemical Society, High Temperature Materials Division;Electrochemical Society, Battery Division;Electrochemical Society, Energy Technology Divisio

Corrosion of stainless steels in NaCl-KCl based melts

Corrosion behavior of stainless steel types AISI 316L, 316Ti and 321 was studied at 750 °C in NaCl-KCl equimolar melts. Iron, chromium and manganese species constitute the major corrosion products. The following mechanism of stainless steel corrosion in molten chlorides was proposed: 1) chemical interaction between the alloy and the salt intensified by the formation of microgalvanic pairs; 2) formation of chromium and molybdenum carbide-containing phases in steel as a result of heating to 750 °C; 3) additional formation of galvanic pairs between the grains of austenitic alloys and the carbide phases at the grain boundaries resulting in enhanced intergranular corrosion. ©The Electrochemical Society.Physical and Analytical Electrochemistry;Electrodeposition;Energy Technolog

PALLADIUM REDUCTION FROM MOLTEN EUTECTIC MIXTURE OF LITHIUM, POTASSIUM AND CAESIUM CHLORIDES

Palladium reduction processes were studied employing cyclic voltammetry technic. LiCl–KCl-CsCl eutectic melt was used as a solvent. Temperature dependences of standard palla-dium deposition potentials were determined in the temperature range of 300–800ºC

ELECTRONIC ABSORPTION SPECTRA OF URANIUM(V) IONS IN ALKALI CHLORIDE MELTS

Electronic absorption spectra of uranium(V) ions were recorded in the melts based on individual alkali chlorides and their mixtures. The spectra were measured between 350 and 850 oC. The effect of temperature and alkali cations forming the second coordination sphere on the spectra is discussed