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According to the traditional wisdom, geomagnetically induced currents (GIC) should occur rarely at mid-to-low latitudes, but in the last decades a growing number of reports have addressed their effects on high-voltage (HV) power grids at mid-to-low latitudes. The growing trend to interconnect national power grids to meet regional integration objectives, may lead to an increase in the size of the present energy transmission networks to form a sort of super-grid at continental scale. Such a broad and heterogeneous super-grid can be exposed to the effects of large GIC if appropriate mitigation actions are not taken into consideration. In the present study, we present GIC estimates for the Uruguayan HV power grid during severe magnetic storm conditions. The GIC intensities are strongly dependent on the rate of variation of the geomagnetic field, conductivity of the ground, power grid resistances and configuration. Calculated GIC are analysed as functions of these parameters. The results show a reasonable agreement with measured data in Brazil and Argentina, thus confirming the reliability of the model. The expansion of the grid leads to a strong increase in GIC intensities in almost all substations. The power grid response to changes in ground conductivity and resistances shows similar results in a minor extent. This leads us to consider GIC as a non-negligible phenomenon in South America. Consequently, GIC must be taken into account in mid-to-low latitude power grids as well. [ABSTRACT FROM AUTHOR]

This paper reviews the main results on the long-term behavior of SON68 nuclear glass towards alpha decay accumulation. The effects of the radiation damage induced by alpha decay were investigated by doping a glass with a short-lived actinide 244 Cm, by using ionic irradiations and by molecular dynamic simulations. The analysis of the behavior of the glass structure subjected to ballistic effects with various spectroscopic studies has identified some local order changes around born and silicon atoms. Moreover a modification of the medium-range order has also been demonstrated through changes in the bond angles between network formers and broadening of the ring size distributions, indicating increasing disorder of the glass structure. This structural evolution induced by alpha decays would be driven by the reconstruction of the glass disorganized by displacement cascades of the recoil nuclei, freezing a glass structure with a higher fictive temperature. This “ballistic disordering (BD) fast quenching” event induce a new glassy state characterized by a higher enthalpy state. [ABSTRACT FROM AUTHOR]

This paper's focus is the failure and hardness properties of pure amorphous silica (Corning 7980 ® ) after β-irradiation at different doses (0-2 GGy). Crack propagation takes place in the SCC regime (10 -7 -10 -10 m.s -1 ) and Vickers indentation techniques probe the hardness properties of the samples. Irradiation is found to create point defects which mainly include E’ centers, Non-Bridging Oxygen Hole Centers and Peroxy Radicals. β-irradiation herein invokes minor changes in the structure. A small effect of β-irradiation on SCC and hardness variations cannot be eliminated, despite minute variations in the SCC and the hardness properties. [ABSTRACT FROM AUTHOR]

Abstract: The mechanisms of oxidizing dissolution of spent MOX fuel (MIMAS TU2®) subjected to water radiolysis were investigated experimentally by leaching spent MOX47 fuel samples in pure water at 25°C under different oxidizing conditions (with and without external gamma irradiation); the leached surfaces were characterized by Raman spectroscopy. The highly oxidizing conditions resulting from external gamma irradiation significantly increased the concentration of plutonium (Pu(V)) and uranium (U(VI)) compared with a benchmark experiment (without external irradiation). The oxidation behavior of the plutonium-enriched aggregates differed significantly from that of the UO2 matrix after several months of leaching in water under gamma irradiation. The plutonium in the aggregates appears to limit fuel oxidation. The only secondary phases formed and identified to date by Raman spectroscopy are uranium peroxides that generally precipitate on the surface of the UO2 grains. Concerning the behavior of plutonium, solution analysis results appear to be compatible with a conventional explanation based on an equilibrium with a Pu(OH)4(am) phase. The fission product release – considered as a general indicator of matrix alteration – from MOX47 fuel also increases under external gamma irradiation and a change in the leaching mode is observed. Diffusive leaching was clearly identified, coinciding with the rapid onset of steady-state actinide concentrations in the bulk solution. [Copyright &y& Elsevier]

OBJECTIVE: This study was undertaken to determine whether the arcus tendineus fascia pelvis (ATFP) can be accurately identified from the paravaginal space (PVS) without entering the retropubic space (RPS). STUDY DESIGN: Eight patients undergoing vaginal paravaginal repair were enrolled. The paravaginal dissection was completed to the most cephalad portion of the PVS without entering the RPS. The apex of each PVS was stained with methylene blue. The RPS was entered, the ATFP visualized, and 4 sutures were placed along its length to be used for the repair. The perpendicular distance between each suture and the most cephalad area of stain was measured. RESULTS: The mean distance from the perceived to actual ATFP at each suture point (1-4) was 3.5 cm, 2.75 cm, 2.0 cm, and 0.91 cm, respectively. CONCLUSION: In these 8 cases, the RPS had to be entered to accurately identify the ATFP. The degree of error increases as the ischial spine is approached (P < .001). [ABSTRACT FROM AUTHOR]

Abstract: Understanding the effect of irradiation in UO2 is a major issue for nuclear industry and for the design of irradiation resistant materials. We have previously evidenced irradiation induced defects in UO2 that can be characterized by Raman spectroscopy. Here we present the Raman characterization of these defects as a function of temperature. UO2 samples were irradiated with 25MeV He2+ ions at room temperature and then heated at different temperature without irradiation. Some samples were also irradiated at high temperature. Heat treatment after irradiation evidenced one annealing temperature on Raman spectra. This annealing temperature is shifted to higher values when the samples are simultaneously heat treated and irradiated. It is compared to the annealing temperatures that are reported in literature on irradiated UO2. This indicates that Raman observed defects would be point defects on uranium sublattice. This attribution is consistent with the one we previously proposed. [Copyright &y& Elsevier]

Abstract: The effects of the nuclear reaction 10B(n, α)7Li on the properties and structure of a sodium borosilicate glass were analysed by density, hardness and fracture toughness measurements, Raman and Nuclear Magnetic Resonance spectroscopy and Transmission Electronic Microscopy (TEM) characterization. The TEM observations showed a homogeneous irradiated glass structure up to the nanometer scale. Modifications of the local order around the main cations were noticed, mainly a slight decrease of the mean boron coordination number and an increase of non-bridging oxygen concentrations. At the glass medium range order, the appearance of the D2 Raman band and a modification of the Si–O–Si angle distribution were also observed after irradiation. A comparison with other irradiation conditions with Swift Heavy Ions (Kr with 74MeV) and Gold irradiation (with energies ranging from 1 to 7MeV) is presented. Raman spectroscopy showed a similar final structure for irradiation conditions under which the glass evolutions are controlled by electronic energy loss in the ion tracks formation regime or nuclear energy loss. Despite important differences in energy deposition regimes, the similarities observed between the final glass structures suggest that structural evolutions are controlled by the glass relaxation mechanisms during the high quenching rate step that follows the energy deposition step. [Copyright &y& Elsevier]

Abstract: A defect formation mechanism is proposed in order to explain recently observed Raman defect lines on He2+ irradiated UO2. These defects are formed by electronic stopping of He2+ even though their dE/dx is less than the threshold for track formation. Referring to literature of self-trapped excitons, this mechanism is divided in three steps: creation of electronic defects by electron stopping, stabilization of self-trapped excitons on uranium sublattice and, after accumulation of self-trapped excitons, formation of structural defect on the oxygen sublattice. This proposed mechanism still needs to be validated by more experimental evidence of the Magneli type defect proposed to be the self-trapped excitons on uranium lattice. [Copyright &y& Elsevier]