Recent progress toward development of reduced activation ferritic/martensitic steels for fusion applications

Significant progress has been achieved in the international research effort on reduced activation ferritic/martensitic steels for fusion structural applications. Because this class of steels is the leading structural material for test blankets in ITER and future fusion power systems, the range of ongoing research activities is extremely broad. Since, it is not possible to discuss all relevant work in this brief review, the objective of this paper is to highlight significant issues that have received recent attention. These include: (1) efforts to measure and understand radiation-induced hardening and embrittlement at temperatures 550 °C) creep resistance by introduction of a high-density of nanometer scale dispersoids or precipitates in the microstructure, (4) progress toward structural design criteria to account for loading conditions involving both creep and fatigue, and (5) development of nondestructive examination methods for flaw detection and evaluation

The European effort towards the development of a demo structural material: Irradiation behaviour of the European reference RAFM steel EUROFER

Worldwide programs aimed at developing materials for future fusion plants are presently concentrating on reduced activation ferritic/martensitic (RAFM) steels. In Europe, a Fusion Long Term Programme is being carried out under the coordination of European Fusion Development Agreement (EFDA) Close Support Unit (Garching, Germany); in the framework of this programme, extensive research is currently in progress for the development and full qualification of the European reference 9Cr RAFM steel, designated EUROFER. This paper focuses on the work being performed within the EFDA Technology Workprogram TTMS-001 task "Irradiation Perfonnance of EUROFER", aimed at defining the post-irradiation mechanical and microstructural characteristics of the material, through irradiations, post-irradiation examinations (PlEs) and theoretical studies. An overview of the progress made will be given, as well as an anticipation of future research activities. (c) 2005 Elsevier B.V. All rights reserved

Present development status of EUROFER and ODS-EUROFER for application in blanket concepts

Within the European Union, the two major breeding blanket concepts presently being developed are the helium cooled pebble bed (HCPB), and the helium cooled lithium lead (HCLL) blankets. For both concepts, different conceptual designs are being discussed with temperature windows in the range 250-550 degrees C for conservative approaches based on reduced activation ferritic-martensific (RAFM) steels, and in the range 250-650 degrees C for more advanced versions, taking into account oxide dispersion strengthened (ODS) steels. As a final result of a systematic development of RAFM-steels in Europe, the 9% CrWVTa alloy EUROFER was specified and produced in an industrial scale with a variety of product forms. A large characterisation program is being performed including irradiation in materials test reactors between 60 and 450 degrees C (<= 15 dpa), and in a fast breeder reactor at 330 degrees C up to 30 dpa. EUROFER is resistant to high temperature ageing, and the existing creep-rupture data (similar to 30,000 h, 450-600 degrees C) indicate long-term stability and predictability. The ODS variant of EUROFER shows superior tensile and creep properties compared to EUROFER. Applying a new production route has diminished the problem of lower ductility and inferior impact properties. A reliable joining technique for ODS and RAFM steels employing diffusion welding was successfully developed. (c) 2005 Published by Elsevier B.V

Materials design data for reduced activation martensitic steel type EUROFER

Materials design limits derived so far from the data generated in Europe for the reduced activation ferritic/martensitic (RAFM) steel type Eurofer are presented. These data address the short-term needs of the ITER Test Blanket Modules and a DEMOnstration fusion reactor. Products tested include plates, bars, tubes, TIG and EB welds, as well as powder consolidated blocks and solid-solid HIP joints. Effects of thermal ageing and low dose neutron irradiation are also included. Results are sorted and screened according to design code requirements before being introduced in reference databases. From the physical properties databases, variations of magnetic properties, modulus of elasticity, density, thermal conductivity, thermal diffusivity, specific heat, mean and instantaneous linear coefficients of thermal expansion versus temperature are derived. From the tensile and creep properties databases design allowable stresses are derived. From the instrumented Charpy impact and fracture toughness databases, ductile to brittle transition temperature, toughness and behavior of materials in different fracture modes are evaluated. From the fatigue database, total strain range versus number of cycles to failure curves are plotted and used to derive fatigue design curves. Cyclic curves are also derived and compared with monotonic hardening curves. Finally, irradiated and aged materials data are compared to ensure that the safety margins incorporated in unirradiated design limits are not exceeded. (C) 2004 Elsevier B.V. All rights reserved

The Public Acceptance of Voluntary Childlessness in the Netherlands: from 20 to 90 per cent in 30 years

Social change, Voluntary childlessness, Public opinion, The Netherlands,