Friday, March 18, 2011

California's Diablo Canyon Nuclear Power Plant - Producing Power on the Fault Line

While the world’s media has been paying very close attention to the issues facing TEPCO’s Fukushima Daiichi Nuclear Power Plant in Japan, a nuclear power plant in the United States sits on a ticking, tectonic time bomb.

Construction on Pacific Gas & Electric’s Diablo Canyon Power Plant began in 1968.  The first unit was commissioned in 1985 followed by the second in 1986.  The plant is located about 12 miles north of San Luis Obispo, about midway between Los Angeles and San Francisco.  Its two reactors are capable of producing 18,000 gigawatts of electricity annually, enough to supply electricity to more than 3 million northern and central California homes.  Here’s a photograph of the plant:

When construction of the plant was started, engineers and regulators were well aware of the location of the San Andreas Fault (located 45 miles inland) and the Rinconada Fault (located 20 miles away).  With that in mind, the plant was designed to withstand an earthquake that had a magnitude of 7.5.  Unfortunately, engineers were unaware of a fault that virtually ran under the Diablo Canyon location.  Geologists prospecting for Shell Oil Company discovered the Hosgri Fault, a thrust fault with some right-lateral slip motion, that runs just over 2 miles offshore from the plant.  This fault is believed to be responsible for a November 4, 1927 seismic event known as the Lompoc earthquake that had a magnitude of 7.1.  This earthquake is one of the most powerful earthquakes in southern California in the twentieth century.  The tsunami produced by the earthquake was about 2 metres high and was noted as far north as San Francisco.  This fault is located as part of the fault system along the plate boundary between the North America Plate and the Pacific Plate which is moving toward the northwest relative to the North America Plate. 

Here is a map showing the location of the Hosgri Fault (depicted in orange in the offshore area on the west side of the map) with respect to the San Andreas Fault (depicted in red):

Here is a close-up map of the Hosgri Fault.  Note the location of Point San Luis.  It is located about 4 miles south of the Diablo Canyon Power Plant which is located right on the Pacific coast:

Here is a map showing the probable location(s) (depending on the seismological interpretation) of the 1927 earthquake located off the coast near Santa Barbara at the south end of the Hosgri Fault:

Fortunately, the Diablo Canyon plant sits 85 feet above sea level so it is relatively well protected from a tsunami.  On site, PG&E has 4.5 million gallons of raw water storage and an additional 725,000 gallons of stored condensate and fire tank water should an emergency arise.  Despite this seemingly ample protection, unfortunately, the plant is not quite as well protected from an earthquake.  According to a New York Times article from October 1981, there was confusion in the use of transparent blueprints during construction which led to the improper placement of supports designed to protect the cooling systems of the two reactors.  Apparently, the plans for installation of the safety supports for the twin reactors were depicted on a single transparency with plans for one reactor on one side of the blueprint and plans for the other on the opposite side.  Unfortunately, someone forgot to tell those in charge of construction that they were to flip the transparency over.  Oops!

The geology of the Hosgri Fault and its seismic record certainly do tell us that it is capable of a rather major earthquake.  One also has to consider the possibility that an earthquake with a magnitude far greater than 7.0 could occur since seismic records do not exist further back than the 1880s when the first reasonably accurate seismometers were invented.   While geoscientists do their best to predict the maximum magnitude earthquake that a fault can produce, they have no real way of knowing the past history of every major seismic event that has occurred along that fault over tens of thousands of years.

PG&E is currently in the process of applying to have its operating licenses extended for another 20 years.  The license for Unit 1 expires in 2024 and the license for Unit 2 expires in 2025 so they are applying to have the plant remain operational until 2044 and 2045.  By that time, despite the fact that PG&E has spent over a billion dollars on upgrades and updates, over 75 years will have passed since construction began on the plant.  Here’s why PG&E wants its neighbours to support the application and postpone decommissioning of the plant:

In addition to providing safe, clean, affordable and reliable electricity, Diablo Canyon is a vital economic engine for San Luis Obispo, if not all of California. As a major employer and purchaser of goods and services, Diablo Canyon has a total economic impact of more than $640 million annually for San Luis Obispo County and another $100 million for the state. The more than $25 million in property taxes paid by Diablo Canyon in fiscal year 2008-2009, helped support municipalities, schools and other crucial public services.

Furthermore, at PG&E, we strive to remain good neighbors to the communities in which we work and live. Diablo Canyon is no exception. Our employees make charitable contributions in excess of $250,000 annually to the community, which funds a wide variety of school programs, senior centers and many other critical community projects.

