L.A. Poggi

Numerical simulations as tool to predict chemical and radiological hazardous diffusion in case of nonconventional events

CFD (Computational Fluid Dynamics) simulations are widely used nowadays to predict the behaviour of fluids in pure research and in industrial applications. This approach makes it possible to get quantitatively meaningful results, often in good agreement with the experimental ones. The aim of this paper is to show how CFD calculations can help to understand the time evolution of two possible CBRNe (Chemical-Biological-Radiological-Nuclear-explosive) events: (1) hazardous dust mobilization due to the interaction between a jet of air and a metallic powder in case of a LOVA (Loss Of Vacuum Accidents) that is one of the possible accidents that can occur in experimental nuclear fusion plants; (2) toxic gas release in atmosphere. The scenario analysed in the paper has consequences similar to those expected in case of a release of dangerous substances (chemical or radioactive) in enclosed or open environment during nonconventional events (like accidents or man-made or natural disasters).

Flow Motion and Dust Tracking Software for PIV and Dust PTV

Dust resuspension and mobilization in case of loss of vacuum accidents and loss of coolant accidents is an important safety issue for Tokamaks. The Quantum Electronics and Plasma Physics Research Group of the University of Rome Tor Vergata has produced an experimental facility, STARDUST-Upgrade, able to replicate these accidents and to obtain fluid dynamic characterization and dust mobilization information in order to validate CFD models. The authors decided to implement two non-intrusive optical methods, particle image velocimetry (PIV) and shadowgraph technique. Two software programs have been developed to compute numerical values from PIV and Shadowgraph frames, namely Flow Motion and Dust Tracking Software. Flow Motion Software has the capability to extract flow velocity field analyzing consecutive frames. Dust Tracking Software follows the path of single objects (i.e., dust particles) tracing their velocity, direction, and position over time. Two experiments have been realized for each software program in order to validate them: cigarette smoke and burning paper plume have been used for flow motion software, while tungsten dust and flour mobilization have been used for dust tracking software.

Non-invasive assessment of dust concentration and relative dustiness in a dust cloud mobilized by a controlled air inlet inside STARDUST-U facility

In the framework of the on-going research on dust explosion, both a physical and chemical theory and numerical models extensively validated are yet to be found. In order to develop control tools essential to continuously measure a set of key parameters for dust explosiveness, the authors performed stainless steel dust mobilization experiments inside STARDUST-U facility using a controlled air inlet whose features are comparable to the ones typical of several industrial scenarios. Dust particles velocity and concentration within the cloud were measured with non-invasive diagnostics involving imaging techniques and a custom software. The STARDUST-U facility showed capability to provide useful data for validation of numerical models. Furthermore, a custom software allowed to determine the relative dustiness, defined as a non-dimensional parameter proportional to dust concentration and not dependent on dust mass and vessel volume. This study is a first step towards a complete integration of the air inlet modeling and dust tracking software, in order to determine dustiness inside the cloud. The authors believe that the imaging techniques presented could represent a valuable tool for industry in order to perform continuous monitoring of vessels with the aim of controlling and mitigating dust explosion risks.

Lidar and Dial application for detection and identification: A proposal to improve safety and security

Nowadays the intentional diffusion in air (both in open and confined environments) of chemical contaminants is a dramatic source of risk for the public health worldwide. The needs of a high-tech networks composed by software, diagnostics, decision support systems and cyber security tools are urging all the stakeholders (military, public, research & academic entities) to create innovative solutions to face this problem and improve both safety and security. The Quantum Electronics and Plasma Physics (QEP) Research Group of the University of Rome Tor Vergata is working since the 1960s on the development of laser-based technologies for the stand-off detection of contaminants in the air. Up to now, four demonstrators have been developed (two LIDAR-based and two DIAL-based) and have been used in experimental campaigns during all 2015. These systems and technologies can be used together to create an innovative solution to the problem of public safety and security: the creation of a network composed by detection systems: A low cost LIDAR based system has been tested in an urban area to detect pollutants coming from urban traffic, in this paper the authors show the results obtained in the city of Crotone (south of Italy). This system can be used as a first alarm and can be coupled with an identification system to investigate the nature of the threat. A laboratory dial based system has been used in order to create a database of absorption spectra of chemical substances that could be release in atmosphere, these spectra can be considered as the fingerprints of the substances that have to be identified. In order to create the database absorption measurements in cell, at different conditions, are in progress and the first results are presented in this paper.

