SAN JUAN CAPISTRANO, Calif. -- Federal regulators said Monday that a botched computer analysis resulted in design flaws that are largely to blame for unprecedented wear in steam tubes at the San Onofre nuclear power plant, but it isn't clear how the problems can be fixed.The preliminary findings by a team of Nuclear Regulatory Commission investigators were disclosed nearly five months after the seaside plant was shut down following a break in a tube that carries radioactive water.