nucleartest

A nuclear test, also referred to as a nucleartest in some contexts, is an experimental detonation of a nuclear device to determine its design, yield, performance, and effects. Tests provide data on weapon physics, engineering reliability, materials behavior, and potential strategic impact. They are usually conducted at designated test sites and may involve atmospheric, underground, or underwater detonations, with measurements including seismic signals, radiological readings, and observational data.

Historically, the first nuclear test was the Trinity device, detonated in 1945. During the Cold War, nations conducted hundreds of tests to advance weapons programs. The atmospheric era ended after the 1963 Partial Test Ban Treaty, which prohibited atmospheric, underwater, and outer-space tests, prompting a shift to underground detonations. By the end of the 20th century, thousands of tests had been conducted by nuclear-armed states. Notable tests include the Soviet Tsar Bomba (1961) and the U.S. Castle Bravo (1954); newer programs have focused on weapon modernization, verification systems, and safety features.

Today, many states observe testing moratoria, and international efforts seek a comprehensive ban. The Comprehensive Nuclear-Test-Ban Treaty, opened for signature in 1996, aims to ban all nuclear explosions, but it has not yet entered into force, pending ratification by several Annex 2 states. In parallel, subcritical tests—which do not produce a nuclear yield—are conducted by some states and are generally not counted as nuclear explosions under the treaty framework.