California Power Gains After Diablo Canyon Nuclear Reactor Shuts

California wholesale electricity gained as hotter weather lifted demand above forecasts and the unplanned shutdown of a Diablo Canyon reactor reduced supplies.

Spot prices rose for the first time in three days after PG&E Corp. shut Diablo Canyon 1, located about midway between Los Angeles and San Francisco, after discovering a socket weld leak, according to a Nuclear Regulatory Commission report. Power consumption topped yesterday’s outlook across the state grid.

Southern California’s SP15 hub, a proxy for Los Angeles and San Diego, rose $11.82, or 41 percent, to average $40.57 a megawatt-hour during the hour ended at 10 a.m. local time from a day earlier, grid data compiled by Bloomberg showed. Yesterday’s day-ahead outlook for the hour was $37.54.

Northern California’s NP15 hub, which includes deliveries to San Francisco, gained $3.39, or 9.2 percent, to average $40.24 a megawatt-hour at 10 a.m., above the day-ahead price of $37.61. The on-peak average is up 7.7 percent at $41.20.

The discount for SP15 spot on-peak power versus NP15 widened to an average of $6.19 a megawatt-hour from $2.99 yesterday.

Repairs to Diablo Canyon 1 “will not be difficult or take very long to complete,” said Lara Uselding, a spokeswoman for the NRC’s Region 4 office in Arlington, Texas.

NRC data shows the unit was operating at 50 percent yesterday. Its capacity is 1,159 megawatts, according to the Energy Information Administration.

Electricity consumption across the state was 31,547 megawatts as of 9:50 a.m., above the day-ahead forecast of 28,842 megawatts for the hour, according to the California Independent System Operator Corp., which manages the grid.

To contact the reporter on this story: Naureen S. Malik in New York at

To contact the editor responsible for this story: Dan Stets at

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