The presidential commission investigating the Three Mile Island accident will recommend that President Carter reorganize the Nuclear Regulatory Commission to strength its powers over nuclear safety, it was learned yesterday.

The 12-member commission will recommend that the five-member NRC be reduced either to a single commissioner or a three-member group headed by a chairman with power to overrule the other two members. The presidential panel will also recommend that the NRC relinquish all authority not directly related to safety.

"That means things like control over nuclear exports and the regulation of weapons-grade uranium," one source close to the presidential commission said. "Whatever can be taken away from the NRC that doesn't have to do with safety we would like to take away."

The presidential panel, known as the Kenneny Commission after chairman John G. Kemeny, will also recommend a major change in locating nuclear power plants, the source said. Instead of plants being built as close as 10 miles to small cities, the Kemeny Commission wil urge that nuclear plants be built at least 20 miles from cities above a certain size. The figure will be set later.

The Three Mile Island accident March 2, at middletown, pa., threatened to force evaculation of Harrisburg, population 65,000 and 10 miles from Three Mile Island.

Source said the Kenney Commission will not recommend a moratorium on construction of nuclear power plants an option considered by the House and Senate sub-committees investigating Three Mile Island.

"This will be an issue that will be confronted in the next two weeks by the commissions," one source said, "but there is a general feeling on the commission against shutting the industry down."

President Carter has ordered recommendations by Oct. 25, but commission sources say that deadline cannot be met. One source said some commission members wanted it extended as much as one month but that a majority of the members rejected this notion.

"We will deliver our final report and recommendations to the White House before Nov. 1," the source said. "We do not want to extend our meetings beyond the month of October."

Among an estimated 100 "findings" on Three Mile Island it will deliver to the White House, the Kennedy Commission will compare the NRC to a ship without a captain.

"Who's their chief executive? The NRC doesn't have a chief executive," one commission source said. "The way the NRC is organized right now, it's handcuffed because all five commissioners are equal; there's no single chief."

Sources said the commission will also recommend that NRC's Inspection and Enforcement Office be upgraded. The Kemeny Commission will also urge that the NRC be given power to levy higher fines against electric companies violating NRC rules.

"The NRC's penalty autohrity is one of the most under-used authoriteis it has," one source said. "We've been told of cases where electric companies could have been fined $100,000 by the NRC and the NRC would end up assessing fines of $10,000."

Besides recommending that the NRC get out of the uranium export and safeguards business, the Kemeny Commission will urge that the NRC relinquish its emergency planning authority to the new Federal Emergency Management Agency, which came into existance after Three Mile Island.

"The NRC shouldn't be in the evacuation business," one source said. "It's another example of an agency being spread too thin to be effective at the things it must do."

The commission will also recommend that all nuclear power plants place emergency radiation detection equipment in secure places. The panel found that many detectors at Three Mile Island were unusable because they had been kept in rooms that were most seriously contaminated by escaping radiation. b