There is no single "most radioactive" country, as radioactivity levels vary greatly within nations due to both natural background radiation and localized contamination from historical nuclear events or industrial activity. The overall average background radiation is relatively similar across most countries, but specific sites can be highly radioactive.
No. 1 Chernobyl – Ukraine
The Chernobyl Disaster has been burnt in history as the worst nuclear catastrophe and has the dubious distinction of being the most radioactive place on earth.
As you might expect, many people wonder which is the most radioactive place on Earth. According to the International Nuclear Event Scale (INES) ranking, Chernobyl in Ukraine, Fukushima in Japan and Mayak in Russia are considered the most radioactive places on Earth due to human activities.
Hiroshima does not have harmful radiation levels today. The residual radiation from the bomb decayed quickly after the explosion, and the city has since maintained radiation levels comparable to natural background radiation elsewhere.
The U.S. tested 67 nuclear weapons in the Marshall Islands from 1946 to 1958. Marshall Islands more radioactive than ChernobylResearchers from Columbia University located external gamma radiation on nine islands and four atolls on the Marshall Islands, a chain of islands in the central Pacific Ocean.
10 of the World's Most Radioactive Places
Yes, Chernobyl is still highly radioactive in many areas, especially near the damaged reactor, but radiation levels vary significantly; some parts of the exclusion zone have contamination low enough for potential limited agriculture, while a 2025 drone strike damaged the New Safe Confinement (NSC) structure, raising concerns about long-term containment, although immediate levels stayed stable as the NSC's function is to contain the original sarcophagus's radioactive material, not the entire zone.
Russia and the United States together possess nearly 90% of the world's nuclear weapons, with Russia holding the largest total stockpile and the U.S. having a substantial number of deployed strategic warheads, making them the dominant nuclear powers by far, despite other nations like China, the UK, France, India, Pakistan, Israel, and North Korea also having nuclear arsenals.
Within the first few months after the bombing, it is estimated by the Radiation Effects Research Foundation (a cooperative Japan-U.S. organization) that between 90,000 and 166,000 people died in Hiroshima, while another 60,000 to 80,000 died in Nagasaki.
How long will Chernobyl stay radioactive? Scientific estimates suggest some radioactive areas may be habitable within 30-60 years, while heavily contaminated areas will stay radioactive for over a millennium.
22 years after the event, the radiation level in the reactor hall has been measured to 34 Sv/h (The Chernobyl Gallery), so 340 million bananas every hour - or 47.6 kt. A bit more than one tenth of the original number.
The middle of the vast moorland that is Dartmoor National Park is the worst place in the country for radon, as the ground rock is mostly granite, which contains small amounts of uranium that decays and produces the gas. Residents in Dartmoor can be exposed to as much as seven millisieverts of radiation per year.
In general, alpha, beta, gamma and x-ray radiation can be stopped by:
In Germany about 100.000 sealed radioactive sources are used in industry, medicine, research and in agriculture. Use of radioactive sources in Germany is generally subject to government supervision according to the Atomic Energy Act as well as the Radiation Protection Act and requires a licence.
RBMK reactors do not have what is known as a containment structure, a concrete and steel dome over the reactor itself designed to keep radiation inside the plant in the event of such an accident. Consequently, radioactive elements including plutonium, iodine, strontium and caesium were scattered over a wide area.
The design was highly inefficient: the weapon used on Hiroshima contained 64 kilograms (141 lb) of uranium, but less than a kilogram underwent nuclear fission.
In the meantime, a policy of imposed starvation—of food, as well as materiel—would have weakened Japanese capabilities without reducing their resolve. Lewis estimates that the bombing of Hiroshima and Nagasaki, to the extent that it induced Japanese surrender, saved the lives of roughly 30 million people.
The Tsar Bomba (code name: Ivan or Vanya, internal designation "AN602") was the most powerful nuclear weapon or weapon of any kind ever constructed and tested. A project of the Soviet Union, it was a thermonuclear aerial bomb, tested on 30 October 1961 at the Novaya Zemlya site in the country's far north.
All five legally recognized nuclear weapon states, as defined by the NPT—China, France, Russia, the UK and the USA—appear determined to remain nuclear powers for the indefinite future. Russia and the USA have major modernization programmes under way for nuclear delivery systems, warheads and production facilities.
The Chernobyl accident in 1986 was the result of a flawed reactor design that was operated with inadequately trained personnel. The resulting steam explosion and fires released at least 5% of the radioactive reactor core into the environment, with the deposition of radioactive materials in many parts of Europe.
Radiation from Chernobyl caused mutations in animals, harming their health and ability to reproduce. Many animals in the Chernobyl exclusion zone are radioactive and some, like birds, show physical abnormalities.
The Chernobyl nuclear disaster was a catastrophic accident, BBC Science Focus looks at whether this could happen again. Probably not.