A federal investigation has revealed what critics say are major design flaws at California’s San Onofre nuclear power plant, which has been shut down since a radioactive leak in January. Monitors at the Nuclear Regulatory Commission say that design flaws caused excessive wear in tubing that carries radioactive water. The plant’s operator, Southern California Edison, had been planning on seeking approval to restart the reactors, but critics say the findings show San Onofre should remain idle. In a statement, Friends of the Earth said the crisis is the result “of a perfect storm of error,” saying: “Edison made significant design changes without seeking an amendment to its license as required by NRC regulations; on the other hand, the NRC appears to have been asleep at the regulatory wheel.”