Monday afternoon at MUSE, Musicians United for Safe Energy, the phones are exploding.

The ad hoc group of old lefties, new lefties and musicians like James Taylor, Jackson Browne, Bruce Springsteen, Graham Nash and Bonnie Raitt, have put together five consecutive Madison Square Garden concerts beginning tonight that may earn up to two million dollars for anti-nuclear causes.

In the New York office, it's a chain reaction:

"David, I've got CBS News on hold."

"Robert Palmer of the Times on two-four for Harvey Wasserman."

"Diane, pick up two-three for Billboard magazine."

"Yes, we do have $100 tickets. Let me take your name."

Call it the New York Syndrome. Within a few hours the phones -- and the receptionist -- were approaching meltdown.

"This is the craziest I've ever seen it," said David Fenton, punching the buttons on his phone console with quick confident thrusts. "But it feels good. There's a lot of good energy here today."

Energy, of course, drew all the musicians, lawyers, journalists, activists and public-relations types together in the first place. Since 1974, East Coast anti-nukers had watched Tom Campbell, a former Disneyland musical events director, promote benefit concerts in the West for environmental causes through an organization called the Pacific Alliance. He had persuaded Jackson Browne, Linda Ronstadt and the Eagles to help raise money and encourage other musicians to join in.

Among those watching were Fenton, Howard Kohn and Susan Kellam, all formerly of Rolling Stone magazine as publicity director, associate editor and staff writer respectively.Last year, in the course of writing about the Karen Silkwood trial, Kohn decided to help raise funds for the defense fund. He and Fenton solicited help from rock celebrities.

Roughly 100 responded by signing a petition drafted by musician John Hall opposing nuclear power. Bonnie Raitt suggested a benefit. The May 9 concert -- at New York's Palladium coproduced by Fenton and Kellam -- that resulted raised $16,000 and got the Rolling Stone bunch and other movement people to thinking that maybe rock power was the energy source everyone had been looking for to challenge nuclear power.

"John Hall came up afterwards," recalls Fenton, "and said we had to do something big that would institutionalize musicians' participation in the movement."

Something big meant the Garden. Meetings went on through the summer and at a Martha's Vineyard benefit in September where James Taylor and Carly Simon joined in.

In November, the group met with Campbell and Jackson Browne on the West Coast: MUSE became a reality -- or at least a corporation. Offices were opened in L.A. and New York. The musicians agreed to stretch the benefit over several days. And everybody got to work.

MUSE secured no-interest loans amounting to about $350,000 from such sources as liberal philanthropist Stewart Mott and two New York foundations -- the Stern Fund and the Morris L. Levinson foundation. Out of that, about a dozen staff members are getting salaries that "average about $300 a week."

MUSE set up an eight-member board to produce the concerts and a 16-member board to distribute the estimated $600,000 to $2 million the concerts and a planned film and album could garner if all goes right. Both boards comprise musicians and anti-nuclear activists, and the distribution board is balanced along racial, sexual and regional lines. Everyone involved maintains that the financial controversies of past rock benefits such as the concert for Bangladesh in 1971 will not be repeated.

Staffer Sam Lovejoy, in a recent interview, put matters in strong terms: "The last thing in the world that is going to happen to this organization is that the money is going to disappear. I will name every name and I will drag this organization through so much mud no one is going to believe it."

Pamela Lippe, a former Friends of the Earth staffer who will be codirecting the distribution of the money, says she's adamant about the integrity of the MUSE operation. "Our books are going to be open. Even if we don't make much money, people will know where it went." Applications for grants out of the MUSE proceeds were due Aug. 1. The foundation has received about 500, and hopes to distribute the money by early December.

And MUSE intends to make a lot of money, mostly by keeping overheads down and trying to get a break on every expense in sight.

From the start, on paper, the shows couldn't miss and the bottom line looked strong -- 19,600 seats a night were going at prices of $15.50 and $18.50, in addition to special $100 and $1,000 tickets available for the privilege of partying with the performers.

There would be no freebies: Even industry executives were expected to pay their way. As Fenton swiveled in his chair, he and his friends gently discussed who was going to tell Jann Wenner, their former boss at Rolling Stone, that they thought he should pay the $1,000. Kellam got the job. The same message went out to one Joe Smith of Elektra/Asylum Records -- "no exceptions."

On other fronts, MUSE negotiators appeared on the verge of closing a deal with Elektra/Asylum for a live album. Barbara Koppel, director of the acclaimed "Harlan County, U.S.A." and cinematographer Haskell Wexler, would be filming the concert and the events surrounding it for a full-length feature. MUSE spokesmen said that proceeds from both projects would go to their cause.

Madison Square Garden is offering MUSE its special price for non-profit events. Rehearsal studios are charging lower than usual rates. Showco, the light and sound company, will not receive any money for its services. Musicians are getting lodging, $30 a day and ground and air transportation. Some, such as Jackson Browne, who reportedly has not played a concert for pay this year, are picking up even those expenses. The acts have also agreed to share a lot of equipment.

"There's an enormous amount of cooperation taking place," says Fenton, a little amazed that things are going smoothly so far.

Still, the musicians have not completely shaken their discomfort with politicians and activists. They decided there would be no proselytizing during the concert -- at least not by nonperformers. A huge rally on Sunday will allow for that.

Another interruption dispelled any doubts about the ongoing sensitivity of rock star/politician relations. As Fenton danced between two callers, all business despite his jeans, boots and open-necked shirt, a staffer asked if Mayor Koch had been invited.

"I tried to get that going," answered a third staffer, "but Jackson shot it down. He's nervous about politicians."

Everyone, however, is invited to sit in the audience -- if he buys a ticket.

The tickets, everyone at MUSE happily reports, are all that's disappearing so far. Friday and Saturday nights are likely sellouts. Yesterday MUSE announced that a fifth night had been added on Sunday, headlined by Crosby, Stills and Nash.

Late Monday, as the pace slackened, Fenton noted that no musician had turned them down for ideological reasons -- pro-nuke rock stars appear to be a rare bunch.If that's the case, MUSE's long-range plan to make such concerts a staple of the anti-nuclear movement should have a growing pool of talen to choose from. Right now, though, that's too far off to worry about.

"We don't know for sure what the future of the organization is," admitted Fenton. "We haven't had a chance to think about it."