The Semipalatinsk nuclear test site in Kazakhstan was officially closed 35 years ago on August 29, 1991, ending four decades of Soviet nuclear testing.
Kazakh President Nursultan Nazarbayev signed the closure decree exactly 42 years after the Soviet Union detonated its first atomic bomb at the site on August 29, 1949. Over its 40-year operational history, the proving ground hosted 456 nuclear explosions before its final test took place on October 19, 1989.
Just 118 days after the closure of the strategic facility, which was built to safeguard the USSR during the Cold War, the Soviet Union collapsed.
Establishment of Soviet Atomic Project
In August 1945, immediately following the atomic bombings of Hiroshima and Nagasaki, Soviet authorities created Special Committee No. 1 to oversee the nuclear weapons project. Lavrentiy Beria was appointed to lead the initiative.
Ninel Epatova, a poet and participant in the atomic project, remembered Beria visiting a plutonium plant at Chelyabinsk-90 in February 1949. She described him as exhausted and wearing a plain coat, noting that he complained about poor roads while remaining entirely focused on the project.
By mid-August 1949, Beria arrived at the Semipalatinsk proving ground and stayed at the site commander's cottage as preparations for the first Soviet nuclear test entered their final phase.
Construction of the Experimental Field
The test site spanned an area equivalent to half the size of Belgium. Authorities selected a Kazakh steppe tract 130 kilometers from Semipalatinsk, where writer Fyodor Dostoevsky had served as a soldier nearly a century earlier after his exile.
Site preparation began between 1946 and 1947, leading to the creation of the Mountain Seismic Station, known as Object-905, in August 1947. The location became Training Polygon No. 2 in 1948 before taking the name Semipalatinsk Test Site under military guard and strict secrecy.
The central testing zone, named the Experimental Field, featured a test tower, a command post, charge assembly facilities, and instrument structures. Scientists divided the area into sectors to evaluate blast effects on residential homes, industrial facilities, military vehicles, aircraft, artillery, and live animals.
Following test detonations, researchers placed the flattened organs of test animals in formalin jars for preservation at the site museum in Kurchatov, documenting internal hemorrhages and tissue ruptures.
The administrative town sat on the banks of the Irtysh River, approximately 120 kilometers from Semipalatinsk, housing headquarters, a hotel, and an Officers' House, while the center of the Experimental Field remained 60 kilometers away from residential quarters.
First Soviet Nuclear Detonation
On August 29, 1949, at 7:00 a.m., scientists detonated the RDS-1 charge, which had an explosive yield of approximately 22 kilotons, atop a testing tower. Scientific lead Kirill Shchelkin oversaw the program, while specialists from KB-11 assembled and prepared the device.
Valery Zhuchikhin, deputy department head at KB-11, described seeing bright rays of sunlight stream through a large opening immediately after the explosion.
The shockwave swept across simulated brick and wooden structures, aircraft, and artillery positioned up to ten kilometers away. A T-34 tank was flipped onto its side, and 345 of the 1,538 test animals died, while dead birds fell from the sky.
The test ended the nuclear monopoly of the United States. Wind conditions carried the resulting radioactive cloud across 11 districts in the neighboring Altai region.
Thermonuclear Tests and Military Exercises
On August 12, 1953, the Soviet Union tested RDS-6s, its first thermonuclear device design. Following the blast, nuclear project lead Igor Kurchatov bowed deeply to physicist Andrey Sakharov and thanked him as the savior of Russia.
The RDS-6s detonation produced severe radioactive contamination across nearby regions. Authorities ordered the partial evacuation of Abai village, but 191 residents were exposed to fallout, leading to high rates of cancer, blindness, infertility, and genetic disorders.
In July 1954, Soviet authorities established a second testing ground at Novaya Zemlya, an Arctic archipelago that later hosted the Tsar Bomba test.
On September 10, 1956, military commanders conducted a troop exercise using a 38-kiloton bomb dropped from a Tu-16 bomber, exploding 270 meters above ground to test whether paratroopers could secure a nuclear impact zone.
Former test site worker Boris Rusakov noted in his memoirs that after the 1986 Chernobyl disaster, he reflected on how staff and families in the closed town of Moskva-400, secretly dubbed Limoniya, lived alongside atmospheric explosions without realizing the danger.
Rusakov recorded that radioactive dust from surface explosions rained down on vegetable gardens, streets, and houses, entering living quarters through open window vents.
Shift to Underground Detonations
Testing moved underground on October 11, 1961, with a 1.2-kiloton explosion inside a mountain tunnel in the Degelen massif. The 1963 Moscow Treaty banning atmospheric, outer space, and underwater tests made underground testing the sole permitted method.
The facility expanded its footprint to include the Balapan, Sary-Uzen, and Telkem testing areas in Kazakhstan. International Atomic Energy Agency data indicates that 340 underground tests occurred between 1964 and 1989, 13 of which released radioactive gas into the atmosphere.
In 1965, an industrial nuclear blast with a yield of 140 kilotons in the Chagan River floodplain created a crater that filled with water, forming Lake Chagan, also known as Atom-Kol.
Minister of Medium Machine Building Yefim Slavsky became the first person to swim in the crater lake to demonstrate safety, though radiation readings around the site remained elevated for decades.
Anti-Nuclear Movement and Closure
Public anger mounted during the perestroika era. Conscript soldiers serving at the site reported eating, drinking, and breathing radiation, while rock musician Viktor Tsoi authored a popular song declaring his home a nuclear-free zone.
On February 12, 1989, an underground test preparation caused a radioactive gas leak. Radiation levels reached 4,000 micro-roentgens per hour two days later in Chagan village, located 110 kilometers away.
On February 25, 1989, poet Olzhas Suleimenov spoke out on live television against the testing site. Three days later, protesters founded the Nevada-Semipalatinsk anti-nuclear movement in Alma-Ata, demanding the shutdown of the facility under Kazakh slogans calling to close the test site.
Due to political pressure, only seven of 18 scheduled tests took place in 1989, culminating in the final explosion on October 19, 1989. Kazakh leaders officially closed the site on August 29, 1991.
Between 1951 and 1992, the United States conducted roughly 1,000 nuclear tests at its Nevada site, while China carried out around 45 tests at Lop Nur between 1964 and 1996, and France executed nearly 190 tests at the Mururoa and Fangataufa atolls from 1966 to 1996.
Post-Soviet Remediation and Security
Following the Soviet collapse, military forces withdrew, allowing scrappers to dig up missile silos and enter test tunnels to recover valuable metals. The period inspired contemporary action films such as Watch Out! Red Mercury! and Ranger from the Atomic Zone.
In the late 1990s, Kazakh and United States authorities recognized the threat of dirty bombs and launched joint operations to seal vulnerable sites. Sergey Lukashenko, director of the Institute of Radiation Safety and Ecology, noted that unsecured tunnels had previously offered easy access to nuclear materials.
Joint remediation efforts buried hazardous areas under thousands of tons of earth, with Russia joining technical operations in the 2000s. By 2013, decontamination efforts at the Experimental Field included digging perimeter trenches to prevent saiga antelopes from carrying radioactive particles outside the boundary.
In 2009, the United Nations designated August 29 as the International Day against Nuclear Tests in recognition of the Semipalatinsk closure.
