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U.S. Department of State

Diplomacy in Action

Domestic U.S. Reactor Conversions

Fact Sheet
Bureau of International Security and Nonproliferation
March 22, 2012


The National Nuclear Security Administration (NNSA) helps convert research reactors around the world from the use of highly-enriched uranium (HEU) fuel to low-enriched uranium (LEU) as a key part of its nuclear nonproliferation mission. Reactor Conversion is part of NNSA’s Global Threat Reduction Initiative (GTRI) efforts to develop and implement technologies to minimize and, to the extent possible, eliminate the civilian use of HEU, including in research reactors and isotope production facilities worldwide.

  • All of the U.S. domestic research reactors that could be converted with existing, licensed fuel are operating on LEU.
  • Since 2004 GTRI has converted seven domestic research reactors (at the University of Florida, Purdue, Oregon State, Washington State, University of Wisconsin, Texas A&M, and Idaho National Laboratory) from the use of HEU to LEU fuel. These conversions represent the elimination of approximately 39 kg of HEU use annually.
  • GTRI has confirmed the shutdown of two HEU-fueled reactors (one in California and one in Idaho). These shutdowns represent the elimination of approximately 3,007 kg of annual HEU use, equivalent to approximately 120 nuclear weapons per year.

GTRI is also working to develop a replacement LEU fuel and the associated fuel fabrication capability for the six remaining High Performance Research Reactors (HPRRs) in the United States that cannot convert with existing fuel. The six HPRRs include nuclear research reactors at the Massachusetts Institute of Technology, University of Missouri, the National Institute of Standards and Technology (NIST), the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory and the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL) and its associated critical assembly (ATRC).

GTRI is working towards qualification and licensing of a new high-density LEU fuel by the U.S. Nuclear Regulatory Commission (NRC). After the fuel has been licensed by the NRC, the MIT research reactor intends to be the first HPRR to convert. 

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