The San Onofre Nuclear Generating Station (SONGS) in California was intentionally operated past its capacity, creating a steam leak that resulted in the shutdown of the facility’s two operating reactors in 2012, according to a report released Tuesday.
Citing Nuclear Regulatory Commission documents obtained through an open records request, Vinod Arora, a former fire protection engineer for SONGS operator Southern California Edison (SCE), said the company is “100 percent” responsible for failure of the site’s replacement steam generators. SCE has blamed Japan-based Mitsubishi, which the utility is suing for $7.6 billion for producing the “faulty” system.
Arora, who consulted five chemical engineers in his report, said SCE pushed the San Onofre steam generators past their original design limit for the sake of short-term profit, while remaining in operation. Higher primary reactor coolant temperatures and higher steam pressure “caused tube-to-tube contact resulting in dangerous and potentially deadly tube ruptures,” according to his report. The generators, which had a 40-year lifespan, failed after 11 months; SCE ultimately determined the breakdown was too expensive to fix and permanently shuttered SONGS in 2013.
SCE spokeswoman Maureen Brown said by email Wednesday that the report relies on information from a former San Onofre employee who is “simply misinformed.”
“As far back as September 2013, the Nuclear Regulatory Commission identified flaws in how Mitsubishi Heavy Industries (MHI) used its computer codes to design the failed steam generators at San Onofre,” Brown wrote. “The commission further issued a ‘Notice of Non-Conformance’ against MHI for its flawed computer modeling in the failed design.”
Brown also drew attention to the commission reports’ indication that Mitsubishi’s use of its computer codes in the design of the steam generators “inaccurately predicted thermal hydraulic conditions in the steam generators, leading to tube vibration and wear and a steam generator tube leak.”
The commission’s inspection findings reinforced an NRC Augmented Inspection Team report from 2012, Brown said, that identified Mitsubishi’s computer modeling errors.
SCE in 2014 struck a $4.7 billion settlement with the California Public Utilities Commission for prematurely shuttering the plant. The agreement dictated that state ratepayers shoulder $3.3 billion of the cost, while SCE parent Edison International and SONGS minority owner San Diego Gas & Electric pay the rest. It was later discovered that former commission President Michael Peevey had engaged in ex parte communication with then-SCE executive Stephen Pickett, during a secret meeting in Poland. CPUC subsequently fined SCE $17 million for violations, and state Attorney General Kamala Harris has opened a criminal investigation against Peevey. CPUC in April reopened the settlement case to determine if it’s still fair in light of the ex parte communications.
Arora says he drew the following information from NRC documents: That SCE ran Unit 3’s generators at higher-than allowable pressure and temperature; that excess heat created “dry steam,” increasing steam velocities and void fractions and causing the tubes to vibrate violently; and that SCE has been disingenuous in its characterization of operation at the plant, among other claims.
“They redlined the generators to increase SCE’s profits and to reduce tube wear to minimize dings and dents,” Arora said in a statement. “They ran them too hard and too fast, and they broke.”
Arora said SCE’s operating logs for Units 2 and 3 will show definitively whether the company operated the reactors “recklessly.”
“Once SCE’s Operating Logs for Units 2 and 3 are secured, they will show that the ratepayer funded bailout of the San Onofre Nuclear Generating Station (SONGS) should never have occurred,” Arora said. “SCE was entirely responsible for the steam generators’ redesign and acted recklessly in their deployment and operation.”
