Ten years ago this Tuesday (March 28), at 3:53 in the morning, an ominous billow of steam erupted from a 372-foot-high cooling tower at the Three Mile Island Power Plant in Middletown, Pa. The blast, the result of a malfunctioning valve in Unit 2's cooling system, signaled the start of the worst nuclear accident in U.S. history. For the next five days, as clouds of radioactive steam drifted over the Susquehanna Valley, Metropolitan Edison technicians struggled to prevent a cataclysmic meltdown of the reactor core.

Although subsequent scientific studies provided no evidence of long-term medical harm to the surrounding community, the incident did have undeniable consequences. In part because of heightened public concern with the nuclear industry, no new plants have started construction since the T.M.I. breakdown a decade ago, and 69 reactors on which preliminary work had begun were scrapped. A less tangible outcome was the fallout of fear that settled on local residents. For many of those who lived through those traumatic days, all of the scientific findings and official assurances remain unconvincing.

Deborah Baker, 32, was at her secretarial job in nearby Harris-burg when Gov. Dick Thornburgh's voice came over the radio advising women and small children within five miles of the plant to leave the area. It was 54 hours after the accident and "the first I'd heard of it," says Baker, who called her husband, Blaine, to pick her up. "We had to drive right by the plant to pick up my baby, Jennifer, at her baby-sitter's. I didn't know it at the time, but I was pregnant."

Nine months later Baker gave birth to a boy who suffers from Down syndrome. Though she concedes that genetic specialists have not been able to connect her son's problem with T.M.I., "in my mind there's no doubt that the accident was responsible. I know plumes of radiation did go over where we lived because all the X-ray films of the dentist up the road were exposed."

In 1981 the Bakers sued Metropolitan Edison, the plant's operators, along with six other related companies, and won a $1.1 million out-of-court settlement, the largest so far. Of more than 2,200 such suits filed against Met Ed and others, nearly 300 have been resolved for damages totaling $14 million. The claims "were settled without regard to evidence simply to avoid the expense of trials," according to the utility's insurer, noting that the awards did not constitute "an admission of liability." Baker remains unconvinced. "The thing that scares me the most," she says, "is, can it happen again?"

Dick Thornburgh, recently named U.S. Attorney General, had been Governor for just 72 days when he was thrown into the job of managing the accident. Although "I had been given a perfunctory briefing about managing a nuclear emergency just after taking office," he says, "nuclear jargon was a foreign language to me." Thornburgh acknowledges having considerable difficulty nailing down accurate information immediately after the incident; at one point, he says, the misreading of a radiation monitor nearly prompted an evacuation of the entire area.

When the crisis ended, the Governor helped devise a plan to divide the anticipated $1 billion-plus in cleanup costs among ratepayers and utility owners. He also demanded more stringent safety measures before the start-up of Unit 1, the stricken plant's sister reactor, which had been shut down for refueling at the time. "Nothing is absolutely safe or risk-free," says Thornburgh, 56. "I have a sense that because of our being brought up short by T.M.I., and Chernobyl, plants that are operating today or that will be built in the future will be a lot safer."

Walter Creitz, Metropolitan Edison's president in 1979, still defends the utility company's handling of the T.M.I. accident. "Hour by hour we were updating our story by what we knew," he says. "It may have sounded like we were changing the story, and we were. We were correcting it. There wasn't any way for us to get into the reactor vessel and find out what was wrong."

Five months later, Creitz was removed from his post as president. "Under the circumstances, it was time to change the team at the top," he says. "The fact that I happened to be president then was unfortunate, but that's the way the cookie crumbles." Now 65, Creitz lives in Reading, Pa., and devotes his spare time to working with the Boy Scouts. At this summer's national scout jamboree in Virginia, "I'm going to be head of the maintenance control center," he says proudly. "Any electrical, refrigeration or mechanical problem, that's mine."

Jean and Paul Trimmer, owners of a cattle farm 10 miles from the reactor, still think back to the rainstorm that struck on the night of March 30,1979. "I went out on the porch to call my cat, Friday," Jean says, "and I felt a gust of heat. The next day people told me I looked like I was sunburned, and then before long I got a lot of white hair that I didn't have before." Despite the studies showing no effect on public health from the radioactive release at T.M.I., Trimmer shares the lingering doubts that still shadow some of those in the region. She attributes an atrophied kidney to radiation exposure and worries as well about an unexplained inner-ear problem. "When we heard Three Mile Island was being planned, we thought it was great," says Trimmer, now 64 and often housebound with her ailments. "Instead, it's turned out like this."

Marjorie Aamodt, 61, was tending her 300-acre organic farm 45 miles from the plant when the shutdown occurred. She and her husband, Paul, knew "an engineer who was working there, and he said, 'Get out, go 200 miles to be on the safe side,' " says Marjorie, who did just that. In 1984 the couple began hearing reports of people who had experienced red faces, rashes and hair loss—symptoms they blamed on radiation exposure. Trained in statistical analysis during their college years, they began an unofficial survey of three neighborhoods near the plant that had been in the direction of the blowing wind on March 28. By December 1984, after interviewing 433 people living in 100 households within 10 miles of the reactor, the Aamodts say they had discovered six times the normal rate of cancer. Hoping to delay Unit 1's long-disputed reopening until their results could be studied further, they instead heard their claims dismissed by the Pennsylvania state health secretary as "contrary to scientific findings."

Three years ago, suffering a severe decline in sales for the chemical-free crops they marketed, the Aamodts moved to Lake Placid, N.Y., and became maple sugar farmers. "Still, we're just a few hundred miles from the nuclear plant at Oswego," says Marjorie worriedly. "There's hardly anywhere you can go these days to get away from those nuclear plants."

Mayor Robert Reid of Middletown was furious when Met Ed waited five hours to notify him of the reactor accident just three miles from his borough hall office. Reid, a native Middletowner and the first elected black mayor in Pennsylvania, demanded changes and says that now "a fish can't jump out of the water in that area without them notifying me."

Although concern that the T.M.I., accident would hurt the economy and local real estate values proved unfounded (in fact, the influx of 1,000 cleanup workers has been a boon), Reid says he still has to deal with a community that is subconsciously fearful of another accident. "It's in the back of everybody's mind," says the 56-year-old mayor. "Last year when our [high school] wrestling team won the conference and the fire trucks were blowing their sirens to celebrate, we got all kinds of calls at the communication center. 'What's going on? Is it T.M.I.? Is something happening down at the Island?' "

Much, in fact, has happened. To date, close to $1 billion has been spent in cleanup operations, and in 1985 Unit 1's sister reactor resumed operation. More than 2 million gallons of radioactive water remain sealed inside the stricken plant, however, and the utility has been seeking permission from the Nuclear Regulatory Commission to turn the liquid into steam and vent it into the atmosphere. Officials for the utility say that the planned 18-month process will expose local residents to no more than two hours of normal background radiation.

—Susan Reed, Melissa Herman in Middletown