Search results for "fusion power"
showing 10 items of 78 documents
First Results of the Testing of the Liquid Gallium Jet Limiter Concept for ISTTOK
2006
The use of liquid metals as plasma facing components in tokamaks has recently experienced a renewed interest stimulated by their advantages to the development of a fusion reactor. Liquid metals have been proposed to solve problems related to the erosion and neutronic activation of solid walls submitted to high power loads allowing an efficient heat exhaustion from fusion devices. Presently the most promising materials are Lithium and Gallium. ISTTOK, a small size tokamak, will be used to test the behavior of a liquid Gallium jet in the vacuum chamber and its influence on the plasma. This paper presents a description of the conceived setup as well as experimental results. The liquid Gallium …
Interaction of a liquid gallium jet with the tokamak ISTTOK edge plasma
2008
Abstract The interaction of a liquid gallium jet with plasma has been investigated in the tokamak ISTTOK. This paper presents a description of the conceived experimental setup, a detailed characterization of the produced jets and the first experimental results related to the gallium–plasma interaction. A stable jet has been obtained, which was not noticeably affected by magnetic field transients. ISTTOK has been successfully operated with the gallium jet without degradation of the discharge or a significant plasma contamination by liquid metal. This observation is supported by spectroscopic measurements showing that gallium radiation is limited to the region around the jet. Furthermore, the…
Interaction of a Liquid Gallium Jet with ISTTOK Edge Plasmas
2008
The use of liquid metals as plasma facing components in tokamaks has recently experienced a renewed interest stimulated by their advantages in the development of a fusion reactor. Liquid metals have been proposed to solve problems related to the erosion and neutronic activation of solid walls submitted to high power loads allowing an efficient heat exhaust from fusion devices. Presently the most promising candidate materials are lithium and gallium. However, lithium has a short liquid state range when compared, for example, with gallium that has essentially better thermal properties and lower vapor pressure. To explore further these properties, ISTTOK tokamak is being used to test the inter…
Progress in the benchmark exercise for analyzing the lithiate breeder pebble bed thermo-mechanical behaviour
2006
The Helium Cooled Pebble Bed (HCPB) Blanket is one of the reference concepts for the European Breeding Blanket Programme for DEMO. In the reference blanket module, alternate layers of lithiated ceramics and beryllium pebbles act, respectively, as tritium breeder and neutron multiplier. The thermo-mechanical behaviour of both the pebble beds and their performances in reactor relevant conditions are also dependent on the pebble size and cell geometries (bed thickness, pebble packing factor, bed thermal conductivity). Therefore, in the EU Fusion Technology Programme, several out-of-pile experimental test campaigns have been performed to determine these behaviours. Theoretical calculations have…
Tritium release from breeding blanket materials in high magnetic field
2007
Abstract Under the operating conditions of a fusion reactor, the blanket materials: ceramic and Be pebbles will be at a high temperature (up to 1123 K), under action of intense radiation (up to 10 19 n m −2 s −1 ) and magnetic field (MF) up to 7–10 T. In order to introduce action of radiation and MF in post-irradiation investigations of the tritium release from the blanket materials, a special rig for thermo-annealing of pre-irradiated samples at a high temperature up to 1120 K under irradiation with fast electrons of 5 MeV and dose rate 14 MGy/h in MF up to 1.7 T was used for this study. A delay of the tritium release in MF of 2.4 T at thermo-annealing of the lithium orthosilicate Li 4 S…
Behaviour of tritium in breeding materials
2005
Abstract The tritium release from ceramic materials of the HCPB under real DEMO operating conditions will depend not only on temperature and neutron flux but also on an intense magnetic field (MF) of 7–9 T. The delay in the tritium release induced by the MF is proportional to the grain size of the ceramics, the squared MF intensity and the abundance ratio of charged tritium forms (T + , T − ) in the grain volume of the ceramics. The effect of MFs of different intensity on the tritium release from the Li 4 SiO 4 pebbles irradiated in the EXOTIC-8 experiment (neutron fluence 2.4 × 10 25 n m −2 , irradiation temperature up to 700 K) was investigated in this study. As a result of the irradiati…
Effects of external energetic factors on tritium release from the EXOTIC 8-3/13 neutron-irradiated beryllium pebbles
2009
Abstract Tritium release from samples of 9–13 mg of the EXOTIC 8-3/13 neutron-irradiated beryllium pebbles under the separate and simultaneous action of temperature 490–770 K, 5 MeV fast-electron radiation 14 MGy h−1 for 3 h and magnetic field (MF) of 1.7 T was investigated. The pebbles were found to be very dissimilar with respect to their total tritium content—2.5–9 MBq g−1. The batch contained also some coarse agglomerates of the pebbles containing 10–19 MBq g−1 of tritium having also a high tritium release. For the pebbles having the total tritium 2.5–5.3 MBq g−1, the electron radiation for 3 h caused the fractional tritium release 17–26% (B = 0) and 21–29% (B = 1.7 T), the temperature …
Radiation effects on stress evolution and dimensional stability of large fusion energy structures
2021
Abstract We assess the effects of neutron irradiation on the deformation and stress evolution of large-scale fusion energy structures. This is accomplished through non-linear finite element structural analysis of the coupled thermal and mechanical fields at the Beginning-Of-Life (BOL), at 45 dpa, and at 90 dpa. Radiation effects include volumetric swelling and the influence of radiation on the mechanical properties. The system studied here is a large section of a full inboard module of an integrated structure comprising the First Wall and Blanket (FW/B) of a Dual Cooled Lithium-Lead (DCLL) energy conversion unit in the Fusion Nuclear Science Facility (FNSF). The structural material is the f…
Safety analysis of the DONES primary heat removal system
2020
Abstract The development of a neutron source able to reproduce the irradiation conditions typical of a nuclear fusion reactor, in order to test candidate structural materials, is the main goal of the Work Package Early Neutron Source (WPENS) of the EUROfusion action. This source, named Demo Oriented NEutron Source (DONES), is a facility where neutrons are produced by means of D-Li interactions. More in detail, a beam of 125 mA deuterium ions at the energy of 40 MeV strikes a lithium jet flowing in a purposely shaped channel in order to obtain an intense and stable neutron flux for the irradiation of material samples. In the framework of these activities, safety analyses are a key aspect in …
Modelling of the thermal mechanical behaviour of a single size beryllium pebble bed
2001
The Helium Cooled Pebble Bed (HCPB) Blanket for fusion power reactors and the ITER breeding blanket are based on the use of pebble beds of lithium ceramics as breeder and beryllium as neutron multiplier. Experimental activities were performed at Forschungszentrum Karlsruhe concerning the measurement of pebble bed heat transfer parameters. At the Department of Nuclear Engineering of the University of Palermo, the experimental results have been reproduced by means of the ABAQUS finite element code. Moreover, a thermal-mechanical theoretical model has been developed for single size beryllium pebble beds. In the paper the results from the numerical and theoretical analyses and the comparison wi…