SAN DIEGO - A series of problems over the past several months will likely delay plans to move a decomissioned nuclear reactor from the San Onofre power plant to South Carolina, Southern California Edison officials acknowledged.

The 900-ton reactor was supposed to be shipped next month to a nuclear waste site in Barnwell County, S.C., but Edison officials believe there may be too many challenges to meet their projected deadlines.

The Panama Canal Authority has denied the energy giant access through the waterway because the reactor is six times heavier than the allowable amount, officials said. The Canal officials are also worried that the reactor could fall off a barge and block the canal, Edison spokesman Ray Golden said.

"We were disappointed," Golden said. But "you could certainly understand their need to make sure transit through the canal is not delayed in any way."

Golden said the firm has offered to send salvaging equipment with the barge, and is urging the Canal Authority to reconsider.

If canal officials don't change their mind, Edison will either have to ship the reactor on a barge 11,000 miles around Cape Horn at the tip of South America, or ship it west, navigating around Asia and Africa in an even longer trip.

Planning for either trip would probably delay the voyage until at least November.

Other problems have occurred such as disputes with the California Department of Transportation and opposition from environmentalists.

"This reactor is likely to become the garbage barge of California, wanted by no one and adrift at sea," said Mark Massara, coastal programs director of the Sierra Club of California.

The reactor was to be loaded onto a barge at the Camp Pendleton Marine base next month and shipped to a burial site in Barnwell County, S.C.

The California Coastal Commission last week narrowly approved a request by Edison to move the reactor by truck 15 miles across a state park and beach lands at the Camp Pendleton base. It must complete the project by March 31, to avoid the primary nesting season of the snowy plover, which lives there.

The reactor is classified as low-level radioactive waste, which is not as dangerous as the spent nuclear fuel that is stored at the San Onofre nuclear plant. However, among the three types of low-level waste, it is the most dangerous, Golden said.