Evening sets on the San Onofre atomic power plant December 6, 2004 in northern San Diego County, south of San Clemente, California. San Onofre nuclear plant was permanently closed on June 7, 2013, and there are no efforts to repair the plant which is being decommissioned. (Photo by David McNew/Getty Images)

Diablo Canyon nuclear power plant owner Pacific Gas & Electric has issued a couple of seismic studies in the past year – one last September and then another last month. The latest conclusion from the utility: “New Analyses Show Diablo Canyon Safe From Extreme Natural Events.”

But Democratic Sen. Barbara Boxer is skeptical of PG&E and of the Nuclear Regulatory Commission’s oversight. And at a Senate committee hearing this week, she said an internal memo showed the NRC and PG&E colluded on talking points ahead of the release of last year’s report.

“Heads should roll on this. You don’t write talking points before you even get the document.” – Sen. Barbara Boxer, during a hearing of the Senate Environment and Public Works Committee, as reported by the San Francisco Chronicle

The number of operating nuclear power plants in California has dwindled to one, and in the wake of Fukushima scrutiny of the seismic safety of Diablo Canyon, which began operation in 1985, has grown. There’s concern, particularly, that new faults discovered in the area, on the Central Coast near San Luis Obispo, could pack more punch than the two-unit plant could withstand.