Originally published in 1961. This book gives the layman a better understanding of the nature of nuclear power and explains some of the major problems which have to be overcome in making practical use of it. It is concerned mainly with the different kinds of nuclear reactors - their underlying principles are explained and illustrated by reference to particular plants or design studies. Interested readers will find that the discussion of principles is full enough, and the range covered wide enough, to provide a broad view of the subject and a useful introduction to some more technical literature.