For young people today, the Fukushima disaster in Japan could be their Nuclear Moment.

Since the 1940s, we have been living in the Atomic Age. Each decade has produced images and imaginings that, when stitched together, add up to our ambivalent relationship with nuclear power.

In a positive light, nuclear power is seen by some as cleaner, greener and less expensive than many other energy options. “I actually think we should explore nuclear power as part of the energy mix,” presidential candidate Barack Obama said in 2007.

In a negative light, our dreams of peace and prosperity are periodically shocked by a nuclear nightmare and reminders that our abundance of nuclear power plants and weaponry could result in a worst-case scenario for humankind.

Now there is Fukushima, a potential catastrophe. And no one knows the ultimate extent of the danger.

The Fukushima disaster “seems like a fairly random accident,” says Reid Detchon of Energy Future Coalition, a nonpartisan public policy group. “But the trouble with nuclear power is that the potential consequences are so terrible. It’s great as long as it works right, but you can’t engineer away every possible calamity.”

Knowing that we have lived with these potential consequences for more than 60 years, we posed this query to NPR followers on Facebook: We want to know the image that first forced you — as a child — to think about the possibility of nuclear annihilation. Mushroom cloud? Bomb shelter? Chernobyl?

We received more than 3,700 replies, including some who chastised us for fear mongering and emphasizing disaster. That was not our intention. We wanted to examine certain Nuclear Moments in recent world history that shocked our consciousness. Here is what we learned:

Nearly everyone who replied carries a nuclear image. It is something we live with.

Sometimes our Nuclear Moments come from actual events — such as Hiroshima or Chernobyl. Or they come from fictional accounts — such as the 1957 novel On the Beach by Nevil Shute or the 1983 made-for-TV movie The Day After. Or they come from preparedness efforts — such as backyard bomb shelters and yellow-and-black Fallout Shelter signs.

A look, then, at a Nuclear Moment through the decades, accompanied by a Facebook correspondent’s response.

Atomic Bomb Tests, 1940s, Janet Poling Toth, Ohio: Probably the mushroom cloud. I was born in 1940, and I remember our calculating how close we lived to a major city (Pittsburgh, in my case) that could be a target for THE BOMB.

Classroom With Gas Masks, 1950s, Dawn Graff-Haight, Oregon: I was in first grade. It was 1956. We watched a film showing us the “duck and cover drill.” Some days later, a blaring alarm screamed in the hall, and the teacher instructed us to crawl under our desks and cover our heads. and even though I was only 5 years old, I KNEW that if a bomb dropped on my school, I could kiss my a** good bye.

Bomb Shelter, 1960s, Corinne Bozin-Grizzell, Ohio: In elementary school outside of Detroit (1961-‘65) I remember having drills on a regular basis, they were like tornado drills but the sound of the alarm was different and we had to go deep into the basement of the school to the “bomb shelter” — sit on the floor with legs crossed and hands locked over our heads until we got an all clear.

Fallout Shelter Sign, 1970s, Summer Gotschall, Georgia: I grew up in the 1970s and my dad was a Ph.D. student in physics for most of my childhood — he often took me to his university lab in a basement, right next to the building’s fallout shelter — the symbol for a fallout shelter is deep in my memory. I can draw one now without Googling. :)

Three Mile Island, 1970s, Midori Green, Minnesota: I was a kid in the ’70s, and it was watching all the reruns of ’50s American and Japanese movies on Saturday afternoons that focused on this endlessly. Godzilla, film noir, Ultra Man, the endless references to uranium and glowing in the dark or changing into a freak of nature. I used to be afraid of glow-in-the-dark dials on wristwatches. Then add Three Mile Island on the news to that and all those fallout shelter signs that were still in the classroom. It’s a bunch of things. I still don’t own a microwave.

The Day After, 1980s, Dianne Pater, New Mexico: I grew up in Albuquerque, and I remember after the TV movie The Day After, the local news showed graphics indicating that the Air Force base here would be a prime target, and showed what neighborhoods would be annihilated by a nuclear attack … including mine. As a 9-year-old, I was terrified.

Chernobyl, 1990s, Anna Howard, Florida: I was 4 years old living in Ukraine when Chernobyl happened. At the time, my parents’ panic to get me out of the city and out to the Black Sea was nothing but a fun vacation. However getting back to the city (Kiev) in the fall changed a lot. … As an outdoor child, I really felt the difference in not being able to play outside, to wear dust masks and not touch anything. Wash hands rigorously even if after just getting the mail. If the rain began, the entire city would disappear inside, instantly, and the puddles were avoided like little ponds of molten lava. Copyright 2011 National Public Radio. To see more, visit http://www.npr.org/.