Development of Mechanical Pipe-Connection Design for DEMO

Maintenance of the DEMO breeding blanket includes the removal and replacement of plasma-facing components. To access the breeding blanket, multiple coolant pipes need to be removed to allow access to the tokamak. As an option to reduce downtime and increase maintenance speed, the pipe-connection concept is developed to allow the removal of multiple pipes at the same time using a remotely operated mechanical connection. The remotely operated multi-pipe Mechanical Pipe Connection (MPC) needs to fulfil multiple requirements, such as high operating temperature and high external forces while at the same time maintaining an acceptable level of sealing between the high-pressure fluid and vacuum surroundings. In addition to the external conditions, the pipes of multiple sizes and fluids are connected in a manifold configuration. Although this will reduce the overall time required to operate the mechanical pipe connection when compared to multiple single-pipe connections, this will introduce additional forces and stresses due the interaction between pipe flow (e.g., simultaneous high- and low-temperature fluid pipes on the same manifold) through the manifold flange. The requirements and the boundary conditions of the multi-pipe MPC are taken into consideration during the design process of MPC. The design process is carried out to find the optimum form and size to allow the mechanical function of the pipe connection during the maintenance phase while withstanding the extreme operating conditions that the MPC will face the during operational phase. The resulting design will then be analyzed using numerical methods to assess the capability of the MPC designs

Concept of Contamination Control Door for DEMO and Proof of Principle Design

During the maintenance period of a future fusion reactor power plant, called DEMOnstration Power Plant (DEMO), remotely handled casks are required to confine and handle DEMO in-vessel components during their transportation between the reactor and the active maintenance facility. In order to limit the dispersion of activated dust, a Contamination Control Door (CCD) is designed to be placed at an interface between separable containments (e.g., vacuum vessels and casks) to inhibit the release of contamination at the interface between them. The remotely operated CCD—technically, a double lidded door system—consists of two separable doors (the cask door and port door) and three different locking mechanisms: (i) between the cask door and cask, (ii) between the cask door and port door and (iii) between the port door and port. The locking mechanisms are selected and assessed according to different criteria, and the structure of the CCD is optimized using an Abaqus Topology Optimization Module. Due to the elastic properties of the CCD, deflections will occur during the lifting procedure, which may lead to malfunctions of the CCD. A test rig is developed to investigate the performance of high-risk components in the CCD in the case of deflections and also malpositioning. Misalignment can be induced along three axes and three angles intentionally to test the single components and items. The aim is to identify a possible range of operating in the case of misalignments. It is expected that the proposed CCD design should be able to operate appropriately in the case of ±3 mm translational misalignments and ±1° rotational misalignments

Pre-conceptual Design Assessment of DEMO Remote Maintenance

EDFA, as part of the Power Plant Physics and Technology programme, has been working on the pre-conceptual design of a Demonstration Power Plant (DEMO). As part of this programme, a review of the remote maintenance strategy considered maintenance solutions compatible with expected environmental conditions, whilst showing potential for meeting the plant availability targets. A key finding was that, for practical purposes, the expected radiation levels prohibit the use of complex remote handling operations to replace the first wall. In 2012/13, these remote maintenance activities were further extended, providing an insight into the requirements, constraints and challenges. In particular, the assessment of blanket and divertor maintenance, in light of the expected radiation conditions and availability, has elaborated the need for a very different approach from that of ITER. This activity has produced some very informative virtual reality simulations of the blanket segments and pipe removal that are exceptionally valuable in communicating the complexity and scale of the required operations. Through these simulations, estimates of the maintenance task durations have been possible demonstrating that a full replacement of the blankets within 6 months could be achieved. The design of the first wall, including the need to use sacrificial limiters must still be investigated. In support of the maintenance operations, a first indication of the requirements of an Active Maintenance Facility (AMF) has been elaborated.Comment: 6 pages, 5 figure

EU DEMO Remote Maintenance System development during the Pre-Concept Design Phase

During the EU DEMO Pre-Concept Design Phase, the remote maintenance team developed maintenance strategies and systems to meet the evolving plant maintenance requirements. These were constrained by the proposed tokamak architecture and the challenging environments but considered a range of port layouts and handling system designs. The design-driving requirements were to have short maintenance durations and to demonstrate power plant relevant technologies. Work concentrated on the in-vessel maintenance systems, where the design constraints are the most challenging and the potential impact on the plant design is highest. A robust blanket handling system design was not identified during the Pre-Concept Design Phase. Novel enabling technologies were identified and, where these were critical to the maintenance strategy and not being pursued elsewhere, proof-of-principle designs were developed and tested. Technology development focused on pipe joining systems such as laser bore cutting and welding, pipe alignment, and on the control systems for handling massive blankets. Maintenance studies were also conducted on the ex-vessel plant to identify the additional transport volumes required to support the plant layout. The strategic implications of using vessel casks, and of using containment cells with cell casks, was explored. This was motivated by the costs associated with the storage of casks, one of several ex-vessel systems that can drive the overall plant layout. This paper introduces the remote maintenance system designs, describes the main developments and achievements, and presents conclusions, lessons learned and recommendations for future work

