A woman's strength amid the corruption of Hollywood; Radiance, by N. Richard Nash. Garden City, N.Y.: Doubleday & Co.496 pp. $17.95.

''Hollywood is the most corrupt city in the world,'' said N. Richard Nash when I asked him if he was bitter about his experiences as a Hollywood screenwriter in the 1940s and '50s. ''Hollywood has an edge on one special kind of corruption that I think is really the worst; it's the corruption of the human spirit.''

I met Mr. Nash, a charming man who looks much younger than his 60-odd years, for lunch recently at the Dorset Hotel in New York. Over chicken salad, we discussed his latest novel, ''Radiance,'' and the Hollywood corruption it describes.

Hollywood, he says, corrupts the best that our culture can offer. Because the movie industry pays so well, it can attract the best writers and artists, who are hired for their uniqueness, their individuality, their skill and artistry. Hollywood then reduces this individuality to banality. The stature of these writers and artists is also reduced, and the public suffers as well.

''That kind of corruption really enrages me,'' he says. ''I've been subject to it, I have responded to it, I have allowed myself to be corrupted just as most other writers have done, and I've always hated myself during and afterwards.

''That's why I left Hollywood, that's why I won't work there anymore. If I can get a Hollywood assignment I do it here in New York. I respond as best I can to the criticism on the first draft. I do what I can do to revise within the limits of what I consider reasonable artistry, and then I run away.''

Nash feels that Hollywood is more corrupt now than in the industry's early days because, he says, the accountants have taken over the business, and their interest is only in the bottom line - money. He thinks it is a peculiar paradox that the men who run the movie studios are, for the most part, honest, decent people who are ''doing corrupt things because that's what they believe to be the right way to run a business. . . . In the old days there were villains who ran the studios, like Harry Cohn, Sam Goldwyn, Jack Warner. . . . They had one saving grace: They had a passion about film, they took chances. . . .''

Nash has a passion about writing. In his long and varied career as a writer he has written poetry, plays, screenplays for television and movies, six novels, and two books on philosophy. He is best known for ''The Rainmaker.'' He wrote the play, first produced on Broadway in 1954, and the screenplay for the movie, released by Paramount in 1956 and starring Katharine Hepburn and Burt Lancaster.

Besides ''The Rainmaker'' he's written ''East Wind, Rain'' (Atheneum, 1977), his best-selling novel so far; and ''Radiance,'' which may end up being the most commercially successful of his novels. These three works have a major point in common: The main character in each is a strong woman.

Calla Stark, the main character of ''Radiance,'' is a successful actress and former political activist. Some of the current publicity for ''Radiance'' suggests that Nash based Calla on Jane Fonda. There are surface similarities between Calla and Miss Fonda. Yet a careful reading of ''Radiance'' convinced me that Calla is no more based on Jane Fonda than she is on Shirley MacLaine or Vanessa Redgrave, who are also politically active actresses. Is Calla based on Jane Fonda?

Nash says he has given many answers to this question, some truly representing his opinion, some of them jokes, some of them hype. ''I think the closest to the answer that I want to give is part all of those things. . . . If (someone) thinks it's Jane Fonda I hope Jane either sues me or plays the part. I think it's unimportant whether it's based on Fonda or not, because anybody who really reads the book sees that there are so many aspects of the character that are not Jane Fonda that it doesn't matter.''

Since the book began to sell well in the stores, the option offers for movie rights have started to come in.

Nash wrote ''Radiance'' because he wanted to tell the story of a strong woman in crisis. ''Two kinds of crisis: a crisis that is external - in this case it happens to be that her life is in danger - but more important, an internal crisis, where she is taking stock of herself and is fearful that she has lost the spark that makes life worthwhile. . . . That character could be anybody. . . . I decided that she should be an actress, because I wanted to put this strong woman in a corrupted society. . . . The political side of her I used simply as an illustration of her strength. . . .''

Nash continued, ''Calla thinks she has lost her radiance, a quality that I describe as an energy . . . a force . . . a quality of will. . . . It's something you can do something about. . . . The great stars have it, and that energy reaches out to an audience, and it says, 'Love me.' '' Unlike charisma, which according to Webster is a divinely inspired gift or talent, radiance is something anyone can have. Everyone has the ability to motivate himself to reach out to others, to radiate.

Calla rediscovers her radiance while starring in a movie called ''The Fabulist.'' Each of the novel's other main characters is also involved in the movie and in his own radiance crisis. Nash says that all of the characters are meant to illustrate the enormous range between reality and illusion that exists in Hollywood.

Calla's life is the most firmly anchored in reality. Julo Julasto, a charismatic black cult leader and one of Calla's costars, lives a life of fantasy. His ability to walk unharmed through fire inspired the movie's director , Lucas O'Hare, to write his dream project, ''The Fabulist.'' Lucas is a Hollywood maverick whose battles with himself and the studios reflect Nash's own experiences. Barney Loftus, Calla's ex-husband and another of her costars, is a talented character actor who turns to drugs because the only part he is unable to play is himself. Willi Axil, Calla's look-alike movie double and secretary, is a lesbian with an unrequited love for Calla. Willi has an identity problem and lives in a dream world. She has also been the victim of a brutal attack meant for Calla.

The incidents of violence, sex, and drug use in the novel may be unpleasant, but they are integral parts of the plot and are not used gratuitously. Nash says that he is ''an exceedingly moral man,'' and that he wanted to write a moral book. ''I was picturing a society that . . . is corrupt. . . . I am dealing with the edge of madness that is Hollywood. . . . My illustrations (of Hollywood corruption) are bland. . . . I don't ever want to use either violence or sexuality . . . or anything gratuitously.''