86,662 research outputs found
Development and Validation of the ECART Code for the Safety Analysis of Nuclear Installations
No full textECART can simulate the thermal-hydraulic behavior of LWR and GCR plants under severe accident conditions together with the transport of radiotoxic substances. This tool is still under improvement and assessment for new applications in non-nuclear risk studies, new advanced and fusion reactors.
As regards accidents with fires within closed environments, specific models can simulate both thermal and chemical processes, accounting for combustion of gases and solids, as well as pool fires. The radiative heat transfer and the action of water sprays on atmosphere cooling and aerosol removal are properly taken into account, as verified by comparing the code predictions to full-scale experiments and to the consequences of fire accidents really occurred.
About its application on tokamak fusion plants, a large validation activity is underway, mainly based on the analyses of ad hoc experimental programs or code benchmark promoted inside EURATOM Fusion Technology Programme. The correct simulation of the main phenomena occurring in ICE and STARDUST facilities, as well as the comparison with the results of codes employed in the fusion safety studies, demonstrates the applicability of ECART models in performing a realistic prediction of the whole incidental sequence, accounting both thermal-hydraulics and dust transport also inside fusion plants
Heat transfer model for the effects of boundary conditions on transient vapor generation rates in pool fires - A Ecart numerical tool dynamics model
No full textMathematical model simulating some phenomena of the dynamical development of a pool fire. The model is finalized to quantify the vapour mass release rate, from the pool to the surrounding air, caused by pool liquid heating consequent of radiative and convective heat transfer phenomena between flame (and eventually other high temperature bodies) and pool. The lumped parameters grid theory is used to model the pool heat transfer and vapor generation phenomena and a “grid” model has been developed to extend the capability of ECART numerical tool (fast running computer code dedicated to predict the consequences of an accident in a risk installation). Model development was focused on the implementation inside such code.
After an approximate first validation of a model stand-alone version, it was implemented inside ECART. The first step model validation was carried out by comparison with references data and experimental pool fire test results performed by the model developer’s team. The maximum burning rate, the pool fire duration and the development of phases I (growth - transitory period corresponding to fire development), II (steady-state period corresponding to fully developed fire, with an about invariable burning rate) and III (exhaustion - transitory period preluding the end of fuel, during which both the size of flames and the burning rate decreased continuously up to fire extinction) are mainly analyzed.
The model approach based on the grid theory appears as a good mechanistic type and fast-running method for simulating the pool fire dynamics and performing interpretative and predictive analysis of fire scenarios including hydrocarbons pool fires. Particularly satisfying is the reproduction of phases I, II and III of the transient. We underline that grid model is focused only on the quantification of vapour mass flow released from the pool to surrounding air, and so it need a combustion model, flame model and other tools to perform fire scenario numerical simulations.
Then, from this point of view, the preliminary comparison between the results provided by the grid model and experimental data is considered rather satisfactory and so the model approach appears as a effective fast-running means for simulating the pool fire dynamics and it is worthy of further investigation and development
Validation of the ECART code for the safety analysis of fusion reactors
No full textRealistic calculation of the radiotoxic substances transport within a fusion facility requires a coupling among thermal–hydraulic, chemistry and aerosol-vapour models. The paper introduces the methodology adopted for the simulation of these phenomena with ECART, a code developed by a pool of Italian institutions with the support of European Union and EDF. In the past, this tool was successfully validated against the major source term tests applied to Light Water Reactor (LWR) safety and it is now employed in investigations about advanced LWRs and non-nuclear risk studies. It also contains information about chemical compounds involved in fusion reactor safety and simulates the related oxidation reactions. With regard to its application on fusion, a large validation activity was performed, mainly based on the analyses of experimental programs promoted inside the EURATOM Fusion Technology Programme. The correct simulation of main phenomena occurring in ICE and STARDUST facilities demonstrates the applicability of ECART in performing a realistic prediction of the whole sequence (thermal–hydraulics and dust transport) inside fusion plants
Pool fires - Heat and mass transfer model for ECART tool
No full textThis paper presents a mathematical model simulating some phenomena of the dynamical development of a pool fire. This model is finalized to quantify the vapor mass release rate, from the pool to the surrounding air, caused by pool liquid heating consequent of radiative and convective heat transfer phenomena between flame (and eventually other high temperature bodies) and pool. The lumped parameters grid theory is employed to model the pool heat transfer and vapor generation phenomena. The “grid” model has been developed to extend the capability of ECART numerical tool and his development was focused on the following implementation inside such code. After an approximate first validation of a model stand-alone version, it was implemented inside ECART. The model validation was carried out by comparison with references data and experimental pool fire test results performed by the model developer’s team. The maximum burning rate, the pool fire duration and the development of phases I (growth - transitory period corresponding to fire development), II (steady-state period corresponding to fully developed fire, with an about invariable burning rate) and III (exhaustion - transitory period preluding the end of fuel, during which both the size of flames and the burning rate decreased continuously up to fire extinction) are mainly analyzed. The model approach appears as a effective fast-running way for simulating the pool fire dynamics
Integrated Thermal-Hydraulic and Aerosol Analysis of the VANAM M3 Test Using the ECART Code
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