Search results for "Clad"
showing 10 items of 495 documents
Study of the fuel/clad bonding of pressurized water reactors fuel rods
2017
Durability and integrity of materials used in nuclear power plants is a continuous concern of the nuclear power plant owners and developers. During the fuel irradiation in pressurised water reactors (PWR), the whole fuel-clad assembly is subjected to several irradiation-induced modifications. In particular, the fuel element expansion concomitant to the cladding creeping, leads to the contacting of both materials, allowing the oxidation of the inner side of the clad, locally at first, then tending to affect the overall cladding inner surface. At high burnup, a bonding of the fuel periphery with the metallic cladding can be observed, forming the fuel-clad bonding phenomenon, which conditions …
Physical, chemical and mechanical evolution of the fuel-cladding interface in irradiated PWR fuel rods
2022
During the fuel irradiation in nuclear reactor, the fuel-cladding assembly is exposed to several irradiation-induced modifications. The fuel swelling coupled with cladding creep leads to a contact between the fuel and the cladding. The oxygen transport from the UO2 fuel to the zirconium layer induces progressively the Zr-cladding oxidation. This oxidation is initially local with the formation of islets. Then, with the increasing burnup of the fuel, it conducts to a continuous layer of about 8-µm thickness, localized at the fuel-cladding interface. At high burnup, zirconia growths anchor themselves in the periphery of the fuel (which is restructured) leading to pellet/cladding interlocking. …
Extreme statistics in Raman fiber amplifiers : influence of pump depletion and dispersion
2010
OSA 2010 NonLinear Photonics Best Student Poster Award; International audience; We experimentally and theoretically investigate the influence of pump depletion effects on extreme statistics observed in fiber Raman amplifiers. We also report on the impact of the dispersion of the fiber.
High Order Harmonic Passive Mode-Locking In Double-Clad Fiber Laser
2009
We report passive mode-locking of a soliton erbium-doped double-clad fiber laser operating at the 322nd harmonic of the fundamental cavity frequency. Repetition rates scalable up to 3 GHz have been obtained with a pulse duration of about 1 ps and a pulse energy of about 18 pJ. The supermode suppression at the 322nd harmonic is better than 25 dB. The dynamics of emergence of this operating regime is also presented revealing a very long timescale.
Radiation-induced defects in fluorine-doped silica-based optical fibers: Influence of a pre-loading with H2
2009
International audience; We investigated the effects of 10-keV X-ray radiation on the transmission properties of F-doped optical fibers in the 200–850 nm range of wavelengths (1.5–6 eV). We also studied the influence of pre-loading this kind of fibers with hydrogen on its radiation sensitivity. Our results showed that, for our experimental conditions (pre-treatment with H2 several months before irradiation with diffusion of all the H2 out the fiber core and cladding before X-ray exposure), this pre-treatment increases the radiation-induced attenuation in the ultraviolet part (200–300 nm) of the spectrum. A previous H2-loading has no influence at greater wavelengths. The nature of the radiati…
Modificētus mālus saturošu materiālu antimikrobiālā iedarbība
2017
Mikroorganismu attīstība uz dažādiem materiāliem izsenis ir ietekmējusi cilvēka dzīves kvalitāti. Vieni no biežāk būvmateriālos sastopamajiem mikroorganismiem ir sēnes. Pētījuma mērķis bija noskaidrot modificēta māla un tā piedevu ietekmi uz mikroskopisko sēņu attīstību uz dažādiem būvniecības materiāliem. Pētīti 12 ar dažādu metālu joniem modificētu māla pulvera paraugu, kas 0,2% un 2% koncentrācijas iestrādāti iesala agara barotnēs, ietekme uz Cladosporium herbarum un Alternaria alternata augšanu. Tika pētīta sēņu attīstība uz dažāda veida krāsām, ar lineļļu apstrādātiem kokmateriāliem un saplākšņa materiāliem. Ietekme tika novērota sešiem no divpadsmit māla pulvera paraugiem Alternaria a…
Usutu virus activity in Austria, 2001–2002
2003
Usutu virus (USUV), a member of the mosquito-borne clade within the Flaviviridae family, was responsible for avian mortality in Austria in 2001. In 2002, the virus continued to kill birds, predominantly blackbirds. High numbers of avian deaths were recorded within the city of Vienna and in surrounding districts of the federal state of Lower Austria, while single die-offs were noticed in the federal states of Styria and Burgenland. A total of 72 birds were submitted for laboratory examination, 30 of which tested positive for USUV by immunohistochemistry and/or polymerase chain reaction. Laboratory-confirmed cases of USUV infection originated from the federal states of Vienna and Lower Austri…
Differences in allozyme patterns between Diaphanosoma brachyurum and Diaphanosoma mongolianum, as revealed in Central European populations
1995
Recent taxonomic revisions in the genus Diaphanosoma have made the uncertainty in species discrimination with morphological characters obvious. Therefore species characterization on a genetic basis seems to be required. Here we examined the genetic structure of two Diaphanosoma mongolianum populations and three Diaphanosoma brachyurum populations in Central Europe by allozyme electrophoresis. A genetic differentiation between both species was evident. 5 out of 9 tested loci carried diagnostic alleles. Both species differed in their habitat choice: D. mongolianum was adapted to higher trophic levels than D. brachyurum. Co-occurrence was observed in a eutrophic lake. Populations sampled from …
Increase of rotifer diversity after sewage diversion in the hypertrophic lagoon, Albufera of Valencia, Spain
2001
The Albufera of Valencia is a large oligohaline hypertrophic lagoon, regulated by sluice gates according to the needs of the surrounding rice field cultivation. It is in a turbid state with permanent cyanobacterial blooms. A slight improvement was detected after diversion in the 1990s of part of the sewage flowing into it. After sewage diversion, we found that: (1) Chlorophyll concentration and rotifer densities decreased; (2) Rotifer proportions declined, due mainly to a relative increase in cladocerans; (3) Rotifer diversity increased. The two dominants of the 1980s, Polyarthra spp. in the colder period and Brachionus angularis in the warmer one, reverted after sewage diversion to a more …
Response of a shallow Mediterranean lake to nutrient diversion: does it follow similar patterns as in northern shallow lakes?
2005
Summary 1. In view of the paucity of data on the response of warm shallow lakes to reductions in nutrient loading, this paper presents a long-term limnological data set to document changes in the food-web of a shallow Mediterranean lake (Lake Albufera, Valencia, Spain) that has experienced reductions in phosphorus (P) (77%) and nitrogen (N) (24%) loading following sewage diversion. 2. Nine years after sewage diversion, P concentration in the lake was reduced by 30% but remained high (TP = 0.34 mg L−1), although the mean water retention time in the lake was only 0.1 years. Nitrate concentrations did not significantly change, probably because the lake continued to receive untreated effluents …