Attorneys for the Karen Silkwood estate rested their case today in a possibly precedent-setting trial in which a federal jury is being asked to find a nuclear firm liable for off-site radiation contamination.

The trial focuses on charges that Kerr-McGee Corp. Negligently allowed toxic plutonium to escape its nuclear facility and contaminate Silkwood and her apartment in 1974.

But it has mushroomed into an explosive debate over the safety of the nuclear industry and the credibility of federal regulatory agencies.

The trial's significance was underscored this week as the presiding judge admonished the jury to ignore the barrage of news accounts of the nuclear accident at the Three Mile Island plant in eastern Pennsylvania.

Silkwood, 24, worked at the Kerr-McGee plutonium processing facility near Crescent, Okla. She died in a car accident Nov. 13, 1974, reportedly while carrying evidence of faulty fuel rods manufactured at the plant. The evidence never surfaced.

Silkwood's supporters maintain she was a victim of corporate vengeance becasue of her sleuthing for the Oil, Chemical and Atomic Workers Union. Kerr-McGee contends that Silkwood found nothing amiss.

Kerr-McGee processed plutonium pellets into fuel rods for use in an experimental breeder reactor program sponsored by the now-defunct Atomic Energy Commission.

Silkwood attorneys have attempted to show a pattern of negligence to back their claim for $11.5 million in damages against Kerr-McGee by presenting testimony that the firm placed production schedules ahead of worker safety.

Nuclear scientists have condemned the Oklahoma facility as being run in a "reckless manner" from its opening in 1970 until its closing in 1975. Dr. John Gorman, who was instrumental in developing the atomic bomb, said, "Such a plant should have never been allowed to open or been allowed to operate for one single day."

Gofman claimed the AEC, predecessor to the Nuclear Regulatory Commission, was "irresponsible" in licensing Kerr-McGee's plant. He particularly criticized plant officials for not clarifying to workers that they ran a risk of cancer from their employment.

Estate attorneys want the jury to find that Silkwood contracted cancer from her exposure to low-level radiation, and suffered severe emotional trauma in knowing she would die from it. They argue that Kerr-McGee is responsible no matter how the plutonium got into her apartment.

Dr. Edward Martell, an environmental radiochemist, testified that federally set radiation exposure limits are "misleading and inadequate" and have not been reduced because of the goverment's "vested interest" in nuclear power.

Kerr-McGee claims that since it followed regulatory guidelines, it cannot be held negligent. One question before the jury is whether nuclear power is so hazardous that it is more a danger than a benefit to the public.

Former plant workers testified that safety training was so deficient, youthful employes raced to see who could get the "hottest." They said plutonium spiils were painted over, workers left the plant contaminated and plant supervisors were warned ahead of AEC inspections.

One former production supervisor testified that if someone wanted to steal plutonium from the plant "about all you had to do was to throw it over the fence."

Kerr-McGee was cited by the AEC for three minor license violations, although Silkwood's union lodged almost 40 allegations against the firm.

Silkwood reported to work contaminated on three successive days during one week in November 1974. Her contamination was traced to her apartment, where radioactivity was discovered in various rooms and on refrigerated food. Kerr-McGee argues that Silkwood caused her own contamination through negligence.

Kerr-McGee attorneys, who find themselves defending the entire nuclear industry, claim the case has been blown out of proportion. Thye plan to present evidence to combat the attack on the manner in which the nuclear facility operated. CAPTION: Picture, Merle and Bill Silkwood and their daughters, Linda, right center, and Rosemary Porter, left center, the family of Karen Silkwood, stand outside the courtroom after testifying in a $11.5 million nuclear contamination damage suit. AP