Fabrication of thin-walled fusion blanket components like flow channel inserts by selective laser melting

Abstract

New manufacturing methods for the production of key components for nuclear fusion reactors by selective laser melting (SLM) are currently under investigation at Karlsruhe Institute of Technology. SLM offers great potential compared to conventional manufacturing methods. Within the framework of feasibility studies, complex 3D structures, such as a thin- and double-walled flow channel inserts (FCIs) for dual-coolant lead lithium (DCLL) blankets, were successfully manufactured and subjected to preliminary tests. The paper shows that fabrication of thin-walled FCIs by the SLM technique is feasible in principle. The complexity of the fabrication process is outlined and application of the SLM technique for production of other fusion blanket sub-components, such as thin-walled cooling plates with internal cooling channels, is addressed.

Introduction

Several manufacturing strategies and methods for test blanket modules (TBM) were developed in recent years to demonstrate applicability of established fabrication methods. The studies reported here focused on blanket components, such as the first wall, stiffening and cooling plates for the helium-cooled pebble bed (HCPB), or helium-cooled lead lithium (HCLL) blankets [1,2], and on fabrication of thin- and double-walled flow channel inserts (FCIs) for use in dual coolant lead lithium (DCLL) blankets [[3], [4], [5]]. The fabrication studies revealed that the methods above produce reasonable results for simple straight geometries, but may have drawbacks in terms of fabrication time and costs. Moreover, only few methods and machines are available for the manufacturing of 3D components.

The present paper focuses on selective laser melting (SLM). It is an additive manufacturing (AM) technique, in which a laser of high power density gradually melts metallic powders in layers to create solid 3D structures. Preliminary studies of SLM-produced components were made to check material properties (see §2 and [6]). In addition, hybrid components consisting of SLM parts welded to conventionally fabricated elements, such as stiffening plates with cooling channels, were fabricated successfully [6]. This paper focuses on feasibility studies to demonstrate that sub-components for fusion reactors with complex shapes and structures can be manufactured by SLM. Results of these studies, mainly for thin- and double-walled components, such as flow channel inserts, are reported in this paper.