KARAN by B. Wongar (Dodd, Mead: $16.95). Australia is known as the old, red land, but in the southern parts of that country, where nuclear testing was carried out in the 1950s and '60s, it has become a new, dead land. The Earth is contaminated for generations to come. Aborigines who have for 40,000 years sustained a nomadic existence on these lands, were not informed of the tests being conducted in their tribal areas, according to this author. These events form the subject matter of "Karan," a novel dedicated "To the unknown tribesman, victim of nuclear testing in Australia," by B. Wongar, the pseudonym of an author who is himself half-Aborigine. At the center of the story is an Aborigine named Anawari who has been reared by whites and works in The Tribal Research and Assimilation Centre, a facility which, as Anawari comes to discover, has a very sinister purpose. As with "Walg," Wongar's first novel, a journey to reclaim tribal heritage is at the heart of the novel. But how can you reclaim a way of life that depended on the land when the land has been radiated? This is not an easy book to read: It produces a sadness, alleviated only by the lyrical passages that evoke, in very specific language and imagery, the beauty and harmony of traditional Aboriginal life. The making of a spear, or methods of securing water from trees, or the fashioning of a belt from human and animal hair, are activities presented with poetic devotion. To read "Karan" is to understand the savagery of the nuclear age from the perspective of those who entered it equipped with a stone ax and a boomerang.