A novel integrated approach for the hazardous radioactive dust source terms estimation in future nuclear fusion power plants

An open issue still under investigation by several international entities working on the safety and security field for the foreseen nuclear fusion reactors is the estimation of source terms that are a hazard for the operators and public, and for the machine itself in terms of efficiency and integrity in case of severe accident scenarios. Source term estimation is a crucial key safety issue to be addressed in the future reactors safety assessments, and the estimates available at the time are not sufficiently satisfactory. The lack of neutronic data along with the insufficiently accurate methodologies used until now, calls for an integrated methodology for source term estimation that can provide predictions with an adequate accuracy. This work proposes a complete methodology to estimate dust source terms starting from a broad information gathering. The wide number of parameters that can influence dust source term production is reduced with statistical tools using a combination of screening, sensitivity analysis, and uncertainty analysis. Finally, a preliminary and simplified methodology for dust source term production prediction for future devices is presented.

Economic Impact of Biological Incidents: A Literature Review

According to the European Union’s point of view, no public authority can afford to ignore chemical, biological, radiological, nuclear, and explosive (CBRNe) threat given its potentially very significant consequences in terms of human life and economic effects. EU carried out investigation activities aiming to the implementation of biological actions like the adoption of risk management standards, the codes of conduct in bio issues for laboratories, and the funding of research projects on biosecurity activities. Since CBRNe incidents and specifically biological events can be profiled through methodological approaches, this paper has the purpose to review the literature production on that field. In the paper, we analyzed different approaches passing through Kaufmann et al., who first modeled economic analyses of a theoretical biological postattack of biological warfare, to Enders and Sandler, who examined the consequence scenarios for biological attacks. Moreover, from Ramseger et al., with his methodology to assess the economic impact of the CBRNe threats, and finally to Cavallini et al., who tried to build an impact profile of this kind of incidents to support the policymakers’ strategic decisions after the events, the paper has the intent to seek the limits and the possible future scenarios of these literature aiming to refine the impact profiling of the biological events and study the related economic costs.

Imaging to study dust re-suspension phenomena in case of loss of vacuum accidents inside the pharmaceutical industries

Dust explosion is one of the most dangerous hazards in process industries. The several accidents happened in the last hundred years led to guidelines to prevent and mitigate industries. Unless these, dust explosion events still happen. Development of advanced tools is necessary to reach a definitive way to face these threats. Dust concentration, particle size, velocity, moisture and turbulence of dust are important parameters in determination of dust explosion severity. Therefore, in industries with high risk of dust explosion, these parameters should be monitored and controlled. In this work, the authors show their experimental facility and software to monitor dust velocity. The experiments are performed inside STARDUST-U, an experimental facility to test dust re-suspension in case of Loss of Vacuum Accidents.

3D numerical simulations of a LOVA reproduction inside the new facility STARDUST-UPGRADE

A loss of vacuum in a vessel, containing or not dust, is the typical case study considered in the STARDUST-UPGRADE facility of the Quantum Electronics and Plasma Group of the university of Rome Tor Vergata. This kind of accident was simulated numerically, without including the presence of dust, for two mass flow rates and three different inlet ports (C, E and F). Numerical settings are explained and the results obtained in each case are shown and discussed. At the end of the work, conclusions about what seen and further foreseen developments of this research are presented.

A novel facility to investigate dust mobilization in confined environments with applications to the security of the pharmaceutical industry

Many pharmaceutical industries all around the world are facing the problem of dust mobilization during the productive process of medicines. This mobilization can be dangerous for the safety of the operators working in the factory and for the safety of the factory itself. It is therefore necessary to develop predictive models to simulate and forecast dust mobilization. The Quantum Electronics and Plasma Physics (QEP) Research Group of the University of Rome Tor Vergata has developed a facility to experimentally replicate dust mobilization in different critical conditions in an enclosed environment. The measurements performed with diagnostics available in the facility, provide the boundary conditions to run numerical simulations and to validate mobilization models . Even if the initial field of application of this novel facility is dust mobilization is nuclear fusion, the methodology developed can be used for the medicine industry, for the agribusiness and others. The authors will present the experimental and numerical results discussing new applications.