A Comparison of Elastic and Mixed Line Rate Optical Slot Switching WDM Metro Rings

We propose optimal resource allocation techniques for two kinds of optical slot switching metro rings: 1) fixed mixed line rate (fMLR), where the rate of each transponder (TRX) is fixed and set at network planning time; and 2) elastic TRX, where the rate may adjust dynamically on a per-slot basis during network operation. We then numerically compare the cost (CAPEX or energy) of fMLR and elastic networks, and investigate the suitability of each of the two considered network technologies for several ring topologies, TRX cost models, and traffic distributions and loads

Characterization of the interactions between uranium and colloids in soil by on-line fractionation multi-detection methods

cited By 1; Conference of 5th International Conference on Uranium Mining and Hydrogeology, UMH 2008 ; Conference Date: 1 September 2008 Through 1 September 2008; Conference Code:103342International audienceIt is acknowledged that colloids can be important for determining contaminant availability and mobility. We have used size exclusion chromatography SEC and asymmetrical flow field-flow fractionation (As-FFFF) coupled with refractometry (RI), multi angle laser light scattering (MALLS), ultraviolet (UV) and inductively coupled plasma mass spectrometry (ICP-MS) detectors to study colloidal binding of uranium in leachates. The nature, the molecular and size distribution and the quantitative uranium distribution over the colloidal phase are obtained

Determination of 236U/238U ratios in environmental samples using ICP-MS/MS.

International audienceOn account of the virtual absence of 236U in nature and its abundance closely related to its provenance, the 236U/238U ratio has been commonly employed as a tracer to provide information in source identification for safeguard purposes, nuclear forensic studies and environmental monitoring. Due to their high performance capabilities, ICP-MS techniques are currently the most widely employed to perform radionuclide determination. However, in the case of 236U and due to its very low relative abundance, its determination is limited by the formation of 235U1H+ in the plasma and by the influence of the tail of the major isotope 238U (abundance sensitivity).In this work, we present an approach based on the ICP-MS/MS technology to determine 236U/238U ratios in environmental samples. The combination of two quadrupole-based mass filters, before (Q1) and after (Q2) the cell, in the MS/MS configuration provides abundance sensitivity values lower than 10-10, avoiding the influence of the 238U tail. In order to reduce the influence of the hydridebased interferences, different desolvation systems have been evaluated in relation to the sensitivity and the hydride rate obtained. In-cell ion-molecule reactions with O2 and CO2 have also been assessed to detect the uranium isotopes in mass-shift mode (Q1 U+ et61664; Q2 UO+). Best conditions provided a hydride rate value (235U16O1H+/235U16O+) in the order of 10-7. Finally, the methodology was validated with IRMM certified standards, and successfully applied to the determination of 236U/238U ratios in U samples from soils originating from the radioactive contamination plume caused by the Fukushima Daiichi Nuclear Power Plant accident. Ratios down to 10-9 have been obtained with precisions lower than 20

Production and characterization of plutonium dioxide particles as a quality control material for safeguards purposes

Plutonium (Pu) dioxide particles were produced from certified reference material (CRM) 136 solution (CRM 136-plutonium isotopic standard, New Brunswick Laboratory, Argonne, IL, U.S.A., 1987) using an atomizer system on December 3, 2009 after chemical separation of americium (Am) on October 27, 2009. The highest density of the size distribution of the particles obtained from 312 particles on a selected impactor stage was in the range of 0.7-0.8 μm. The flattening degree of 312 particles was also estimated. The isotopic composition of Pu and uranium (U) and the amount of Am were estimated by thermal ionization mass spectrometry (TIMS), inductively coupled plasma mass spectrometry (ICPMS), and α-spectrometry. Within uncertainties the isotopic composition of the produced particles is in agreement with the expected values, which were derived from the decay correction of the Pu isotopes in the CRM 136. The elemental ratio of Am to Pu in the produced particles was determined on the 317th and 674th day after Am separation, and the residual amount of Am in the solution was estimated. The analytical results of single particles by micro-Raman-scanning electron microscopy (SEM)-energy-dispersive X-ray spectrometry (EDX) indicate that the produced particles are Pu dioxide. Our initial attempts to measure the density of two single particles gave results with a spread value accompanied by a large uncertainty