NagasakiCity  > Peace&Atomic Bomb  > Kids  > Before A-bombings > What is an atomic bomb? > Theory of the Atomic Bomb
FontSize large medium small   print
Kids heiwa Nagasaki
Peace&Atomic Bomb Nagasaki City WWW
> Japanese
Theory of the Atomic Bomb

When neutrons strike the nucleus at the center of an atom, the nucleus undergoes fission and releases fission energy, at the same time releasing two or three neutrons. The newly released neutrons strike other nuclei, splitting them in the same way, causing a sequence of fissions so as to continuously produce energy. This is called a “nuclear chain reaction.” Although materials such as uranium and plutonium can undergo nuclear fission, they will not reach a state of criticality, at which the chain reaction will continue, if the material is not of a specific amount. This amount is called the “critical mass.” If the material has critical mass and fission accelerates, tremendous quantities of strong energy will be produced. This energy is of high temperature, and generates dangerous radiation. The atomic bomb (A-bomb) is a weapon of destruction that uses the power released by the splitting of atomic nuclei.

Source: “Book about Atomic Power,” supervised by Atushi Tateno,
published by Suken Shuppan)

Nagasaki Atomic Bomb Museum
TEL 095-844-3913 FAX 095-846-5170 Email
Copyright © 2009 Nagasaki City. All Rights Reserved.