Armor for a Fusion Sun: Russia Tests Tungsten for ITER Reactor
The Efremov Institute of Electrophysical Apparatus (NIIEFA) has completed a qualification testing phase for tungsten intended for the first-wall panels of the International Thermonuclear Experimental Reactor (ITER).
The brazed mockups passed ultrasonic inspection using a robotic system and withstood 10,000 thermal pulses on a specialized test stand.
A Unique Vacuum Brazing Technology
ITER’s blanket first wall forms a barrier between the superheated plasma and the tokamak’s main equipment. It protects in-vessel systems from plasma particles and removes heat so it can subsequently be converted into energy. The extreme operating loads place stringent demands on both structural strength and material performance.
Three years ago, the project partners made a strategic decision to replace beryllium with tungsten for the first-wall panel facing material, requiring the introduction of specialized technologies. Engineers at NIIEFA, part of Rosatom State Corporation, were tasked with reworking the entire manufacturing process.
To preserve the strength of the copper alloy and maximize the thermal conductivity of the tungsten-copper facing, engineers developed a unique rapid vacuum brazing method. It prevents metal oxidation and ensures a strong bond between the tungsten tiles and the copper substrate. The method has no direct equivalent in current international practice.
Robotic Ultrasonic Inspection
The quality of brazed joints is critical to the reliability of the entire first-wall structure. Any hidden defect could cause cooling channels to lose their integrity and a panel to fail under plasma heat loads. To detect microscopic flaws, NIIEFA developed a specialized robotic system for nondestructive testing.
At the heart of the installation is a six-axis industrial robotic arm. It positions ultrasonic sensors precisely on the complex curved surfaces of the brazed mockups. The robot moves the inspection probes along a programmed path, covering all critical areas of the joints.
NIIEFA engineers developed the system’s control software in-house. Its algorithms process ultrasonic inspection signals and generate a three-dimensional map of the component’s internal structure. The system detects pores, cavities and incomplete brazing at an early stage of production. The inspection process is automated and does not require direct operator involvement.
Extreme Testing on the Tsefei Test Stand
After the brazed joints passed quality checks, the mockups underwent thermal cycling on the Tsefei thermal test stand. This specialized facility simulates actual operating conditions at a tokamak’s first wall, subjecting materials to extreme thermal loads.
Engineers applied heat pulses with a heat flux of 3 MW/m² to the facing surface. The materials successfully withstood 10,000 heating and cooling cycles without losing strength or compromising leak-tightness.
ITER’s first-wall panels are among the reactor’s most highly heat-loaded components. Under normal operating conditions, they must withstand heat fluxes of up to 4.7 MW/m². The next testing stages will use a more complex cooling-channel configuration known as a hypervapotron, where the heat flux will reach 5 MW/m².
Serial Production and International Commitments
Research and development involving tungsten will continue through 2028. During this period, NIIEFA specialists will refine the technologies and manufacturing processes ahead of the transition to full-scale production.
Under international agreements, Russian companies are required to manufacture and deliver 179 enhanced-heat-flux first-wall panels to the ITER site in France. These panels account for 40% of the total. Russia’s main manufacturers of this equipment are NIIEFA and NIKIET, the N. A. Dollezhal Research and Development Institute of Power Engineering, which is also part of Rosatom State Corporation.
NIKIET has already developed the technical documentation for the load-bearing structures of the first-wall panels. The two organizations are working together to establish a complete manufacturing cycle for key ITER components.
Russia’s first-wall panels are considered among the reactor’s most complex components. Their development strengthens the position of Russian industry as a technological leader in fusion materials science.
