Performances evaluation of the optical techniques developed and used to map the velocities vectors of radioactive dust

Radioactive dust mobilization is a risk that can occur in many nuclear plants and, in order to reduce the risk related to this event, it is necessary map the velocity vectors of dust during its mobilization. The authors have designed and used a chain of measurements for air pressure and velocity, temperature, and dust velocity used on the experimental facility STARDUST-Upgrade that can replicate the thermos-fluidodynamic conditions of the loss of vacuum accidents with a pressurization rate in a range of 10–1000 Pa/s and a temperature in a range of 20–140 ℃. In this work, the authors present the optical experimental setups and software used to track dust velocities. These techniques are based on the particle tracking velocimetry and flow motion algorithms. Two different experimental setups are used to take into account the different optical properties of dust, each image obtained during the experiments has been analysed with customized software. Three different of algorithms are analysed and criticaly compared in this work: Lucas-Kanade, feature matching and Horn-Schunck. The authors will evaluate the performances of these optical techniques developed and used to map the velocities vectors of radioactive dust

Explosion of Undried and Dried Rice Flour with Ignition Time of 20 ms

In this work, the explosion characteristics of rice flour towards difference concentration at ignition time of 20 ms were analyzed. A series of experiments were performed in a 20 L spherical chamber to obtain a maximum overpressure (Pmax), rate of the pressure rise (dP/dT), and deflagration index (Kst) of undried and dried commercial rice flour. The dust sample and air were ignited by two chemical ignitors. Kistler piezoelectric pressure sensor was used to determine the propagation of pressure wave during the explosion. The moisture content of the samples was measured via proximate analysis. The Pmax was obtained at the highest pressure over the range of concentrations. Pmax for undried rice flour was 10.9 bar at concentration of 1000 kg/m3. Pmax for dried rice flour was 14.4 bar at concentration of 1000 kg/m3. The highest dP/dT rise was 103 bar/s for undried flour achieved at concentration of 750 kg/m3 and 202 bar/s for dried flour achieved at concentration of 1000 kg/m3. Kst for undried and dried rice flour are 27.96 bar.m/s and 54.83 bar.m/s respectively. It was found that the explosion severity increased as the dust flour concentration increases

Comments About the Human Health Risks Related to Additive Manufacturing

Additive Manufacturing processes are establishing themselves in different fields, especially due to the possibility to realize free-form and highly personalized products. Life Cycle Cost and Life Cycle Assessment analyses have been conducted to evaluate the economic and environmental sustainability of AM techniques. However, a consolidated knowledge of the risks for exposures to AM materials (as metallic powders) and of the hazards for fire and dust explosions is still missing. The paper performs an investigation on these aspects focusing on the existing literature and on the standards proposed by different international regulatory organizations. A critical review of the achieved awareness in the domestic and industrial environments is carried out, and the importance of models for the construction of risk indicators is highlighted