Thomas Neff, who helped turn Soviet nukes into electricity, dies at 80

While Western diplomats wrestled with the threat of “loose nukes,” an MIT physicist, Thomas L. Neff, came up with a solution that was daringly ambitious yet appealingly straightforward: The Soviet Union could convert the highly enriched uranium from old weapons into fuel for nuclear power plants, then sell it to the United States for use in reactors.

His proposal, which Dr. Neff pushed to the finish line and guided from behind the scenes, turned about 20,000 Russian nuclear weapons into a source of American energy, accounting for some 10 percent of the country’s electricity across two decades. Although it is now little known, the swords-to-ploughshares deal that Dr. Neff pioneered was hailed for reducing the global stockpile of nuclear weapons and helping stabilize the former Soviet Union after its end in 1991.

Frank N. von Hippel, a physicist who advised the Clinton White House, told the New York Times in 2014 that the arrangement eliminated as much as a third of the world’s nuclear warhead fuel, making it “the biggest single step” in the history of atomic arms reduction.

“Once Tom formulated it, quite a few people thought it was attractive,” von Hippel told The Washington Post in a phone interview. “They probably thought it wasn’t feasible — until he showed them there really was a deal there to be had.”

Dr. Neff, who made at least 20 trips to Moscow while seeing the nuclear deal to fruition, was 80 when he died July 11 at a hospital in Concord, Mass. His daughter, Catherine C. Harris, said the cause was a subdural hematoma, in which blood pools near the brain.

As a researcher at the Ford Foundation and then MIT, Dr. Neff spent years working in arms control, nuclear weapons proliferation and uranium markets, bridging the divide between experts who specialized in the kind of highly enriched uranium used for warheads and the far less enriched version used for electricity generation.

When he first came up with the concept for a nuclear deal with the Soviet Union, “I was naive,” he said. “I thought the idea would take care of itself.” Instead, it required him and other advocates to navigate a host of commercial, bureaucratic and political challenges, including determining a price for the uranium, addressing opposition from the U.S. uranium industry and finding space in the federal budget to pay for the first shipments.

Dr. Neff began pushing for the proposal on Oct. 19, 1991, while attending a meeting on nuclear demilitarization at the State Plaza Hotel in Washington. U.S. and Soviet representatives were both “talking past each other,” he recalled, but during a break he met with Viktor N. Mikhailov, a chain-smoking leader of the Soviet delegation, and asked whether Moscow might consider selling its weapons-grade uranium.

“Interesting,” he recalled Mikhailov saying, in between puffs on his cigarette. “How much?”

Dr. Neff hadn’t given the question much thought.

“Five hundred metric tons,” he replied, offering what he thought was an especially high number. To his surprise, Mikhailov said he thought they might be able to make that work. (“If I had known how much they really had,” Dr. Neff later said, “I would have said 700 tons.”)

Days later, Dr. Neff pitched his idea in a New York Times opinion essay, “A Grand Uranium Bargain,” in which he argued that the program would benefit both sides, with a uranium sales program serving “to diminish the threat of large volumes of material that might destroy commercial markets and pose a major threat to international security.”

U.S. officials were initially hesitant to back the program, according to Dr. Neff, and moved only after Mikhailov and his colleagues suggested the agreement in a letter to Washington. But when the Bush administration announced in 1992 that it had cut a deal with Moscow, officials were giddy.

“Instead of lighting up mushroom clouds, this stuff is going to light up homes in the United States with electricity,” Philip G. Sewell, a deputy assistant secretary at the Energy Department said. “It’s kind of incredible.”

The agreement, dubbed Megatons to Megawatts, was signed under the Clinton administration in 1993. Dr. Neff continued to champion the program over the next two decades, and wrote so many memos in support of the deal, according to an account in the MIT Technology Review, that “at one point he was told to change his typeface, because everyone who saw his memos lying on a desk would recognize them.”

Dr. Neff cheered each uranium shipment that arrived in the United States, from the first in 1995 to the last in 2013, when fuel processed from some 80 nuclear bombs arrived in Baltimore aboard a freighter. A reception commemorating the program was held at the Russian Embassy in Washington, where a brochure estimated the overall cost of the deal at $17 billion and declared that the weapons had provided 15,432 tons of low-enriched uranium, according to the Times.

Bruce G. Blair, a co-founder of the nuclear policy organization Global Zero, later described the program as “the pinnacle of U.S.-Russian nuclear security cooperation,” and officials from both countries credited Dr. Neff with seeing it through.

“If he hadn’t stuck…