August 2013 Plutonium Mountain Inside the 17-year mission to secure a dangerous legacy of Soviet nuclear testing By Eben Harrell & David E. Hoffman Project on Managing the Atom

Belfer Center for Science and International Affairs  |  

Harvard Kennedy School

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‘Physics is Physics in Any Language’

Byron L. Ristvet is Assistant for Nuclear Matters in the Test Technology Division of the U.S. De-

fense Threat Reduction Agency. He is also one of the few scientists who participated in the U.S. 

nuclear testing program who is not yet retired. Hunched, short-sighted, and garrulous, he bears 

the manner of a man who has spent many years of his life underground. A geologist by training, 

it was his job to ensure the environmental safety of U.S. nuclear tests performed underground in 

the United States’ counterpart to Degelen Mountain: the Rainier Mesa complex in Nevada.

In the mid-2000s, Ristvet took over the project management for DTRA at Semipalatinsk. He 

recalled that he loved the work. It presented Ristvet, somewhat of a maverick, with technological 

challenges and the leeway to look for novel solutions. Ristvet didn’t like to follow rules, and Ka-

zakhstan’s remote steppe provided freedom from bureaucratic oversight. His deputies in Semi-

palatinsk, who were both Navy pilots on secondment to DTRA, followed U.S. safety procedures 

by wearing dosimeters at all times while near Degelen Mountain. Ristvet didn’t bother, believing 

that low-dose radiation had a protective effect on his health. “Byron does his own thing,” Mark 

Sullivan, one of those Navy pilots said. “He loves it out here.” 

“I’ve come to love this country,” Ristvet concurred when interviewed at Semipalatinsk in 2012 in 

a ceremony to celebrate the completion of the work at Degelen Mountain. “I have a real under-

standing with the Kazakhs and Russians working on this project.” 

In the mid-2000s, Ristvet forged a particularly close bond with Valery Demen, chief engineer 

of Russia’s Institute for Geophysical Research, who died of lung cancer before the operation at 

Degelen Mountain was completed. Demen was a heavy smoker. But it was a death Ristvet (his 

disregard for dosimeters aside) believes may have been related to radiation exposure. In 2012, 

Ristvet oversaw the unveiling of a plaque at 

Degelen Mountain to commemorate De-

men’s work.  Before the death, Demen and 

Ristvet often drove out to the Degelen site 

together with blueprints and technical draw-

ings. Demen had worked at Semipalatinsk 

for over forty years, and had overseen the 

construction of many of the tunnels at Degel-

en Mountain during the phase of active test-

ing. Although they did not speak each other’s 

language, the duo worked without an inter-

preter, relying only on their shared scientific 

vocabulary and hand gestures. “Our friend-

ship was based on science,” Ristvet recalled 

wistfully, “which made it easy and uncompli-

cated. Physics is physics in any language.” 

Ristvet’s friendship with Demen was deep-

ened by Ristvet’s sensitivity to the mixed 

emotions Demen and many of the Russian 

Source: Siegfried Hecker

“Kolba” used for containing small explosions involving 

nuclear material.

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Plutonium Mountain: Inside the 17-year mission to secure a dangerous legacy of Soviet nuclear testing

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scientists felt upon returning to Semipalatinsk. He shared their nostalgia for the heady days of 

scientific exploration during Cold War nuclear testing. And he understood that for the Russians, 

many of whom had been involved in the testing program at Semipalatinsk in the early 1980s, this 

nostalgia was coupled with a sense of displacement, as they were now treated as visitors to the 

city where they were once venerated inhabitants. 

“I was in my 20s when I worked at Semipalatinsk. I spent my youth here,” said Sergei Borenkov, 

a scientist from Arzamas-16, who remembers emplacing many of the test devices in Degelen 

Mountain, “So there is a certain nostalgia for us here.” When asked why he and his colleagues 

left so much plutonium behind, Borenkov shrugged. “When we left, Kazakhstan had become an 

independent country—it was not our responsibility anymore.”

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 A number of other Russian scien-

tists who also had experience at the test site felt a stronger responsibility to clean up the plutoni-

um, but they also believed they had to respect decisions made at higher levels of the government 

not to return to Semipalatinsk. Once the decision was made to cooperate, Stepanyuk called it a 

“principled choice.”

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Coaxing cooperation from the Russian scientists took years, according to Ristvet and other U.S. 

officials. The most useful tool to build trust was technical collaboration. As scientists, the Rus-

sians were naturally drawn into attempts to solve the conundrum of what to do with the material 

at Degelen Mountain. Asking the Russians for technical advice became a favorite tactic of U.S. 

officials attempting to elicit further insight into the threats at Degelen. But some Russian officials 

were more helpful than others. 

Short, stout, and energetic, Vladimir Kutsenko had served five years as head of security at Semi-

palatinsk in the 1980s. By the mid-2000s, he had risen to become assistant to the head of Ro-

satom, the successor to Minatom. Like many of his senior Rosatom colleagues, Kutsenko had 

ambiguous feelings about the collapse of the Soviet Union. He often gave lachrymose vodka 

toasts to the patriotism of the Soviet scientists who worked at Semipalatinsk, and would confide 

to U.S. officials his belief that Kazakhstan should never have been given independence, U.S. of-

ficials recalled. But his bulldog loyalty also applied to his role as security manager at Semipala-

tinsk—he felt it was his responsibility to ensure that no nuclear material was stolen from Degelen 

Mountain. In his mind, his mission had not ended after his initial departure from Semipalatinsk.

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In the mid-2000s, Kutsenko witnessed the professional relationship blossom between Demen, 

Ristvet, and other scientists. One of the officials on the U.S. side, John Booker, was awarded the 

Kazakh Medal of Freedom upon his retirement mid-way through the project. Kutsenko felt the 

time was right to extend cooperation to the entire Degelen Mountain site. He assumed the role of 

main emissary for U.S. and Russian officials in this period, steadily lobbying Rosatom to release 

all remaining information to the United States. Negotiations were at times delicate: in several in-

stances, Kutsenko insisted on talking to U.S. counterparts on his cell phone while driving in a car 

in order to speak freely, according to DTRA officials. “The work couldn’t have been done with-

out the cooperation from the Russian side,” Kutsenko said. “The site itself contains materials that 

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   Interview at Semipalatinsk test site, October 2012.

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   Stepanyuk, “Liquidation of Consequences…”

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   This portrait of Vladimir Kutsenko draws from various interviews with U.S. officials. The authors conducted one brief inter-

view with Kutsenko, but he was reticent to discuss the operation or his motivations in depth.

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