The hard news from the Crystal River nuclear plant is that yesterday's on-site emergency never turned into the nightmare that was Three Mile Island.

Not only did the uranium core of the 855,000-kilowatt plant escape damage and not only was there no radiation release beyond the plant, said James F. O'Reilly, director of a Nuclear Regulatory Commission task force dispatched to the scene, but the plant tonight "was in a normal state, like any plant in the country."

It could have been different. Said O'Reilly: "This was a serious accident." Said NRC Commissioner Joseph Hendrie in Washington: "The first 30 minutes of this accident were just as complex as the events at Three Mile Island. They [at Crystal River] were having the whole drill."

The drill began at 2:23 p.m. Tuesday, when a simple power failure shut down a big part of the plant's instrument panel, automatically signalling the turbines and nuclear reactor to shut themselves off. The next 24 minutes were as tense as Three Mile Island ever was. The Crystal River operators couldn't read their insturments. They were operating in the dark.

"They were left in a bad position, but they proceeded to do precisely what they should have done," Hendrie said.

In a sense, what the operators chose to do was to do nothing. They let the cooling water run into the reactor vessel so rapidly that it flooded out of the reactor vessel and into the reactor's concrete containment. By the time the operators had things under control, they had 43,000 gallons of water on the floor of the containment.

"The water spillage was inconvenient, but I think our focus on training of operators since Three Mile Island really paid off," said Victor Stello, director of inspection and enforcement for the NRC. "When something like this happens, you just open up the throttles on the pumps and keep the water moving."

The excess water flooded through relief valves, filled the quench tank, and burst a control disc. Radioactive from its contact with the core, the water gushed into the containment building around the reactor, and caused high readings there of 50 rem, 10 times the radiation dosage to make a person ill. For 24 minutes it flowed; then the auxiliary power supply came on and the operators regained the use of their instruments. Then they shut off the water.

Crystal River will not generate power for its owner, Florida Light and Power Co., for at least one week and possibly two, while the causes of the incident are assessed and the water in the basement removed, said William C. Johnson, a spokesman for the utility. After that, a decision will be made on whether to return the reactor to service or proceed immediately with a refueling that had been scheduled to begin March 28.

In Washington, meanwhile, the NRC's chairman told Congress the Crystal River mishap isn't likely to affect the commission's intention to shortly resume licensing of new plants.

NRC Chairman John F. Ahearne, testifying before a Senate Appropriations subcommittee on energy, said that "all indications we have are that there's no fuel failure." Asked if the mishap would change the commission's plan to lift the licensing moratorium imposed after the Three Mile Island incident, he replied: "As far as I can see now, it wouldn't have any effect."

Crystal River townspeople took the event in stride. Only a few fishermen, isolated families and real estate salesmen touting bargains from highway trailers live within a five-mile radius of the plant, which sits at the mouth of the Crystal River about seven miles northwest of town.

The spot is serene, with scrub pine and oranges to the south, a cattle ranch to the north. The only signs of the plant's presence are the huge, X-shaped power line support towers that march away from the coast in seried ranks toward the east.

"Everybody's making a lot of fuss over nothing," said Wilbur Jones, whose trailer is set back just some feet from busy Highway 19. "The radio said there was no radiation so I wasn't worried."

His sentiments were shared by tourists, several of whom said they saw no reason to cancel overnight stops here on their way further south.

"We've got these things in Illinois, too," said a Byron, Ill., woman, who did not want to be named. "We have got to have some kind of power."

On a normal day, Cyrstal River III supplies 20 percent of Florida Power's generation to 3.5 million customers in northwestern and central Florida. The accident coincides with the onset of a cold snap that brought 40-degree temperatures this morning. However, the utility was able to avoid any power shortage by purchasing 1,200 megawatts from neighboring utilities Johnson said. He added it was too early to tell what effect the shutdown will have on customer's bills.

No one knows why there was a sudden loss of power to the instrument panel and why a backup power source didn't come on.

Nevertheless, the NRC had only praise for the performance of the Crystal River operators.

Almost as soon as the accident began two direct telephone lines were opened up between the Crystal River control room and NRC headquarters in Bethesda, Md. to keep the outside world informed of what was happening.

"Were you satisfied with the arrangement?" an NRC commissioner asked Inspection and Enforcement Director Stello. "I was delighted," Stello answered. "The system worked."