Numerical Simulations as Tool to Predict Chemical and Radiological Hazardous Diffusion in Case of Nonconventional Events

Abstract

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).

A Review of Dangerous Dust in Fusion Reactors: from Its Creation to Its Resuspension in Case of LOCA and LOVA

“…The dimension of dust created inside the tokamaks that are used worldwide is in the range 0,1-1000 µm and the most dangerous for the respiratory system are the one in the range 0,1-1 µm that can be withheld from the lungs. These particle dimensions, in the pressurization regime used inside STARDUST and STARDUST-U, has a behaviour comparable to those of the air streamlines and this is way in this work we will analyse the thermodynamic behaviour both from an experimental and numerical point of view [136][137][138][139][140][141][142][143][144][145][146][147][148][149].…”

“…It has been obtained through a structural and mechanical upgrade of STARDUST facility. It has been build up to reproduce thermos-fluid dynamic conditions comparable to those expected in a fusion reactor vessel during vacuum failures [136][137][138][139][140][141][142][143][144][145][146][147][148][149]. The vacuum failures are replicated through the inlet of pressurized air by different ports of the facility (C-D-E-F, see Figure 5).…”

“…If the three uncertainties ∆x 1 , ∆x 2 , ∆x 3 on the variables of the velocity function v " f px 1 , x 2 , x 3 q are not likely of the same sign, and if variables correlations are neglected, and if this applies also to the Ma function Ma " g py 1 , y 2 q, it is possible to use the following Equations 2 and 3 [135][136][137][138][139][140][141][142][143][144][145] respectively for total uncertainty ∆v of velocity and ∆Ma of Ma. "…”

Enhancing Radiation Detection by Drones through Numerical Fluid Dynamics Simulations

“…In this work the benefits of modeling and simulations approaches versus real experimentation on the field are first introduced, then a detailed approach to computational fluid dynamics based on the Navier-Stokes equations is presented; eventually, the modus operandi needed to fulfill the expected results is also described [10]. The computational software used in the modeling and simulations phases will be introduced along with the design of a virtual drone; the description of the subsequent Computational Fluid Dynamics (CFD) simulations, the collection of the results and their analysis for the above-mentioned goal will also be shown.…”

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

“…Modeling of a fusion reactor vacuum vessel is crucial for accident analysis and to predict materials inventory and mobilization, both from the experimental and numerical point of view. For that reason, along with experimental facilities to reproduce source term mobilization phenomena [26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36] it is also very important to develop a numerical model [37, 38] in order to predict particles quantities, velocity and direction in case of accidents such as a loss of vacuum, and not referring just to administrative limits but to estimates based on a more accurate methodology.…”