A soft morning rain was dripping from the eaves when Jim Larry brought his family back home, and for the first time Larry said he found himself worrying about the awful question of the nuclear age: What have they done to the rain?

"It hit me when I drove up to the house," Larry said. "I mean, yeah, we were home and all, and it looked okay, you know, but how do you know it's safe?"

After a wandering four-day exile in their Winnebago, the Larry family, like most of the other nuclear refugees who evacuated the area around the Three Mile Island nuclear plant, decided today that the time had come to head for home. The kids were getting cranky, and Jim needed to get back to work. But it was a nervous homecoming.

State civil defense officials estimate that some 80,000 people living near the plant left their homes last weekend after the nuclear accident vented radioactive gases into the air. By late today, the state said, about 85 percent of the evacuees had come home, and life here, in the rolling country just south of Harrisburg, was returning, in many ways, to normal.

For the first time this week, there was a traffic jam during Harrisburg's morning rush hour. Hospitals began admitting non-emergency patients again. Grocery sales, except milk, came close to normal weekday volume. Most children went to school, except in the two towns nearest Three Mile Island, where schools still are closed.

But the return to routine could not extinguish the worry, distrust and muted anger among the people who had left their homes and jobs last weekend after the nation's most serious nuclear mishap.

"People are calling us day and night to ask if it's safe to stay home now," said John Brabits of the Dauphin County Civil Defense Office.

"I can tell in their voices they want me to say it's okay. They're very concerned. And jezz, I just don't know the answer. How can I tell them whether it's okay to have babies or whatever? Who knows what's safe now?"

For the people covered by Pennysylvaniahs evacuation advisory last Friday-pregnant women and preschool age children living within five miles of the plant-it still is not officially "safe," because the advisory has not been lifted.

But most of the refugees apparently concluded that it was all right to return after Gov. Richard Thornburgh announced Tuesday that the risk of a catastrophe at the plant seemed to have passed.

In addition to worrying about lingering radiation hazards, the returning evacuees are concerned about getting recompense for the losses and costs they incurred.

Most employers apparently are not willing to pay workers for days missed because of the nuclear threat. The state government, the region's largest employer, says missed days should be treated as vacation. Metropolitan Edison, the operator of the damaged plant, said it too would refuse to pay its pregnant employees who were advised to evacuate.

People who can prove they fall into the categories covered by the evacuation order can receive "emergency relocation assistance" from the two insurance pools, American Nuclear Insurers and Mutual Atomic Energy Liability Underwriters, covering the plant.

The insurance claims office, a long stuffy room in downtown Harrisburg, looks like the waiting room of an extremely busy obstetrician.

Row after row of pregnant women, most with toddlers playing at their feet, sit waiting-usually for two hours-to present their case to the teams of adjusters brought in by the insurance companies.

"You must have a birth certificate or other proof of age of your children," declares a sign on the wall, and the applicants are all clutching folders or worn manila envelopes containing the documentary proof that they are, certifiably, victims.

Those who can prove eligibility can receive payments for travel and lodging expenses incurred because of the evacuation. American Nuclear Insurers says it has paid about 1,000 families an average of $256 apiece, and expects at least as many more applications in the days to come.

But not even the prospect of an on-the-spot insurance payment could eliminate all of the displeasure among the patient, glum people waiting to make their claims.

"Hey, before I bought the sales pitch," said Jim Larry, "the whole ten yards-that the chances of anything bad at the plant are minuscule. And now here we are.

"I've changed my views on the thing, personally. I don't believe them."

The same attitude was evident in a young couple who were arguing with an insurance adjuster who said he could not pay for lost wages right now.

"Don't get mad, honey," the pregnant young wife said to her husband. "This is just the evacuation money now. They'll pay the claim for your wages later."

"That's what you say," the husband snapped back. "I want to hear the company tell me that. But hell, I probably wouldn't believe them even if they said it." CAPTION: Picture, Beverly Phillips, of Middletown, folds her family's clothing, preparing to return from an evacuation center. UPI