Nippon Steel’s Contract Awarded for 20 Units of ITER’s Divertor Outer Vertical Targets in France

MHI Secures contract for Critical ITER Components

Tokyo, September 18, 2025 – Mitsubishi Heavy Industries (MHI) has been awarded a contract from Japan’s National Institutes for Quantum Science and Technology (QST) to manufacture 20 units of outer vertical targets – critical components for the divertors of ITER, the international fusion reactor currently under construction in France.

This order adds to MHI’s existing commitment to the project,as thay are already slated to manufacture 58 divertors in total. MHI has secured contracts for the initial and second batches of these high-tech components and continues to be a key player in realizing this enterprising endeavor.

The company’s involvement underscores its dedication to advancing fusion technology. With ITER facing delays – recently pushing the timeline for first plasma to 2035 – and with increasing activity from private fusion companies, questions are being raised about the future and significance of the project. However, MHI’s ongoing commitment suggests confidence in ITER’s ultimate importance and the enduring need for collaborative, large-scale scientific ventures in the pursuit of sustainable energy solutions.

What are the key material science challenges in developing components for the ITER divertor?

Nippon Steel Secures Key Contract for ITER Divertor Targets in France

Nippon Steel Corporation has been awarded a significant contract by ITER Institution to manufacture 20 units of the Divertor Outer Vertical Targets (OVTs) for the International Thermonuclear Experimental Reactor (ITER) project,currently under construction in Saint-Paul-lès-Durance,France.This represents a crucial step forward for the aspiring fusion energy project and highlights Nippon Steel’s expertise in advanced materials and manufacturing. The contract underscores the global collaboration required to realize practical fusion power.

Understanding the ITER Divertor and its challenges

The ITER divertor is one of the most challenging components of the reactor. Its primary function is to extract heat and impurities from the plasma, protecting the core plasma-facing components.the divertor faces extreme conditions:

* Intense Heat Flux: temperatures reaching tens of millions of degrees Celsius.

* Neutron Irradiation: High-energy neutron bombardment causing material degradation.

* Plasma Erosion: Direct impact from the plasma itself.

These conditions necessitate materials with remarkable thermal resistance,mechanical strength,and erosion resistance. The Outer Vertical Targets are specifically designed to handle the asymmetric heat loads within the divertor. Plasma control is paramount to the divertor’s success.

Nippon Steel’s Role and Manufacturing Process

Nippon Steel’s selection is based on their proven capabilities in producing high-quality, specialized steel components. The contract involves the full manufacturing process, from raw material selection to final machining and quality control. Key aspects of their work include:

1. Material Selection: Utilizing advanced tungsten alloys specifically formulated for the extreme environment within the ITER divertor. Tungsten is favored for its high melting point and low sputtering yield.
2. Hot Isostatic Pressing (HIP): Employing HIP technology to eliminate internal porosity in the tungsten, enhancing its mechanical properties and resistance to cracking.
3. Precision Machining: Utilizing advanced CNC machining techniques to achieve the tight tolerances required for the complex geometry of the OVTs.
4. Quality Assurance: Implementing rigorous quality control procedures,including non-destructive testing (NDT) methods like ultrasonic inspection and X-ray radiography,to ensure the integrity of each component. ITER components require unparalleled quality control.

The Importance of Tungsten Alloys in Fusion Reactors

Tungsten alloys are considered a leading candidate material for plasma-facing components (PFCs) in fusion reactors like ITER and future devices like DEMO. Their advantages include:

* High Melting Point: 3,422 °C, crucial for withstanding the extreme heat loads.

* Low Sputtering Yield: Minimizes erosion caused by plasma bombardment.

* Good thermal Conductivity: Helps dissipate heat effectively.

* High Density: Provides good shielding against neutron radiation.

However, tungsten also presents challenges, including its brittleness at lower temperatures and the potential for tritium retention. Ongoing research focuses on mitigating these issues through alloy development and surface modification techniques. materials science is central to fusion energy development.

ITER Project Status and potential Delays

While Nippon steel’s contract represents positive progress, the ITER project has faced significant delays and cost overruns. Recent reports,including those highlighted by Scientific American and discussed on platforms like Zhihu,suggest the project may be at risk of becoming a “major stalled project.” Factors contributing to these challenges include:

* Complex Engineering: The sheer complexity of building the world’s largest tokamak.

* International Collaboration: Coordinating contributions from 35 nations.

* Supply Chain Issues: Disruptions impacting the delivery of critical components.

* Technical Challenges: Unexpected issues arising during construction and assembly.

The current schedule anticipates first plasma in 2025, but this remains uncertain.The CFETR (China Fusion Engineering Test Reactor) project, intended as a follow-on to ITER, has also experienced setbacks, further emphasizing the difficulties in realizing fusion energy. Fusion energy research is a long-term endeavor.

Benefits of Successful ITER Implementation

Despite the challenges, the potential benefits of a successful ITER are immense:

* Demonstration of Fusion Feasibility: Proving that fusion energy