[en] The Advanced Stellarator WENDELSTEIN VII-AS is under construction in the Max-Planck-Institut fuer Plasmaphysik (IPP) at Garching, Federal Republic of Germany. In contrast to classical Stellarators the confinement field of the new machine is generated by only one set on nonplanar coils. This way the toroidally closed helical windings are avoided and modularity - which is a reactor design criterion - is achieved. The nonplanar coils are supported by a structure outside the coil set. The vacuum vessel is free of magnetically caused helical conductor forces. The construction of the machine requires extended 3D magnetic force and mechanical stress calculations and also a corresponding design. A description of essential machine components is presented. FEM-calculation results and newly developed fabrication methods are reported. (orig.)

[en] The Next Europian Torus (NET) is the major plasma device envisaged, in the European strategy towards fusion, between JET and DEMO. NET aims to produce a plasma with reactor like parameters and will adopt, as far as possible, reactor relevant technologies. A reference parameter set is being defined which offers considerable safety margins against physics uncertainties and it is optimized for minimum cost. The degree of extrapolation between NET and DEMO appears offers to be acceptable. (orig.)

[en] Of the many components and systems comprising a fusion reactor like the Tokamak Fusion Test Reactor (TFTR), few, if any, are subjected to more extreme and severe conditions than the protective armor for the interior vacuum vessel wall. The primary TFTR limiter, referred to as the Phase II bumper limiter, provides protection of the inner vacuum vessel wall from neutral beam shine-through, normal plasma loads, and major disruptive instabilities. The highly transient nature of forces and temperatures induced by these conditions produces significant dynamic responses in various parts of the bumper limiter structural system. This paper addresses the incorporation of a finite element dynamic analysis in the study of bumper limiter behavior when subjected to several electromagnetic load scenarios. These loads, due to a variety of realistic plasma conditions, were used in the interactive design and optimization of limiter components and support locations and flexibilities which enable the structure to perform within established criteria. (orig.)

[en] Mirror experiments have led the way in applying superconductivity to fusion research because of unique requirements for high and steady magnetic fields. The first significant applications were Baseball II at LLNL HENNING and IMP EFFERSON at ORNL. More recently, the MFTF-B Yin-Yang Coil HENNING was successfully tested KOZMAN and the entire tandem configuration is nearing completion. Tokamak magnets have also enjoyed recent success with the large coil project tests at ORNL HAUBENREICH, preceded by single coil tests in Japan and Germany. In the USSR, the T-7 Tokamak has been operational for many years and the T-15 Tokamak is under construction, with the TF coils nearing completion. Also the Tore Supra is being built in France. (orig.)

[en] This paper has been prepared in the framework of the safety analysis of blanket designs proposed for NET (Next European Torus). Two different concepts of blanket using 17Li83Pb as breeder and pressurized water as coolant have been developed with a ''modular'' and a ''tubular'' configuration, respectively. In both concepts the shell of the vessel containing the breeder represents the first barrier against accident propagation in case of coolant pipe break (LOCA). A mechanical analysis of the ''modular concept'' is presented where the vessel shell is subjected to the pressure transient due to a LOCA. The mechanical behaviour, evaluated in dynamic conditions taking into account non-linearities and fluid-structure interaction, shows that the structural reliability cannot be guaranteed, and suggests to continue the development of the ''tubular concept'' for which a much better mechanical behaviour is expected. (orig.)

[en] The sensitivity of lifetime predictions for fusion reactor blanket structures is investigated by applying the Monte Carlo numerical technique. A structural computer code, STAIRE, which has been developed for the analysis of mirror fusion blankets is used for the prediction of structural lifetime. Uncertainties in material variables are treated as probabilistic input to the STAIRE code. Irradiation Creep rates are shown to be sufficient for relaxation of swelling stresses under the majority of conditions. An engineering swelling limit, which is dependent on blanket geometry, is shown to be an important failure criterion. In the case of HT-9, it appears that the blanket structure lifetime could be several hundred displacements per atom. (orig.)

[en] The dynamic response of different water-cooled liquid Li₁₇Pb₈₃ breeder blanket modules has been calculated to study the potential of these modules in case of coolant tube rupture. Numerical calculations with the code PISCES have been carried out taking into account the fluid-structure interaction and the elasto-plastic behaviour of the structural material. The results show that for inert coolant characteristics the proposed conceptual designs for NET and INTOR have sufficient resistance against coolant tube rupture but when taking into account energy release due to chemical reaction of water with LiPb-alloy up to doubling of the wall thickness has to be envisaged to guarantee structural reliability. (orig.)

[en] This paper aimed at giving an overview and arguments for the various requirements under which the individual INTOR components have to work. (orig./GG)

[en] Thermal fatigue tests were perfomed on prototype beryllium limiter tiles for the JET tokamak using a 30 kW, 1 amp rastered electron beam system. A heat flux of 250 W/cm² was applied for 15 seconds to a tile 9.5 cm . 6.35 cm . 1 cm for a total of 10,000 cycles. The only damage to the tile was the formation of thermal fatigue microcracks on the heated surface. The depth of microcracking corresponds closely to the region of cyclic plasticity that was predicted by elastic-plastic finite element stress analyses. The surface cracking did not cause gross structural failure; hence, the beryllium, limiters in JET are expected to survive operation at 250 W/cm² for at least 10,000 plasma discharges. (orig.)

[en] The residual stresses in a bonded tile-substrate structure were analyzed using both analytical and finite element methods. Beam theory and 2-D elasticity solutions were compared and the latter was found to be more accurate, due to inadequate boundary conditions used in beam theories. Agreement between analytical elasticity and finite element solutions was favorable, but the increased flexibility of finite element codes makes them superior when non-linear problems are considered. The response of the calculated stress states to changes in various model dimensions and material parameters was studied parametrically. In general, dimensional changes were found to be significant only for short, thin tiles. (orig.)