US debates its future needs for enriched uranium for military and other purposes

Frank von Hippel

The US Congress is raising questions about Department of Energy plans for uranium enrichment for military and civilian purposes and of the role of Centrus, a private company which formerly was the US Enrichment Corporation (USEC). USEC had been created in 1992 by the privatization of the DOE-managed government enrichment monopoly. When USEC reorganized as Centrus, the Obama Administration's Deputy Secretary of Energy Daniel Poneman, moved over to become its President and CEO.

US HEU production and use. The privatization of US enrichment activities was made possible because the United States ended production of HEU for naval reactor fuel in 1992, having ended its enrichment of uranium for weapons in 1964. With a large HEU stockpile in hand, the US transferred about half of its Cold War weapons stock of highly enriched uranium (HEU) to non-weapons uses in two decisions: one by the Clinton Administration in 1994 and one by the Bush Administration in 2005.

Most of the HEU declared excess in 1994 was blended down to low-enriched uranium (LEU) and sold for power-reactor fuel. Most of the HEU declared excess in 2005 was transferred to a reserve to fuel US naval reactors. That reserve is projected to satisfy US navy needs until 2060. US stocks of excess Cold War HEU will not last forever. In 2015, DOE reported to Congress on its projected future needs for enrichment.

Tritium. DOE argued that the first requirement for new enrichment services would be about 2040 for LEU to fuel two Tennessee Valley Authority (TVA) power reactors that produce tritium for US nuclear weapons. Tritium has a 12-year half-life and therefore, unlike the HEU in weapons, must be replenished. (In an earlier IPFM post, it was pointed out that the US could declare an additional amount of weapons HEU excess sufficient to supply the tritium-production reactors with LEU until after 2060. )

URENCO, the world's second larger supplier of enrichment services, co-owned by the governments of the Netherlands and the UK, and two German utilities, has an enrichment plant in New Mexico and has offered to supply the LEU required for US tritium production. The Department of Energy has taken the position, however, that the intergovernmental agreement under which URENCO's plant was established "obligates" the LEU it produces to peaceful use.

Stimulated in part by a recent article on potential alternatives to a new national enrichment plant, other Congressional committees are asking questions about these alternatives. In its report on the Defense Authorization Act for Fiscal Year 2020, the House Armed Services Committee directed (pp. 339-340):

"the Administrator [of the National Nuclear Security Administration (NNSA) within DOE] to provide a report to the congressional defense committee [on] options to declare additional HEU as excess and down-blend it [...], options to load the Tennessee Valley Authority (TVA) reactor cores with a mix of [US and foreign] LEU [reflecting the fact that most of the LEU consumed to produce power for civilian purposes rather than tritium for weapons], a plan to engage URENCO and European allies about the use of ... LEU [enriched by URENCO or France]; amount and timelines related to HEU stocks for naval reactors and how much would be available if LEU (not from blend-down of HEU) fuel were available to use in aircraft carrier reactors and potentially in submarine reactors ..."

We understand that DOE will deliver the report in late 2020 or early 2021.

In the report of the House-Senate conference on the Defense Authorization Act, the Senate Committee on Armed Services added its own idea (Sec. 3138):

"Not later than February 15, 2020, the Secretary of Energy shall: (1) determine whether the Agreement for Cooperation on the Uses of Atomic Energy for Mutual Defense Purposes, signed at Washington, July 3, 1958 (9 UST 1028), between the United States and the United Kingdom, permits the United States to obtain low-enriched uranium for the purposes of producing tritium in the United States; and (2) submit to the congressional defense committees a report on that determination."

The Senate idea appears to be to take advantage of the fact that the UK government, which is a part owner of URENCO and has a URENCO enrichment plant on its territory, also has a special relationship with the US with regard to sharing materials and technology for defense purposes. And while the uranium enriched by URENCO centrifuges in the U.S. "shall only be used for peaceful, non-explosive purposes" the restrictions on the uranium enriched in the UK are different. The Treaty of Almelo stipulates that "[URENCO enterprises] shall not produce weapons grade uranium for the manufacture of nuclear weapons or other nuclear explosive devices."

HALEU. A second DOE-proposed demand for new uranium enrichment has come in response to the collapse of DOE-supported efforts to build a new generation of conventional nuclear power plants in the United States, DOE is promoting the commercialization of "small modular" power reactors. Some of the proposed reactor designs would require "high-assay LEU" (HALEU) with an enrichment between 5 and 20 percent. (Conventional light water reactors are fueled with LEU enriched to less than five percent.)

In January 2019, DOE gave Centrus an exclusive contract for $115 million to set up 16 of its large centrifuges in a cascade to show that it can produce a "small quantity" of HALEU. Centrus and DOE argue that the DOE contract is a first step toward building an enrichment plant for future US military enrichment needs. According to an article by David Kramer in the January 2020 issue of Physics Today, the appropriateness of this contract is being questioned by members of the House Science, Space, and Technology Committee. Kramer had previously reported objections to this deal from Wyoming Senator Barrasso, the chair of the Senate Committee on the Environment and Public Works.

Congressional questioners pointed out that no power reactors that require HALEU are in the US licensing process and the DOE's own Nuclear Energy Advisory Committee has complained that the DOE funded the Centrus contract with funds allocated for civilian R&D, including 73% of a fund that had been appropriated to support university research.