M. Richou

Technological Study on Manufacturing of Multifinger Module of He-Cooled DEMO Divertor and Investigation of NDE Method

Abstract A helium-cooled divertor concept for DEMO, which is currently being developed at the Karlsruhe Institute of Technology, uses a modular structure of tungsten 9-finger units composed of smaller individual one-finger modules. As the development of the 1-finger design is so far advanced, the work currently focuses on the manufacturing technology of a larger unit, the 9-finger module. The requirements for a larger grouping of individual cooling fingers are associated with the three-dimensional dimensions and orientations of all components in the assembly; their inaccuracy will affect the He flow distribution and cooling capacity of the divertor. In this paper, the necessary production steps, the order of assembly, and the principle of SATIR non destructive examination are described, as a result of a technological study.

Recent Progress in the Development of Helium-Cooled Divertor for DEMO

Abstract A helium-cooled divertor concept for DEMO has been continuously developed over the past decade at the Karlsruhe Institute of Technology within the framework of the former European Fusion Power Plant Conceptual Study. Over the years, research results and progress of the divertor development with numerous earnings representations have been continually reported. This paper first gives a retrospect of the past results achieved so far and then reports on recent progress of the divertor development. In the course of developing the conceptual design with the goal of reaching a divertor heat flux performance of 10 MW/m2, the He-cooled modular divertor with jet cooling (HEMJ) was selected in the early 2000s as the reference concept out of a series of conceptual design studies. For verification of the design principle, a combined high-heat-flux (HHF) test facility with helium loop was built in 2004 at the Efremov Institute for the divertor experiments under specified DEMO conditions. There, the cooling performance of the divertor finger with helium under the heat load of 10 MW/m2 was confirmed already at an early stage. In parallel, the HEMJ divertor design was successively improved in terms of its robustness and quality of production in order to achieve a long service life against thermocyclic loading. A breakthrough was achieved in 2010 when an optimized HEMJ cooling finger survived more than 1000 HHF cycles at 10 MW/m2 without damage. In the context of long-term planning for DEMO divertor development, research and development work on the development of larger divertor components has been started, particularly focusing on certain fabrication techniques covering, e.g., high-temperature brazing and mass production of the divertor components. Recent progress—a part of this paper—was achieved in the HHF experiment of the tungsten nine-finger module in Efremov, development of nondestructive testing methods for testing multifinger modules in collaboration with CEA, and a study on the integration of multifinger modules on the target plate.

Assessment of an ITER-like water-cooled divertor for DEMO

This paper presents main outcomes of activities, performed in the frame of the EFDA task WP12-DAS-02-T02 and whose main objective was to investigate the feasibility and the range of applicability of a water-cooled divertor (WCD) based on technology developed for ITER to DEMO1. That includes the analysis of the power handling limits, the impact of the end-of-life irradiation fluence, as well as the assessment of available material properties. The considered divertor configuration is a water-cooled monoblock divertor which should be suitable for DEMO operation. For this purpose also Copper alloys, with their high thermal conductivities and relative high strengths, have to be considered when high heat flux handling is required but the aspect of n-irradiation cannot be neglected. All these aspects are assessed for two heat sink materials possible candidates: CuCrZr-IG, EUROFER. For these materials the psychical and mechanical properties were investigated considering their behaviour under n-irradiation and focusing the attention on the conceivable DEMO operational window with respect to temperatures and n-irradiation material properties degradation. The work is then concluded with thermo-mechanical studies of appropriate FE models to predict the heat flux performance capability and lifetime of a W mono-block with cooling pipes made of different Cu-alloys and EUROFER.