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Diablo Canyon Power Plant

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Diablo Canyon Power Plant


Diablo Nuclear Plant Faces Threats and Threatens: Part I

From Cyber Attack to Tsunami, Facility Hazards Are Too Great to Ignore


The operator of Diablo Canyon nuclear power plant, PG&E, announced in June that it would close the plant by August 2025. Longtime activist Harvey Sherback wrote this letter, published in two parts and edited by The Santa Barbara Independent, to the state Public Utilities Commission prior to its vote regarding the decision. Part I follows.

Open Letter to Michael Picker, president of California Public Utilities Commission; and PUC Members and Staff:

The Diablo Canyon nuclear power plant (DCNPP) is vulnerable and dangerous from within and without as well as from above and below. The environmental disasters that can be caused by Diablo are truly devastating. In this letter I list some of the many reasons why it’s imperative that we close down the DCNPP as soon as possible.

The Danger from Within

The Diablo Canyon nuclear generating station has two aging Westinghouse-designed 4-loop pressurized-water nuclear reactors that went online over 30 years ago. As nuclear plants age, neutron impingement hardens and embrittles these reactors. This loss of flexibility makes the plant’s containment vessels susceptible to sudden shocks and aftershocks.

On May 4, 2016, at the National Earthquake Conference in Long Beach, a leading scientist, Dr. Tom H. Jordan, chairman of the Southern California Earthquake Center, revealed that Southern California’s section of the San Andreas Fault is “locked, loaded and ready to roll.” The San Andreas Fault is one of California’s most dangerous and longest fault systems. At the conference, Dr. Jordan warned that the springs on the San Andreas Fault have been wound very, very tight. “It’s been quiet since 1857 — too quiet.” The idea that nuclear power plants are durable enough to withstand strong quakes like “The Big One,” a mega-thrust magnitude 9 earthquake, is a total myth.

Another of the many problems associated with the aging DCNPP is that critical parts like the feed-water pumps keep failing but are impossible to replace because of their location. It is no longer rational for us to live with the risks posed by the Diablo Canyon nuclear power plant. We need to adopt a new reality and begin the removal of this more than dangerous eyesore from our coastline.

The Danger from Without

We now live in a world where much of our infrastructure is controlled by artificial intelligence (AI). Everything from traffic lights to our electric grid is run by these AI systems. The problem is that with the introduction of the World Wide Web, these systems can be breached by unscrupulous saboteurs who can be located anywhere on the planet. The truth is that we are under constant “Cyber Attack” by hackers both domestic and foreign. Last December, several Ukrainian power companies experienced a cyber attack that resulted in unscheduled power outages that lasted up to six hours and impacted over 200,000 customers. Welcome to the world of Cyberwarfare.

On March 7, 2016, the Department of Homeland Security’s Assistant Secretary Dr. Andy Ozment and Deputy Assistant Secretary Brigadier General Gregory J. Touhill wrote: “U.S. critical infrastructure entities have been affected by targeted intrusions in recent years, and it is imperative that critical infrastructure owners and operators across all sectors are aware and up-to-date on the cyber threat landscape and the measures they can take to protect their assets.”

There is a real possibility that California’s electric grid can be brought down by sophisticated cyber attacks at any time over the next nine years. Because the DCNPP is grid powered, these malicious digital assaults could trigger a devastating nuclear meltdown. Better safe than sorry; let’s close Diablo down while we’re still in control.

The Danger from Above

The effects of an electromagnetic pulse (EMP) or geomagnetic storms created by coronal mass ejections (CME) from the sun could also cause a catastrophic meltdown at the Diablo Canyon nuclear power plant. I believe that an EMP attack from a rogue nation or terrorist organization is perhaps one of the most serious security threats that our nation faces today.

Unfortunately, nuclear plants are tied to and dependent upon the electric grid to function. Without electricity the operator loses instrumentation and control power leading to an inability to cool the reactor core. There’s the very real possibility of a “station blackout,” where all off-site power is lost. Every nuclear power plant has emergency diesel generators just for this purpose, assuming that the generators will start after an electromagnetic pulse. In the event of a station blackout, core damage is estimated to begin in approximately one hour if the auxiliary feed-water system and high pressure injection flow isn’t restored in time. A CME or an EMP attack could cause the grid to go down and not come back up for months or years.

The loss of off-site power could also cause a failure of the spent-fuel-rod cooling systems. When the spent fuel cooling pumps stop working, the water in the pools starts to boil off. Once Diablo’s overcrowded spent fuel assemblies become uncovered, the fuel rods’ cladding will start to melt. As bits of the melting fuel fall into what’s left of the water, the water will flash to steam, causing the pressure in the buildings to increase. Radioactive particles carried in the steam would then begin to exit the buildings through non-sealed portals and doors.

Exposing hot zirconium fuel rod cladding to the air causes an exothermic reaction, and the cladding will actually catch fire at about 1,000 degrees centigrade, causing toxic radioactive isotopes to be released into the atmosphere. Even the Nuclear Regulatory Commission (NRC) concedes that this type of fire cannot be extinguished. Why must we continue to live with this unnecessary danger?

