Twenty years ago today, on the afternoon of Saturday, April 22, 2006, I started this blog and wrote the first post. I was thirty-one years old. I was working at NASA’s Marshall Space Flight Center in Huntsville, Alabama, as an aerospace engineer on nuclear-power concepts for deep-space missions. I was in my third year of the University of Tennessee’s nuclear engineering distance program. My wife and I had two young children. I had been reading the Oak Ridge molten-salt reactor literature for six years, ever since Bruce Patton had let me borrow an old copy of Fluid Fuel Reactors that he borrowed from the Redstone library.

The first post said that the site was “intended to be a location for discussion and education about the value of thorium as a future energy source.” It noted that “despite the fact that our world is desperately searching for new sources of energy, the value of thorium is not well-understood, even in the ‘nuclear engineering’ community.” That framing was, if anything, an understatement. The value of thorium in 2006 was understood by very few one outside of a handful of retired engineers and scientists, a scattering of their students, and a small circle of readers who had stumbled across the same body of documents I had been reading.

I did not know, writing that first post, whether anyone would read the site. I did not know whether a community of interest existed. I suspected it did, because the documents I had been reading were too good to have left nobody affected — but I had little evidence. I had a Google blogspot, a few CDs of scanned technical reports from a 1960s research program that had been terminated, and a conviction that what had happened to the molten-salt reactor program was a loss the country had made to itself for reasons that, the more I understood them, the less they held up.

Twenty years later, I am still writing and trying to make this argument to a world that hasn’t changed as much as I would have hoped around this issue. The site is still running. The community I did not know existed has grown to thousands of active participants and, through Google Tech Talks and TEDx videos and subsequent coverage, has introduced the thorium case to audiences in the millions. The molten-salt technology I was writing about in obscurity in 2006 is, as of 2026, being pursued commercially by a number of companies in the United States and by substantial state-sponsored programs in China, India, and several other nations. Some of the people I used to correspond with through the EFT forum now run major parts of that industry. Some are on corporate boards. Some are in Congressional staff offices. Some are senior figures at the Department of Energy’s Advanced Reactor Demonstration Program. Yet thorium molten-salt reactors in the United States, as Oak Ridge envisioned them, are still only pursued by Flibe Energy.

Many of these accomplishments are important…and yet…

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The United States strategic thorium reserve — 3,200 metric tons of the material I was writing about in 2006, accumulated over four decades of federal stewardship — had by 2006 already been declared surplus and buried in shallow-land disposal at the Nevada National Security Site. The thorium that the Manhattan Project generation had recognized, in Seaborg’s phrase, as “a fifty-quadrillion-dollar discovery” was buried in the desert alongside low-level radioactive waste. The material cost little to produce, little to transport, and little to store. The Department of Energy destroyed it anyway, because no program existed in 1998 that needed it, and because the bureaucratic category of “surplus strategic material” had to be cleared from the books.

The U-233 inventory at Oak Ridge — approximately four hundred kilograms of the starter fuel that any American thorium-reactor program would have needed — was scheduled for destruction under the 2003 Final Environmental Impact Statement for the Disposition of Surplus Highly Enriched Uranium. The contractor Isotek was eventually selected to perform the downblending. The program, which began in earnest in the 2010s, is nearly halfway complete as I write this in 2026. The technology our grandparents developed produced the material; our parents preserved it at modest expense for forty years; our generation has watched the federal government destroy it while we fought unsuccessfully to stop the destruction.

No commercial molten-salt reactor has yet achieved criticality anywhere in the United States. China brought its TMSR-LF1 research reactor to first criticality in 2023 — the first molten-salt reactor to operate anywhere in the world since the MSRE was shut down at Oak Ridge in December 1969. That fifty-four-year gap is not a gap in physics or engineering. It is a gap in political will. The American molten-salt reactor program of the 1960s produced working reactors. The Chinese program of the 2020s is producing working reactors. The American program of the 2020s is still, as I write this, producing proposals, site permits, and fundraising rounds.

The Lithium-Fluoride Thorium Reactor (LFTR) that Flibe Energy has been developing since 2011 has not yet been built. The TerraPower Natrium reactor, a liquid-sodium-cooled, solid-fueled, fast-spectrum reactor with molten-salt energy storage, is under construction in Wyoming and is the leading American candidate for first-criticality of any Generation IV reactor. Kairos Power is building a salt-cooled demonstration reactor in Oak Ridge that uses solid HALEU TRISO fuel cooled by FLiBe salt. It is several steps in the right direction, but still not a molten-salt reactor nor a thorium reactor. ThorCon, Copenhagen Atomics, Moltex, Seaborg, and several other companies are pursuing various fluid-fuel concepts. Terrestrial Energy, which once represented a compelling Canadian effort in this space, has struggled and partially regrouped. The advanced-reactor industry in 2026 is larger, better-funded, and more diverse than anyone twenty years ago would have predicted. It has also not yet delivered the thing it set out to deliver.

