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Edison Never Told Federal Regulators Of San Onofre Equipment Design Flaw

Edison Never Told Federal Regulators Of San Onofre Equipment Design Flaw

Records show Southern California Edison knew in 2005 about a flaw in the San Onofre nuclear power plant's new steam generator design but omitted that detail in a meeting with the Nuclear Regulatory Commission. Critics say the omission deserves legal scrutiny.

Overlooked in the saga of the 2012 failure of the steam generators at the now shuttered San Onofre Nuclear Generating Station is what the owner told federal regulators about the equipment before it was installed.

Experts say a June 2006 meeting Southern California Edison had with the Nuclear Regulatory Commission is notable both for what the company claimed and omitted.

In the 19 months before that critical meeting with federal regulators, Edison executives knew of a flaw in the new steam generator design, according to records.

Steam too hot to handle, otherwise known as void fraction, was making its way through the equipment. A consequence could be excessive tube wear, the same problem that led to the permanent closure of San Onofre in 2013.


Nov. 30, 2004, letter to Akira Sawa

Nov. 30, 2004, letter to Akira Sawa

Nov. 30, 2004, letter to Akira Sawa

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June 16, 2005, letter to Akira Sawa

June 16, 2005, letter to Akira Sawa

June 16, 2005, letter to Akira Sawa

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To view PDF files, download Acrobat Reader.

In 2004 and 2005, then-Edison Vice President Dwight Nunn expressed worry about the matter in two letters to Akira Sawa, general manager at Mitsubishi Heavy Industries — the maker of the steam generators.

“Tube dry out is an undesirable phenomenon as it may eventually result in tube cracking,” wrote Nunn in June 2005. “The information presented to Edison in the most recent Technical Meeting, indicated that for the SONGS RSG (San Onofre Nuclear Generating Station Replacement Steam Generators) the expected void fraction is very high.”

A letter from Mitsubishi to Edison also mentions potential tube wear.

Yet Edison never alerted the NRC about the void fraction problem in its 22-page power point presentation at the June 2006 meeting.

“To know you have a problem and to not inform the regulator that you had a problem raises questions about Edison attempting, in essence, to hide something that could have serious safety significance,” said Daniel Hirsch, nuclear policy lecturer at UC Santa Cruz.

In January 2012, less than a year after the new steam generators were turned on, the void fraction problem caused a tube to spring a radioactive leak. The leak forced Edison to close San Onofre for good. Ratepayers were left with a $3.3 billion tab that included shutdown costs and compensation to Edison for its lost profits on the plant. Customers are also paying billions more for new power plants to make up for the lost energy from San Onofre.

Edison spokeswoman Maureen Brown acknowledged to KPBS in an email that void fraction was not discussed at the June 2006 meeting with the NRC.

“Mitsubishi assured SCE (Southern California Edison) that void fraction would not be an issue and that the replacement steam generators would operate within specifications,” Brown said.

But according to a report by Mitsubishi, the manufacturer did consider fixes for the void fraction problem. They were not implemented, however, because Edison did not want to impede its ability to avoid a license amendment process. It is during that process that federal regulators evaluate safety risks.

The Edison spokeswoman also wrote that “design errors” by Mitsubishi that led to the steam generator failures “did not begin to be identified” until after the 2012 tube leak. But the NRC, in its own 2013 inspection, found that from the time Edison awarded the steam generator contract to Mitsubishi in 2004 until 2006, there were letters, emails, meeting minutes, action item lists and internal memos detailing concerns about void fraction.

And there’s more.

During Edison’s June 2006 presentation to the NRC, the company refers to the equipment design as “improved.” And yet the NRC’s inspection found that Edison failed to verify the adequacy of its design.

The NRC did not respond to a request seeking comment.

San Diego lawyer Mike Aguirre said Edison’s 2006 presentation to the NRC is grounds for a federal investigation.

“It’s against the law for a company to misrepresent material information to a safety regulator,” said Aguirre, who is challenging a settlement agreement that forces customers to pay for most of San Onofre’s closure costs.

Edison has already been cited by the NRC for dishonesty. Federal regulators ordered the company to take integrity training after it falsified fire safety records at the nuclear plant between 2001 and 2006.

“You measure violations of law by their consequences and yet you have a situation here where there was a radiation leak in our own backyard because our own companies were not being straight,” Aguirre said. “What people have to understand is there has not been one single person placed under oath and examined about what happened. If you had a minor car accident in San Diego, there would be a more thorough investigation than what happened here.”

He said the stakes are even higher because Edison is now in charge of more than 3 million pounds of nuclear waste from San Onofre on the shoreline in San Diego County.


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Photo of Amita Sharma

Amita Sharma
Investigative Reporter

opening quote marksclosing quote marksAs an investigative reporter for KPBS, I've helped expose political scandals and dug into intractable issues like sex trafficking. I've raised tough questions about how government treats foster kids. I've spotlighted the problem of pollution in poor neighborhoods. And I've chronicled corporate mistakes and how the public sometimes ends up paying for them.

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