Heiko Neuberger

Design Update and Mock-Up Test Strategy for the Validation of the EU-HCPB-TBM Concept

In the frame of the activities of the EU Breeder Blanket Programme and of the Test Blanket Working Group of ITER, the Helium Cooled Pebble Bed Test Blanket Module (HCPB-TBM) is developed to investigate DEMO relevant concepts for blanket modules. The main functions of a blanket module (heat removal, tritium breeding and sensitive components shielding) will be tested in DEMO relevant conditions during four different test campaigns in ITER. One TBM of the HCPB concept will be installed into the vacuum vessel connected to one equatorial port designed for vertical TBM orientation during each of the four test campaigns. This paper describes the FZK activities in order to verify the design of the HCPB TBM with regard to operational conditions in ITER and to prove the feasibility of the manufacturing techniques proposed. As the studies performed in FZK up to 2006 concerned a horizontal orientation of the HCPB, a review of the design was necessary to match with the new ITER specifications. Even if the general architecture of the horizontal TBM is maintained, nevertheless the change of configuration has significant impact on the design of the TBM sub-components. An overview of the new vertical HCPB design is presented, detailing the strategy adopted to assess the design and the thermal and fluid dynamic analyses performed for the TBM First Wall. In parallel to the TBM design and analysis, a large mock-up programme addresses the main issues of manufacturing and performances for single components and systems. The three medium-size mock-ups foreseen in FZK to validate the fabrication and mounting processes are presented detailing their purposes.

Two Different Medium-Scale First Wall Fabrication Experiments at KIT for ITER Helium-Cooled Pebble Bed Test Blanket Module

Abstract Subcomponent manufacturing and assembly concepts for the fabrication of the helium-cooled pebble bed test blanket module (TBM) for ITER have been developed over more than one decade at KIT, in particular the first wall (FW), which is a key element for the TBM fabrication. The design of this subcomponent foresees the manufacturing of a large U-bended plate of EUROFER with built-in channels for helium cooling. Manufacturing technologies developed at KIT are based on diffusion welding of two half-plates as the most promising option. This paper deals with the manufacturing of two medium-scale TBM FW mock ups according to two different industrial processes: a uni-axial diffusion welding process realized in a mechanic press at high temperature and a hot isostatic pressing process applied to a canned assembly at relatively low pressure. The qualification of the welds produced is described, and the results are compared to previous small- and medium-size scale experiments. The results of the recent FW fabrication mock ups are presented with regard to material data (e.g., ultimate strength, ductile-brittle transition temperature) and TBM-relevant parameters (e.g., deformation of cooling channels). The paper concludes with an overview of the strategy to evolve from 1/8th-scale experiments to TBM-relevant dimensions.

Overview of the HCPB Research Activities in EUROfusion

In the framework of the EUROfusion’s Power Plant Physics and Technology, the working package breeding blanket (BB) aims at investigating four different BB concepts for an EU demonstration fusion reactor (DEMO). One of these concepts is the helium-cooled pebble bed (HCPB) BB, which is based on the use of pebble beds of lithiated ternary compounds and Be or beryllides as tritium breeder and multiplier materials, respectively, EUROFER97 as structural steel and He as coolant. This paper aims at giving an overview of the EU HCPB BB Research and Development (R&D) being developed at KIT, in collaboration with Wigner-RCP, BUTE-INT, and CIEMAT. The paper gives an outline of the HCPB BB design evolution, state-of-the-art basic functionalities, requirements and performances, and the associated R&D activities in the areas of design, functional materials, manufacturing, and testing. In addition, attention is given also to the activities dedicated to the development of heat transfer augmentation techniques for the first wall and the corresponding testing. Due to their nature as design drivers, a brief overview in the R&D of key HCPB interfacing areas is given as well, namely, the tritium extraction and recovery system, the primary heat transfer and power conversion systems, and safety topics, as well as some specific activities regarding the integration of in-vessel systems through the BB. As concluding remarks, an outline of the standing challenges and future R&D plans is summarized.