Greenpeace published the report amid heightened concern over safety on Navy vessels because of the explosion in April on the battleship Iowa that killed 47 sailors.

The report acknowledged that disaster and death at sea ''are a fact of life,'' even in peacetime. But William M. Arkin, a military analyst for the Institute for Policy Studies who was a co-author of the report, said the number of accidents involving ships carrying nuclear weapons indicated that it was not safe to continue to keep such weapons on ships. Navy 'Extremely Proud'

In a statement, the Navy said, ''There is no aspect of Navy operations that gets more emphasis, more attention, than the safety, training, operational procedures and material condition surrounding Navy nuclear weapons and reactors,'' adding, ''We are extremely proud of our track record in this area.''

The majority of the accidents detailed in the report, 799, involved American vessels. The study's authors said the report did not reflect ''many hundreds'' of accidents involving Soviet vessels about which little is known, and they suggested that the accident record of the Soviet Navy is far worse than that of the United States Navy. Soviet Accident Is Worst

The report said the worst accident involving nuclear weapons at sea occured Oct. 6, 1986, when a Soviet submarine sank 600 miles northeast of Bermuda, leaving two nuclear reactors and 32 nuclear warheads on the ocean floor.

Most recently, a Soviet submarine powered by two nuclear reactors and carrying two nuclear torpedos sank in the Norwegian Sea on April 7.

The United States lost the nuclear-powered submarine Thresher 100 miles east of Cape Cod in 1963, and the submarine Scorpion sank in 1968 in more than 10,000 feet of water 400 miles southwest of the Azores. The Scorpion carried one nuclear reactor and two nuclear torpedoes.