The Department of Energy (DOE) should develop an early warning capability to address dropping quantities of unobligated low-enriched uranium (LEU), a trend that could jeopardize U.S. compliance with international nuclear cooperation agreements, the Government Accountability Office (GAO) said in a report released Monday.
The United States’ nuclear cooperation agreements with other countries feature peaceful use provisions barring material obtained under those deals from being used for nuclear explosive devices or other military purposes – making that material “obligated.” The material is tracked by the Nuclear Materials and Management Safeguards System (NMMSS), a database managed by the National Nuclear Security Administration that is intended to ensure U.S. compliance with those international agreements.
The GAO said that from 2003-2015, DOE contractors and Nuclear Regulatory Commission-licensed facilities conducted 817 obligated nuclear material exchanges, allowing for obligations to be transferred between facilities in the U.S. without physically moving any nuclear material. “The total amounts of nuclear material at each facility do not change, and no material is physically moved, but the conditions on the use of the material have changed,” the GAO said.
Congressional auditors identified two issues that could impact the agencies’ ability to monitor nuclear material inventories. The first involved some facilities carrying negative obligation balances for a long period of time, which occurs when the facility makes an exchange without having enough of that material in its own inventory to cover the move. “In certain circumstances, negative balances may place the United States at risk of noncompliance with nuclear agreements,” GAO said.
The second issue involved the declining U.S. inventory of unobligated LEU, which could otherwise be used to correct negative obligation balances. LEU is considered a vital national security need because of its use in production of tritium, used in nuclear weapons development. “NMMSS does not have an early-warning monitoring capability to alert DOE when the inventory is particularly low,” GAO said; that situation puts the U.S. at risk of not complying with its nuclear agreements.
DOE has estimated that the domestic unobligated LEU inventory will last until 2038-2041. The inventory has declined in recent years, namely because the U.S. lost its sole supplier of the material in 2013 when the U.S. Enrichment Corp. – now Centrus Energy Corp. – ceased its uranium enrichment operations. Most of the LEU in the U.S. carries foreign obligations, GAO noted.
The GAO recommended that the NNSA and NRC clarify the conditions under which facilities can have negative obligation balances, and develop an early warning monitoring capability that will alert DOE officials of a low unobligated LEU inventory.
DOE and the NRC said they are implementing actions to address the recommendations, but “did not explicitly state whether they concur,” the GAO said.
