Taxonomy of Big Nuclear Fusion Chambers Provided by Means of Nanosecond Neutron Pulses

A methodology is elaborated and applied to taxonomy of large chambers of thermonuclear fusion reactors. It ensures a feasibility to describe impairments produced by environment and details of the chamber into the neutron field generated during the operation of a reactor. The method is based on application of very bright nanosecond neutron flashes irradiated from a compact neutron source of a dense plasma focus type. A number of neutron activation procedures as well as a neutron time-of-flight method were applied to trace deviations of neutron 3-D fields after their interaction with the simulator of the above chamber. Monte-Carlo modeling of these processes gained the data on the most important elements that influenced on the fields

Neutronics assessment of EU DEMO alternative divertor configurations

Abstract As a demonstration fusion power plant, EU DEMO has to prove the maturity of fusion technology and its viability for electricity production. The central requirements for DEMO rest on its capability to generate significant net electric power to the grid (300 MW to 500 MW) safely and consistently. Plant availability and lifetime will approach that of a commercial fusion power plant. Operating at such regimes presents many complex challenges, of which one is plasma exhaust. To mitigate the risk that the implementation in preceding experimental devices, namely ITER, does not extrapolate to the requirement of DEMO, alternative solutions must be sought. The investigation of alternative divertor configurations was born out of this motive, seeking to resolve a 'critical' challenge for the realisation of DEMO. In this paper, we study the neutronics performance of three concepts: Single Null (SN), Super-X (SX) and X-divertor (XD). This is the first time a preliminary analysis of alternative configurations to the SN baseline has been performed. The shielding proposals and design recommendations presented herein should be integrated with other engineering and physics constraints in future iterations of the chosen divertor concept

Geographical and temporal distribution of SARS-CoV-2 clades in the WHO European Region, January to June 2020

We show the distribution of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) genetic clades over time and between countries and outline potential genomic surveillance objectives. We applied three genomic nomenclature systems to all sequence data from the World Health Organization European Region available until 10 July 2020. We highlight the importance of real-time sequencing and data dissemination in a pandemic situation, compare the nomenclatures and lay a foundation for future European genomic surveillance of SARS-CoV-2

Modelling of drifts and currents in the edge plasma

For the purpose of modelling the plasma transport in the boundary layer of limiter tokamaks, a complete set of multifluid equations is derived for general curvilinear coordinates, which are for TEXTOR or Tore Supra adapted to circular magnetic flux surfaces . The classical parallel and the anomalous radial and perpendicular viscosities are carefully taken into account . All drifts and electric currents are calculated and analyzed in detail . In the scrape-off layer the electric potential (and electric field) is essentially determined by the sheath potential drop at. the limiter surfaces, whereas in the transition layer inside the separatrix the global ambipolarity constraint and the perpendicular viscosity must be used, such that the problem is reduced to the solution of a second order differential equation for the radial electric field at. some poloidal reference position. The derivation of the coefficients and the numerical procedure is outlined

A new concept of fusion neutron monitoring for PF-1000 device

The power output of plasma experiments and fusion reactors is a crucial parameter. It is determined by neutron yields that are proportional and directly related to the fusion yield. The number of emitted neutrons should be known for safety reasons and for neutron budget management. The PF-1000 is the large plasma facility based on the plasma focus phenomenon. PF-1000 is operating in the Institute of Plasma Physics and Laser Microfusion in Warsaw. Neutron yield changes during subsequent pulses, which is immanent part of this type device and so it must be monitored in terms of neutron emission. The reference diagnostic intended for this purpose is the silver activation counter (SAC) used for many years. Our previous studies demonstrated the applicability of radio-yttrium for neutron yield measurements during the deuterium campaign on the PF-1000 facility. The obtained results were compared with data from silver activation counter and shown linear dependence but with some protuberances in local scale. Correlation between results for both neutron monitors was maintained. But the yttrium monitor registered the fast energy neutron that reached measurement apparatus directly from the plasma pinch. Based on the preliminary experiences, the yttrium monitor was designed to automatically register neutron-induced yttrium activity. The MCNP geometrical model of PF-1000 and yttrium monitor were both used for calculation of the activation coefficient for yttrium. The yttrium monitor has been established as the permanent diagnostic for monitoring fusion reactions in the PF-1000 device

Monte Carlo tools evaluation for nuclear analyses of the European DEMO

This paper presents the status of different Monte Carlo (MC) particle transport codes regarding their capabilities to model the European fusion power demonstration reactor (DEMO). This work was carried out, via a collaboration between CEA, CCFE, IPPLM and KIT to evaluate MC codes which could replace MCNP for nuclear analysis on DEMO. Each association has participated using a different MC code: CEA with TRIPOLI-4, CCFE with Serpent, and IPPLM with FLUKA. The common DEMO model studied has been developed by KIT with MCNP. Considerable effort was required to translate the MCNP input deck into the syntax of Serpent and FLUKA codes; so no real nuclear analysis has been performed in the frame of this work. Regarding TRIPOLI-4, a benchmark has been successfully conducted; the results obtained are statistically similar to those of MCNP with comparable computation times