Is Nuclear Fusion a Dream Energy? — Risks Hidden Behind the Technology
In recent years, the increasingly frequent extreme weather events around the world may be confronting us with the sobering reality that global boiling is approaching a critical threshold.
Nevertheless, U.S. President Donald Trump continues to insist that climate change is “the greatest hoax in history,” refusing to retract this claim. (Speech at the UN General Assembly on September 23, 2025)
The United States, the second-largest emitter of greenhouse gases, did not send a government delegation to this year’s COP30 (the 30th Conference of the Parties to the UN Framework Convention on Climate Change).
At COP30, although negotiators managed to include financial targets for supporting developing countries in adapting to climate change, the conference ended without adopting a roadmap for phasing out fossil fuels.
As a result, it seems that achieving the Paris Agreement goal — limiting the global average temperature increase to 1.5°C above pre-industrial levels — has become even more distant.
Humanity has only a very limited amount of time left to reduce the ever-increasing volume of greenhouse gas emissions.
Yet the global adoption of renewable energy has not progressed as hoped.
At the same time, many people feel uneasy about increasing our dependence on dangerous nuclear power plants.
Nonetheless, on the 21st of this month, Governor Hanazumi of Niigata Prefecture announced his approval for restarting the Kashiwazaki-Kariwa Nuclear Power Plant, which had been shut down since the Fukushima Daiichi accident.
How must the more than 23,000 evacuees — who were forced to leave their homes by the Fukushima disaster and still cannot return — have felt upon hearing this news?
“There is no remembering the heat once the throat has passed the hot water.”
Is TEPCO now experiencing the truth of this old proverb?
In this context, nuclear fusion energy has recently come into the spotlight as a clean energy source.
As a so-called “dream energy” that would allow us to create a miniature sun on Earth, ITER and other fusion programs around the world are now competing intensely to achieve practical implementation.
In her recent policy speech, Prime Minister Takaichi stated that the early social implementation of fusion energy is one of the pillars of Japan’s energy security strategy.
Fusion energy is promoted as a clean energy source that does not emit greenhouse gases, unlike fossil fuels, and as a technology with fewer safety issues and less nuclear waste than nuclear fission — in short, a “dream energy.”
If realized, it is said that humanity will finally be freed from energy shortages and that a rosy future will await us.
But is that really true?
Whenever a new energy source has been developed — coal, oil, nuclear fission — humanity has embraced it as a dream energy.
Yet the result has been environmental degradation and ecological crises of unprecedented scale.
It is now time for us to examine nuclear fusion with the same critical eye, evaluating both its benefits and risks.
From this perspective, I discussed the issue with a generative AI and have summarized the fusion-related concerns that can be identified at this point.
---
1. Nuclear fusion is not an “absolutely safe technology.”
【¹】【²】
Inside a fusion reactor, plasma exceeding 100 million degrees Celsius must be confined using extremely strong magnetic fields — a set of conditions unparalleled in human engineering. If plasma confinement fails:
Major equipment damage
Leakage of radioactive materials
could occur.【³】
---
2. Tritium is neither a “convenient fuel” nor a “harmless waste.”
【⁴】【⁵】
Tritium — a principal fuel for fusion — not only emits weak radiation but also:
penetrates metals and concrete
easily disperses into air and water
does not bioaccumulate but readily binds with water inside the body
【⁶】
Furthermore, tritium is an essential material for “boosted nuclear weapons” and hydrogen bombs.
【⁷】
---
3. Fusion reactors will generate new radioactive waste.
【⁸】
ITER and other research institutions acknowledge that neutron irradiation will activate structural materials, and commercial reactors are expected to produce large volumes of intermediate-level radioactive waste.
---
4. Fusion inherently carries military risks.
【⁹】【¹⁰】
Because tritium is strategically important for nuclear weapons, large-scale tritium production enabled by fusion could raise a country’s military potential and increase the risk of nuclear proliferation.
---
5. The timeline for commercialization remains highly uncertain.
【¹¹】
Fusion still faces numerous unresolved challenges (materials, heat loads, tritium breeding, plasma control). For decades, experts have repeatedly claimed that commercialization is “30 years away.”
Going forward, we must rigorously assess total costs — R&D, construction, operation, waste management, safety measures, and potential accident compensation — to evaluate its true economic feasibility.
---
6. Fusion may accelerate economic growth and increase global environmental burdens.
【¹²】【¹³】
Excessive faith in fusion could justify limitless energy consumption and economic expansion, leading to intensified resource depletion, massive waste generation, and ecological destruction — pushing the Earth system toward collapse.
---
Having outlined these concerns, the issue I fear most is that the realization of fusion energy could be used to justify the continuation — or even the expansion — of our long-standing growth-first economic system.
If that happens, the present pattern of mass production, mass consumption, and mass disposal will expand without limit.
At the end of that path may lie catastrophic environmental destruction, mass extinction, and ultimately, the collapse of human civilization.
Before acquiring infinite energy, humanity must eliminate war through international cooperation and build a sustainable socioeconomic system that allows us to coexist with the Earth’s ecosystems.
Humanity may be able to build a “vessel for plasma,” but we have not yet built the “vessel of civilization” capable of responsibly receiving such immense energy.
And that vessel must not be based on the old paradigm of human-centrism; it must be grounded in Earthism, which puts the planet’s ecosystems first.
To prevent humanity’s dream energy from becoming a nightmare energy, our collective wisdom is now being tested.
Thank you.
【List of References】
¹
ITER Organization, Safety Approach and Design Requirements, ITER Technical Reports, 2020–2023.
Stacey, W. M., Fusion: An Introduction to the Physics and Technology of Magnetic Confinement Fusion, Wiley-VCH, 2010.
²
Abdou, M. et al., “On the Safety and Environmental Characteristics of Fusion Power,” Fusion Engineering and Design, 2001.
IAEA, Fusion Safety Standards and Guidelines, IAEA Nuclear Safety Standards Series.
³
Hender, T. et al., “Disruption Mitigation in Tokamaks,” Nuclear Fusion, 2007.
ITER, Disruption Risks and Mitigation Systems, Technical Brief, 2022.
⁴
IAEA, Tritium Handling and Safe Storage, Safety Series.
DOE (U.S. Department of Energy), Tritium Primer, 2021.
⁵
UNSCEAR, Sources and Effects of Ionizing Radiation, Annex B: Tritium, 2016.
Kim, J. et al., “Environmental Behavior of Tritium,” Journal of Environmental Radioactivity, 2013.
⁶
Health Canada, Human Health Fact Sheet: Tritium, 2020.
Little, M. P., “Tritium Risk Reassessment,” Radiation Research, 2009.
⁷
Cochran, T. et al., Nuclear Weapons Databook, NRDC, 1987–2014.
International Panel on Fissile Materials (IPFM), Tritium and Nuclear Weapons, 2015.
⁸
IAEA, Radioactive Waste from Fusion Facilities, Technical Reports Series.
Federici, G. et al., “Fusion Materials and Activation,” Journal of Nuclear Materials, 2014.
⁹
IPFM, Fusion Energy and Nuclear Proliferation Risks, 2017.
Krivit, S., Fusion Fiasco, 2014
¹⁰
U.S. Congressional Research Service, Tritium Production and National Security, CRS Reports.
Pellaud, B., “Nuclear Fusion and Proliferation,” IAEA Bulletin, 1983.
¹¹
ITER, Roadmap to Fusion Energy, 2023.
U.K. Royal Society, Prospects for Fusion Energy, 2021.
¹²
Smil, Vaclav, Energy and Civilization: A History, MIT Press, 2018.
Heinberg, Richard, Our Renewable Future, 2016.
¹³
Rockström, J. et al., “Planetary Boundaries,” Science, 2009.
Meadows, D. et al., Limits to Growth: The 30-Year Update, 2004.
□ Here is the Japanese version.
⬜ 核融合は夢のエネルギーか？ ―― 技術の裏に潜むリスク
【Related Posts】
⬜ Toward an “Earth First” Future—Now at a Turning Point in History—