Supervisors at the atomic power plant here deliberately falsified or destroyed records documenting discharges of radioactive water into the James River, lawyers at a nuclear sabotage trial charged today.

Richard Ben-Veniste, attorney for one of two defendants accused of sabotaging fuel rods at the Virginia Electric and Power Company plant, also told jurors that plant management encouraged cheating on federally-required tests of safety equipment and refused to repair broken testing equipment.

Vepco spokesman August Wallmeyer, who attended the trail, said the company would not respond to the charges until the end of the trial, considered to be the first in the nation involving deliberate and extensive damage to a nuclear plant by employes.

Ben-Veniste's charges came during opening statements in the trial of former plant employes William E. Kuykendal, 26, and James A. Merril, jr., 24, both of whom are charged with destroying at least $800,000 worth of the fuel at the plant last April.

The two have admitted damaging the fuel but have contended they committed an act of conscience in order to draw attention to unsafe conditions at the plant.

Circuit Court Judge Ligon L. Jones had ruled yesterday that the defendants could not invoke "moral justification" as a defense against the charges.Nonetheless, both Ben-Veniste and fellow defence attorney Maurice Nessen argued today that their clients were compelled to commit acts that could result in up to 51 years each in jail.

The lawyers painted both defendants as propenents of nuclear power who took action only after realizing the Surry plant was hazardous. BenVensite said Kuykendall recieved more radiation in one day at Surry than in more than a year of service aboard a Navy nuclear aircraft carrier.

"In the Navy he learned the right way to operate a nuclear plant," said Ben-Veniste. "At Vepco he was shocked to see the difference."

"He came [to the Surry, plant] believing in nuclear power," said Nessen of Merrill. "He wasn't antinuke . . . he isn't today.

Neither defense attorney went into specifics today about safety problems, but in a statement released by the defendants alleged that:

The plant circumvented federal rules by mixing unsampled radioactive water from the plant with sampled water before dumping both into the James River. The result, the defendants allege, is that radioactive contamination of the water deliberately was understated.

The chart recording temperature of the water dumped was deliberately destroyed by plant personnell because it showed the water was hotter than allowed.

Radiation alarms and detectors used in the water discharge system were defective and continually broken because they were not properly repaired.

In order to get leaking safety valves to pass inspection, the company attempted makeshift measures among them: using beeswax as seals and long poles called "cheater bars" to jam the valves.

Prosecutor Gammiel G. Poindexter, presented a low key opening statement in which she outlined how the defendants entered the fuel building using Kuykendall's security card and poured five gallons of caustic soda on 62 nuclear fuel rod assemblies.

Ben-veniste, a Washington lawyer who was chief assistant Watergate prosecutor, and Nessen, a New York attorney, were more flamboyant.

At one point this afternoon the judge threateded Nessen with contempt of court after the attorney responded angrily to a prosecution charge that the defense was attempting to put Vepco on trial instead of their clients. The judge warned Nessen and the other attorneys to direct their comments to the bench and not to opposing lawyers.

Six prosecution witnesses, all of them Vepco employes, testified today on the design of the plant, location of the spare fuel rods and the damage done.

Under cross-examination, plant manager William L. Stewart conceded that employes at times circumvented security requirements by "doubling up" -- two or more employes using one access card to open a security door. Each worker is only supposed to enter areas to which his individual card gives access.

Plant Security Supervisor Henry J. Van Dyke testified that both defendants had access cards allowing them entry to any of the buildings at the plant.

The testimony appeared to bolster defense arguments against the charge that the defendants illegally broke into the fuel building, which is one of five charges against each man.