"Sixty Minutes to Meltdown," billed as television's first minute-by-minute chronicle of what actually went wrong four years ago at Three Mile Island, could be as damaging to the docudrama art form as the accident was to nuclear power.

Absurdly one-dimensional portrayals of the fictionalized principals in the drama can only turn off any serious viewer who is interested in the issues surrounding nuclear power and who followed the news coverage of the nation's worst nuclear accident.

And that's a shame. Because the final third of this 90-minute PBS special, which airs at 8 tonight on Channel 26, presents an illuminating discussion of the changes that have taken place in the operation and regulation of atomic power plants in the United States since the accident.

But the first 60 minutes, produced by Brian Kaufman--who won a national Emmy award for his last NOVA special, "Why America Burns"--is simplistic in the extreme. Even committed opponents of nuclear power are likely to cringe at the performances by the actors who play the sincere but stupid reactor operators, the venal officials of the power plant manufacturer and the utility, and the indifferent representative of the Nuclear Regulatory Commission.

The real life principals hardly covered themselves with distinction. But the caricatures portrayed in this show are ridiculous.

Raising the irritation level even further are the two omniscent narrators, Malcolm McCalman and Deborah White, who guide the viewer through a fictional hearing on the accident by inserting supercilious put-downs of the principals at every opportunity. The level of their dialogue, unfortunately, is more suited to "Love Story" than to TV journalism. A sample taken from the point in the hearing where the reactor operators told how the main primary pumps had just begun to vibrate:

White: "This is just like the China Syndrome."

McCalman: "China Syndrome?"

White: "The movie. Remember those huge vibrating pumps that rattled Jack Lemmon?"

McCalman: "The movie had it right."

White: "Yes. Do you know something? A manager at the plant had just seen that movie."

McCalman: "So he should have known what to do."

Really. And the rest of the docudrama is at about that level. While the notion of giving people a "real understanding of what actually happened" is a worthy goal, this effort fails miserably.

Anyone truly interested in gaining a better understanding of the accident at Three Mile Island would do better to read the book, "The Warning," by Michael Gray (author of the movie "The China Syndrome") and Ira Rosen, who have written a factually accurate account in the form of a thriller.

The final 30-minutes of the PBS program is considerably better. It presents a me'lange of views on what lessons have been learned as a result of Three Mile Island, and whether enough has been done to prevent a future nuclear catastrophe.

While the opponents of nuclear power (led on this program by Michio Kaku) always seem to get the last word, the discussion includes representatives of both the NRC and the nuclear industry, as well as such thoughtful observers as former NRC commissioner Peter Bradford and S. David Freeman, director of the Tennessee Valley Authority.

Unfortunately, this program was completed before the accidents last month at the Salem atomic power plant in New Jersey. Since the NRC says these accidents have had the most serious implications since TMI, the failure of this show to include them in a discussion of nuclear power plant safety leaves it incomplete.

But viewers concerned about nuclear issues still will find the discussion rewarding. Perhaps the best thing to be said about the docudrama is that you won't have missed anything if dinner runs late.