International Atomic Energy Agency in the context of Background to the Iran–Israel war

Radiation protection, also known as radiological protection, is defined by the International Atomic Energy Agency (IAEA) as "The protection of people from harmful effects of exposure to ionizing radiation, and the means for achieving this". Exposure can be from a source of radiation external to the human body or due to internal irradiation caused by the ingestion of radioactive contamination.

Ionizing radiation is widely used in industry and medicine, and can present a significant health hazard by causing microscopic damage to living tissue. There are two main categories of ionizing radiation health effects. At high exposures, it can cause "tissue" effects, also called "deterministic" effects due to the certainty of them happening, conventionally indicated by the unit gray and resulting in acute radiation syndrome. For low level exposures there can be statistically elevated risks of radiation-induced cancer, called "stochastic effects" due to the uncertainty of them happening, conventionally indicated by the unit sievert.

A nuclear power plant (NPP), also known as a nuclear power station (NPS), nuclear generating station (NGS) or atomic power station (APS) is a thermal power station in which the heat source is a nuclear reactor. As is typical of thermal power stations, heat is used to generate steam that drives a steam turbine connected to a generator that produces electricity. As of October 2025, the International Atomic Energy Agency reported that there were 416 nuclear power reactors in operation in 31 countries around the world, and 62 nuclear power reactors under construction.

Most nuclear power plants use thermal reactors with enriched uranium in a once-through fuel cycle. Fuel is removed when the percentage of neutron absorbing atoms becomes so large that a chain reaction can no longer be sustained, typically three years. It is then cooled for several years in on-site spent fuel pools before being transferred to long-term storage. The spent fuel, though low in volume, is high-level radioactive waste. While its radioactivity decreases exponentially, it must be isolated from the biosphere for hundreds of thousands of years, though newer technologies (like fast reactors) have the potential to significantly reduce this. Because the spent fuel is still mostly fissionable material, some countries (e.g. France and Russia) reprocess their spent fuel by extracting fissile and fertile elements for fabrication into new fuel, although this process is more expensive than producing new fuel from mined uranium. All reactors breed some plutonium-239, which is found in the spent fuel, and because Pu-239 is the preferred material for nuclear weapons, reprocessing is seen as a weapon proliferation risk.

The International Nuclear and Radiological Event Scale (INES) was introduced in 1990 by the International Atomic Energy Agency (IAEA) in order to enable prompt communication of safety and significant information in case of nuclear accidents.

The scale is intended to be logarithmic, similar to the moment magnitude scale that is used to describe the comparative magnitude of earthquakes. Each increasing level represents an accident approximately ten times as severe as the previous level. Compared to earthquakes, where the event intensity can be quantitatively evaluated, the level of severity of a human-made disaster, such as a nuclear accident, is more subject to interpretation. Because of this subjectivity, the INES level of an incident is assigned well after the occurrence. The scale is therefore intended to assist in disaster-aid deployment.

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.

The Joint Comprehensive Plan of Action (JCPOA; Persian: برنامه جامع اقدام مشترک, romanized: barnāmeye jāme'e eqdāme moshtarak (برجام, BARJAM)), also known as the Iran nuclear deal or Iran deal, was an agreement to limit the Iranian nuclear program in return for sanctions relief and other provisions. The agreement was finalized in Vienna on 14 July 2015, between Iran and the P5+1 (the five permanent members of the United Nations Security Council (UNSC)—China, France, Russia, the U.K., U.S.—plus Germany) together with the European Union.

Formal negotiations began with the adoption of the Joint Plan of Action, an interim agreement signed between Iran and the P5+1 countries in November 2013. Iran and the P5+1 countries engaged in negotiations for the following 20 months and, in April 2015, agreed on an Iran nuclear deal framework, which later led to JCPOA, along with a Roadmap Agreement between Iran and the International Atomic Energy Agency (IAEA).

Radioactive contamination, also called radiological pollution, is the deposition of, or presence of radioactive substances on surfaces or within solids, liquids, or gases (including the human body), where their presence is unintended or undesirable (from the International Atomic Energy Agency (IAEA) definition).

Such contamination presents a hazard because the radioactive decay of the contaminants produces ionizing radiation (namely alpha, beta, gamma rays and free neutrons). The degree of hazard is determined by the concentration of the contaminants, the energy of the radiation being emitted, the type of radiation, and the proximity of the contamination to organs of the body. It is important to be clear that the contamination gives rise to the radiation hazard, and the terms "radiation" and "contamination" are not interchangeable.

The Iran–Israel war (13 June – 24 June 2025), also known as the Twelve-Day War, was an armed conflict in the Middle East. The war began when Israel bombed military and nuclear facilities in Iran in a surprise attack, assassinating prominent military leaders, nuclear scientists, and politicians, killing civilians, and damaging or destroying air defenses. Iran retaliated with over 550 ballistic missiles and over 1,000 suicide drones, hitting civilian population centers, one hospital and at least twelve military, energy, and government sites. The United States intercepted Iranian attacks, and bombed three Iranian nuclear sites on 22 June. Iran retaliated by firing missiles at a US base in Qatar. On 24 June, Israel and Iran agreed to a ceasefire under US pressure.

