Bestsy Fowlkes sat on the grass on the Ellipse yesterday and gaped at the trappings of a mass protest demonstration - the kind her parents once forbade her to attend.

"It's my first demonstration like this," said the 23-year-old Richmond resident who came up for the day with a friend. "I wanted to come to an antiwar demonstration here, but I was only 13 or 14 and my parents wouldn't let me."

Her friend, Nancy Poland, 25, grew up in Arlington, where the famous marches and rallies of a decade ago were just a bus ride away. So yesterday, she felt right at home.

Re-enacting a scene from the late 1960s and early '70s, tens of thousands of demonstrators turned their attention to the subject of nuclear power.But nostalgia quickly gave way to some clever updating.

Chants of "Hell no, we won't glow" echoed off governmet buildings once surrounded by draft resisters.

And a numerical rhyme formerly directed against the Vietnam War became "Two, four, six, eight, We don't want to radiate."

People who agonized over that war, people who grew up with it and people who now study it in school were among the generally festive crowd. Some of the reasons for being on hand, however, were as diverse as the many signs attacking nuclear power.

"basically, I'm here to hear the music," said Charlie Harrison, 20, who lives in Northern Virginia and attends college in North Carolina. "I really haven't looked at nuclear power enough to know, and these people don't seem to have any alternative."

Still, Harrison acknowledge, he probably will "look into it more after seeing all these people here."

Philip and Mary Lou Crifasi of Oxon Hill tried to remember the last time they had come to a protest demonstration and finally decided it was just before the May Day anti-war protest in 1971.

"Everybody our age has sort of gone straight," she said. She is 28, her husband, 30, and the children they brought with them are 1 and 2 years old.

While they enjoyed the sun, the music and the excitement of having a cause again, the Crifasi couple's own misgivings about nuclear power marred their outing. "I feel sad that you have to have something like this demonstration to call attention to such a serious problem," she said.

For Helen Trandler, 57, participation in the antinuclear demonstration was a logical step in her antiwar involvement.

"I feel nuclear power, including the weapons, is going to just destroy our world," said Tandler, who drove down from Long Island, N.Y., with her husband and was surprised to see so many "youngsters" in the crowd.

"We used to get more people my age at the antiwar rallies, but the older people just aren't as involved now," she said. "For one thing, they're not taking our sons."

But she expects that the accident at Pennsylvania's Three Mile Island plant will have "sort of the same effect as Cambodia" in educating people about the problem.

Like the protest days of old, yesterday's march to the Capitol and star-studded rally had a little bit of everything. Socialist groups hawked newspapers among the crowd, "anti-nuke" buttons were doing a brisk business and ballons and flowers were plentiful.

But there also were constant reminders that this was a demonstration of a different sort. Scores of protesters arrived on bicycles, skate boards and roller skates. The few gas masks in evidence were only for visual effect. Organically grown snacks were sold at stands alongside junk food vendors. The rally's organizers arranged with a local restaurant to have vegetarian lunches delivered at the staging area.

And when the crowd jammed the Capitol grounds and kept growing, people got ecological admonishment over a loudspeaker to "get out of the trees and don't step on the tulips."

The signs focused on one theme.

Just a sampling: "Genetic Alteration While You Wait"; "Melt Down Corporate Power"; "I Survived TMI . . . I Think"; "Honk If You Hate Fission"; Power is Beyond Human Wisdom - Take It Out of Human Hands."

Still, Stephanie Klein, 20, looked over the signs, the mimes, the banners and the cheering protestors and decided she was watching history repeat itself.

"I imagine this is what the 60s was Vietnam Veteran Ron Kovic, a paraplegic who showed up in his wheelchair. He tried to see actress Jane Fonda, who was seated behind the staging area, waiting to speak.

"He's personal friend of Jane's," a man with Kovic shouted as the two began to push through the group of reporters and photographers who had gathered around her.

Kovic, an organizer of Vietnam Veterans Against the War, had managed to get to within five feet of Fonda when he was stopped by one of the organizers of yesterday's events.

"She's sorry," the organizer said after speaking to Fonda. "She can't see you right now. But she loves you and she's thinking of you." CAPTION: Picture 1, A statue at the Capitol became a participant in yesterday's rally, as a demonstrator gave it his shirt. Photos by Frank Johnston - The Washington Post; Picture 2, Death masks, banners and T-shirts were among the methods used to express a common viewpoint as yesterday's rally against nuclear power began at the Ellipse; Picture 3, Part of the crowd of more than 65,000 who demonstrated against nuclear power at the Ellipse and the Capitol yesterday. by Frank Johnston - The Washington Post