A letter from Mitsubishi Heavy Industries (MHI) to the Nuclear Regulatory Commission (NRC) proves false the latest round of allegations from activists, Southern California Edison (SCE) said Tuesday. It also confirms that SCE believed the San Onofre nuclear plant’s steam generators were safe when installed and that safety measures were not sacrificed for licensing reasons. The letter, posted on the NRC’s website, accompanied a redacted copy of the MHI Root Cause Evaluation which has been grossly distorted by the national anti-nuclear activist group, Friends of the Earth.
“The anti-nuclear activists have called the MHI report a ‘bombshell’ which couldn’t be further from the truth,” said Pete Dietrich, SCE senior vice president and chief nuclear officer. “In fact, the MHI letter explains that SCE and MHI rejected the proposed design changes referenced in the evaluation because those changes were either unnecessary, didn’t achieve objectives or would have had adverse safety consequences.
“Our decisions were grounded in our commitment to safety. SCE did not, and would never install steam generators that it believed would impact public safety or impair reliability.”
MHI repeatedly reassured SCE that based on their testing, the steam generators met safety requirements and would function for 20 years.The MHI letter specifically confirms that at the time the replacement steam generators were designed, MHI and SCE believed that the “replacement steam generators had greater margin against U-bend tube vibration and wear than other similar steam generators.” MHI warranted the steam generators for 20 years. “As with all engineering evaluations, the MHI letter and report describe a technical evaluation process and need to be read in their entirety to understand the conclusions reached,” said Dietrich. “The activists are taking portions of paragraphs and sentences out of context, and using them as the basis of their allegations that SCE knew of design defects when the generators were installed, but failed to make changes to avoid licensing requirements. That is untrue.”