Diablo Canyon is closing, but here’s why that’s not a surprise

Diablo Canyon near Avila Beach is the last operating nuclear power plant in California.
Diablo Canyon near Avila Beach is the last operating nuclear power plant in California. dmiddlecamp@thetribunenews.com

Diablo Canyon is the latest in a string of nuclear power plants to either shut down — four in the past few years — or announce closure. In nearly all cases, decisions were based not on perennial issues such as seismic safety, storage of spent fuel or the presence or absense of greenhouse gas emissions, but on dollars and cents.

While other issues have continued to fuel public debate over nuclear power, concerns about profitability have been at the forefront in the United States.

How did this happen to an industry once associated with the catchphrase “too cheap to meter”?

Financial analysts and energy experts point to a few key reasons:

▪  The decline in the cost of other forms of energy — especially natural gas — is making it less attractive to operate nuclear power plants, which require a large and expensive labor force.

▪  Trends in the energy world are changing; some large utilities are focusing less on power generation and more on transmission, distribution and on the emerging field of energy storage.

▪  And finally, mistakes have been made. San Onofre in San Diego County is a prime example: The plant shut down in 2012, after a leak of radioactive material and discovery of premature wear on over 3,000 tubes in replacement steam generators. Ultimately, the plant’s owner, Southern California Edison, decided to permanently close the plant rather than make expensive repairs.

San Onofre’s closure left Diablo Canyon as the last nuclear plant operating in a state with what’s arguably the toughest regulatory climate in the nation. On top of that, PG&E has faced uncertainty over whether it would be required to make additional seismic upgrades and/or install cooling towers that could cost as much as $12 billion.

To friends and foes of Diablo, it was a foregone conclusion the plant would be forced to close if the state required cooling towers to replace the existing once-through cooling system, which runs 2.5 billion gallons of seawater through the plant each day, and then discharges the heated water back into the ocean.

PG&E also recognized it as a make-or-break issue: “If the California Water Board requires the installation of cooling towers that the Utility believes are not technically or economically feasible, the utility may be forced to cease operations at Diablo Canyon,” it wrote in its 2015 report to stockholders.

Employees and other supporters of Diablo Canyon tried to counter pessimism with a grassroots “Save Diablo” effort complete with yard signs, marches and fundraisers. All the while, though, PG&E executives have been conspicuously silent.

They said little about Diablo’s future in public, other than some oblique statements about the utility having a lot on its plate.

Supporters worried that lack of an aggressive posture spelled doom for Diablo. Michael Shellenberger, an author and noted environmentalist who founded an organization called Save Diablo Canyon, warned last month that the decision had already been made.

At a rally in San Luis Obispo, he told supporters that PG&E’s chief executive officer, Tony Earley, had been brought on board to “de-risk” PG&E following the San Bruno gas line explosion.

In a follow-up interview with The Tribune, he asserted that Diablo Canyon executives wanted to move ahead with relicensing, but Earley believed it would be too costly and too much hassle to keep the plant open.

“They’ve been treated ridiculously by everybody,” Shellenberger said of PG&E. “People just think that thing (Diablo) is going to blow up.”


Shellenberger and other supporters warn that the loss of Diablo Canyon will devastate the environment, since the nuclear plant — which supplies 9 percent of the state’s energy — will likely be replaced with natural gas. That’s what happened when San Onofre closed.

Not so, say opponents. They counter that Diablo Canyon actually hinders development of renewables such as solar and wind. That’s because Diablo Canyon operates at full power, 24 hours per day; it can’t ramp up and down to meet demand. On rare occasions, there have been surpluses of energy, necessitating curtailment of wind and solar.

In announcing the closure agreement, PG&E stressed that it’s committed to replacing Diablo Canyon with energy efficiency and renewables.

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