The Danger from Below

California’s coastline lies along the active Pacific Ring of Fire earthquake zone. The accelerated rate of melting at polar caps and glaciers reduces the weight at the planet’s poles, causing the earth’s tectonic plates to shift, leading to larger and more frequent earthquakes. Scientists assure us that it is only a matter of time before California experiences The Big One, a horrific natural geological disaster.

When Diablo was built some 30 years ago, PG&E stated there were no fault lines within 30 miles of the nuclear facility. The truth is that the plant sits on and is surrounded by a maze of faults. In his July 26, 2011, California Energy Commission’s Integrated Energy Policy Report, geologist Douglas H. Hamilton, PhD, stated there are “two dangerous faults” that run directly underneath the Diablo Canyon nuclear power plant: the San Luis Range Thrust and the Diablo Cove Fault.

The San Luis Range Thrust

The San Luis Range Thrust, as thus defined, underlies the DCNPP at a depth as shallow as one km and is clearly seismically active. It has dimensions that suggest a deterministic earthquake generation capability in the range of magnitude 6.75>M7.0.

The Diablo Cove Fault

The potential for future renewed surface movement along the Diablo Cove Fault in the foundation beneath the Unit 1 turbine-generator power block, the Unit 1 reactor, and probably the Unit 1 spent fuel-rod pool should be considered as part of any reevaluation of seismic margins at the Diablo Canyon nuclear power station.

The Diablo Cove Fault runs east to west and cuts across the seismically active Shoreline Fault. The Shoreline Fault is connected to the feared Hosgri Fault, a component of the San Andreas Fault System.

According to PG&E, the DCNPP can withstand earthquakes up to a magnitude of 7.5, and these faults don’t pose significant threats to Diablo’s integrity. But a USGS seismologist, Jeanne L. Hardebeck, believes that a joint seismic event of the Hosgri and Shoreline faults could exceed the plant’s design capacity for safe operation, possibly reaching a magnitude 7.7.

In addition to these major faults, there are undiscovered collaterals. Collaterals are faults that branch off of major fault lines. Because this location is so tectonically active, and the system of faults is so complex, no one can predict safety with confidence. The Diablo Cove Fault, the Shoreline Fault, the Hosgri Fault, and the San Andreas Fault are all seismically linked, and the power stored within the combined network of fault systems could create an earthquake sufficient to exceed Diablo Canyon’s safeguards.

Diablo’s Spent Fuel Pool Water Storage Reservoirs, Seiche Hazard

Dr. Hamilton also stated in his July 26, 2011, California Energy Commission’s Integrated Energy Policy Report that Diablo Canyon’s two broad, relatively shallow 2.5 million gallon “Spent Fuel Pool Supplemental Water Source” reservoirs might not be there when needed as a backup source of emergency cooling water. This is due to the effect of earthquake-induced seiches, which are waves in an enclosed or partially exposed body of water that have been observed on lakes, reservoirs, and swimming pools.

Seiches caused by the 1989 magnitude 6.9 Loma Prieta earthquake in the San Francisco Bay area were widespread. Swimming pools and other open-water basins lost much of their water as it sloshed out of their basins. Seiches occurred in close proximity to the earthquakes’ epicenter in the Santa Cruz Mountains as well as at places as far away as Walnut Creek, nearly 100 km from the epicenter.

The Tsunami Danger

Regrettably, the Diablo Canyon nuclear power plant is also vulnerable to tsunami. It sits perched on a bluff that’s 85 feet above sea level. According to Pacific Gas & Electric, its tsunami wall is robust, with the plant expected to survive a wave of up to 25 feet in height. Japanese authorities made similar claims before the wall that protected the Fukushima plant fell. Like the earthquake hazard, the tsunami threat is underestimated. In 1812, the Santa Barbara Channel earthquake produced five tsunami waves in front of the Santa Barbara Presidio. The USGS estimated the largest wave was about 50 feet high.

In 1878, a tsunami at Morro Bay destroyed both Avila and Point Sal piers, and in 1913, a tsunami wrecked the Monterey area. Nearby, at Seaside, immense domes of water appeared to observers to be higher than the highest sand hills along the shore. (The current quad sheet shows elevations as high as 120 feet.)

The epicenter of the magnitude 9 earthquake and tsunami that struck the Fukushima Daiichi nuclear power plant lay 110 miles offshore, whereas the Shoreline Fault is located within 650 yards of Diablo Canyon. After more than 11 years, the Nuclear Regulatory Commission released a tsunami assessment of the Diablo Canyon nuclear power plant that identified 11 scenarios in which quakes or underwater landslides could produce a tsunami tall enough to damage Diablo. Dr. Robert Sewell’s report, “A Preliminary Numerical Study of the Hazard from Local Landslide Tsunami Scenarios at the Diablo Canyon Site in Central California,” was released in response to a Freedom of Information Act request by San Luis Obispo Mothers for Peace attorney Diane Curran. The NRC considered Dr. Sewell’s devastating report as pre-decisional and exempt from public disclosure.

Part II of Sherback’s letter will run August 4, 2016. It can be found here.



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