Yet, not all of the contributions are strictly measured in dollars and cents. Many of Diablo Canyon’s employees volunteer thousands-of-hours of their personal time to after-school athletic programs, environmental organizations, churches and other community organizations.”

There comes that warm, cozy feeling again!

As if the proximal location of the Hosgri Fault weren’t bad enough, seismologists discovered a new strike-slip fault just off the coast near the Diablo Canyon Power Plant even closer than the Hosgri Fault.  This fault, named the Shoreline Fault, was discovered in 2008.  Here is a map showing the Shoreline Fault as a heavy dashed line, the Hosgri Fault and other faults in relation to the location of the power plant (labeled as DCPP):

As technology improves, it is likely that geoscientists will discover additional faults and gain a better understanding of their potential to cause damage to the Diablo Canyon Power Plant.  Unfortunately, this possibility seems to have evaded the decision-makers who approved construction of a nuclear power plant in a very active tectonic setting in the first place.


  1. Thank you for sharing this info with us. Our governments around the world continue to do things that endanger people, seemingly, without a care in the world.

  2. It appears that you're ignoring quite a bit. First, these reactors have self-contained systems designed to generate electricity from steam from the "overheating rods" to run the cooling systems, thus keeping the temperature in check.

    Showing that you haven't done your due diligence, is the fact that these reactors are not rated to withstand certain magnitudes of earthquakes. Instead, they're rated to withstand an amount of ground movement. Scientists can accurately predict the largest possible movement based on the size of the fault, and, unlike the Japanese, our plants are designed to withstand movement beyond this maximum - and even still it wasn't the earthquake that caused any substantial damage to the cooling systems. It was the tsunami, which you've responsibly noted could not damage diablo canyon.

    Honestly, you've chosen to ignore nearly every fact that doesn't support your anti-nuclear beliefs that its borderline ridiculous.

  3. I'm not anti-nuke; I think it's a very acceptable alternative when plants are built and maintained properly and options are available for the disposal of used fuel. That said, I don't believe that a 75 year old refurbished plant is a reasonable option no matter how many billions are spent of refurbishment.

    As far as ground movement rating, in their own documentation released to the media, PG&E uses the 7.5 magnitude number.

    Despite your beliefs, as a geoscientist, I know that earthquake magnitude prediction is far from precise and is only predictable within a range of values since earthquake measurement is a relatively new science, especially when compared to the millennia that these faults have been around for.

    Thanks for your comments even though we may choose to disagree.

  4. Here's a quote Kory Raftery of PG&E:

    "Diablo Canyon, meanwhile, could operate safely during up to a 7.5-magnitude earthquake, according to PG&E spokesman Kory Raftery. The four faults near the plant could potentially produce an earthquake of up to 6 to 6.5 magnitude, he said.

    Once again, even PG&E uses the 7.5 magnitude number.

  5. The investigation of the construction blunder is part of an inquiry by the Federal Nuclear Regulatory Commission into design errors in the earthquake-safeguard systems at the plant.

  6. It was the tsunami, which you've responsibly noted could not damage diablo canyon.

  7. Scientists can accurately predict the largest possible movement based on the size of the fault, and, unlike the Japanese, our plants are designed to withstand movement beyond this maximum - and even still it wasn't the earthquake that caused any substantial damage to the cooling systems.

  8. The plans for installation of the safety supports for the twin reactors were depicted on a single transparency with plans for one reactor on one side of the blueprint and plans for the other on the opposite side.

  9. Why oh why did we begin building and approving nuclear plants when we knew we had a finite amount of space with no way of disposing spent rods? I don't get it. I know it's off topic, but I'm so frustrated. Thanks for the info on your site.

  10. I can't believe that this radiation has traveled so far so quickly. They are trying to downplay the safety issues and magnifying the less harmful substance. The fact is that the cesium 137 is also approaching maximum safe levels in our drinking water and food supply. We need to be sure to rinse our foods in sea salt or nascent iodine and treat our water with a Water Purification Tablet and reverse osmosis or distillation or get it from a source that does that. This is really important to keeping us all healthy.

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  11. Oh, these so nuclear people are so unbelievably naive and ignorant... "It can't happen to our nuclear plants! They are completely safe and secure!" Guess who's been saying the same thing? The owner of the Fukushima plants. And what did they say when their plants were on the verge of a nuclear meltdown? "It was unexpected".

