Nuclear and radiation accidents and incidents in the context of "Fallout"

Human error is an action that has been done but that was "not intended by the actor; not desired by a set of rules or an external observer; or that led the task or system outside its acceptable limits". Human error has been cited as a primary cause and contributing factor in disasters and accidents in industries as diverse as nuclear power (e.g., the Three Mile Island accident), aviation, space exploration (e.g., the Space Shuttle Challenger disaster and Space Shuttle Columbia disaster), and medicine. Prevention of human error is generally seen as a major contributor to reliability and safety of (complex) systems. Human error is one of the many contributing causes of risk events.

Nuclear fallout is residual radioisotope material that is created by the reactions producing a nuclear explosion or nuclear accident. In explosions, it is initially present in the radioactive cloud created by the explosion, and "falls out" of the cloud as it is moved by the atmosphere in the minutes, hours, and days after the explosion. The amount of fallout and its distribution is dependent on several factors, including the overall yield of the weapon, the fission yield of the weapon, the height of burst of the weapon, and meteorological conditions.

Fission weapons and many thermonuclear weapons use a large mass of fissionable fuel (such as uranium or plutonium), so their fallout is primarily fission products, and some unfissioned fuel. Cleaner thermonuclear weapons primarily produce fallout via neutron activation. Salted bombs, not widely developed, are tailored to produce and disperse specific radioisotopes selected for their half-life and radiation type.

A ghost town, deserted city, extinct town, or abandoned city is an abandoned settlement, usually one that contains substantial visible remaining buildings and infrastructure such as roads. A town often becomes a ghost town because the economic activity that supported it (usually industrial or agricultural) has failed or ended for any reason (e.g. a host ore deposit exhausted by mining). The town may have also declined because of natural or human-caused disasters such as floods, prolonged droughts, extreme heat or extreme cold, government actions, uncontrolled lawlessness, war, pollution, or nuclear and radiation-related accidents and incidents. The term can sometimes refer to cities, towns, and neighborhoods that, though still populated, are significantly less so than in past years; for example, those affected by high levels of unemployment and dereliction.

Some ghost towns, especially those that preserve period-specific architecture, have become tourist attractions. Some examples are Bannack, Montana and Oatman, Arizona in the United States; Barkerville, British Columbia in Canada; Craco and Pompeii in Italy; Aghdam in Azerbaijan; Kolmanskop in Namibia; Pripyat and Chernobyl in Ukraine; Dhanushkodi in India; Fordlândia in Brazil and Villa Epecuén in Argentina.

Energy is sustainable if it "meets the needs of the present without compromising the ability of future generations to meet their own needs." Definitions of sustainable energy usually look at its effects on the environment, the economy, and society. These impacts range from greenhouse gas emissions and air pollution to energy poverty and toxic waste. Renewable energy sources such as wind, hydro, solar, and geothermal energy can cause environmental damage but are generally far more sustainable than fossil fuel sources.

The role of non-renewable energy sources in sustainable energy is controversial. Nuclear power does not produce carbon pollution or air pollution, but has drawbacks that include radioactive waste, the risk of nuclear proliferation, and the risk of accidents. Switching from coal to natural gas has environmental benefits, including a lower climate impact, but may lead to a delay in switching to more sustainable options. Carbon capture and storage can be built into power plants to remove their carbon dioxide (CO₂) emissions, but this technology is expensive and has rarely been implemented.

A nuclear meltdown (core meltdown, core melt accident, meltdown or partial core melt) is a severe nuclear reactor accident that results in core damage from overheating. The term nuclear meltdown is not officially defined by the International Atomic Energy Agency, however it has been defined to mean the accidental melting of the core or fuel of a nuclear reactor, and is in common usage a reference to the core's either complete or partial collapse.

A core meltdown accident occurs when the heat generated by a nuclear reactor exceeds the heat removed by the cooling systems to the point where at least one nuclear fuel element exceeds its melting point. This differs from a fuel element failure, which is not caused by high temperatures. A meltdown may be caused by a loss of coolant, loss of coolant pressure, or low coolant flow rate, or be the result of a criticality excursion in which the reactor's power level exceeds its design limits.