The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
All other sections in this Literature Study Guide are owned and copyrighted by BookRags, Inc.
A chain reaction is a self-propagating reaction that continues without additional outside assistance once it is started. Like a series of dominoes falling in regular succession after the first is toppled, chain reactions proceed by themselves once started. Nuclear chain reactions advance in a somewhat similar way, where the effects of one reaction induce the start of the next. With regard to nuclear chain reactions, however, critical mass must first be achieved.
Critical mass is the amount of material necessary to sustain a nuclear chain reaction at a constant rate. The amount is critical because if the threshold mass is not met, the chain reaction will not occur. Controlled nuclear chain reactions are important in nuclear power plants. Nuclear energy is harnessed in these plants to produce electricity. The nuclear chain reaction requires a critical mass of nuclear material. Similarly, atomic explosions require a critical mass of fissionable or fusionable material in order for the nuclear chain reaction to occur. In nuclear fission explosions, where atoms are split apart to release immense quantities of energy, critical mass is needed to slow the emitted neutrons of the nuclear reaction. When atoms are split, they eject neutrons at very high speeds. The critical mass provides the minimum material to ensure that an emitted neutron will adequately collide with another atom causing it in turn to split, initiating the chain reaction. In fusion reactions, samples of less than critical mass are forced together to create one portion with supercritical mass that then proceeds as a nuclear chain reaction.