Best of the new soft-covers; Atomic doubletalk; Nukespeak, by Steven Hilgartner, Richard C. Bell, and Rory O'Connor. New York: Penguin Books. 282 pp. $6.95.

Three Mile Island was not an accident; it was an ''abnormal evolution.'' Safety reports are not doctored, they are ''word engineered.'' These terms belong to the vocabulary of ''nukespeak,'' a whole way of thinking. This book helps untangle it. A monthly roundup, compiled from staff and free-lance contributions and previously published Monitor reviews.