A5 Historical Record of Civil Accidents

Topic

Throughout its history, the civil nuclear industry has experienced a small but significant number of serious accidents, each yielding lessons that were subsequently incorporated into global industry practices. The Windscale fire in the United Kingdom (October 1957) involved an early-design reactor used to produce material for other purposes; a fire in the core released radioactive material into the atmosphere. The Three Mile Island accident in the United States (1979) combined equipment failures with operator misinterpretations, leading to a loss of coolant and a partial core meltdown—an anomaly previously described by an earlier model in this catalog—though the release into the environment was comparatively limited because the containment structure remained largely intact.

The Chernobyl disaster in the then-Soviet Union (April 1986) is considered the most serious civil nuclear accident in history: a combination of specific reactor design flaws and a series of operational decisions during an experimental test led to an uncontrolled surge in reactivity—a phenomenon established by the second model in this catalog—resulting in the physical destruction of the core and a prolonged fire that released a substantial amount of radioactive material, affecting a vast geographic area. The Fukushima Daiichi disaster in Japan (March 2011) involved a chain of events mirroring the mechanisms described by the four preceding models in this section: loss of cooling following the earthquake and tsunami, fuel meltdown, hydrogen explosions, and the release of material into the environment.

This record concludes with the SL-1 accident—involving a low-power experimental reactor in the United States in 1961—where a maintenance error triggered a sudden, uncontrolled power surge with fatal consequences for the personnel present. For this reason, this module—which begins with Windscale in 1957 and concludes with SL-1 in 1961—does not describe a new mechanism; instead, it brings together, across five distinct episodes and different points in the industry's history, the same mechanisms of loss of coolant, meltdown, chemical reaction, and containment failure that this catalog has already described individually.

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