In a letter to U.S. Nuclear Regulatory Commission Chairman Allison Macfarlane, Senator Barbara Boxer and Representative Edward Markey said a 2012 document by Mitsubishi Heavy Industries Ltd, maker of the San Onofre power plant’s steam generators, found that some safety modifications were rejected by both Mitsubishi Heavy Industries and plant owner Southern California Edison due to “unacceptable consequences.”
The potential changes may have raised the possibility that the plant would need to seek a license amendment because of changes to the steam generators’ design, the lawmakers said the report showed.
"SCE is fully cooperating with the NRC review process and is complying with all requests for information and documents related to the company’s San Onofre Nuclear Generating Station," Southern California Edison spokeswoman Jennifer Manfre said in an emailed statement. "SCE leadership takes very seriously all allegations raised by the letter."
In the letter, the lawmakers said the report also showed that Edison’s and Mitsubishi’s decision to reject those modifications contributed to problems with the faulty steam generators and the shutdown of two nuclear reactors at the San Onofre nuclear power plant.
"This newly obtained information concerns us greatly," Boxer and Markey wrote in the letter."