Parting from the Nuclear Regulatory Commission is such sweet sorrow, according to Chariman Joseph M. Hendrie, that he can hardly wait.

Hendri, 56, returns tomorrow to the Brookhaven National Laboratories on Long Island, having worked during his four-year term, he said, "to coax, coerce, hornswoggle or just plain amuse three commissioners into some kind of coherent position." Fighting for a majority on the five-member body remains the chairman's main headache, he said.

Hendrie has one bit of advice for his successor, Pennsylvania State University nuclear engineer Nunzio Joseph Palladino: "Try to take some pleasure in the job."

While the mysterious ways of the NRC have changed somewhat during Hendrie's tenure, he says "they're not different in any substantial way" from the day he took office in 1977.

That will come as a surprise to the people who reorganized the NRC last year to try to give the chairman more power. The various investigations into the March, 1979, nuclear plant accident at Three Mile Island in Pennsylvania all found that the NRC's collegial debating society style was incompatible with swift decision-making. In response, President Carter beefed up the Chairman's job and sacked Hendrie as chairman, although he remained on the commission.

The action was seen then as symbol that nuclear safety concerns were to take precedence over nuclear advocacy. When President Reagan restored Hendrie to the charimanship last March, the action appeared as the opposite symbol: a go-ahead for the industry, a notice that Three Mile Island worries were over.

Far from it, Hendrie said in an interview. Riding herd on the bookful of recommended TMI fixes will be one of Palladino's first problems. "There are so many that we've oversaturated people's ability to get things done," Hendrie said. "He'll want to shake them down, look at places where we're not getting a big safety bang for the buck."

The accident was "heavy trauma" for the commission and, in hindsight, there are "some tactical things" he would have done differently, Hendrie said. He refused to be specfic. But reorganization "didn't strengthen the chairman's hand enough to operate like a single-head agency across the range of functions," he said.

"Any three commissioners who think a thing is a policy matter [can vote to] define it as such," and that can hamstring the chairman, Hendrie said. "Having a working three-member majority is a hell of a lot more important to the way the commission functions than the reorganization."

Looking back on it all, Hendrie recalls with some pride his work to protect dissident voices in the NRC. Where internal critics had previously been transferred or hounded out of the agency. Hendrie, evolved a policy to recognize and deal with their concerns. "It was a useful achievement," he said.

Now, however, Hendrie is eager to return to Brookhaven's applied science division laboratories. "I'm not actually crossing out the days on the calendar," he said, "but figuratively I am -- chortling as I go."