Minimize weapons-usable nuclear material by committing to permanent disposal of spent nuclear fuel

Countries and areas should minimize their current and future quantities of weapons-usable
nuclear material by committing to permanent disposal of spent nuclear fuel.

• Commit to spent fuel strategies that keep weapons-usable material out of the fuel cycle and reject reprocessing technologies that separate plutonium from fission products
• Update nuclear waste management guidance to clearly classify spent nuclear fuel as waste for disposal
• Cap separated plutonium inventories and designate any existing material for emplacement in a deep geological repository, using a dilute-and-dispose approach
• Conduct feasibility studies and initiate consent-based siting processes for placement of deep geological repositories
• Establish a government body to be responsible for long-term management of spent nuclear fuel and associated facilities
• Exchange technical and political lessons learned with international partners who have made significant progress on deep geological repositories (e.g., Canada, Finland, and Sweden).

What the Data Show

Countries operating the largest spent fuel reprocessing facilities are posing significant and unnecessary risks to global nuclear security by rapidly accumulating stocks of separated plutonium and falling short of international nuclear security standards.

Data Details

Two general strategies exist for managing spent nuclear fuel—and they have fundamentally different nuclear security implications. Most countries pursue a once-through fuel cycle, where spent fuel assemblies are removed from reactors, cooled in spent fuel pools, and permanently disposed of. This pathway avoids weapons-usable material by keeping nuclear material commingled with highly radioactive fission products, making theft or diversion extremely difficult.

The alternative is reprocessing, an economically costly endeavor to chemically separate fission products from spent fuel to isolate potentially reusable nuclear materials, primarily plutonium and uranium, with the goal of fabricating fresh fuel to be burned in reactors. Separated plutonium from reprocessing is a weapons-usable material. Four countries—France, India, Japan, and Russia—engage in commercial-scale reprocessing efforts, whereas China, Israel, North Korea, and Pakistan operate pilot-scale or military reprocessing facilities. Since the 2023 NTI Index, global inventories of separated plutonium have grown by a net 17,721 kilograms, with the countries operating reprocessing facilities responsible for 99 percent of that increase. Just 8 kilograms of separated plutonium is sufficient to build a nuclear weapon, meaning that the increase is enough for more than 2,200 bombs. Because just a small amount of separated plutonium could be directly used in a nuclear weapon, countries that choose reprocessing thereby commit to operating and securing the highest-consequence category of nuclear facility for as long as their separated plutonium stockpiles exist, an ongoing security burden that direct disposal avoids.

The 2026 NTI Index finds that nearly every country that reprocesses spent fuel is falling short of International Atomic Energy Agency (IAEA) security guidance for necessary security measures to protect these facilities. Reprocessing involves regular shipment of separated plutonium between facilities, but India, Israel, and North Korea do not have national laws or regulations that align with the IAEA’s transportation security best practices. Even fewer countries meet standards for effectively tracking nuclear materials through inventory accounting protocols, which raises significant concerns for reprocessing facilities handling separated plutonium. When materials arrive at facilities, the international standard is for them to be moved through designated “material balance” areas, or zones within nuclear facilities where all incoming and outgoing nuclear materials are tracked to reduce the risk of theft or diversion. France is the only country with reprocessing that has met the full international standard for securing material balance areas. Japan’s regulations do not require the designation of a single custodian and alternate backup to oversee the area and track inventories of nuclear materials. This additional oversight is an essential tool for maintaining the chain of custody when nuclear materials move into and out of facilities. Neither India, Israel, nor Pakistan have ever defined material balance areas within their facilities, a necessary step for strengthening security measures in these zones. Of the eight countries with reprocessing, only Japan has regulatory requirements for insider threat awareness programs at nuclear facilities—which helps reduce the risk of theft or diversion by insiders.

Several countries that currently employ a once-through fuel cycle, including China and the United States, have shown a renewed interest in large-scale reprocessing, which would increase global separated plutonium inventories even further. A once-through fuel cycle, where spent nuclear fuel is permanently disposed of, is the only available path that keeps weapons-usable material out of the fuel cycle. The significant financial burdens associated with reprocessing are compounded by the additional costs of increased nuclear security measures. Countries have shown in nearly every case that they do not have the capacity to manage these issues.