March 5, 1986

The death of a worker at a Kerr-McGee nuclear fuel plant in Oklahoma stemmed from a safety violation that occurred often, rather than rarely or never, as the company had maintained, Federal officials said yesterday. The Jan. 4 chemical accident occurred when a worker heated an overfilled cylinder of uranium hexafluoride, in direct violation of plant procedures. The cask ruptured and the chemical escaped, sending 100 people to the hospital and killing the worker. At the time, company officials told the public and Federal regulators that they did not recall another instance of an overfilled cask's being heated at Kerr-McGee's Sequoyah Fuels Corporation plant in Gore, Okla. #20 Similar Incidents Cited But interviews and a review of documents since then by investigators from the Nuclear Regulatory Commission have suggested that workers there heated cylinders to expand and remove excess material 20 times in 1985, 20 percent of the occasions on which a cask was filled.

Opposition from Westchester and Long Island school officials is delaying Governor Cuomo's efforts to create showcase regional high schools in the arts, science and mathematics around the state. When the Governor proposed the special schools over a year ago as a way to create new challenges for a region's brightest students, state officials said they could open in the fall of 1987. But now, Mr. Cuomo's aides say, the Governor has said he would not create a school without local support and would not seek operating funds for any of the schools - even those with support - before 1988. He still backs the proposal, called ''high schools of excellence,'' and is asking the Legislature for $750,000 to continue planning for the schools around the state.

A fleet of 40,000 cabin cruisers, sailboats, motor launches, ferryboats and yachts - not to mention 100 tall ships - is expected to sail into New York Harbor over the July 4th weekend for the Statue of Liberty centennial. And the Coast Guard is planning a major naval exercise to handle this extraordinary waterborne audience. If the fleet is as large as expected, it will comprise more than twice the 15,000 boats that attended the Bicentennial celebration in 1976. ''Forty thousand boats in this harbor?'' Capt. James L. McDonald, chief of the Operations Division of the Third Coast Guard District said with a grin. ''This harbor can absorb that kind of numbers easily.''

ON appointed mornings, fair weather or foul, a cluster of women can be seen standing on a point of rocks here, scanning Long Island Sound with binoculars. ''When you see that little speck in the ocean, everyone starts shouting and letting loose balloons,'' said Sherry Determan, who has stood several of these vigils. While widow's walks may be out of fashion on houses here, the same age-old loneliness still grips women who see their husbands off to sea. After the submariners from the Naval Submarine Base New London here in Groton have disappeared below the waves, the women are left behind to cope alone with broken washing machines, uncommemorated wedding anniversaries and, often, the births of babies. In Nautilus Park, a Navy housing development here, Mrs. Determan shared a moment on her living room sofa with her husband, Gregory, 24 hours before he was to leave port with the fast-attack submarine Dallas. ''I love him, I hate for him to go away but I have to cope,'' Mrs. Determan said. ''When I know he's coming back, I get giggly - clean the house, fix the dinner, perfume the sheets.'' Family separation has been a fact of life for sailors and their wives for centuries, but increasingly in the military, the long months alone take their toll. In an era of voluntary military service, family separation is routinely cited in surveys as the primary cause for leaving the Navy, Navy officials say.

The Government's index of economic predictors registered an unexpected decline in January after six straight monthly advances, the Commerce Department reported today. The drop of six-tenths of 1 percent in the index of leading indicators drew various interpretations, but Administration and private analysts generally agreed that it was unlikely to presage a recession. ''An occasional setback in the index is not unusual during expansion periods,'' Commerce Secretary Malcolm Baldrige said. He noted that the index had still climbed at a 5.7 percent annual rate over the last six months, more than twice as fast as in the preceding six months. ''This pick-up points toward healthy economic growth during the near term,'' he added.

