ON Oct. 6, 1986, a fire erupted in the bowels of a Soviet nuclear-powered submarine stationed in international waters off Bermuda, armed with 32 atomic warheads.
Three of the estimated 120 sailors aboard perished. The rest were rescued before the Yankee-class submarine plummeted to the bottom of the Atlantic Ocean with its nuclear arsenal and two uranium-fueled reactors.
The disaster is among only a handful of nuclear submarine accidents that have gained public attention. But such mishaps may be more common and potentially more dangerous than most people surmise, and in the wake of the cold war there's growing global interest in guarding against the lost nuclear dangers that may lie under the seas.
Last month, the European Parliament passed a resolution urging major naval powers to make a full accounting to the UN of all nuclear weapons and reactors lost on the bottom of the ocean. US congressional panels recently opened hearings on the question. And a new report by a Washington-based antinuclear group represents one of the first comprehensive attempts to catalogue undersea accidents involving some of the most lethal weapons of the world's military powers.
The study by the Center for Technology Assessment (CTA) found that between 1969 and 1989, there were at least 1,445 mishaps of varying severities involving US nuclear submarines. The group is still collecting data on the nuclear-sub operations of other nations. It expects the number of Soviet/Russian accidents to exceed those of the United States.
In addition, 19 Soviet and US reactors from damaged vessels were dumped or lost in mishaps at sea. In the same period, at least 43 Soviet and seven US nuclear weapons - missile warheads, torpedoes, and bombs - were lost at sea. The Soviet weapons were on five submarines that sank in accidents. A total of four nuclear torpedoes were believed to have been aboard the USS Thresher, which sank in 1964, and the USS Scorpion, which was lost in 1968. The rest were lost in non-submarine mishaps.
The weapons cannot explode. But what concerns many officials, environmentalists, and others are the radioactive poisons the sunken bombs and reactors may be leaking and the potential for future accidents that could create new contamination sources. Concludes the report: ''Global nuclear submarine operations pose a grave danger to global environmental safety, health, and security.''
''There is currently no way to secure these weapons and reactors and make them a non-threat to the environment,'' asserts Kay van der Horst, CTA director of defense and security policy. Mr. van der Horst calls the study preliminary. A more in-depth version will provide greater details of the mishaps, such as correlating locations with major fishing grounds, he says.
The CTA report comes amid growing calls for an international effort to assess and halt the contamination of oceans by nuclear navies. While many experts say there is no firm evidence that existing contamination poses significant dangers, they worry the problem could worsen as countries, especially Russia, run out of space to store and dispose of accumulating radioactive stockpiles.
Citing the situation in Russia and the CTA study, the European Parliament on Nov. 16 passed its resolution urging major naval powers to tell the UN about their oceanic nuclear accidents. The largely advisory body also called on the European Commission to seek immediate international negotiations ''to halt the global danger emanating from lost nuclear weapons.''
In the US, concern over ocean nuclear contamination has been mounting since 1993, when Alexei Yablokov, a member of Russian President Boris Yeltsin's National Security Council, disclosed that the Russian Navy and its Soviet predecessor had been dumping radioactive wastes and reactors from decommissioned submarines in the Arctic waters of the Kara, Barents, and White Seas for several decades. The practice stopped in 1991.
CONTAMINATION has been restricted to the immediate areas of dumped materials, and there is yet no evidence of serious environmental damage. But experts say the situation remains critical: The Russian Navy will soon exhaust storage space for radioactive wastes from its sub force and existing facilities are in dangerous disrepair. ''The problem is not the wastes now in the oceans, but of materials that will be added,'' says Kaare Bryn, a Norwegian Foreign Ministry official.
The US and Norway are cooperating with Russia in trying to assess and curb Arctic contamination. The issue is expected to come up when the G-7 Group of industrialized democracies and Russia meet in April to discuss global nuclear safety and security. Meanwhile, two congressional subcommittees opened hearings last week on the question. Testifying before the panels, Dr. Yablokov warned: ''This is a problem for Arctic countries ... and maybe all countries that belong to the Northern Hemisphere.''
Though the contamination in the Arctic is the worst known, the US Navy has also dumped low-level nuclear wastes in US coastal waters. The Navy says monitoring has found no environmental hazards. But Rep. Kurt Weldon (R) of Pennsylvania, chairman of the House Military Research and Development Subcommittee, says there is a pressing need for an international effort to assess radioactive military contamination of the seas.
''While we have no appreciable evidence of damage, we don't have any scientific evidence that is genuine and would allow us to really appreciate the problem,'' says Mr. Weldon.
The Soviets discarded radioactive waste into Arctic waters, making them the world's most contaminated.