The FBI is investigating what the Virginia Electric and Power Co. said yesterday was probably an attempt to sabotage $30 million worth of atomic fuel supplies at one of its nuclear generating plants.

Vepco inspectors discovered Monday that a corrosive white crystalline substance had been dumped into 62 of 64 fresh, unradiated nuclear fuel elements being stored in a building near its Surry reactor in southeast Virginia.

The fuel was intended for the utility firm's Surry No. 2 unit and represented about one-third of the total fuel needed to operate the unit for a year, utility officials said.

Calling the incident "suspected willful damage," Vepco spokesman August Wallmeyer said the FBI's Richmond office has begun investigating persons who have had recent access to the plant's fuel storage area.

"Obviously, this leads to a whole raft of problems," Wallmeyer said, noting that chief among them is concern about plant security.

At a news conference in Richmond yesterday, Vepco Vice President C. M. Stallings said pollution of the fuel elements had "no effect on the health and safety of the general public or Vepco employes."

Three laboratories analyzing the contaminating substance have not yet identified it, but Wallmeyer said preliminary findings show it did not damage the fuel. The uranium fuel pellets are contained in zirconium metal tubes, and the substance did not permanently damage the tubes or other fuel storage equipment, he said.

Stallings said the substance was dumped into storage units through manhole-like openings in the floor of the fuel storage building.

The fuel, according to Vepco, began arriving at Surry in February and was in normal condition then. On April 18, two of the 64 fuel units were inspected and fould to be normal.

Stallings said Vepco has no way of knowing whether all the fuel units were uncontaminated on that date, but he said he thinks the caustic substance-between a couple of cups to a gallon in each unit-was dumped in "over a period of time."

Security is heavy at the Surry plant, located across from Jamestown on the James River about 140 miles from Washington, Vepco officials said. Entrance to the storage area was restricted to persons who had special "card keys" to open the doors.

Stallings noted, however, that the fuel storage building usually is unoccupied when no fuel is being taken in or out, so it would have been possible for someone to move about the fuel elements unobserved.

"Whoever got in there knew what he was doing," Stallings said.

Wallmeyer said Vepco and the FBI impounded records of entry to the fuel storage area and will be going over them to see which Vepco employes and construction contract workers had access to the site.

About 200 to 250 Vepco employes work at the Surry plant, whose two nuclear units are shut down pending the repair of steam generators at Surry No. 1 and inspection of equipment for safety at Surry No. 2.

Vepco has notified the Nuclear Regulatory Commission about the incident, and a regional spokesman for the agency said yesterday that the investigation of "what appears to be a criminal act" would be left to the FBI.