The pipe bomb planted by the woman terrorist exploded within the Calvert Cliffs nuclear plant this week and, just as the fictitious scenario called for, residents within 10 miles of the plant were evacauated and a state of emergency was declared.

The incident was imaginary, but the response to the first full scale emergency exercise held at Calvert Cliffs was not. For 15 hours this week, dozens of government and utility company workers raced against the clock and hypothetical plumes of radioactivity to return the plant to normal. They dispatched orders, helicopters and ambulances that would have evacuated citizens and provided shelter, food and medical help during any serious release of radioactivity at the plant.

The drill, which federal officials judged to be "adequate," reflects the increased consciousness of safety issues at the six-year-old plant, the closest nuclear facility to Washington. Because of new federal regulations and a heightened awareness of accidents at nuclear plants, more time and money is being spent on safety plans at Calvert Cliffs.

Federal regulators consider the plant "clean," but a survey of federal inspection files indicate that the plant has experienced a number of equipment breakdowns and human errors in the last two years.

Although initial worries that the plant's output of warm water would harm life in the Chesapeake Bay have proved groundless, minor accidents have plagued the plant.

In April, a safety valve monitor malfunctioned and was not fixed within 30 days as required. Plant officials also failed to report the incident to the Nuclear Regulatory Commission within one hour as federal rules state.

Other incidents were more serious.

In May 1980, employes accidently disconnected the reactor's back-up cooling system. In February, June, August and October, 1980, small amounts of radioactivity escaped during leaks of short duration. Two leaks were reported in 1975, including one with radioactivity 3 to 10 times greater than normal.

The incidents, coupled with stricter regulation by the Nuclear Regulatory Commission, have prompted state and county officials to devote new energies to planning for nuclear disaster.

"No one took this seriously a few years ago," said Charles C. Meagher Jr., director of 21-member Emergency Management Council, established by Gov. Harry Hughes in July.

"We have made a quantum leap in safety at Calvert Cliffs," he said, surveying the "emergency command center" at state civil defense headquarters at Pikesville on Tuesday, the day of the emergency alert. "People are going about their business confidently because of all the extra planning. There's no mad dashing about" like the 30-minute drill conducted in 1980.

In that exercise, jumbled communication caused police to report to locked plant gates and officials couldn't agree which way the wind was blowing or what measure to use to determine how much hypothetical radiation was leaking.

"It was a disaster within a disaster," said Meagher.

Still, Tuesday's exercise was far from flawless.

Five emergency sirens failed to sound, forcing police to mount loudspeakers on cruisers to warn certain communities of the evacuation.

Within the plant, an employe monitoring radioactivity at the leak site used the wrong equipment and would have absorbed an excess dose, said Arthur Lundvall, a vice president for Baltimore Gas & Electric, which operates the plant. "There were a myriad of minor glitches," Lundvall said of the exercise, blaming them on "inadequate training" and "breakdowns in communication."

Overall, the drill was a successful result of the "several million dollars" Lundvall said the utility has spent on safety procedures in the years since Three Mile Island nuclear incident in Pennsylvania.

William Kinney, an observer from the Nuclear Regulatory Commission, which now requires the nation's 96 nuclear plants to complete a full-scale exercise yearly, agreed the Maryland alert was "a significant improvement over last year."

But his tone was cautionary. The plant's safety procedures are "adequate now, but they should get better," Kinney said, noting that state health officials need to become more proficient with their computers in order to better predict doses of radioactivity and more accurately judge the direction of its air-borne plumes.

Other specific deficiencies were raised by Thomas Hardy, head of the Federal Emergency Management Agency's office that assists local nuclear plants with emergency drills.

Dorchester County, for example, didn't have enough people trained to measure radiation to back up its existing health officials. Samples of milk and agricultural products sent to the state labs for testing weren't ranked in order of importance, so technicians simply tested "whatever they put their hands on first," said Hardy.

Also, local officials need more training in how to "decontaminate" evacuees, he added. And St. Mary's and Calvert County officials need to plan ahead on how to handle mass health care, "instead of waiting to receive word that it's needed."

However, the state director of civil defense and emergency preparedness, Joseph Langer, said the length and complexity of the drill showed that government could successfully handle a nuclear incident. "I was pleased with the exercise."