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Perianez R.,University of Seville | Thiessen K.M.,Oak Ridge Center for Risk Analysis | Chouhan S.L.,Canadian Nuclear Laboratories | Mancini F.,SOGIN S.p.A. | And 3 more authors.
Journal of Environmental Radioactivity | Year: 2016

An intercomparison of atmospheric dispersion models has been carried out for a hypothetical accident occurring in a nuclear power plant in the center of Spain. The accident consisted of a steam generator tube rupture, and two radionuclides have been considered for the exercise: 137-Cs and 131-I. Meteorological conditions and radionuclide release rates were supplied. Models provided deposition maps, timeintegrated concentrations in air and arrival times of the plumes to specific locations. The effect of the meteorological conditions used in the modelling was clear, with different behavior of the plume with neutral stability vs. stable conditions. The predicted arrival times of the plume at specific locations showed much less variability than deposition and air concentrations. This variability in part reflects the uncertainties inherent in atmospheric dispersion modelling and in the selection of parameter values, such as deposition velocities or diffusivities. © 2016 Elsevier Ltd.


PubMed | SOGIN S.p.A., Federal Authority for Nuclear Regulation, Chalk River Laboratories, Institute for Radiological Protection and Nuclear Safety and 3 more.
Type: | Journal: Journal of environmental radioactivity | Year: 2016

An intercomparison of atmospheric dispersion models has been carried out for a hypothetical accident occurring in a nuclear power plant in the center of Spain. The accident consisted of a steam generator tube rupture, and two radionuclides have been considered for the exercise: 137-Cs and 131-I. Meteorological conditions and radionuclide release rates were supplied. Models provided deposition maps, timeintegrated concentrations in air and arrival times of the plumes to specific locations. The effect of the meteorological conditions used in the modelling was clear, with different behavior of the plume with neutral stability vs. stable conditions. The predicted arrival times of the plume at specific locations showed much less variability than deposition and air concentrations. This variability in part reflects the uncertainties inherent in atmospheric dispersion modelling and in the selection of parameter values, such as deposition velocities or diffusivities.


Maggini A.,University of Pisa | Ciolini R.,University of Pisa | Pistelli S.,Sogin S.p.A. | Garneri E.,Sogin S.p.A.
Progress in Nuclear Energy | Year: 2016

The last step of nuclear power plants’ life is the decommissioning phase. Many strategies have been developed in the last decades; the main options consists in: immediate dismantling, safe storage and entombment. In Italy, due to the premature shutdown of nuclear power plants (NPP) as a consequence of the 1986 referendum following the Chernobyl accident, all the NPPs were shut down. Therefore, currently decommissioning activities are under way. In this work specifically the dismantling procedures of the “Enrico Fermi” NPP reactor pressure vessel (RPV) are dealt with. The attention is so focused on the optimization of number, position and length of the Internals cuts, optimization of volume and number of waste containers, and of the dose rates, according to the imposed site and the transport requirements. The systematic approach developed to identify the optimum dismantling solution is presented and discussed. To the intent three solutions have been identified as more advantageous. In addition, the evaluation of dose rate outside the container has been performed by means of VISIPLAN software, in order to guarantee the respect of the limits imposed by National and International regulations. The obtained results suggest that the cutting of Zircalloy elements in correspondence of the gap between two non-consecutive central stumps, with the possibility to re-arrange the element, led to a significant reduction of the number of containers, with consequent decrease of the stowed RWs volume and overall supplying costs of the activity. © 2016 Elsevier Ltd


Lo Frano R.,University of Pisa | Pugliese G.,University of Pisa | Nasta M.,Sogin S.p.A
Nuclear Engineering and Design | Year: 2014

The casks or packaging systems used for the transportation of nuclear materials, especially spent fuel elements, have to be designed according to rigorous acceptance requirements, like the IAEA ones, in order to provide protection to human beings and environment against radiation exposure and contamination. This study deals with the free drop test of an Italian design packaging system to be used for the transportation of low and intermediate level radioactive wastes. Impact drop experiments were performed in the Lab. Scalbatraio of the DICI - University of Pisa. Dynamic analyses too have been carried out, by refined models of both the cask and target surface to predict the effects of the impact shock (vertical drop) on the package. The experimental tests and numerical analyses are thoroughly compared, presented and discussed. The numerical approach shows to be suitable to reproduce with good reliability the test situations and results. © 2014 Elsevier B.V. All rights reserved.


