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Evangeliou N.,Institute of Nuclear Technology Radiation Protection | Evangeliou N.,National and Kapodistrian University of Athens | Florou H.,Institute of Nuclear Technology Radiation Protection | Scoullos M.,National and Kapodistrian University of Athens
Desalination and Water Treatment | Year: 2010

In the present study the particle export flux in the water column of 3 sampling stations (one of them near the pipeline outfall of the Waste Water Treatment Plant-WWTP of Psitalia) in the Eastern Saronikos gulf, Central Greece, is investigated based on the disequilibrium ratio of 234Th with its parent 238U. This approach is based on direct measurements of the activity concentrations of 234Th and calculated ones of 238U from the respective salinity measurements. From the derived results, the values of the activity concentrations of particulate and dissolved fraction of 234Th in the surface layer of the studied area range from 2.7 ± 1.4 to 3.8 ± 1.8 Bq m -3 and 13.2 ± 1.4 to 28.2 ± 1.9 Bq m 3 respectively, which educe fluctuation according to the station environmental features. Regarding the vertical distribution of radionuclides, the observed profile curves from the 3 sampling stations follow the same pattern of dispersion in the water column. However, the calculated export flux (sinking rate) of particles associated with 234Th results to a wide range of values depending on the sampling station. From the calculated residence times in the 3 stations, the station near the WWTP shows the longer residence time for the dissolved fraction, which is attributed to the sewage outflow. Besides, total suspended matter (TSM) and dissolved organic carbon (DOC) have been analyzed in the samples and the correlation coefficients with the particulate and dissolved 234Th have been calculated on the basis of the relation of 234Th cycling with particulate matter and organic substances. © 2010 Desalination Publications.

Catsaros N.,Institute of Nuclear Technology Radiation Protection | Gaveau B.,University Pierre and Marie Curie | Jaekel M.-T.,Ecole Normale Superieure de Paris | Maillard J.,Institut Universitaire de France | And 5 more authors.
Nuclear Engineering and Design | Year: 2012

Innovative nuclear reactor designs have been proposed, such as the Accelerator Driven Systems (ADSs), the "candle" reactors, etc. These reactor designs introduce computational nuclear technology problems the solution of which necessitates a new, global and dynamic computational approach of the system. A continuous feedback procedure must be established between the main inter-related parameters of the system such as the chemical, physical and isotopic composition of the core, the neutron flux distribution and the temperature field. Furthermore, as far as ADSs are concerned, the ability of the computational tool to simulate the nuclear cascade created from the interaction of accelerated protons with the spallation target as well as the produced neutrons, is also required. The new Monte Carlo code ANET (Advanced Neutronics with Evolution and Thermal hydraulic feedback) is being developed based on the GEANT3 High Energy Physics code, aiming to progressively satisfy all the above requirements. A description of the capabilities and methodologies implemented in the present version of ANET is given here, together with some illustrative applications of the code. © 2011 Elsevier B.V. All rights reserved.

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