Semipalatinsk Test Site

Semipalatinsk Test Site
Near Kurchatov in Kazakhstan
Wfm sts overview.png
The 18,000 km2 expanse of the Semipalatinsk Test Site (indicated in red), attached to Kurchatov (along the Irtysh river), and near Semey, as well as Karagandy, and Nur-Sultan. The site comprised an area the size of Wales
Coordinates50°07′N 78°43′E / 50°07′N 78°43′E / 50.117; 78.717
TypeNuclear test site
Area18,000 km2 (6,950 sq mi)
Site information
OperatorSoviet Union
Site history
In use1949 – 1991
Test information
Subcritical testsnot known
Nuclear tests456 (340 underground and 116 aboveground)[1]

The Semipalatinsk Test Site (STS or Semipalatinsk-21), also known as "The Polygon", was the primary testing venue for the Soviet Union's nuclear weapons. It is located on the steppe in northeast Kazakhstan (then the Kazakh SSR), south of the valley of the Irtysh River. The scientific buildings for the test site were located around 150 km (93 mi) west of the town of Semipalatinsk (later renamed Semey), near the border of East Kazakhstan Region and Pavlodar Region with most of the nuclear tests taking place at various sites further to the west and south, some as far as into Karagandy Region.

The Soviet Union conducted 456 nuclear tests at Semipalatinsk from 1949 until 1989 with little regard for their effect on the local people or environment. The full impact of radiation exposure was hidden for many years by Soviet authorities and has only come to light since the test site closed in 1991.[2]

From 1996 to 2012, a secret joint operation of Kazakh, Russian, and U.S. nuclear scientists and engineers secured the waste plutonium in the tunnels of the mountains.[3]

Since its closure, the STS has become the best-researched atomic testing site in the world, and the only one in the world open to the public.[4]


The various facilities grouped inside the Semipalatinsk Test Site

The site was selected in 1947 by Lavrentiy Beria, political head of the Soviet atomic bomb project (Beria falsely claimed the vast 18,000 km² steppe was "uninhabited").[5][6] Gulag labour was employed to build the primitive test facilities, including the laboratory complex in the northeast corner on the southern bank of the Irtysh River. The first Soviet bomb test, Operation First Lightning (nicknamed Joe One by the Americans) was conducted in 1949 from a tower at the Semipalatinsk Test Site, scattering fallout on nearby villages (which Beria had neglected to evacuate).[citation needed] The same area ("the experimental field", a region 64 km (40 mi) west of Kurchatov city) was used for more than 100 subsequent above-ground weapons tests.

Later tests were moved to the Chagan River complex and nearby Balapan in the east of the STS (including the site of the Chagan test, which formed Chagan Lake). Once atmospheric tests were banned, testing was transferred to underground locations at Chagan, Murzhik (in the west), and at the Degelen Mountain complex in the south, which is riddled with boreholes and drifts for both subcritical and supercritical tests. After the closure of the Semipalatinsk labour camp, construction duties were performed by the 217th Separate Engineering and Mining Battalion (who later built the Baikonur Cosmodrome). Between 1949 and the cessation of atomic testing in 1989, 456 explosions were conducted at the STS, including 340 underground (borehole and tunnel) shots and 116 atmospheric (either air-drop or tower shots). The lab complex, still the administrative and scientific centre of the STS, was renamed Kurchatov City after Igor Kurchatov, leader of the initial Soviet nuclear programme. The location of Kurchatov city has been typically shown on various maps as "Konechnaya" (the name of the train station; now Degelen) or "Moldary" (the name of the village that was later incorporated into the city).

The Semipalatinsk Complex was of acute interest to foreign governments during its operation, particularly during the phase when explosions were carried out above ground at the experimental field. Several U-2 overflights examined preparations and weapons effects, before being replaced with satellite reconnaissance. The US Defense Intelligence Agency is said to have been convinced that the Soviets had constructed an enormous beam weapon station at a small research station located on the testing site.[7] This smaller research station, known to the Department of Defense as PNUTS (Possible Nuclear Underground Test Site) and the CIA as URDF-3 (Unidentified Research and Development Facility-3) was of great interest to American observers. After the fall of the Soviet Union in 1991, it was discovered that the mysterious URDF-3 was tasked with researching a nuclear thermal rocket similar to the US's NERVA.[8]

The site was officially closed by the President of the Kazakh Soviet Socialist Republic Nursultan Nazarbayev on 29 August 1991.[9]


The Soviet Union conducted its last tests in 1989.[10] After the Soviet Union collapsed in 1991, the site was neglected. Fissile material was left behind in mountain tunnels and bore holes, virtually unguarded and vulnerable to scavengers, rogue states, or potential terrorists. The secret cleanup of Semipalatinsk was made public in the 2010s.[11]

After some of the tests, radioactive material remained on the now abandoned area, including significant amounts of plutonium. The risk that material might fall into the hands of scavengers or terrorists was considered one of the largest nuclear security threats since the collapse of the Soviet Union. The operation to address the problem involved, in part, pouring special concrete into test holes, to bind the waste plutonium. In other cases, horizontal mine test holes were sealed and the entrances covered over. Finally in October 2012, Kazakh, Russian, and American nuclear scientists and engineers celebrated the completion of a secret 17-year, $150 million operation to secure the plutonium in the tunnels of the mountains.[3]

Large parts of the STS have opened up since 2014, and economic activity has resumed: mostly mining, but also agriculture and tourism. Like other areas affected by radioactivity, the lack of human interference has made the STS a haven for wildlife.[4]