Safety Analysis in Large Volume Vacuum Systems Like Tokamak: Experiments and Numerical Simulation to Analyze Vacuum Ruptures Consequences

Abstract

The large volume vacuum systems are used in many industrial operations and research laboratories. Accidents in these systems should have a relevant economical and safety impact. A loss of vacuum accident (LOVA) due to a failure of the main vacuum vessel can result in a fast pressurization of the vessel and consequent mobilization dispersion of hazardous internal material through the braches. It is clear that the influence of flow fields, consequence of accidents like LOVA, on dust resuspension is a key safety issue. In order to develop this analysis an experimental facility is been developed: STARDUST. This last facility has been used to improve the knowledge about LOVA to replicate a condition more similar to appropriate operative condition like to kamaks. By the experimental data the boundary conditions have been extrapolated to give the proper input for the 2D thermofluid-dynamics numerical simulations, developed by the commercial CFD numerical code. The benchmark of numerical simulation results with the experimental ones has been used to validate and tune the 2D thermofluid-dynamics numerical model that has been developed by the authors to replicate the LOVA conditions inside STARDUST. In present work, the facility, materials, numerical model, and relevant results will be presented.

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

“…In some applications the macroscopic erosion of hazardous materials (radioactive, toxic, or explosive) and consequent accumulation of dust represent a risk for the workers and the population, for example, if the dust is mobilized during a loss of vacuum inside the vacuum vessel due to an accident in the system of a nuclear fusion power device. Improvement of accident management guidelines and mitigation measures of experimental nuclear fusion plants will significantly enhance the level of safety of the fusion facilities currently designed and the foreseen ITER and DEMO concepts [19].…”

“…The globalization and the simplicity to access information from one side have improved technologies and quality of life but from the other side have created a higher facility to gather information to offend or create terror. The cases of the dispersion of toxic gas in the past and in the recent history [1][2][3][4][5], the DAESH progression in the Arabic Countries [6][7][8][9][10], the Ebola diffusion through the aerial transportation [11][12][13][14][15][16][17], and the radiological dispersion due to failures in fission or fusion devices [18][19][20][21][22][23][24] are all examples on how the new merge between the well-known risks and the new "dangerous ideas" has exponentially increased the uncertainties of the human health all around the world. The University of Rome Tor Vergata, counting on the synergic work between the Faculty of Engineering and the Faculty of Medicine and Surgery, is facing these new problems with innovative working approaches voted to use the expertise developed in classic scientific disciplines in an unconventional way.…”

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

“…There are safety and security concerns related to several technological peculiarities of these plants, one of the most important is the creation of dust due to the plasma material interaction inside the vacuum vessel (VV) of the nuclear fusion plants [5][6][7][8][9][10][11][12] and its resuspension due to accidents like Loss of Vacuum (LOVA), Loss of Coolant (LOCA) [13,14]. There are safety and security concerns related to several technological peculiarities of these plants, one of the most important is the creation of dust due to the plasma material interaction inside the vacuum vessel (VV) of the nuclear fusion plants [5][6][7][8][9][10][11][12] and its resuspension due to accidents like Loss of Vacuum (LOVA), Loss of Coolant (LOCA) [13,14].…”

“…There are safety and security concerns related to several technological peculiarities of these plants, one of the most important is the creation of dust due to the plasma material interaction inside the vacuum vessel (VV) of the nuclear fusion plants [5][6][7][8][9][10][11][12] and its resuspension due to accidents like Loss of Vacuum (LOVA), Loss of Coolant (LOCA) [13,14].…”

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

“…A very important issue related to the reactor safety and security is the amount of activated material of different composition and shape that is produced inside the vacuum vessel as a consequence of the interactions between plasma and materials (PMIs) [8, 9, 10, 11]. Plasma-facing components can be eroded by the plasma particles, mostly during short pulses of high heat loads.…”