---
title: "Comparison of Chernobyl and other radioactivity releases"
chunk: 1/3
source: "https://en.wikipedia.org/wiki/Comparison_of_Chernobyl_and_other_radioactivity_releases"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T03:36:03.433289+00:00"
instance: "kb-cron"
---

This article compares the radioactivity release and decay from the Chernobyl disaster with various other events which involved a release of uncontrolled radioactivity.

== Chernobyl compared to background radiation ==

Natural sources of radiation are prevalent in the environment, and come from cosmic rays, food sources (bananas have a particularly high source due to potassium-40 but all foods contain carbon and thereby carbon-14), radon gas, granite and other dense rocks, and others. The banana equivalent dose is sometimes used in science communication to visualize different levels of ionizing radiation. The collective radiation background dose for natural sources in Europe is about 500,000 man-Sieverts per year. The total dose from Chernobyl is estimated at 80,000 man-sieverts, or roughly 1/6 as much. However, some individuals, particularly in areas adjacent to the reactor, received massively higher doses.
Chernobyl's radiation was detectable across Western Europe. Average doses received ranged from 0.02 mrem (Portugal) to 38 mrem (portions of Germany).

== Chernobyl compared with an atomic bomb ==
Far fewer people died as an immediate result of the Chernobyl event than the immediate deaths from radiation at Hiroshima. Chernobyl is eventually predicted to result in up to 4,000 total deaths from cancer, sometime in the future, according to the WHO and create around 41,000 excess cancer according to the International Journal of Cancer, with, depending on treatment, not all cancers resulting in death. Due to the differences in half-life, the different radioactive fission products undergo exponential decay at different rates. Hence the isotopic signature of an event where more than one radioisotope is involved will change with time.
"Compared with other nuclear events: The Chernobyl explosion put 400 times more radioactive material into the Earth's atmosphere than the atomic bomb dropped on Hiroshima; atomic weapons tests conducted in the 1950s and 1960s all together are estimated to have put some 100 to 1,000 times more radioactive material into the atmosphere than the Chernobyl accident."
The radioactivity released at Chernobyl tended to be more long-lived than that released by a bomb detonation hence it is not possible to draw a simple comparison between the two events. Also, a dose of radiation spread over many years (as is the case with Chernobyl) is much less harmful than the same dose received over a short period.
The relative size of the Chernobyl release when compared with the release due to a hypothetical ground burst of a bomb similar to the Fat Man device dropped on Nagasaki.

A comparison of the gamma dose rates due to the Chernobyl accident and the hypothetical nuclear weapon.

The graph of dose rate as a function of time for the bomb fallout was created using a method similar to that of T. Imanaka, S. Fukutani, M. Yamamoto, A. Sakaguchi and M. Hoshi, J. Radiation Research, 2006, 47, Suppl A121-A127. The graph exhibits the same shape as that obtained in the paper. The bomb fallout graph is for a ground burst of an implosion-based plutonium bomb which has a depleted uranium tamper. The fission was assumed to have been caused by 1 MeV neutrons and 20% occurred in the 238U tamper of the bomb. It was assumed, for the sake of simplicity, that no plume separation of the isotopes occurred between the detonation and the deposit of radioactivity. The following gamma-emitting isotopes are modeled 131I, 133I, 132Te, 133I, 135I, 140Ba, 95Zr, 97Zr, 99Mo, 99mTc, 103Ru, 105Ru, 106Ru, 142La, 143Ce, 137Cs, 91Y, 91Sr, 92Sr, 128Sb, and 129Sb. The graph ignores the effects of beta emission and shielding. The data for the isotopes was obtained from the Korean table of the isotopes. The graphs for the Chernobyl accident were computed by an analogous method. Note that in the event of a low altitude or ground burst nuclear detonation that fractionation of the volatile and non volatile radionuclides occurs. Also during the Chernobyl accident, the ratio between the different elements released by the accident changed as a function of time.
A ground burst of a nuclear weapon creates considerably more local deposited fallout than the air bursts used at Hiroshima or Nagasaki. This is due in part to neutron activation of ground soil and greater amounts of soil being sucked into the nuclear fireball in a ground burst than in a high air burst. In the above, neutron activation is neglected, and only the fission product fraction of the total activity resulting from the ground burst is shown.

== Chernobyl compared with Tomsk-7 ==
The release of radioactivity which occurred at Tomsk-7 (an industrial nuclear complex located in Seversk rather than the city of Tomsk) in 1993, is another comparison with the Chernobyl release. During reprocessing activities, some of the feed for the second cycle (medium active part) of the PUREX process escaped in an accident involving red oil. According to the IAEA it was estimated that the following isotopes were released from the reaction vessel: