In September 1945, just weeks after an atom bomb was dropped on Nagasaki, a young Marine guard arrived with the first group of Americans for the "clean up."

What he saw, Harry Coppola recalled yesterday, was a "city two feet high with dead, charred bodies everywhere. People were walking around with flesh hanging off their faces, their bodies. Granite had turned to dust. We were walking on dust. Dust. And when it rained, the rain was black. And the stink, well, it was something you never forget."

When the bomb dropped on Nagasaki on Aug. 9, 1945, Coppola was stationed in Hawaii, preparing to celebrate his 25th birthday. Within weeks he was sent into the Japanese city to work as a policeman. Two weeks later, complaining of loss of appetite and nausea, he was discharged. He had done his duty and went home to forget.

For nearly 30 years he did erase the grisly scene. Only in infrequent dreams, dreams prompted by a Spencer Tracy of Humphrey Bogart war movie, did his sense of horror come back to him. Only recently has Nagasaki become to Coppola a fullfledged nightmare.

Since July 1974, he has been ill, first from rib fractures that wouldn't heal, then chest pains, then blood discharges. His sickness was finally diagnosed as a rare and fatal form of bone-marrow cancer, multiple myeloma. He claims that it is directly related to his radiation exposure at Nagasaki.

"I never heard the word radiation until a few years ago. I didn't know what it meant. All we were told was to keep the people out of the city. We had no protection, no warning," says Coppola, 59. He says his doctors told him yesterday he has fewer than six months to live.

Harry Coppola is broke. His life savings of $29,000 has been spent for cancer treatment. From a Veterans of Foreign Wars patriot, he has become bitter about what he feels is a lack of attention from the Veterans Administration and Department of Defense. From one of the faceless thousands who served in World War II, Coppola is now a news personality. Mike Wallace has been by. The picture of the silver-haired Coppola was flashed on network news after the recent 34th anniversary of Nagasaki.

In his public appearances, there's an urgency to Coppola's motions and manners, the way his hazel eyes burn with annoyance, the heavy wheezing of his barrel chest, the quick snap of the rapid retelling of his story in a gruff Massachusetts accent.

His crusade brings both pain and pleasure. "Every time I go out for a political speech, I live on dope pills. I do it with great pain. But I'm trying to get what's coming to us," says Coppola, who was in Washington yesterday preparing for a press conference this morning. Coppola is part of a group calling for congressional hearings on radiation victims.

"I like speaking out. I didn't want to at the beginning. I was convinced the government would take care of us," says Coppola. "Now every time we get out there, we get new names. The last time I was in Washington, I got 600 letters."

Coppola is part of a growing group of Hiroshima and Nagasaki veterans claiming their serious health problems are directly related to radiation exposure. Norman Solomon, a journalist and coordinator for the Citizen Hearings group, who has been tracking down other veterans, says, "I have talked to about 50 of the Nagasaki marines, and we have discovered extraordinarily high incidences of blood disorders in general, and multiple myeloma in particular. The incidents of bone marrow cancer with the Nagasaki marines far exceeded the 1/2 or 1/4 cases per 1,000 in the normal population." On Monday, a Board of Veteran Appeals in Washington granted benefits to a cancer-stricken veteran who worked at an atomic test site in the first acknowledgement that exposure to radiation and a subsequent cancer could be related.

Until recent weeks the Defense Nuclear Agency did not include the Hiroshima and Nagasaki veterans in a research review of all Defense Department personnel exposed to nuclear tests from 1946 to 1962. Now it has included those personnel and is reviewing the 231 claims from those veterans that the Defense Department had denied. Nevertheless the agency continues to downplay any connection.

"Our calculations show that someone who stayed for the entire ten-month period, even without protection, was exposed to one rem or less of radiation. The international standard for adverse health effects was five rems," says Lt. Col. Hartman Mowery of the DNA. "So it is highly unlikely that there's a direct cause and effect. Also, 16 percent of all Americans get some form of cancer, and these men are now in that age bracket where they are susceptible. Nevertheless, they are concerned, so we are concerned."

Until the concern turns into some form of reparation, Coppola vows to fight. He was on Nagasaki a total of 14 days, becoming so sick, he recalls, that he was sent back to the States and quickly discharged. Back home in Revere, Mass., with only a seventh-grade education, he joined a bakery corporation as dishwasher. Seventeen years later he was general manager. At age 33 he married. He had three sons and never allowed his wife to work. He liked to read. "But I couldn't read about wars. I have a collection of Washington Irving that I especially like," says Coppola.

Occasionally he developed lumps on his head, which would stay a couple of weeks. "In 1953 I had tremendous pains in the stomach, went to a VA hospital. They took a blood test, decided it was appendicitis, opened me up and nothing was wrong. They took itout anyway." Then, four years ago, he fell off a ladder and broke five ribs that wouldn't heal.

When his condition was diagnosed as cancer, the veteran of Guam and Iwo Jima was ordered to retire. The doctors wondered if he had ever been exposed to radiation. "Yes," he told them, remembering how he heard the news of the atom bomb. "We were happy about it. It ended the war." Then he had to sell his family's jewelry and his own childhood coin collection to pay the bills. He asked for financial help from the Veterans Administration.

Gradually, he became a critic of the government.

"I'm always rapping Carter. When he wanted that straw vote in Florida, he sent his wife four times, his mother, his son, and wasted gallons of fuel.I was very outspoken in all my interviews," says Coppola. "I am more bitter than hell against the government. I can accept what's happened to me, my family can't, but the only thing I can't accept is the way they are screwing me."

This past August, Coppola went back to Nagasaki, his fare for the anniversary commemoration paid by a committee of veterans. He saw an ultra-modern city. He distributed flowers to cancer patients who had been hospitalized for years.

"And they gave me a piece of the atomic bomb, a shell fragment. And a reporter asked me what I was going to do with it. And I said, if the government wants to examine it they can give me $750,000. If the Smithsonian wants it, a million. But they've got to give me something."