A lawyer for residents who live near Pennsylvania's Three Mile Island nuclear power plant told the Supreme Court yesterday that restarting the plant, site of the nation's worst nuclear accident four years ago, would cause additional severe mental stress for this "traumatized population."

But a Justice Department attorney contended that the Nuclear Regulatory Commission need not conduct a separate inquiry into the "fears of recurring catastrophe" of local residents before deciding whether to relicense an undamaged reactor at the Pennsylvania plant.

"There are many government actions that create anxiety," argued Justice Department lawyer Paul Bator. "If the government raises taxes, people might go crazy with worry and fear. Stress caused by fear and anxiety that government actions may be harmful to you is not an environmental impact."

Bator urged the high court to overturn a 2-to-1 appellate court decision that the NRC must weigh claims by residents of the Middletown, Pa., area that they would suffer "severe psychological stress" if Metropolitan Edison Co. puts the TMI 1 reactor back into operation.

The reactor was shut down for refueling when the adjacent TMI 2 reactor was damaged in March, 1979. For a week, local residents lived with the fear of a meltdown. Although the TMI 1 reactor was not damaged, it has remained shut down while the NRC held relicensing hearings.

Despite the finding of the presidential commission that investigated the Three Mile Island accident that its "major health effect . . . appears to have been on the mental health of the people living in the region," the NRC excluded testimony on psychological stress from its hearings.

The U.S. Circuit Court of Appeals here in Washington ruled last year, however, that consideration of psychological stress is required under the National Environmental Policy Act of 1969.

William Jordan, the attorney for a group of Middletown residents, "People Against Nuclear Energy" (PANE), encountered skepticism yesterday as he tried to persuade the Supreme Court that severe mental stress is comparable under the environmental act to "the potential for cancer."

"Does the view of one psychiatrist about one, two or three patients control these things?" asked Chief Justice Warren E. Burger. "Your people don't want this plant at this site at all. Isn't that true?"

Jordan agreed that, "If you never restart TMI 1, further health damage would not occur." But he contended that there were a number of "mitigative actions," short of keeping the reactor closed, that the NRC could take.

"And isn't there any significance to the fact that there was an accident there?" asked Justice Thurgood Marshall.

"That is crucial," Jordan agreed.

"Tell us how many people were killed and injured in that accident," Burger interjected.

Jordan noted that no fatalities or physical injuries have been attributed to the accident, but cited the presidential commission's finding that the accident has had a significant impact on the mental health of people in the area.