World’s Largest Fusion Project in Trouble: ITER Faces Major Challenges, New Documents Reveal

By Pranav Mahapatra

June 16, 2023
Construction site of a cylindrical building, the fusion reactor site of The International Thermonuclear Experimental Reactor (ITER)
ITER construction status in 2018

The International Thermonuclear Experimental Reactor (ITER), a collaboration among 35 countries to build the world’s largest and most powerful fusion reactor, is in big trouble, according to new documents obtained by Scientific American via a lawsuit.1

Project ITER aims to demonstrate that fusion energy can be a viable source of clean and abundant power.

The documents reveal that ITER is facing massive delays and cost overruns that threaten to derail its progress and undermine its credibility.

The ITER project was formally launched in 2006, with an estimated budget of €5 billion (then $6.3 billion) and a completion date of 2016, located in the South of France.

However, over the years, the project has encountered numerous technical and managerial difficulties that have pushed back its schedule and increased its cost.

The most recent official estimate puts the budget at more than €20 billion ($22 billion), with the first plasma expected in 2025.

But the documents reveal that these figures are outdated and unrealistic and that the project is not even close to being ready for operation.

Challenges that ITER is Facing

The documents, which include internal reports, memos, and presentations, evince that the ITER project is facing several major challenges that could further delay its completion and inflate its cost.

Even though the problems had been accumulating for years, backed by additional delays, bad management, and accountability as well as influenced by the 2020 Covid pandemic, the ITER Organization did not reveal them until recently with the documents.

Magnet Problems

The design and fabrication of the 18 giant superconducting magnets will confine and heat the plasma inside the tokamak, the doughnut-shaped vessel that is the heart of the fusion machine.

The magnets are extremely complex and require unprecedented levels of precision and quality control; several of them have already experienced problems such as cracks, defects, and delays in delivery.

The documents reveal that some of the magnets are not meeting the required specifications and that their installation could take much longer than expected.


The magnets are also vulnerable to damage from thermal stress, electrical faults, and plasma disruptions.

Installation and Integration Issues

The installation and integration of the various components of the tokamak involves thousands of workers and hundreds of contractors from different countries.

The process is highly challenging and risky, as any mistake or mishap could damage the delicate and expensive parts or compromise the safety and performance of the machine.

The documents show that the installation and integration schedule is unrealistic and optimistic and that there are many uncertainties and risks associated with the assembly of such a large and complex device.

It also warns that some of the components may not fit together properly or may not function as intended.

System Development and Testing Challenges

The development and testing of the systems and technologies will control, monitor and maintain the plasma once it is ignited.

These include heating, fueling, diagnostics, cooling, and vacuum systems that are essential for achieving and sustaining a stable fusion reaction.

Many of these systems are still under development or have not been tested at the required scale or conditions.


The documents indicate that some of the systems are behind schedule or over budget and that some of them may not be compatible with each other or with the tokamak, and highlight the difficulties of testing and validating the systems in realistic scenarios before operation.

Management and Coordination Difficulties

The ITER project involves multiple stakeholders with different interests, expectations, and cultures.

It likely has been troubled by bureaucratic inefficiencies, communication gaps, conflicts, and disputes that have hampered its decision-making and execution.

And the project also lacks a clear and realistic roadmap for achieving its goals and milestones.

The documents reveal that the project’s leaders have not been transparent or accountable about the project’s status and problems and that they have not communicated effectively with their partners or with the public.

It’s explained that the project’s leaders have not been able to resolve some of the key technical and organizational issues that affect the project’s success.

What Will Happen to ITER Now?

ITER project is unlikely to meet its current schedule and budget targets and it will need more time and money to overcome its challenges and achieve its objectives.

However, the project’s leaders have not publicly acknowledged or addressed these issues, and have instead maintained an optimistic and confident tone.

A chart showing status of current schedule, budget estimates and future projection of the International Thermonuclear Experimental Reactor (ITER) project
The ITER Project’s status of schedule and budget estimates with future projections. Credit: Amanda Montañez, Source: Scientific American

This has raised concerns among some observers and insiders that the project is hiding or downplaying its problems and risks, and that it is losing credibility and trust among its partners and supporters.

The ITER project is widely seen as an important step for advancing fusion energy research and development, as it aims to demonstrate that fusion can produce more energy than it consumes, a condition known as net energy gain.

Although fusion energy has also been notoriously difficult to achieve and harness, as it requires creating and controlling extreme conditions similar to those inside stars, it has long been touted as a potential solution for meeting the world’s growing energy needs while reducing greenhouse gas emissions and nuclear waste.

A drone as it flies in and around the main buildings of the ITER scientific installation to show you what has been happening on the worksite. ITER by drone – latest update, iterorganization (YouTube), 30 May 2023

The ITER project is not the only fusion endeavor in the world, as there are several other public and private initiatives that are pursuing different approaches and technologies for achieving fusion energy.

Some of these initiatives claim to be faster, cheaper, or more innovative than ITER, but none of them have yet proven their feasibility or viability.

The success or failure of ITER will have strong implications for the future of fusion energy research and development, as well as for global cooperation and leadership in science and technology.


  1. Charles Seife, ‘World’s Largest Fusion Project Is in Big Trouble, New Documents Reveal‘, Scientific American, 15 June 2023,[]