---
title: "Comparison of Chernobyl and other radioactivity releases"
chunk: 2/3
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"
---

106Ru 7.9 TBq
103Ru 340 GBq
95Nb 11.2 TBq
95Zr 5.1 TBq
137Cs 505 GBq (estimated from the IAEA data)
141Ce 370 GBq
144Ce 240 GBq
125Sb 100 GBq
239Pu 5.2 GBq
The very short-lived isotopes such as 140Ba and 131I were absent from this mixture, and the long-lived 137Cs was at a small concentration. This is because it is not able to enter the tributyl phosphate/hydrocarbon organic phase used in the first liquid-liquid extraction cycle of the PUREX process. The second cycle is normally to clean up the uranium and plutonium product. In the PUREX process, some zirconium, technetium, and other elements are extracted by the tributyl phosphate. Due to the radiation induced degradation of tributyl phosphate, the first cycle organic phase is always contaminated with ruthenium (later extracted by dibutyl hydrogen phosphate). Because the very short-lived radioisotopes and the relatively long-lived caesium isotopes are either absent or in low concentrations, the shape of the dose rate vs. time graph is different from Chernobyl, both for short times and long times after the accident.
The size of the radioactive release at Tomsk-7 was much smaller, and while it caused moderate environmental contamination, it did not cause any early deaths.

== Chernobyl compared to Fukushima Daiichi ==

== Chernobyl compared with the Goiânia accident ==
While both events released 137Cs, the isotopic signature for the Goiânia accident was much simpler. It was a single isotope which has a half-life of about 30 years. To show how the activity vs. time graph for a single isotope differs from the dose rate due to Chernobyl (in the open air), the adjacent chart is shown with calculated data for a hypothetical release of 106Ru.

== Chernobyl compared with the Three Mile Island accident ==

Three Mile Island-2 was an accident of a completely different type from Chernobyl. However, both accidents have vague similarities.
Chernobyl was a design flaw-caused power excursion causing a steam explosion resulting in a graphite fire, uncontained, which lofted radioactive smoke high into the atmosphere; TMI was a slow, undetected leak – caused by the technical malfunction of a pilot-operated relief valve – which lowered the water level around the nuclear fuel, resulting in over a third of it shattering when refilled rapidly with coolant.
Similar to Chernobyl, operator error played a role but did not directly cause the accident. Both accidents had grueling and costly cleanup efforts. Chernobyl and TMI's unaffected reactors were restarted and continued operation until 2000 and 2019, respectively.
Unlike Chernobyl, TMI-2's reactor vessel did not fail and contained almost all of the radioactive material. Containment at TMI was not breached. On the day of the accident, a small "hydrogen burn" occurred inside the reactor building, but it was not enough to affect normal operation of the reactor.
Following the accident, an estimated 44,000 Ci (1,600,000 GBq) (curies) of radioactive gases – particularly Krypton-85 – from the leak were vented into the atmosphere through specially designed filters under operator control. A government report concluded that the accident caused no increase in cancer rates for local residents.

== Chernobyl compared with criticality accidents ==
During the time between the start of the Manhattan Project and the present day, a series of accidents have occurred in which nuclear criticality has played a central role. The criticality accidents may be divided into two classes. For more details see nuclear and radiation accidents. A review of the topic was published in 2000, "A Review of Criticality Accidents" by Los Alamos National Laboratory (Report LA-13638), May 2000. Coverage includes United States, Russia, United Kingdom, and Japan. Also available at this page, which also tries to track down documents referenced in the report.

Press release on a report on criticality accidents from Los Alamos National Laboratory
List of radiation accidents
U.S. report from 1971 on criticality accidents to date

=== Process accidents ===
In the first class (process accidents) during the processing of fissile material, accidents have occurred when a critical mass has been created by accident. For instance at Charlestown, Rhode Island, United States, on July 24, 1964, one death occurred. At Tokaimura, Japan, nuclear fuel reprocessing plant, on September 30, 1999, two deaths and one non fatal overexposure occurred as result of accidents where too much fissile matter was placed in a vessel. Radioactivity was released as a result of the Tokaimura accident. The building in which the accident occurred was not designed as a containment building, yet it was able to retard the spread of radioactivity. Because the temperature rise in the nuclear reaction vessel was small, the majority of the fission products remained in the vessel.
These accidents tend to lead to very high doses due to direct irradiation of the workers within the site, but due to the inverse square law the dose suffered by members of the general public tends to be very small. Also very little environmental contamination normally occurs as a result of these accidents.