A Question A Day in May - Part 1
This month, in honour of fusion energy week (5-9th May), we have been posting A Question A Day in May for our subscribers (we're on Circle*). We asked our readers for input, and Karl Tischler is answering the fusion questions you've been wanting answered in comprehensive detail.
Check out this summary of the questions so far and read the extended versions on our Circle platform by following the links. It's free to subscribe.
*Circle is a bit like Substack but with extra community features.
Q1: What are the engineering challenges of building a fusion reactor?
There’s no single breakthrough that will make fusion work. It’s not just about creating fusion reactions—it’s about building an entire system that can do it affordably, safely, and continuously.
That system has to be engineered from the ground up: from the fuels and materials to the magnets, robotics, cooling systems, and power generation. It’s one of the biggest technical puzzles humanity has ever tried to solve.
But the payoff? A new, clean, long-term source of energy—built to last. And thanks to the work of thousands of researchers and engineers around the world, it’s getting closer every day.
Q2: What are the 35 ITER countries?
Currently 33 nations (the EU’s 27 members + 6 others) fund and govern ITER. Switzerland is set to rejoin, raising that to 34. The UK is no longer an ITER member post-Brexit. Meanwhile, Australia, Kazakhstan, and Canada contribute through cooperation agreements.
Q3: Are any companies investigating superconductors other than REBCO?
REBCO opened the door to compact fusion magnets — but it’s not the whole story. A growing ecosystem of companies and labs is working on both new superconductors and new ways to produce them, ensuring that future fusion reactors have a full magnet toolbox, not just one star player.
Each breakthrough in superconductors brings us closer to practical fusion — and helps turn giant machines into something we can build, operate, and eventually power the grid with.
Q4: What recent papers do you recommend for Commonwealth Fusion Systems and Tokamak Energy?
Two of the most closely watched private fusion companies – Commonwealth Fusion Systems (CFS) and Tokamak Energy (TE) – have been moving from design concepts to real-world results, backed by peer-reviewed research.
Q5: Do you see any of those FIA member companies going public any time soon?
Going public is possible—but it won’t happen just because fusion is exciting.
It will happen when a company can show it has a valuable product, a reliable system, or a realistic path to revenue—whether that’s a fusion powerplant or a technology along the way.
So while we may see IPOs in the future, they will likely be driven by strategic milestones, not scientific enthusiasm. Fusion’s path to the public markets will depend on progress—measured not just in plasmas and prototypes, but in economics, reliability, and complete systems.
Q6: Do you know of any online training opportunities/postgraduate University programs which are connected to fusion?
Whether you’re after a full degree, a summer school, or a flexible online course, there’s never been a better time to train in fusion. From the IAEA and EPFL to world-class universities and national labs, the educational infrastructure is there — and growing. And with demand for fusion talent rising, the next generation of scientists and engineers is being trained today to power tomorrow.
Q7: As Prof. Harald Lesch theorizes, will the waste heat of fusion power plants be a problem in the future? Is direct energy conversion (as proposed by Helion Energy) the solution?
Waste heat from fusion is not expected to be a major problem in the near future—certainly not compared to today’s carbon emissions. But if fusion scales globally over time, improving plant efficiency will become increasingly important. Direct conversion is one potential solution. It won’t solve everything, but it could help ensure fusion’s long-term impact on Earth’s heat balance stays small—just one more reason why innovation in fusion matters now.
Q8: What do you think about the ITER dates moving from 2025-2036? Is this due to money, a lack of manpower, or technical problems?
The ITER delay wasn’t due to lack of money or people. It was due to the scale, novelty, and international complexity of the project—and a mismatch between scientific ambition and engineering reality. The lessons are painful but valuable. If DEMO, and future public-private fusion ventures, are to succeed, they must learn from ITER’s mistakes—and build differently.
ITER is not a failure. It’s a first draft. And that’s exactly what the world needs right now. Every setback has revealed something future reactors must do differently—and that knowledge alone is worth the investment.
Q9: When creating a fusion reactor, how can one ascertain the quantity of tritium needed at the reactor startup stage with any degree of accuracy?
Estimating startup tritium isn’t just about plasma fuel. It’s about the entire system: burning, recycling, breeding, and losses. Accurate modeling can help engineers size the initial inventory — but until reactors prove they can reliably close the fuel loop, every gram counts.
Tritium scarcity may not be today’s headline issue. But without a clear path to scale, it could become fusion’s bottleneck.
Q10: How easily can tritium be extracted from breeding blankets
Tritium extraction is theoretically possible — but it’s not easy. In liquid metal blankets, tritium can be extracted continuously at moderate temperatures (~450 °C). In solid ceramic blankets, tritium recovery is harder and requires operation near 700 °C. Designs account for this, but the real test will come with ITER and future demonstration plants.
Getting this right — efficiently and safely — is essential to making fusion power self-sustaining. It’s not solved yet, but the tools and plans are in place to try. Until these systems are validated, there’s no guarantee fusion reactors will be able to fuel themselves — and that makes tritium extraction one of the most critical challenges in making fusion power a reality.
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