Two former workers at the atomic power plant here who said they damaged nuclear fuel assemblies as an act of conscience were convicted tonight of committing a crime but received the minimum sentence.

After three hours of deliberations, a state court jury found the two men guilty of intentionally damaging a power plant and recommended they be sentenced to two years in the state penitentiary.

The jury could have given each man as much as 10 years in prison for the felony crime of deliberately damaging nuclear fuel rod assemblies at the plant -- a deed power industry spokesmen have called the first known act of sabotage at any nuclear plant in the nation. Officials of the Virginia Electric and Power Co., operators of the plant, estimated damage was at least $810,000.

Circuit Judge Ligon L. Jones immediately imposed the sentence on William E. Kuykendall and James A. Merrill Jr., who worked at Vepco's Surry nuclear plant, located 130 miles south of Washington on an elbow curve in the James River.

The defendants, clinging to their wives on the courthouse steps after the verdict, said they felt they had won a moral victory in their fight against allegedly unsafe conditions at the plant but were disappointed in the outcome.

Merrill, the younger of the two men, said if he had to do it over again, he would not have followed the same course. Kuykendall added: "I don't know whether it's been worth it."

The judge allowed the two men to remain free on $5,000 bond pending a post-sentence report and hearing on Nov. 27, at which time he has the option to reduce the sentence.

Prosecutor Gammiel G. Poindexter said she was satisfied with the verdict and that she believed the jury had been fair in fixing the minimum sentence.

Defense Attorney Richard Ben-Veniste of Washington said the defendants plan to appeal the case. "There were several rulings restricting the evidence which we differed with," said Ben-Veniste, a former Watergate prosecutor.

The jury foreman, John Edmonds, said jurors heeded the judge's instruction that they were only to consider actual evidence in reaching their verdict. But he said the jurors felt enough smypathy for the defendants to impose the minimum sentence.

About 45 minutes before the jury returned its verdict tonight, the jurors sent a note to Jones reporting that they were deadlocked, although it was not made clear whether their indecision was over a verdict or a sentence. The judge instructed them to continue deliberating.

One juror was removed from the panel this morning by the judge, who stated this evening that the juror received a bomb threat at her home last night. It was unclear whether the threat was connected to the case.

Earlier in the day, defense attorneys in their final arguments hammered at their main contention: the defendants acted to alert the community to unsafe plant conditions that Vepco's management ignored.

"They were afraid, based on what they say, that an accident worse than Three Mile Island would occur," said Ben-Veniste, attorney for Kuykendall.

"He was gagged," said Maurice Nessen of his client Merrill. "He couldn't get Vepco to listen."

But prosecutors Poindexter and H. Woodrow Crook Jr. told the jurors the only issue was whether the defendants -- as they themselves admitted -- damaged the fuel rod assemblies. Both said the defendants were guilty of a breach of trust and Poindexter asked the jurors to consider returning the maximum sentence of 10 years.

"It is not open season in Surry County on nuclear power plants," said Crook. "Do you do a million dollars worth of damage to your employer to get his attention?"

As for the defense attorneys' pleas that their clients had suffered enough and should be allowed to go free, Crook responded: "If persons can do a million dollars worth of damage . . . (and) go home . . . then what deterent is there to breaking the law?"

Today's events climaxed a case that began on April 27 when Kuykendall and Merrill poured five gallons of caustic soda on 62 spare fuel rod assemblies in storage in the plant's fuel building.

Kuykendall, 26, a veteran of the Navy's nuclear reactor program, testified that he targeted the spare assemblies, each worth $500,000, because they were not crucial to the plant's safe operation and because damaging them would not cause a health hazard. He noted repeatedly that a saboteur could just as easily have lifted a highly radioactive spent fuel rod assembly from a storage pool in the same building and contaminated the plant with deadly radioactive material.

Vepco discovered the damage in early May and the FBI started an investigation.But the case was not resolved until more than a month later when the two men said in a newspaper interview that they had done the damage to protest safety and health problems at the plant.

The two men contended that the plant management deliberately falsified federally required records, that operators were not adequately trained and that makeshift methods were used to cheat on safety tests of the equipment. Kuykendall also asserted he was exposed to far more radiation in less than four months at the plant than he received during 16 months of operating a Navy reactor.

The jury heard none of that. The judge said before the trial that he would not allow defense attorneys to place Vepco on trial instead of their clients and he barred them from bringing specific plant problems into evidence.

Almost every time that either defendant raised the subject of plant safety during their testimony yesterday, the judge cut them off -- sometimes not even waiting for prosecutors to object.

The judge also ruled out a defense of "moral necessity" that the defense attorneys had hoped to argue. But he did allow Kuykendall and Merrill to tell the jurors they had damaged the fuel rods only after months of futile efforts to get their superiors to respond to their complaints.

The ultimate impact of the case on the troubled plant, which has been shut down since early this year for a variety of repairs, is uncertain. The Nuclear Regulatory Commission, which over the years has fined Vepco more than any other utility, has said it will investigate the two defendants' charges.

The cases impact on this predominantly black, rural county of 6,100 is also uncertain. Residents have welcomed the millions of dollars in tax revenues the plant has produced but recently some have begun to question its safety.

"Maybe, just maybe," defense attorney Nessen told the jurors today, "it [the case] will have rubbed off on Vepco and you will be living in a safer community."