Saving the World at Plutonium Mountain

Last October, at the foot of a rocky hillside near here, at a spot known as Degelen Mountain, several dozen Kazakh, Russian and American nuclear scientists and engineers gathered for a ceremony. After a few speeches, they unveiled a three-sided stone monument, etched in English, Russian and Kazakh, which declared:

“1996-2012. The world has become safer.”

The modest ribbon-cutting marked the conclusion of one of the largest and most complex nuclear security operations since the Cold War. The secret mission was to secure plutonium — enough to build a dozen or more nuclear weapons — that Soviet authorities had buried at the testing site years before and forgotten, leaving it vulnerable to terrorists and rogue states.

The effort spanned 17 years, cost $150 million and involved a complex mix of intelligence, science, engineering, politics and sleuthing. This account is based on documents and interviews with Kazakh, Russian and U.S. participants, and reveals the scope of the operation for the first time. The effort was almost entirely conceived and implemented by scientists and government officials operating without formal agreements among the nations involved. Many of these scientists were veterans of Cold War nuclear-testing programs, but they overcame their mistrust and joined forces to clean up and secure the Semipalatinsk testing site, a dangerous legacy of the nuclear arms race.

They succeeded, but what they accomplished here may have to be done all over again if the walls of secrecy ever come down and reveal security vulnerabilities in other states that have developed the atomic bomb, including North Korea, Pakistan, China, India and Israel, or in countries that may develop weapons in the future, such as Iran.

During the Cold War, the Soviet Union carried out more than 450 nuclear explosive tests at the Semipalatinsk site, which sprawls over a portion of the Kazakh plains slightly larger than Connecticut. Most of the tests involved atomic explosions, while others were carried out to improve weapons safety, in part by examining the impact of conventional explosives on plutonium metal. A network of tunnels built under Degelen Mountain became the epicenter of these tests.

After the Soviet Union collapsed in 1991, the Russians gradually abandoned the site. Economic conditions in the main city near the testing grounds grew desperate, and residents began to search the tunnels for metal to sell. They used mining equipment to steal copper from the electrical wiring and to scavenge rails that once carried nuclear devices far underground for explosive testing.

In the 1990s, the United States, through an agency in the Pentagon dealing with nuclear security, funded a program to close off the entrances to the tunnels at Semipalatinsk so they could never again be used for nuclear tests. The tunnels were sealed at the portals but not explored to any depth. Plutonium from the earlier safety tests lay deep inside.

In 1995, two scientists from the Los Alamos National Laboratory visited Degelen Mountain and came away convinced that the site was a potential plutonium “mine” for thieves and terrorists. Then, in January 1998, Siegfried S. Hecker, who had just retired as the laboratory’s director, heard from a Kazakh scientist that the Degelen Mountain area was wide open, despite the U.S.-led tunnel-closing effort, and scavengers were searching it.

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