Untersuchung der Schwingungseigenschaften von teleskopierbaren Maschinenelementen mit Spiel am Beispiel eines Gabelstapler-Hubgerüstes

Teleskopierbare, spielbehaftete Hubgerüste von Gabelstaplern werden während eines Arbeitszyklus oftmals zu Schwingungen angeregt. Die charakteristischen Schwingungseigenschaften, bedingt durch das usammenwirken von Spiel, auskragender Last und Schwerkraft, werden experimentell untersucht und durch ein 5-Massen-Modell sehr gut abgebildet.Sowohl mit aktiven als auch mit passiven Maßnahmen lassen sich die Schwingungen schnell und deutlich reduzieren

Einheit in der Ökologie?Eine Untersuchung von Mustern, Problemen und vereinheitlichenden Konzepten in Populationsökologie, Systemökologie und Evolutionärer Ökologie

Ecology is a pluralist discipline in which I distinguish between three basic approaches according to their way of explaining. These approaches are population ecology, systems ecology and evolutionary ecology. However, I demonstrate that it is possible to unify the different theories and methods in ecology by means of evolutionary theory. There are many connections between ecology and evolution. Complex systems probably evolved via different forms of co-evolution. In case of strong co-evolution, ecological and evolutionary units can hardly be distinguished and they evolve together. It is possible to arrive at a unity of ecology by means of evolutionary explanations that increase our understanding and derive the existence of contemporary systems from simpler states of a past long ago. This form of unifying explanation does not need fundamental laws. One just needs general causal mechanisms of change like mutation and selection and some starting points from which all the investigated phenomena evolved. Nevertheless, physics is considered the paradigmatic scientific discipline providing unity by means of fundamental laws. By assuming that there are no fundamental laws in physics, the differences between the structure of physical and ecological explanation will decrease. The individual-historical aspect of ecology will as well become an important part of physics. For this reason, one should consider ecology a discipline that is nearer to nature than physics. Therefore, ecology should replace physics as the paradigmatic scientific discipline

Unity in Ecology?An Investigation of Patterns, Problems, and Unifying Concepts of Population Ecology, Systems Ecology and Evolutionary Ecology

Ecology is a pluralist discipline in which I distinguish between three basic approaches according to their way of explaining. These approaches are population ecology, systems ecology and evolutionary ecology. However, I demonstrate that it is possible to unify the different theories and methods in ecology by means of evolutionary theory. There are many connections between ecology and evolution. Complex systems probably evolved via different forms of co-evolution. In case of strong co-evolution, ecological and evolutionary units can hardly be distinguished and they evolve together. It is possible to arrive at a unity of ecology by means of evolutionary explanations that increase our understanding and derive the existence of contemporary systems from simpler states of a past long ago. This form of unifying explanation does not need fundamental laws. One just needs general causal mechanisms of change like mutation and selection and some starting points from which all the investigated phenomena evolved. Nevertheless, physics is considered the paradigmatic scientific discipline providing unity by means of fundamental laws. By assuming that there are no fundamental laws in physics, the differences between the structure of physical and ecological explanation will decrease. The individual-historical aspect of ecology will as well become an important part of physics. For this reason, one should consider ecology a discipline that is nearer to nature than physics. Therefore, ecology should replace physics as the paradigmatic scientific discipline

Untersuchung der Schwingungseigenschaften von teleskopierbaren Maschinenelementen mit Spiel am Beispiel eines Gabelstapler-Hubgerüstes

Teleskopierbare, spielbehaftete Hubgerüste von Gabelstaplern werden während eines Arbeitszyklus oftmals zu Schwingungen angeregt. Die charakteristischen Schwingungseigenschaften, bedingt durch das usammenwirken von Spiel, auskragender Last und Schwerkraft, werden experimentell untersucht und durch ein 5-Massen-Modell sehr gut abgebildet. Sowohl mit aktiven als auch mit passiven Maßnahmen lassen sich die Schwingungen schnell und deutlich reduzieren