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A New Chapter in the Story of Fusion Energy: Michel Claessens’ Updated Edition of “ITER: The Giant Fusion Reactor”

The world of fusion energy has seen significant developments in recent years, and with it comes the much-anticipated second edition of Michel Claessens’ book, ITER: The Giant Fusion Reactor: Bringing a Sun to Earth. This updated edition provides an in-depth and personal exploration of one of the most ambitious scientific projects in human history, offering fresh insights and reflecting the latest advancements and challenges in the journey toward sustainable energy.

A Visionary Work with a Unique Perspective

“ITER: The Giant Fusion Reactor – Bringing a Sun to Earth” by Michel Claessens. Published: 06 November 2023 by Springer. Copyright: The Author, under exclusive license to Springer Nature Switzerland AG 2022

Michel Claessens, with his extensive background as the former Head of Communications at ITER and a former EU official, brings a unique and invaluable perspective to the narrative. His experience allows him to offer readers a comprehensive view of the ITER project, enriched with personal anecdotes and memories that make the technical and political complexities accessible and engaging for a broad audience.

The genesis of Claessens’ book was inspired by his realization of the lack of comprehensive, non-technical information about the ITER project. This was highlighted during his time in Cadarache, where frequent visitor inquiries about the project’s communication spurred him to document its full scope. The book’s first edition was lauded for its thorough coverage and readability, as noted by physicist Robert Aymar, often considered the “father” of ITER, who commended it as essential reading for any study on the project.

Addressing the New and the Now

In the second edition, Claessens includes three new chapters that address the significant progress and the emerging challenges faced by ITER since the first edition. The updated content reflects the impressive advancements in the construction and assembly of the ITER machine, which are visible both on-site and through online updates. However, it also candidly discusses the technical and managerial issues that have arisen, including critical problems in 2022 that led to the interruption of the tokamak assembly.

Claessens provides a balanced view of these developments, emphasizing the need for honest and transparent communication about the project’s hurdles and achievements. This transparency is crucial not only for public understanding but also for maintaining the trust of decision-makers and stakeholders in the scientific community.

A Diplomatic and Scientific Odyssey

The ITER project is a prime example of scientific diplomacy, born in the politically charged environment of the Cold War and continuing to foster international cooperation despite geopolitical tensions. Claessens highlights how ITER has brought together nations that were once adversaries, such as Russia and the United States, to work collaboratively on a peaceful and groundbreaking endeavour. This aspect of ITER as both a technological and diplomatic project underscores its significance beyond just the scientific and technical realms.

Reflecting on the Future of Fusion

Claessens’ book is not just a historical account but also a forward-looking examination of fusion energy’s potential role in addressing global energy needs. The depletion of fossil fuels and the urgent need to mitigate climate change make fusion energy a promising solution. Claessens explores the socio-philosophical dimensions of this pursuit, invoking the ideas of sociologist Jacques Ellul on technological necessity. He posits that ITER exists because it was achievable, reflecting a broader truth about humanity’s relentless drive to harness and master new forms of energy.

A Personal and Engaging Narrative

What sets Claessens’ work apart is its ability to humanize the vast and complex ITER project. His narrative is peppered with personal stories and observations that bring the reader closer to the individuals and the collective human effort behind the machine. From the multilingual communication challenges at ITER’s international offices to the dedicated scientists and engineers working tirelessly, Claessens paints a vivid picture of the project’s day-to-day realities.


Michel Claessens’ second edition of ITER: The Giant Fusion Reactor is a must-read for anyone interested in the future of energy, fusion technology, and large-scale international scientific projects. It provides an accessible yet detailed account of ITER, celebrating its achievements while honestly addressing its challenges. This updated edition not only informs but also inspires, showcasing the potential of human ingenuity and cooperation in solving some of the most pressing challenges of our time.

For further details on Michel Claessens’ insights and the latest developments in the ITER project, visit the book review by ITER Newsline here.

Link to the book on Springer website:

Author Michel Claessens and family at the ITER Open Doors Day on April 13, 2024. Photo courtesy of Michel Claessens.
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