The Nuclear Regulatory Commission has been hamstrung by internal political differences to the point that its safety-related functions are affected, outgoing commissioner Richard T. Kennedy said yesterday.

In a parting blast on his first day as ex-commissioner, Kennedy called the NRC "the most politicized agency in town." He said in an interview that the five-member panel spends "far too much time . . . debating in one guise or another whether nuclear power is a reasonable approach to meeting our energy needs" instead of focusing on health and safety issues.

Kennedy, 60, a former Army colonel and National Security Council planner, completed his five-year NRC term Monday. President Carter plans to use the vacancy to appoint a new NRC chairman, in place of John Ahearne, possibly this week. Ahearne was named interim chairman last December.

Antinuclear groups have long regarded Kennedy as evil incarnate for his unabashedly pronuclear views, while industry spokesmen saw him as a reliable vote for speeding nuclear development. "It is definitely an understatement to say we're pleased to see him leave the commission," said Richard Pollock of Ralph Nader's Critical Mass Energy Project.

The division within the NRC has slowed everything down, including approval of safety changes needed after the accident last year at Three Mile Island, Kennedy said. "They're constantly being debated as to their efficacy and everything else just stands fact," he said. "We're looking for perfection and that's not likely to be achieved."

The problem is not NRC's structure but its membership, Kennedy continued.

"Reorganization is not likely to help," he said."It's the appointment process . . . they [in the White House] have to appoint people who don't have serious doubts about the desirability of nuclear power."

Instead, he continued, "The commissioners' concern should be that, to the extent it is used, it is used safely. That's what the agency was set up for."

Although Kennedy refused to name anyone, he was clearly referring to Commissioners Victor Gilinsky and Peter A. Bradford as those who have "serious doubts." They are usually on the opposite side from him. But Bradford said he agreed with Kennedy on the nature of the NRC function and denied any "serious doubts" on his part.

"To the extent that plants are needed and comply with the law, and to the extent that they can be licensed consistent with concerns about waste management and radioactive safety, and [licensed] overseas consistent with concerns about proliferation, I'm all for them," he said.

Gilinsky could not be reached.

With Kennedy's departure, pressure intensified for President Carter to name a new chairman soon to give the confirmation time to get through the Senate before adjournment. All sides are concerned that the NRC not be left with only four members for months because of the virtual certainty of frequent 2-to-2 votes, a worry that in some measure confirms Kennedy's views.

The most likely candidate for the nomination, according to various sources in the nuclear community, is a man thought to be politically unpredictable. He is Albert Carnesale, 42 today, a New York native and international arms control specialist who is now a professor of public policy at the John F. Kennedy School of Government at Harvard University.

Neither the nuclear industry nor its critics have a clear view of Carnesale yet, and he refused to discuss his outlook.

A number of other Republicans and independents are known to have been approached for the job, since political balance is required by law and Kennedy is a Republican. Among them were former Washington governor Daniel J. Evans, former Environmental Protection Agency Administrator William D. Ruckelshaus and Henry Diamond, former natural resources secretary in New York under Gov. Nelson A. Rockefeller. All of them reportedly turned it down.