THEIR legends are legion and not entirely to be believed: Oysters should be eaten only in months that have R's; they are aphrodisiacs; a surfeit of them is a sure cause of gout. Their history is prodigious, if a bit more credible: The ancient Romans gorged themselves on British oysters brought over the Alps in barrels of ice, and the earliest Americans left great kitchen middens of oyster shells on the shores, to the delight of modern archeologists. Legend and history aside, one fact is incontrovertible: Oysters are delicious, especially on the half shell - so fresh, old-time oystermen say, that they wince when touched with a drop of lemon juice. Although oysters, at least on this side of the Atlantic, may be eaten year round, the time to enjoy them is now, during the cold weeks of winter when they are at their peak -plump, sweet and fragrantly fresh. The oyster most commonly available in the Northeast is the native East Coast oyster, or Crassostrea virginica. Whether called Cotuits (from Massachusetts), bluepoints (from Long Island), Chincoteagues (from Virginia), Apalachicolas (from Florida) or any of a dozen other names, it is the same C. virginica.

An unmanned Soviet spacecraft today sent back data from its first close glimpse of Halley's comet to international observers, both scientists and machines, assembled at the Institute for Space Research. The spacecraft, Vega 1, was nearly nine million miles from the comet's nucleus when the sensors went on this morning, so the initial data were sparse. But the ship, streaking at 47 miles a second, was set to carry out what would be man's first encounter with the solar system's best-known comet. That meeting is to take place Thursday at 10:15 A.M. (2:15 A.M., Eastern standard time) as Vega 1, one of two Soviet spacecraft aimed at the comet, passes 5,600 miles in front of the comet's icy nucleus. The European space agency's Giotto spacecraft and two Japanese craft are to rendezvous with the comet in the next seven days.

Before AIDS education began at Murry Bergtraum High School in Manhattan, misconceptions and wild fears about the disease abounded. ''Kids were scared they could get it from a mosquito,'' said Colette Richardson, who is 16 years old and vice president of the school's student organization. ''They thought they could get it from crying, or from sweat.'' ''AIDS was the mystery disease,'' said Elaine Moy, a senior at the school, which is on the Lower East Side, at 411 Pearl Street.

''He should practice the magic of Manila on Managua.'' - Speaker Thomas P. O'Neill Jr., on President Reagan's Nicaragua policy. [ A4:3. ]

The Adelettes from H. B. Thompson Junior High School in Syosset, L.I., wore pleated shirts and snappy red bow ties and crooned ''Basin Street Blues'' under the banner of the New York State School Music Association. Nearby, in the concourse of the Legislative Office Building, five middle-aged women in slacks and bulky sweaters, members of the Nassau County chapter of the Displaced Homemakers, consulted mimeographed schedules of meetings with assemblymen and senators, or more likely their aides. One floor up, at a lobbying program presented by the Arts Council of the Empire State, the Rod Rodgers Dance Company from the East Village in Manhattan offered an excerpt from ''Rhythm Ritual,'' and Kelly Conroy, an upstate fourth-grader in a special creative-writing program, told an audience that ''when I write I feel like I fell off the world and onto a star.'' From college students to milk wholesalers, countless special-interest groups descended on the State Capitol today, as they do on Tuesdays throughout the Legislative session.

SOLITARY diners traditionally have had a rough time of it. Waiters tend to ignore them for the meager tips they bring, restaurateurs resent them for tying up tables and the other customers always seem to be staring at them. Even these slights might be tolerated if the dining rooms were quiet enough and bright enough for reading - but generally they are not. All that is changing. Options for those dining alone in New York have expanded in the past year as restaurants have started catering to their needs with specially designed counters and bars, some featuring special menus. Communal tables and strategically placed banquettes are appearing, where solo diners can have a sense of privacy or camaraderie, as desired. The restaurateurs who indulge solitary patrons in this fashion are not always motivated by sympathy for their plight. Rather, it is good business in the ever more competitive restaurant scene. While no reliable statistics exist, interviews with restaurant owners, maitres d'hotel and industry observers suggest that more people are dining alone today than ever, whether by necessity or choice.

For all its promise, the machine vision industry is shaping up as a classic example of a dazzling new high-tech business that, in its infant stages, has attracted far more players than it could support. Annual sales of machine vision systems - camera-computer linkups that can dramatically improve productivity and quality on assembly lines - are expected to pass $1 billion by the end of the decade. But the crowded industry, beset with marketing and development problems, is already heading for a shakeout, analysts say. One big company that has had a strong interest in machine vision, the General Electric Company, has reportedly cut back its efforts to market the systems, which help perform inspection, assembly and maintenance functions. And most suppliers of the equipment are struggling to survive.