The regulatory framework under which any American molten-salt reactor must be licensed is the same Nuclear Regulatory Commission framework that was built around pressurized-water reactors in the 1960s and 1970s. The NRC has, in recent years, begun to develop a framework for advanced reactors that does not require the solid-fuel-and-water assumptions of the original regulations, but the development has been slow and the framework is not yet complete. No commercial fluid-fuel reactor has yet been licensed in the United States. No commercial thorium-fueled reactor has yet been licensed. The regulatory path that Weinberg and MacPherson were trying to navigate in 1972 when they asked the AEC to fund the MSBR reference design is, functionally, the path Flibe Energy and its competitors are still trying to navigate in 2026.

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What has been done, in twenty years, is the intellectual rehabilitation of a technology that in 2006 was viewed by essentially everyone outside a small community as a historical curiosity. The molten-salt reactor, the thorium fuel cycle, the liquid fluoride thorium reactor — these were obscure terms when I started writing about them. In 2026 they are the subject of books, television documentaries, Congressional testimony, corporate strategy sessions, state-level legislative action, and venture-capital due diligence. The Alabama Legislature passed a thorium resolution in March. The U.S. Congress has considered, and may yet pass, a Thorium Energy Security Act. Senators write to the Secretary of Energy about U-233 preservation. Investors commit hundreds of millions of dollars to advanced-reactor startups pursuing some form of the technology. The case that we were making in 2006 to an audience of maybe a thousand people is now being made, in one form or another, by governments.

What has not been done, in twenty years, is the commercial deployment of a thorium molten-salt reactor anywhere in the United States.

Both of these statements are true simultaneously. Both of them have to be grappled with honestly.

The first statement — that the intellectual case has been won — is something no one in 2006 would have predicted. I did not predict it. I was hoping, when I started the blog, that a few hundred readers might find the site and that some of them might find the subject as interesting as I had found it. What happened instead was that a community formed, and the community built institutions, and the institutions generated public visibility, and the public visibility produced political and commercial attention, and the attention produced investment, and the investment produced companies, and the companies produced regulatory engagement, and the regulatory engagement is now producing — slowly — the framework under which a commercial thorium reactor could eventually be licensed. Every step of that chain was work done by somebody. Much of it was work done by people who first encountered the subject on this blog or in a talk that was advertised on this blog or through a community that formed around this blog. The chain is not complete, but it exists.

The second statement — that the commercial deployment has not happened — has to be understood against the backdrop of what commercial nuclear deployment looks like in the United States generally. Vogtle Units 3 and 4, the first new nuclear plants to come online in the United States in a generation, were completed in 2023 and 2024 at a cost of roughly $35 billion for 2.2 gigawatts of capacity. The AP1000 is a mature light-water reactor design that the Nuclear Regulatory Commission knows how to license and that the American nuclear industry has been building for forty years. Even so, Vogtle took more than a decade to complete. If the commercial deployment of a mature light-water reactor design, built on an existing site by the country’s largest nuclear utility, with guaranteed cost recovery through state public utility commissions, takes that long and costs that much — then the commercial deployment of a novel fluid-fuel reactor, built by a small company without a utility’s balance sheet, licensed under a regulatory framework that doesn’t yet fully exist, is facing deployment challenges that will daunt many stakeholders.

That is a hard thing to admit. It is also true. The American civilian nuclear industry has lost, over two generations, most of the institutional capacity it would need to deploy new reactor technologies rapidly. The supply chain is thin. The workforce is aging. The regulatory expertise is concentrated in a few firms. The utility business model does not reward taking risks on novel reactors when well-understood alternatives are available. All of these problems predate thorium; all of them will outlast any particular thorium-reactor company. They are problems of the American nuclear industry as a whole, and they will have to be solved for any advanced reactor — thorium or otherwise — to be deployed.

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Alvin Weinberg died in October 2006, about six months after this blog launched. I once had a brief phone call with him. It was clear to me that he was suffering from the effects of a stroke. But he told me that molten-salt reactors were once a good idea. Then he stopped and added as a quick correction, that molten-salt reactors are still a great idea.

