Minimizing Weapons-Usable Nuclear Material: A Nuclear Security Success Story Still in Progress

One of the most significant achievements in reducing the risk of nuclear terrorism over the past two decades is something that rarely makes headlines: the complex, painstaking work of eliminating weapons-usable nuclear material from countries that once held it. Over that period, 25 countries have removed all highly enriched uranium (HEU) or separated plutonium from their borders—representing dozens of facilities that no longer need to be protected against theft, sabotage, or misuse.

The forum that has helped encourage this progress is the International Symposium on HEU Minimization, convened four times by the Norwegian government since 2006. In March 2026, the International Atomic Energy Agency (IAEA) partnered with the Norway to host the symposium’s 20th anniversary meeting, gathering approximately 70 experts, diplomats, and civil society representatives from 20 countries to reflect on the remarkable progress that has been made and the challenges that lie ahead.

Perhaps the most exciting achievement highlighted in the recently released 2026 Chair’s Summary of the meeting is the completion of a goal that earlier symposia aspired to achieve: the conversion of all major producers of molybdenum-99 (the isotope used in millions of medical diagnostic procedures each year) from using HEU to low-enriched uranium (LEU) in their fabrication process. The second symposium, in 2012, recorded political commitments to complete these conversions by 2015. That timeline slipped, but the task was not abandoned. The result is that a global industry that was using approximately 40-50 kilograms of HEU per year at the turn of the century is now using none. That’s more than one bomb a year’s worth of weapons-grade material permanently removed from the civilian nuclear fuel cycle.

This year’s symposium also illustrated how much the underlying debate around HEU minimization has evolved. In 2006, there were questions whether major HEU minimization projects were even technically feasible: could high-performance research reactors and large-scale isotope production facilities operate with LEU fuel? Twenty years later, those have largely been settled. The global research reactor community has demonstrated that the requirements for new high-performance research reactors and industrial-scale radioisotope production can be met with LEU fuel. The discussion has shifted from whether minimization is possible to how to preserve progress and address remaining challenges—like the fact that weapons-usable nuclear material still sits in 24 countries.

Looking ahead, participants identified several areas where attention is needed, including:

• Keeping up with evolving threats. Geopolitical instability and rapid technological change are reshaping the security landscape and making the case for minimization more urgent. Ukraine provides a powerful example of the stakes. Had HEU not been removed from the country more than a decade ago, facilities with weapons-usable nuclear material could be caught in the crossfire of the ongoing war with Russia.
• Maintaining momentum. Progress on minimization can be quiet and incremental, making it vulnerable to neglect. Upcoming international meetings, including the 2027 Review Conference of the Amendment to the Convention on the Physical Protection of Nuclear Material (CPPNM), provide important opportunities for nuclear-weapon states and non–nuclear-weapon states alike to take stock of progress, reaffirm commitments, share lessons learned, and announce new steps. For example, announcing participation in IAEA Information Circular 912, the voluntary initiative on minimizing and eliminating civilian use of HEU, would be a valuable demonstration of progress.
• Sustaining necessary resources. Continued progress requires political attention and adequate resources. This is particularly relevant in the United States, where funding for international nuclear security programs faces increasing budget pressure even as important HEU minimization work remains unfinished. It is also relevant to the sustainability of the IAEA’s central role in this process, given the essential technical expertise, coordination support, and other assistance it has provided to states seeking to reduce or eliminate HEU use for decades. The IAEA will remain indispensable if the international community hopes to build on the progress achieved over the past twenty years, but the agency’s ability to fulfill this mandate will depend on the support it receives from member states.

At the time of the 2026 Oslo Symposium, it had been eight years since a country last eliminated all of its civilian HEU. Shortly after the meeting’s conclusion, Venezuela—a country not publicly known to possess weapons-usable material—shipped away its remaining HEU. When fellow participants asked me what I hoped to see by the time we next convened, my answer was that I hope it does not take another eight years for the next country to eliminate its HEU.

After two decades, the Oslo Symposium has earned its place in the history of nuclear security as a source of inspiration for one of the field’s clearest success stories. Its value has come from its ability to keep governments engaged and accountable to overcoming barriers that once seemed daunting. The next two decades of progress will require sustained political commitment, technical cooperation, resources, and the continuation of essential international forums, like the Oslo Symposium.