VIDEO: San Onofre Nuke Plant To Remain Shut, Officials Say

After touring San Onofre's troubled nuclear power plant Friday, Nuclear Regulatory Chairman Gregory Jazcko attempted to reassure the public with a news conference that detailed inspections done in the wake of a radioactive steam leak that shut the station down in January.

along with Sen. Dianne Feinstein and Rep. Darrell Issa.

Jazcko said that heat exchanger. The tubes, when working properly, carry superheated radioactive water at several thousand pounds-per-square-inch of pressure. The heat passes through the tube walls to boil pure water, creating steam to turn the turbines that generate electricity.

The tube wear in Unit 2 isn't as bad. That unit was offline for maintenence when the Unit 3 tube leaked. , Jazcko said.

The steam generators are made by Mitsubishi, and their design is unique to the San Onofre plant, Jaczko said.

Neither unit will be allowed to restart until the exact cause or causes of the wear and leak are determined, Jaczko said.

The fact that the NRC is treating the tube wear in both units as separate issues outraged , head of the anti-nuclear group San Clemente Green.

"My biggest concern is that I get the impression that what they are saying is that even though the generators are identical, they're treating them differently," he said. "I can't find it in my logic that they would shut down Unit 3 and allow Unit 2 to operate."

The whole plant has been shut off for more than two months, and the Independent System Operator that allocates electricity throughout the state

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Jaczko wouldn't speculate further as to the root cause of the damage, but said testing had been done on the tubes and several will be plugged and removed from service--NRC officials have said steam generators can still operate safely with up to 30 percent of their tubes plugged. Now, he said, inspectors are analyzing the data they've collected.

An asserted that Southern California Edison officials used a bureaucratic procedural loophole to improperly hide from the NRC changes in the design of the tube support structures and the alloy from which the tubes themselves were made.

These design changes likely led to the damage, the independent report states.

Jaczko said the NRC hasn't determined whether Edison acted improperly in filing its required inspection documents, but he said analysis of all the paperwork related to the recent installation of the tubes is part of the NRC's investigation.

If the NRC finds Edison acted improperly, the agency will take regulatory action, he said.