The Soviet leadership created a top-level body to push a nuclear weapons program after World War II, with Lavrentiy Beria placed in charge. This decision centralized control over research, industry, security, and labor needed to build the bomb quickly.
A secret design center, KB-11, was established at Sarov (later known as Arzamas-16), becoming the main weapons-design site for the Soviet program. It brought together leading physicists and engineers and linked them to guarded, purpose-built production and test facilities.
The F-1 research reactor in Moscow achieved a self-sustaining nuclear chain reaction, a key step in mastering reactor physics. This work helped the program move from laboratory theory to industrial plutonium production for weapons.
The USSR selected a large steppe area in Kazakhstan as its main nuclear proving ground, later called the Semipalatinsk Test Site (“the Polygon”). Building the site created a dedicated place to measure blast, heat, and radiation effects of new weapon designs.
At the Mayak complex (a closed city then known as Chelyabinsk-40), the A-1 production reactor became critical, beginning industrial-scale plutonium production. This reactor-and-reprocessing chain supplied key material for the first Soviet weapons.
The USSR detonated its first nuclear device, RDS-1 (U.S. code name “Joe-1”), at Semipalatinsk. The successful test ended the U.S. nuclear monopoly and confirmed that Soviet design and production facilities could deliver a working weapon.
The Ministry of Medium Machine-Building (Sredmash) was created to supervise the nuclear weapons complex. It coordinated closed cities, reactors, reprocessing, warhead assembly, and supporting construction—turning the program into a long-term industrial system.
The USSR tested RDS-6s at Semipalatinsk, a “layer-cake” design combining fission and fusion reactions to greatly increase yield. While not yet a full two-stage hydrogen bomb, it showed rapid progress toward megaton-class weapons.
The Obninsk plant began supplying electricity to the power grid, using a reactor technology base closely tied to the weapons program. It demonstrated that Soviet reactor engineering could be scaled and managed in continuous operation, not only for bombs but also for power.
The USSR authorized construction of “Object-700” on the Arctic archipelago Novaya Zemlya, creating a second major nuclear test range. This remote site supported larger and different test types, including underwater and high-yield atmospheric explosions.
Novaya Zemlya hosted its first nuclear test, an underwater detonation, marking the start of regular testing at the Arctic range. The expansion reduced reliance on Semipalatinsk alone and supported the move toward higher-yield weapons testing.
The USSR tested RDS-37 at Semipalatinsk, its first two-stage thermonuclear device (a design using radiation-driven compression to ignite fusion fuel). This was a major turning point: the Soviet program could now field scalable, megaton-range weapons.
A chemical explosion in a high-level radioactive waste tank at Mayak released contamination over a large region, later called the East Urals Radioactive Trace. The accident showed the human and environmental costs of rushing production and keeping safety problems secret in closed nuclear cities.
After a period of restraint, the Soviet Union resumed atmospheric nuclear testing in 1961, using Novaya Zemlya for many shots. This escalation aimed to demonstrate capability and increase the reliability and variety of deliverable warheads during the Cold War arms race.
The USSR detonated AN602 (“Tsar Bomba”) over Novaya Zemlya, the largest nuclear explosion ever tested (about 50 megatons). The test served as a peak demonstration of Soviet thermonuclear engineering and helped define the program’s 1945–1961 arc: from first fission bomb to extreme-yield weapons.
Soviet Nuclear Weapons Program in Russian Facilities (1945–1961)