The war followed a decades-long proxy war. Iran has called for Israel's destruction, and armed Hamas in Gaza and Hezbollah in Lebanon. Following the October 7 attacks in 2023, both entered open conflict with Israel. In April 2024, Israel bombed Iran's consulate in Damascus, Syria, killing senior Iranian military officials. Direct conflict continued in April and October. Iran's nuclear program has caused international concern for over a decade. Israel considers it an existential threat. In 2015, under the Joint Comprehensive Plan of Action (JCPOA), six countries lifted sanctions on Iran, which froze its nuclear program. In 2018, US president Donald Trump unilaterally withdrew from the plan. Iran began stockpiling enriched uranium and largely suspended International Atomic Energy Agency (IAEA) monitoring. The day before Israel attacked, the IAEA declared Iran non-compliant with its nuclear obligations in a resolution put forward by the United States, United Kingdom, France, and Germany.

A nuclear and radiation accident is defined by the International Atomic Energy Agency (IAEA) as "an event that has led to significant consequences to people, the environment or the facility." Examples include lethal effects to individuals, large radioactivity release to the environment, or a reactor core melt. The prime example of a "major nuclear accident" is one in which a reactor core is damaged and significant amounts of radioactive isotopes are released, such as in the Chernobyl disaster in 1986 and Fukushima nuclear accident in 2011.

The impact of nuclear accidents has been a topic of debate since the first nuclear reactors were constructed in 1954 and has been a key factor in public concern about nuclear facilities. Technical measures to reduce the risk of accidents or to minimize the amount of radioactivity released to the environment have been adopted; however, human error remains, and "there have been many accidents with varying impacts as well near misses and incidents". As of 2014, there have been more than 100 serious nuclear accidents and incidents from the use of nuclear power. Fifty-seven accidents or severe incidents have occurred since the Chernobyl disaster, and about 60% of all nuclear-related accidents/severe incidents have occurred in the USA. Serious nuclear power plant accidents include the Fukushima nuclear accident (2011), the Chernobyl disaster (1986), the Three Mile Island accident (1979), and the SL-1 accident (1961). Nuclear power accidents can involve loss of life and large monetary costs for remediation work.

Low-level waste (LLW) or low-level radioactive waste (LLRW) is a category of nuclear waste. The definition of low-level waste is set by the nuclear regulators of individual countries, though the International Atomic Energy Agency (IAEA) provides recommendations.

LLW includes items that have become contaminated with radioactive material or have become radioactive through exposure to neutron radiation. This waste typically consists of contaminated protective shoe covers and clothing, wiping rags, mops, filters, reactor water treatment residues, equipments and tools, luminous dials, medical tubes, swabs, injection needles, syringes, and laboratory animal carcasses and tissues.

The Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal, usually known as the Basel Convention, is an international treaty that was designed to reduce the movements of hazardous waste between nations, and specifically to restrict the transfer of hazardous waste from developed to less developed countries. It does not address the movement of radioactive waste, controlled by the International Atomic Energy Agency. The Basel Convention is also intended to minimize the rate and toxicity of wastes generated, to ensure their environmentally sound management as closely as possible to the source of generation, and to assist developing countries in environmentally sound management of the hazardous and other wastes they generate.

The convention was opened for signature on 21 March 1989, and entered into force on 5 May 1992. As of June 2024, there are 191 parties to the convention. In addition, Haiti and the United States have signed the convention but did not ratify it.

AMAD Project (or AMAD Plan, Persian: پروژه آماد) is an alleged Iranian scientific project with the aim of developing nuclear weapons. It began in 1989, ended in 2003 according to the International Atomic Energy Agency (IAEA), but elements are alleged by Israel to have continued nonetheless. Iran has denied the existence of any program aimed at the development of a nuclear explosive device, and in particular denied the existence of the AMAD Plan when reporting additional details to the IAEA in 2015.

Uranium ore deposits are economically recoverable concentrations of uranium within Earth's crust. Uranium is one of the most common elements in Earth's crust, being 40 times more common than silver and 500 times more common than gold. It can be found almost everywhere in rock, soil, rivers, and oceans. The challenge for commercial uranium extraction is to find those areas where the concentrations are adequate to form an economically viable deposit. The primary use for uranium obtained from mining is in fuel for nuclear reactors.

Globally, the distribution of uranium ore deposits is widespread on all continents, with the largest deposits found in Australia, Kazakhstan, and Canada. To date, high-grade deposits are only found in the Athabasca Basin region of Canada. Uranium deposits are generally classified based on host rocks, structural setting, and mineralogy of the deposit. The most widely used classification scheme was developed by the International Atomic Energy Agency and subdivides deposits into 15 categories.

Nuclear safety is defined by the International Atomic Energy Agency (IAEA) as "The achievement of proper operating conditions, prevention of accidents or mitigation of accident consequences, resulting in protection of workers, the public and the environment from undue radiation hazards". The IAEA defines nuclear security as "The prevention and detection of and response to, theft, sabotage, unauthorized access, illegal transfer or other malicious acts involving nuclear materials, other radioactive substances or their associated facilities".

This covers nuclear power plants and all other nuclear facilities, the transportation of nuclear materials, and the use and storage of nuclear materials for medical, power, industry, and military uses.