The Uranium Hidden in Cobalt: How DRC's Mining Boom Created a Nuclear Blind Spot

A new study published July 30, 2026 in Nature Communications has uncovered a massive blind spot in global nuclear accounting: large quantities of undeclared uranium have been extracted and exported from the Democratic Republic of the Congo (DRC) through its booming cobalt supply chain over the past 25 years, with most shipments going completely undetected by international safeguards .

The research, conducted by Ryan Manzuk, a postdoctoral research associate at Princeton University's Program on Science and Global Security, and Sébastien Philippe, an assistant professor of nuclear engineering and engineering physics at the University of Wisconsin–Madison, reveals that this hidden uranium flow has continued largely unreported, even as the DRC has officially produced no uranium for decades .

The scale of undeclared uranium exports

The researchers estimate that 2,000 to 5,000 metric tons of natural uranium were exported from the DRC embedded in cobalt-hydroxide shipments between 2000 and 2024 . This is not a small amount: according to the study, it is enough to produce fissile material for roughly 600 to 1,500 nuclear weapons, or to fuel a standard light-water nuclear reactor for 10 to 25 years .

Despite the massive volume, less than 10% of this material appears to have been publicly declared and placed under International Atomic Energy Agency (IAEA) safeguards . The vast majority of these shipments went to China, which hosts approximately 95% of the world's cobalt refineries . The researchers note that there is no evidence the uranium was intentionally exported for weapons purposes, but the lack of declaration means the material has no limitations on its end use .

Uranium in mine tailings: a hidden environmental threat

The study also found that an estimated 1,000 to 4,000 metric tons of uranium were discarded into mine tailings — the waste stream from mining — in chemically mobile forms . This means the uranium can be transported by rainwater or groundwater, posing risks of radioactive dust inhalation, water contamination, and soil pollution for miners and surrounding communities .

For mine workers, exposure to low doses of radiation over long periods, or breathing radon gas generated by radioactive material, can increase cancer rates and cause other health problems . The DRC has been seeking overseas funding to install radiation detectors for trucks leaving the country .

Why this matters for global security

Because the uranium is undeclared and not officially reported to the IAEA, there is no limitation on its end use. Researchers warn it could enter a civilian nuclear program or a military program without any oversight . This creates a significant nuclear proliferation risk that has gone largely unnoticed by the international community.

The research builds on earlier work presented by Manzuk at Princeton in October 2025, which used geologic and chemical models of how uranium and cobalt co-occur in ores to trace this understudied uranium resource pathway . The team combined mineral distribution data, geochemical data, mine-by-mine trade records, and chemical models of cobalt processing to track the uranium's movement .

Researchers' recommended actions

The study's authors outline several urgent steps to address the problem :

• Conduct an extensive national audit of mining in the DRC and establish new rules for separating uranium from the cobalt supply chain.
• Implement systematic assay measurement of cobalt-hydroxide shipments and worker radiation monitoring.
• Create surveillance and monitoring mechanisms to ensure environmentally responsible mining.
• Ultimately, prevent uranium exports by refining cobalt to metal within the DRC, rather than exporting crude cobalt hydroxide.
• Improve accounting of uranium extraction and shipments as an urgent first step.

"Based on what we found, I think there needs to be an extensive national audit of mining in the DRC and new rules for separating uranium from the cobalt supply chain," Philippe said in a university press release .

The findings have been covered by major international media including the Financial Times and Le Monde, and the project brought together scientists with investigative journalists from Lighthouse Reports .