Federal Energy Administration chief John O'Leary yesterday dismissed categorically any implication that he or the Nuclear Regulatory Commission were involved in concealing the existence of a geological fault under a Virginia nuclear reactor site in 1973.

Five consumer groups have asked that O'Leary's nomination to be deputy director of the new Department of Energy be held up until his role in a three-month delay in the public disclosure of the fault can be clarified.

In a telephone interview, O'Leary said "categorically there was not" any concealment of the fault by the commission, which at that time was called the Atomic Energy Commission, O'Leary was director of nuclear reactor regulation at the AEC in May 1973, when the fault was discovered beneath the nuclear power plant being built by the Virginia Electric and Power Co. on the North Anna River.

Opponents of the North Anna plant have said Vepco and the AEC should have called immediately for reopened public hearings on the safety of the plant when they learned of the fault, since fault lines are common sites of earthquakes. Vepco discovered the fault on April 24, 1973, confirmed it May 14, and notified the AEC on May 17. which then notified the Atomic Safety and Licensing Board, the AEC's independent licensing arm, on Aug. 3.

O'Leary said an AEC inspection of the site on June 18 determined that the fault was not active "and there was no threat to public health and safety" because of the delay.

"In hindsight we (the AEC) should have adopted earlier the procedure we ultimately adopted - immediate notification of the licensing board whenever one of these things (reports of trouble) came in . But was there concealment? Categorically there was not," he said. A report of the inspection trip was placed in the public document room on June 26, 1973, "and from the point forward the public was at least technically on notice," he said.

O'Leary also rejected the contention of a May 11, 1977, Justice Department memorandum that the NRC role in the matter made it impossible for Justice to prosecute Vepco for concealment of the fault. "That's a nonsequitur," he said.

Once Vepco officials notified the NRC as they were supposed to do, all possibility of any charges against Vepco ended, he said. That means, O'Leary continued, that there is no substance to any allegation he "somehow presided over a dilatory regime or poisoned the Justice Department's ability to prosecute."

O'Leary defended the overall performance of the NRC and its staff as "superb . . . a monument to conservatism" in assuring safe and efficient nuclear power plants.

"The unfortunate thing is that the intervenor (public participation) process has gone to the point where we may well have seen the end of nuclear energy as a live option in this country," he said. He noted that plans for 40 to 50 plants have been canceled in the last two years. "I wish as much as anyone else that we had solar energy at hand, but we don't. I consider it a responsibility of myself and my staff to drive solar energy as fast as it can be driven," he said.

In a related development, the Justice Department confirmed that most of its files on its entire North Anna probe will be made available at the department to interested members of the NRC and the House subcommittee on energy and power.