    They point out that "it was the tsunami"... yet a tsunami is only one of the many things that could go wrong in a nuclear accident. It wasn't just the tsunami, all the tsunami did was take out all the backup diesel generators. The earthquake also did a considerable amount of damage. It took out the all coolants, as well as the emergency coolants (ECCS). It also damaged some of the pipes, caused some cracks and leakages in the containment vessels, wet wells, damaged the spent nuclear fuel pools, etc. It also heavily damaged the central control room, which is required to get all the information about the containment vessel. What would happen if the building happens to collapse? Or worse, what would happen if the containment vessel or the pressure vessel gets knocked out, cracked, explode, etc? They were only lucky that the control rods could be inserted into the pressure vessel during the SCRAM to avoid re-criticality, which could have lead to a Chernobyl style meltdown. Basically, there's A LOT of things that could go wrong in a nuclear accident.

    It's unbelievable how little these nuclear people know about the very nuclear plants that they allegedly support...

  12. Love that photo of the Diablo Canyon nuclear power plant. The original is from Marya Figueroa:
    BTW, great blog - good information and analysis, well presented.


    I spotted a couple statements which you might want to verify: 1) DCPP is about 12 miles West Southwest (as the crow flies) from San Luis Obispo, not North as indicated; and 2) The notation about the "transparent" BLUEprints is quite interesting. As a resident for over 25 years and a person with an avid interest in DCPP, I heard another version with different facts: The BLUEPRINTS from Unit 1 were reproduced for Unit 2, but were reversed (the lettering was backwards!) and they built Unit 2 ass-backwards. My business accountant worked at DCPP and my landlord (an engineer) also worked there -- both verified this story. Engineers hate being caught doing these things! I think it's funny -- apparently the "containment dome" was supposed to be at the opposite end of the building. Oh well...

    On a more serious note, the x-rays of the thousands and thousands of welds were never inspected -- they took them and filed them without inspecting to verify quality and continuity. I believe one could say this goes to the integrity issue of earthquake resistance. Snap, Crackle & Pop!

    Sidebar: At the beginning of the canyon going south from San Luis Obispo to the five cities area was a sign placed by PG&E (DCPP operators) that had as part of the message: "Diablo Canyon Nuclear Power Plant", but someone (I'm not saying who) changed it during the night to read: "Diablo Canyon UNclear Power Plant". I wish I had taken a photo!

    WOW -- All that money they generate for San Luis Obispo County and California! What they don't say is the profit generated by each of the two units every day they pump electricity onto the grid -- did someone say $1,000,000? Good, you're correct. BTW, they're running at 110% as often as possible to give their shareholders and CEO a financial gift beyond all expectations. What was that sound -- a bearing going bad?

    So many stories, so little time.

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  17. all this theoretical discussion is a waste of time and money. Solar power is cheaper and has no clean up costs, (which by the way were never included into the economic models the nuclear proponents used in selling this dishonest boondoggle to us.) The writing is on the wall. Nukes are a stupid mans solution only supported by lies at this point. TURN IT OFF.

  18. When the Federal Nuclear Regulatory Commission wanted other plants shut down, they closed. Despite warnings from the commission, along with the scathing report against PG&E from the Union of Concerned Scientists, PG&E has arrogantly refused to shut down Diablo Canyon.

    This is extremely unethical behavior on the part of a public utility. When the Hosgri fault quake strikes, there will be class action lawsuits against the utilities.

    We must contact our elected representatives - federal, state, and local, and also President Obama and Vice President Biden, and shut down Diablo Canyon.

    Think about an offshore oil facility that sustains damage from a natural disaster and catches on fire. That does not create permanent damage to the ecosystem. However, if Diablo Canyon goes, then the entire Central Valley and California Coast from Thousand Oaks to Salinas is contaminated.

    Nuclear power is "safer" in places without any earthquakes, such as the Palo Verde generating station SW of Phoenix. But Diablo Canyon is just 2 miles from the powerful Hosgri Fault. The Lompoc 7+ quake on the Hosgri fault was one of the most powerful quakes in southern California.

    Here is a summary of the Union of Concerned Scientists report, released on November 13, 2013 -

    NRC Fails to Apply Standard Earthquake Protection Protocols to Diablo Canyon Nuclear Plant, Report Finds
    WASHINGTON (November 13, 2013)—The Nuclear Regulatory Commission is not holding the Diablo Canyon nuclear plant in California to the same standards it requires of every other nuclear facility to address potential earthquake hazards, according to a report released today by the Union of Concerned Scientists. UCS prepared the report, “Seismic Shift: Diablo Canyon Literally and Figuratively on Shaky Ground,” for the Alliance for Nuclear Responsibility.

    On the union of concerned scientists web site, note the new book for 2014 that discusses how reactors in the
    US are not safe - "Fukushima: The Story of a Nuclear Disaster"