Frequently Asked Questions
|There was severe ground contamination
after the Chernobyl accident. Why wasn't it so serious after the
Hiroshima and Nagasaki bombings?
Release of radioactive materials after the Chernobyl reactor accident
The Chernobyl reactor contained about 180 tons of nuclear fuel consisting
of two percent, or 3,600 kg, total uranium. The amount of nuclear
fuel released is estimated at seven tons (corresponding to 200
kg of uranium). Fission products increase the longer the fuel is
The Hiroshima bomb contained 25 kg of uranium, and about four percent
(or 1 kg) underwent nuclear fission.
In a nuclear reactor, when the nuclear bed melts, volatile radioactive
materials are released extensively. It is estimated that 100% of
the rare gases, about 50-60% of the iodine, and about 20-40% of
the cesium contained in the reactor are released.
- The total nuclear fuel in the Chernobyl reactor was 180 tons
(corresponding to 3,600 kg of Uranium-235), more than 100 times
greater than that of the Hiroshima bomb (total weight of the
bomb was about four tons, but Uranium-235 is estimated at 25
- In the case of the Chernobyl accident, the nuclear fuel melted
and volatile radioisotopes were released in large quantities.
For example, as stated, 100% of the rare gases, 50-60% of iodine,
and 20-40% of cesium were released. Thus, although the total
nuclear fuel released is estimated at a few percent (7-10 tons),
the release of other radioactive materials was quite extensive,
in disproportion to the amount of nuclear fuel released.
- It is estimated that about four percent (or 1 kg) of the uranium
of the Hiroshima bomb underwent nuclear fission. The bomb exploded
in the air and formed a large fireball that subsequently ascended
to reach the stratosphere. Part of it fell to the ground in
black rain while the remainder was widely dispersed.