It was a sleepy, snowy morning in this suburban community when a nuclear emergency was "announced" at the $4.5 billion Shoreham power plant -- and it remained a sleepy, snowy morning.

Officials of the Long Island Lighting Co. (Lilco) hoped their emergency evacuation drill would prove that the controversial 809-megawatt plant was safe to operate.

But none of the utility's 89 sirens sounded this morning, although that is normal procedure for evacuation drills.

No radio broadcasts were tested. No police officers showed up to direct panicked citizens at major intersections. No state health workers appeared to measure radiation.

And the reaction of the 138,000 citizens living in the 10-mile radius around the plant was summed up by Liz Jenkins, 20, a hairdresser at the La Combe Unisex salon, two miles away. "I haven't heard anything about a drill," she shrugged. "But everybody knows that if they had an accident, there's no way we'd get off this island."

Today, for the first time in the history of the nuclear power program, a utility, with the cooperation of the federal government, tested -- or tried to test -- an evacuation plan, despite the vehement refusal of state and local governments to cooperate.

The result was "Alice in Wonderland," said Fabian Palomino, a top aide to Gov. Mario M. Cuomo (D), who observed the make-believe drill. "In every respect this departs from reality."

Sen. Daniel Patrick Moynihan (D-N.Y.), in a letter to President Reagan Wednesday, called the drill "a peculiar exercise . . . forced on the people of Long Island in an apparent attempt to open the plant at all costs."

The plant -- 55 miles from Manhattan -- was completed two years ago, 10 years past schedule and at 10 times its projected cost, but its federal license has been held up by the refusal of Suffolk County and the state to participate in an evacuation plan.

County and state officials say a safe evacuation would be impossible partly because the densely populated Long Island community is surrounded on three sides by water.

The drill was conducted with utility workers and Federal Emergency Management Agency employes pretending to substitute for state coordinators, police officers, bus drivers and other boycotting personnel.

"It would have been a more meaningful exercise if we had had the cooperation of state and local officials," said Lilco Vice President Ira L. Freilicher. But he added, "In the event of a real emergency, we know we would have their cooperation. State law requires it."

Last week the Suffolk legislature, in an effort to block the drill, passed a law making it a crime to simulate the role of a county employe. A federal judge blocked enforcement of the law, but county officials said they may appeal.

Because of the threat, utility workers did not perform the functions they were drilling for.

Those who were to direct traffic, for example, merely drove to intersections and parked. FEMA employes were dispatched to verify whether the traffic directors would know where to send traffic.

In a basement room of a Holiday Inn at Ronkonkema, a half-hour drive from the plant, an eerie scene was played out in the pretend news center. At half-hour intervals, a utility official announced in somber tones an ever worsening scenario of breakdowns, leaks and radioactive emissions at the plant.

Another utility official, speaking for the "Local Emergency Response Organization" (LERO) -- a euphemism for the missing state and county officials -- announced evacuation of the 10-mile zone around the plant.

Over the 11-hour emergency period, everything went smoothly, according to LERO. During the simulation traffic was detoured around an overturned truck; radios were used for a 15-minute period when phone service broke down; 95,000people were tested for radiation effects at the Nassau Coliseum with no delays.

"People do behave rationally," LERO spokeswoman Elaine Robinson told skeptical reporters. John Leonard Jr., a Lilco vice president, said evacuees did not panic; the atmosphere was as calm as during the bombing of London during World War II. He noted the "playing of the band" during the sinking of the Titanic.

Palomino said that lack of state and county participation meant that the plan could never work, even if police and other officials ended up trying to help during an accident.

For example, he said, 16 of the 17 schools in the evacuation zone refused to cooperate, so the utility lacked information on where children were to be sent.

Freilicher said schools' plans for sending children home during snowstorms could be used.

Palomino said phone circuits were tied up during last year's Hurricane Gloria for four hours -- an indication that another disaster would also block communications. Freilicher denied the circuits were blocked.

Lilco would evacuate only a 10-mile zone, although the utility's surveys show that more than a million people would try to jump in cars and drive west to New York in the event of an accident, Palomino said.

Lilco has said it would block roads to prevent residents of the eastern end of the island from moving west.

FEMA will report in six weeks to the Nuclear Regulatory Commission on how Lilco officials managed the drill, but they would not make a finding as to whether people could be safely evacuated.

It will be up to the NRC to decide whether to approve the evacuation plan. If it does, Palomino said the state and county will file suit. A state panel headed by John C. Sawhill, a former Energy Department deputy secretary and former federal energy administrator, is examining whether the state should take over Shoreham by eminent domain.

About 50 protesters gathered around a Lilco operations center, some dressed in colonial garb to draw an analogy of local citizens fighting federal interference. "This plant is like an atom bomb waiting to go off," said Carol Collins, 49, a housewife who pointed toward passing cars on the highway with a sign reading, "Are You Aware You Are Being Evacuated?" CAPTION: Picture, The $4.5 billion Shoreham nuclear power plant on Long Island: State and local officials sat out "peculiar exercise" aimed at proving facility is safe to operate. AP