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WEST is an acronym for tungsten (W) Environment in Steady-state Tokamak. WEST derives from the upgrade of the Tore Supra tokamak, moving from a limiter configuration with carbon plasma-facing components (PFCs) to a divertor configuration with W PFCs. It is located in the south of France (CEA Cadarache) and it assumes a key role as a testing facility for ITER. A computational analysis campaign has been carried out to investigate electromagnetic (EM) loads during plasma disruptions in WEST, the first one with the actual WEST experimental configuration. The applied methodologies as well as the obtained results have been benchmarked and could be employed to assess the behavior of WEST and analogous tokamak machines during plasma disruptions. Specifically, the research campaign has focused on a 20° sector of the WEST tokamak and it has been carried out by means of the ANSYS APDL v19.2 code. The input disruptions have been simulated with the free-boundary plasma equilibrium code FEEQS, while the obtained results mainly relate to the evaluation of eddy currents as well as the magnetic field distribution inside the tokamak. Furthermore, two different configurations of the WEST sector have been analyzed. The analyses in Configuration A are characterized by the same axisymmetric geometrical domain and electrical resistances as in the FEEQS analysis. As a consequence, they allow making a direct comparison between FEEQS and APDL results, benchmarking the model. On the other hand, the analyses of Configuration B are based on an improved configuration, characterized by more realistic 3-D geometry, electrical properties, and loads. Therefore, these last calculations can be employed to evaluate the magnetic field distribution inside the tokamak as well as the EM loads of in-vessel components.

AbstractThis paper deals with the evaluation of the first flight escape probability of nuclear particles from convex bodies with spherical symmetry by means of some geometrical arguments and very simple probability considerations. The cases of a full sphere, a one-region spherical shell with an empty central zone, a spherical shell region containing a black central zone, and a full sphere with a sourceless shell have been considered. In all the aforementioned cases, a homogeneous medium and uniform isotropic source have been taken into account. Moreover, a simple and general formula has been derived for the calculation of the uncollided flux that is presupposed to be valid for arbitrary geometries. The results obtained have been validated by Monte Carlo analyses performed by the Monte Carlo N-Particle (MCNP5) code and critically discussed.