ary Moore was born here, reigned as a Fiesta Queen here, and now she and her affinity group, "The Chuckleheads," plan to kill off the nuclear industry here.

Moore, 46, has run a concession store in a tiny mountain town 250 miles away the last several years, but she quickly got into her brown Volvo and drove here Wednesday night to join the first wave of what is expected to be a landmark attempt at a human blockade of a nuclear power plant.

Thousands of antinuclear protesters from throughout the country have been called to surround the $2.3 billion Diablo Canyon plant on the rocky Pacific Coast 12 miles west of here, considered a weak link in the whole shaky structure of U.S. nuclear power. The protest will measure not only the industry's ability to withstand more sustained controversy but also the strength of an antinuclear movement that has appeared to replace civil rights and opposition to the Vietnam war as a magnet for college youth and older political activists.

While the plant's defenders are harnessing the best of modern technology--helicopters to transport workers inside, well-equipped police to make arrests and a Coast Guard patrol to stop a planned "sea blockade"--the demonstrators are launching their unprecedented action in an amorphous, almost mystical fashion. Their odd style of organization, typified by Mary Moore and the friends she helped bring down from Sonoma County, leaves everyone in doubt as to the outcome.

Since 1978, members of the Abalone Alliance and the Alliance for Survival, two coalitions encompassing dozens of antinuclear groups, have trained thousands of people for a nonviolent assault on Diablo Canyon. Moore said the first lesson she learned when she was trained in 1978 was that protesters should form five- to 15-member "affinity groups" which must look out for each other. "If a person starts freaking out, it's up to the affinity group to control that person," she said. A big hug is one recommended procedure.

The affinity groups are formed in the six-hour training sessions that are still continuing today at a campsite here. The groups have become the key to the whole process, but operate in a way that causes much head-shaking among the San Luis Obispo County sheriff's deputies, now diligently organizing their countermeasures.

The alliances have described the general purpose of the protest: to try to stop workers from entering the plant and beginning the process of loading uranium oxide fuel into the first of the plant's two reactors. At the very least, they want to draw as much attention as possible to the movement's warning that all nuclear plants are subject to mishaps that could cause dangerous leaks of radiation.

Each of the dozens of affinity groups must decide its own blockade strategy, however, and not take any action "until everything is talked out," Moore said. A blockade handbook advises them to accept only ad hoc leadership from members acting in a rotating capacity as "facilitators" or "vibes-watchers."

The handbook also describes a system for joint action by affinity group "spokes" meeting in a "spokescouncil": "spokes do try to consolidate, synthesize and iron out differences between proposals so as to create proposals agreeable to all. Information is then relayed back to the affinity groups by spokes, the issue at hand reconsidered, and a new position (or perhaps the same old one) is reached."

Moore said she does not know how many of the thousands who have been trained will drop other plans on such short notice--the alert went out Wednesday--and come to this little college town of 34,000.