Largest Nuclear Test Site Closes for Good

KURCHATOV, Kazakhstan -- A controlled weekend explosion that made the vast Kazakh steppe shake has closed for good what was the world's largest nuclear test range, Semipalatinsk.

The Soviet-era site, where more than 500 nuclear explosions were conducted during the Cold War years between 1949 and 1989, was closed Saturday after the last of 181 underground tunnels at the complex collapsed in the explosion.

U.S Deputy Defense Secretary Susan Koch said the project, conducted jointly with the United States, had not only closed the test complex but also had opened the way to peaceful scientific work at the site.

"This is ? the largest such test site to be closed and certainly the only one to be closed through cooperative efforts," Koch said.

"We are very happy, as this has been a model of cooperation. It has worked smoothly and quickly and is a tribute to the ? scientists who realize the potential use of the tests for CTBT."

The blast, termed the Omega-3 calibration experiment, destroyed the last infrastructure for atomic testing in Kazakhstan, a signatory to the Comprehensive Test Ban Treaty, which once had the world's fourth-largest nuclear arsenal.

The blast was conducted at tunnel 160, part of the warren of passages under the 18,000-square-meter grounds.

The explosion, which sent a cloud of dust over the steppe and made the earth shake, was part of a project involving the U.S. Defense Department and the Kazakh National Nuclear Center.

It was funded by the Defense Department's Cooperative Threat Reduction Program, which allotted $172 million to support disarmament in Kazakhstan. Kazakhstan in 1993 signed a treaty to eliminate all nuclear weapons infrastructure.

A news release said data from the calibration experiment would help scientists identify nuclear tests more precisely and distinguish them from earthquakes.

But the test site at the Degelen mountains, 150 kilometers from the town of Semipalatinsk, carries a legacy of death and disease. A decade after the last test, health problems are rife.

Many babies born in the region have congenital deformities, while cancer, mental illness and muscular dystrophy are common. A United Nations study in 1998 said agriculture and land systems had been severely contaminated by radioactive elements.

Yury Cherednin, the head of Kazakhstan's National Nuclear Center, said blocking the tunnels was a key step for safety.

"First, the tunnels are now closed to people and animals," he said. "Second, radioactive contaminated water can no longer come to the surface, so the entire area will be cleaner."

Cherednin said U.S. support now allowed Kazakh scientists to participate in international and commercial projects.

"It was not easy for specialists to switch to new projects," he said. "But on the positive side, we have moral satisfaction that never again will our land be used for nuclear tests."