A lawmaker leveled new allegations Thursday against operators of the crippled San Onofre nuclear power plant, which remains shut down more than a year after one of its generators leaked radiation.

In a letter to the Securities and Exchange Commission, Rep. Ed Markey (D-Mass.) asked whether Southern California Edison violated securities laws by supposedly failing to tell investors about “serious problems” with the steam generators before they were installed.

“Edison’s SEC filings suggest that the company was surprised when a leak developed in the San Onofre nuclear power plant’s Unit 3 steam generators,” Markey wrote.

Yet, he added, a secret report by generator manufacturer Mitsubishi “appears to suggest that Edison knew there were potential safety problems with the generators but explicitly opted against making recommended safety modifications for fear that those modifications would prove troublesome to the license process.”

The Securities Act of 1933, Markey wrote, prohibits publicly-traded companies “from omitting material facts — information that a reasonable investor would consider important — from security filings.”

He asked the commission what penalties could result and whether the SEC has ever prosecuted an energy company for failing to disclose similar issues. He requested a reply by March 15.

Markey’s concerns came after a politically explosive letter by him and Sen. Barbara Boxer (D-Calif.) accusing Edison of knowingly installing faulty generators against the advice of their own engineers.

That prompted the U.S. Nuclear Regulatory Commission to announce it was conducting a broad investigation into whether Edison lied when it got approval for installing the generators.

Edison is disputing Markey’s latest allegation.

“It is simply not accurate to suggest, as Rep. Ed Markey has, that when the steam generators at San Onofre were installed, Southern California Edison (SCE) was ‘aware of serious problems with the design,’ ” reads the utility’s statement.

Yet despite claims it was “open and transparent” about the generators, Edison hasn’t shown any interest in releasing to the public the Mitsubishi report at the center of the lawmakers’ concerns.

Mitsubishi itself has defied a deadline from federal regulators to provide a redacted version of its report for public release.

If Boxer and Markey’s description of the Mitsubishi report is true, it would stand in stark contrast to Edison’s claims of being caught off guard by the leak, a result of extremely rapid damage to the generators’ tubes.

As recently as last month, Edison officials told the NRC there was no advance warning of those problems when the $15-billion utility giant analyzed the generators’ safety risks.

Also on Thursday, hundreds of people turned out for a California Public Utilities Commission hearing in Costa Mesa on whether to give a refund to utility customers for the faulty generators’ $670-million bill.

You can reach Nick Gerda at ngerda@gmail.com and follow him on Twitter: @nicholasgerda.

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