Heat shock tests on beryllium before and after neutron irradiation

Beside carbon materials and tungsten, beryllium will play an important role as plasma facing material (PFM) in the International Thermonuclear Experimental Reactor (ITER). It will mainly be used for the primary wall, the limiter and the upper baffle. During off normal operation the surface of Be may be loaded by severe thermal shocks, caused by plasma disruptions with energies of several ten MJ/m(2) within tens of milliseconds.The influence of high heat fluxes on several un-irradiated Be grade have been investigated before. During the operation of ITER the material will suffer irradiation with 14 MeV neutrons generated in the fusion process. In order to study the material degradation caused by fast neutrons, different samples have been neutron irradiated in the High Flux Reactor (HFR) at Petten. The thermal shock behaviour of the different beryllium grade before and after neutron irradiation is now compared

Nachbestrahlungsuntersuchungen an Testplatten fuer niedrig angereicherte Brennelemente fuer Forschungsreaktoren

SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Neutron-irradiation effects on high heat flux components : examination of plasma-facing materials and their joints

The neutron-irradiation experiments PARIDE 1 and PARIDE 2 have been performed at 350 degreesC and 700 degreesC with fluences of 0.35 dpa. The major part of the post-irradiation tests are high heat flux simulation experiments carried out in the electron beam facility JUDITH. These tests cover thermal fatigue experiments with small-scale high heat flux components, and on the other hand, thermal shock tests on the plasma-facing materials. Actively cooled samples were made from CFC, or beryllium as plasma-facing materials and copper alloys as heat sink materials. Different designs (flat tile, monoblock) and joining techniques (brazing, welding) were used. Best performance was found for CFC/Cu monoblock mock-ups, but also the brazed Be/Cu hat tile mock-ups fulfill the operational requirements for first wall components. Thermal shock experiments show a higher erosion after neutron irradiation. This degradation is either due to a reduced thermal conductivity (carbon) or to a decreased ductility after irradiation (beryllium). (C) 2000 Elsevier Science B.V. All rights reserved

Bewertungsmastäbe zur Beurteilung von Schadstoffbelastungen in Böden anhand der Bioverfügbarkeit: Zielstellung des Verbundvorhabens BioRefine

Until now, assessment of contaminated sites is based on variable protection goals, whereby total contents and in part mobile contents are considered. Due to interactions of pollutants in soil and bound residues, total contents do not reflect the actual risk. In contrast an investigation based on availability/bioavailability of contaminants would enable a harmonization of the protection-goal-based evaluation and a closer-to-reality risk assessment for the individual location

A multiple-rendezvous, sample-return mission to two near-Earth asteroids

International audienceWe propose a dual-rendezvous mission, targeting near-Earth asteroids, including sample-return. The mission, Asteroid Sampling Mission (ASM), consists of two parts: (i) flyby and remote sensing of a Q-type asteroid, and (ii) sampling of a V-type asteroid. The targeted undifferentiated Q-type are found mainly in the near-Earth space, and to this date have not been the target of a space mission. We have chosen, for our sampling target, an asteroid from the basaltic class (V-type), as asteroids in this class exhibit spectral signatures that resemble those of the well-studied Howardite-Eucrite-Diogenite (HED) meteorite suite. With this mission, we expect to answer specific questions about the links between differentiated meteorites and asteroids, as well as gain further insight into the broader issues of early Solar System (SS) evolution and the formation of terrestrial planets. To achieve the mission, we designed a spacecraft with a dry mass of less than 3 tonnes that uses electric propulsion with a solar-electric power supply of 15 kW at 1 Astronomical Unit (AU). The mission includes a series of remote sensing instruments, envisages landing of the whole spacecraft on the sampling target, and employs an innovative sampling mechanism. Launch is foreseen to occur in 2018, as the designed timetable, and the mission would last about 10 years, bringing back a 150 g subsurface sample within a small re-entry capsule. This paper is a work presented at the 2008 Summer School Alpbach,"Sample return from the Moon, asteroids and comets" organized by the Aeronautics and Space Agency of the Austrian Research Promotion Agency. It is co-sponsored by ESA and the national space authorities of its Member and Co-operating States, with the support of the International Space Science Institute and Austrospace