Nonfiction forms are making new inroads into prime-time network television this season, and there is probably no series going farther out on a limb of innovation in this category than NBC's "Lifeline," which will first be seen on Channel 4 at 10 tonight and then move to Sundays at 10 p.m. starting Oct. 8.

The program evolved from "The Body Human," a collection of medical documentaries produced last year for CBS which followed case histories of actual patients as they underwent surgeries and treatments of various kinds. The first "Lifeline" concentrates not on a single malady or area of disease but on a single doctor, Judson Randolph of Children Hospital in Washington.

It has been boasted in NBC promotion that "Lifeline," with its documentary footage of real hospitals and operating rooms, will take us beyond the Marcus Welby and Ben Casey hope operas and into a more sober and realistic consciousness about medicine. However, Dr. Randolph emerges, in this one-hour portrait, as a gallant knight in white without even the threat of a blemish.

He is warm and kind to his young patients, he sings "country Roads" with his kids at home, and he plays cards with friends who, it appears, would never dream of saying anything so strong as "poo-poo." The program hardly seems a revolution in realism.

The real drama, of course, is with the patients, and some of the footage by Robert Eletrom and other cinematographers is remarkable and very moving. A newborn baby with a breathing obstruction lies linked to life by plastic tubes. A 15-year-old diabetic, hospitalized with an inflamed pancreas, is asked by the doctor if he prefers being called "Jerry" or "Jerome" and you hear a tiny panicked sob say, "Jerome."

And when the parents of the sick baby hear that their child is out of danger at last, and the mother cries, and the father shakes the surgeon's hand and tells him, "I would like to say, thank you, Dr. Randolph," this program comes closer to the specter of mortality and to the mysteries of life and death than any other series on television.

The first three "Lifeline" programs have been picked up for sponsorship by the Xerox Corp. suggesting that NBC is going after not so much the vast mass audience as one with a handsome demographic profile. If this can keep "Lifeline" alive, so much the better, because its imperfections (and the fact that some of its "real-life" scenes seem obvious reenactments) do not alter the fact that the program is an encouraging departure from prime-time routines and a true alternative to the prevailing escapist fluff.

"Grandpa Goes to Washington" may be the first TV comedy series for the age of Proposition 13. Its cunningly cantankerous hero, played in the finest of old fettles by Jack Albertson, suggest a cross between bombastic populist Howard Jarvis and Paddy Chayefskys nearly immortal Howard Beale, "the mad prophet of the airwaves" in "Network."

But the writers of this new one-hour NBC series, premiering tonight at 9 on Channel 4, should give Gramps punchier dialogue and a more distinctive identity if the show is going to succeed and, in the best tradition of American humor, exploit the home truth that no politician is above suspicion.

Even in its present form, the program has a zestier personality than most comedy shows and Grandpa himself poses a considerable threat to one's skepticism. Albertson's repetitious line readings grew awfully tedious in he poorly written "Chico and the llan," but here he seems far more pliable and far more credible.

In the premiere, cut down from the show's original two-hour pilot, Gramps is ejected from his job as a college professor because he reached, and in fact passed, the mandatory retirement age of 65. A TV news crew visiting the campus captures him grumping about the corruption of the (unnamed) state's governor and soon he finds himself a candidate for s Senate seat.

He runs on a platform opposing "the tyranny of the middle-aged hack politicians" because they are "anti-young and anti-old." No, this is not a [WORD ILLEGIBLE]political satire, nor even a rabble rouser in the Frank Capra style, but Grandpa does have his moments.

Asked his opinion of permissive sex, he moans, "Where was it when I needed it?" Asked what he thinks of socialized medicine, he huffs, "I think it stinks. I, for one, don't want the guys who run Amtrak or the post office taking out my appendix."

Topicality in a TV series is considered bad business because it endangers future syndication sales. So Grandpa belongs to a political party known only as "the party" and the script pulls the very punches one would expect to be pulled. There are references in the premiere, however, to a certain senator who resigns his office when linked in the papers with a certain Boom-Boom Brazilia, exotic dancer and frequenter of wanton bashes. And a future episode will find Sen. Gramps investigating funds spent on a birthday party for the president's young daughter.

Of the supporting cast, William Daniels is impeccably sleazy as the governor and Larry Linville a touching simp as the military-career son whom Grandpa calls "a fathead" and adds, "the Pentagon is the perfect place for him."

Rue McClanahan sparkles briefly as an old flame of Grandpa's but will not be seen on subsequent episodes because she has a series of her own, "Apple Pie," premiering soon on ABC. And subsequent episodes of "Grandpa" will not be seen on Thursday at 8 p.m. effective Sept. 19. Tonight's premiere is part of NBC "Sneak Preview Week," a successful attempt by the network to turn the bedlam of early-season scheduling into outright anarchy.

"I just happen to be the kind of guy who can tell when something's not gonna work out," says Joe Namath, "and this is not gonna work out." He is not talking about his new TV sitcom, "The Waverly Wonders," but he might as well be. The idea of this slack hack job working out is not an encouraging one for those with a remaining ounce of respect for series television.

The pilot for Namath's new half-hour NBC comedy will be shown sometime during a one-hour "Welcome to Joe Namath" special at 8 tonight on Channel 4. The so-called special is really just a chance to trot out stars of other NBC shows for mucho promola - one of the slick tricks that Freddie Silverman should have left in the pocket of his own old rumpled suits at ABC.

Broadway Joe, who has now become Hollywood Joe, plays the part of Harry Casey, one-time mediocre pro basketball player now a teacher of history and basketball coach at Midwestern Waverly High. The program attempts to combine elements of "Welcome Back, Kotter," "Happy Days" and, because the team is of the raggle-taggle sort and is redeemed only by the presence of a spitfire woman player, "The Bad News Bears."

Apparently "Welcome Back, Happy Bears" was considered too long a title.

The school is stocked with stock characters including dull cardboard targets for Casey to capsize. The real villain, according to the script, is the idea that kids in classrooms should be forced to do anything so funless as study; teacher Casey's ignorance of history and reluctance to bore the kids with it is held up as a model of macho virtue.

Naturally there is a Fonzian tough on the premises - an Italian kid called Tony Fagoozi - plus appealingly spunky Kim Lankford as the woman on the team and Charles Bloom as a blond boy whose lifelong shyness is cured with just one stiff bormide from cool Mr. Teach.

Namath himself recites lines and stalks about the set as if under remote control from a scientist's lab. It is said he scores high among women viewers in TV testing. They must be lonely women. The man is a walking chalk talk, about as expressive as a plaster cast, and "Waverly" is no wonder.