Pilo F.,University of Pisa | Fontani E.,Sogin Spa | Aquaro D.,University of Pisa
Nuclear Engineering and Design | Year: 2014

This paper deals with laboratory tests that analyze the acid attack of metallic samples, contaminated by Co60 in the Caorso nuclear power plant in Italy. The main aim was to establish the working parameters of the decontamination plant for metallic components. The study took into consideration the steam piping, located in the turbine building, that is, piping from the main header to the high pressure turbine stage, as well as other steam piping, connecting different turbine stages or that had other functions. The Co 60 is produced in the reactor vessel by neutron capture in the iron nuclei of the materials located in the pressure vessel. The coolant erodes the steel surfaces and deposits these products along the piping. In the first phase of the activity the chemical decontamination process was simulated in the laboratory, in particular the acid attack and the subsequent high pressure water washing. For the various parts of the piping (straight lines, bends, intersections) smear tests enabled the radioactivity distribution to be determined. Metallographic analyses of the samples, core bored by the piping, determined the composition of the deposit (crud) on the internal surface of the components and the radioactivity along the thickness of the crud, and consequently the time of the acid attack in order to obtain the Clearance. Numerical simulations of the Co60 deposition by means of CFD codes are currently being carried out in order to compare the results to those obtained experimentally. This will enable us to classify the systems from a radiological point of view by estimating 'a priori' the time required for decontamination. © 2013 Elsevier B.V.


Tripputi I.,Sogin S.p.A.
Atoms for Peace | Year: 2013

After a short review of radioactive waste origins and inventories in Italy, the paper deals with the current major challenges that Italy has to cope with to pursue its radioactive waste sustainable management and safe disposal. Site restoration by Sogin of dismissed nuclear installations is part of the waste management challenge. The importance of assuring the highest levels of safety culture among the employees and an overall manpower, adequate both in number and qualification according to the best international good practices, is underlined and included in the largest effort of the knowledge management project. Sogin is coping with the above challenges also with the Italian School on Radioprotection, Safety and Environment, a unique centre of know-how and know-why transfer in Italy. © 2013 Inderscience Enterprises Ltd.


Perrone L.,Sogin S.p.A.
Atoms for Peace | Year: 2013

The purchasing and procurement policy of the Italian Sogin company, which is engaged in the reclamation of nuclear sites and management of radioactive waste, helps to ensure safety and quality during all work stages so as to protect workers, citizens and the environment. © 2013 Inderscience Enterprises Ltd.


Bonavigo L.,Polytechnic University of Turin | De Salve M.,Polytechnic University of Turin | Zucchetti M.,Polytechnic University of Turin | Annunziata D.,SOGIN S.p.A.
Progress in Nuclear Energy | Year: 2010

This paper concerns the cutting operations and spread of radioactive contamination during the dismantling of a nuclear metal component, carried on with thermal cutting. Our analysis relates to E. Fermi nuclear power plant (Trino Vercellese, Italy), a Pressurized Water Reactor, which had an electrical power of 272 MWe, and was in operation from 1965 to 1987. The plant included four primary loops and a pressurizer, each loop equipped with a circulation pump and a steam generator. The criteria for choosing between all the cutting technologies available for dismantling a nuclear component are considered, as well as the methodology allowing the characterization of the primary system. Some cutting scenarios are proposed, with a calculation methodology to evaluate the amount of material involved in main components segmentation. Afterwards, exposition risks are highlighted and the possibility of safely cutting this system is pointed out. © 2009 Elsevier Ltd. All rights reserved.


Contessa G.M.,ENEA | Grandi C.,Instituto Nazionale per lAssicurazione Contro Gli Infortuni sul Lavoro INAIL | Scognamiglio M.,Sogin SpA | Genovese E.,Ospedale Pediatrico Bambino Gesu | Sandri S.,ENEA
Annali dell'Istituto Superiore di Sanita | Year: 2016

The accident at Tokyo Electric Power Company's (TEPCO's) Fukushima Daiichi nuclear power plant (NPP) has been one of the dominant topic in nuclear safety and it has brought new attention on the matter of accidents in NPPs due to external events related to natural causes. Climate change has risen new risks and the growing probability of extreme external events has increased exposure and vulnerability of workers in the nuclear sector. However extreme natural events are a threat not only to NPPs but to all facilities dealing with radioactive material and in an emergency scenario they can affect the effectiveness and implementation of safety devices and procedures and also prevent communications, causing delays in the readiness of response. It is clear that adaptation strategies are necessary to cope with emerging changes in climate and a new nuclear safety culture is growing, that addresses accidents initiated not only by internal but also by external events.


PubMed | Instituto Nazionale per lAssicurazione contro gli Infortuni sul Lavoro INAIL, Ospedale Pediatrico Bambino Gesu, Sogin SpA and ENEA
Type: Journal Article | Journal: Annali dell'Istituto superiore di sanita | Year: 2016

The accident at Tokyo Electric Power Companys (TEPCOs) Fukushima Daiichi nuclear power plant (NPP) has been one of the dominant topic in nuclear safety and it has brought new attention on the matter of accidents in NPPs due to external events related to natural causes. Climate change has risen new risks and the growing probability of extreme external events has increased exposure and vulnerability of workers in the nuclear sector. However extreme natural events are a threat not only to NPPs but to all facilities dealing with radioactive material and in an emergency scenario they can affect the effectiveness and implementation of safety devices and procedures and also prevent communications, causing delays in the readiness of response. It is clear that adaptation strategies are necessary to cope with emerging changes in climate and a new nuclear safety culture is growing, that addresses accidents initiated not only by internal but also by external events.

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