Twenty years on, the distance has closed in ways Weinberg did not live to see. The technology he advocated for is being pursued by a number of companies, albeit mostly in ways he would not have recognized. His autobiography, The First Nuclear Era, is read by people who were not yet born when he wrote it. His name appears on buildings, in academic programs, in corporate marketing materials, in legislative citations. The phrase “Second Nuclear Era,” which he used in his autobiography’s final chapter to describe the thorium-powered future he did not expect to live to see, is a phrase that is now, thirty years after he coined it, being used in earnest by people who do believe they will see it.

I do not know whether they will. I do not know whether I will. The work remaining to be done is larger than the work that has been done. What we have accomplished in twenty years is the intellectual foundation. What remains to be accomplished is the reactor.

A reactor is not a blog post. A reactor is a piece of engineered equipment that costs hundreds of millions of dollars, requires a site, requires a licensed operator, requires a fuel supply, requires a decommissioning plan, and requires decades of operation before anyone can say whether it has fulfilled its purpose. Building one takes capital, political support, technical workforce, and time. We have, as a community, spent twenty years developing the conditions under which such a reactor could be built. We have not yet built it.

If I were writing to a version of myself on April 22, 2006 — sitting at a laptop, publishing a first post into essential silence — I would tell him this. The work you are starting matters. The community you do not yet know exists will find you. The documents you have digitized will outlive you. The people you will work with over the coming decades will include some of the best people you will ever know. The technology you are advocating for will be taken seriously by governments and corporations within ten years of this moment, and within twenty years will be pursued commercially by companies worth millions of dollars.

And I would tell him: it will still not be enough. Twenty years from now, there will still not be a commercial molten-salt reactor operating in the United States. The strategic thorium reserve will be gone. Almost half of the U-233 will be gone. The country that invented the technology will be watching, twenty years on, as a Chinese reactor becomes the first fluid-fuel reactor in the world to achieve criticality in half a century. The work of your generation will be necessary. It will not be sufficient. There will still be much to do.

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To the readers who have been with this blog for some or all of the twenty years: thank you. The site exists because you read it, argued with it, corrected it, extended it, and built the community that turned it from an engineer’s side project into something that mattered. Every substantive exchange in the comments, every forum thread that ran for hundreds of posts, every time a reader sent me a document I had not seen before, every talk I was invited to give because someone had read the blog and thought the argument was worth hearing — all of that is the blog’s actual achievement. The words on the screen are the smaller part. The readers are the larger part.

To the newer readers, arriving at the site because they’ve encountered thorium in some recent news story and want to understand what it is: welcome. You have arrived at a long conversation. The archives go back twenty years. The primary-source documents go back to the 1940s. The arguments being made here now are continuous with arguments that were being made at Oak Ridge in the 1960s and at the University of Chicago in the 1940s. You are not encountering a new topic. You are encountering an old topic that has been preserved by a community that cares about it, and that is now, finally, emerging into the public consciousness it deserved all along.

To those who are working, in whatever capacity, on advanced reactors, on thorium fuel cycles, on the preservation of the remaining U-233, on the regulatory frameworks that will determine whether any of this technology can be deployed: the work is harder than you probably expect, but you have more support than my generation had. Use it. The people who started this conversation are still alive, most of us. We are available. Reach out. The thorium community is a small community, and its institutional memory is concentrated in a relatively small number of people. If you are doing work that needs access to that memory, ask. You will be surprised how much help you can get.

To the Department of Energy, the Nuclear Regulatory Commission, and the national laboratories: twenty years ago, you were not part of the conversation. Today you are. Some of you are genuinely committed to seeing advanced reactors deployed. Some of you are institutionally committed to the light-water status quo and will need to be persuaded, over time, that the advanced-reactor future is real and requires your active engagement rather than your passive tolerance. The preservation of the remaining U-233 is a specific issue on which your decisions over the next few years will determine whether a substantial national resource is retained or destroyed. The decision is yours. We have told you what we believe the right decision is. What you do is up to you.

And to whoever reads this site in 2046 — if the site is still running, and if anyone is still reading it — I hope that by the time you see this, the reactor has been built. I hope that the second nuclear era Weinberg described has actually begun, in the United States, and that thorium is providing a meaningful share of the country’s energy. I hope that the question we have spent twenty years arguing about is, by then, settled.

If it is not — if twenty years from now, the situation looks much as it looks today, and the arguments we are making now need to be made again — then the work of this site and this community will have to continue. The argument for thorium does not age. The arguments against it are not improving. Whatever remains to be done, we will keep doing it, for as long as it takes.

Twenty years was always going to be a beginning, not an end.

Thank you for reading.