Diablo Canyon earthquake vulnerability: Difference between revisions - Wikipedia

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{{Short description|Environmental issue in California}}

{{Merge to|Diablo Canyon Power Plant|discuss=Talk:Diablo Canyon Power Plant#Proposed merge of Diablo Canyon earthquake vulnerability into Diablo Canyon Power Plant|date=January 2024}}

'''Diablo Canyon (Nuclear) Power Plant''', located in San Luis Obispo County California, was originally designed to withstand a 6.75 magnitude [[earthquake]] from four faults, including the nearby [[San Andreas fault|San AndreasFault]] and [[Hosgri faultFault]]s,<ref>{{cite magazine| url=http://www.time.com/time/magazine/article/0,9171,917988,00.html | archive-url=https://web.archive.org/web/20090326060511/http://www.time.com/time/magazine/article/0,9171,917988,00.html | url-status=dead | archive-date=March 26, 2009 | magazine=Time | title=Energy: A Nuclear Horror | date=February 9, 1976 | access-date=July 14, 2010}}</ref> but was later upgraded to withstand a 7.5&nbsp;magnitude quake.<ref>{{cite news | author=David Sneed | title=Diablo Canyon workshop to focus on earthquakes | work=The San Luis Obispo Tribune | date=August 9, 2011 | url=http://www.sanluisobispo.com/2010/08/08/1244213/diablo-canyon-workshop-september.html | access-date=June 23, 2011 | archive-url=https://web.archive.org/web/20110317193217/http://www.sanluisobispo.com/2010/08/08/1244213/diablo-canyon-workshop-september.html | archive-date=March 17, 2011 | url-status=dead }}</ref> It has redundant seismic monitoring and a safety system designed to shut it down promptly in the event of significant [[ground motion]].

In 2008 the [[Shoreline Fault]], which passes less than a mile from the plant, was discovered.<ref name="sciencedaily.com">{{Cite web|url=https://www.sciencedaily.com/releases/2010/06/100602215239.htm|title=Revised seismotectonic model for California Central Coast: More complex than previously thought|website=ScienceDaily}}</ref> The fault has the potential of triggering a 6.5-magnitude earthquake.<ref>{{Cite web|url=https://santamariatimes.com/news/local/govt-and-politics/supervisors-request-delay-for-diablo-relicensing/article_8c1f14cc-2c11-11df-b385-001cc4c03286.html|title=Supervisors request delay for Diablo relicensing|first=April|last=Charlton|website=Santa Maria Times|date=10 March 2010 }}</ref> Because the [[Richter magnitude scale]] is logarithmic, Diablo Canyon is designed to withstand an earthquake of shaking amplitude ten times larger than that which the Shoreline fault is capable of triggering, based on an analysis by plant owner Pacific Gas & Electric (PG&E).

==Introduction==

[[Diablo Canyon Power Plant]] (DCNPP/DCPP) is located proximal to the [[Los Osos fault|Los Osos]], [[Hosgri fault|Hosgri]], San Andreas and [[Shoreline fault]]s. The discovery of these faults required design modifications during construction of the plant.

The Shoreline Fault is described in the November 2008 PG&E report as an "alignment of microseismicity subparallel to the coastline indicating the possible presence of a previously unidentified fault located about 1 km offshore of DCPP."<ref name="pge.com">{{cite web|url=http://www.pge.com/includes/docs/pdfs/shared/edusafety/systemworks/dcpp/2_SFZ_EXECUTIVE_SUMMARY.pdf|title=Shoreline Fault Zone Executive Summary|date=n.d.|publisher=PGE.com|url-status=live|archive-date=2011-07-09|archive-url=https://web.archive.org/web/20110709031854/https://www.pge.com/includes/docs/pdfs/shared/edusafety/systemworks/dcpp/2_SFZ_EXECUTIVE_SUMMARY.pdf}}</ref> The plant's current operating license expires in 20242030 and, in the aftermath of the Tohoku earthquake and tsunami, there is renewed opposition due to public perception that the risk of earthquake or tsunami might make the plant unsafe. Re-licensing is contingent upon consistency with the Coastal Act and thus review by the [[California Coastal Commission]], however seismic issues are more properly within the purview of the Nuclear Regulatory Commission. The NRC in June 2011 announced that it had already completed its Safety Evaluation Report (SER) for the plant.<ref>{{cite web|url=http://pbadupws.nrc.gov/docs/ML1115/ML11153A103.pdf|title=Safety Evaluation Report|date=2011|publisher=US Nuclear Regulatory Commission Office of Nuclear Reactor Regulation|url-status=live|archive-date=2017-05-17|archive-url=https://web.archive.org/web/20170517212533/https://www.nrc.gov/docs/ML1115/ML11153A103.pdf}}</ref> In July, 2016 PG&E announced that it does not plan on relicensing either of its two Units.

==Public controversy==

Critics contend that the Diablo Canyon (Nuclear) Power Plant was built so close to a set of geological fault lines that it is "for all practical purposes" to be regarded as built "directly over" a [[Fault (geology)|fault]].<ref>{{cite book|last1=Wolff|first1=Paul|last2=Conn|first2=Dianne|last3=Evered|first3=Judith|date=2010|title=Protest Diablo: Living and Dying Under the Shadow of a Nuclear Power Plant – Living and Dying Under the Shadow of a Nuclear Power Plant|publisher=Judith Evered |isbn=978-1-4536-3619-60}}</ref><ref name="mothersforpeace.org">{{Cite web |url=http://www.mothersforpeace.org/ |title=Mothers for Peace|access-date=2019-07-24 |archive-url=https://web.archive.org/web/20110723112526/http://www.mothersforpeace.org/ |archive-date=2011-07-23 |url-status=dead }}</ref> They refer to the Hosgri fault, which was discovered while the plant was under construction. No scientific corroboration for these opinions has been presented, and PG&E maintains that "new and extensive scientific re-evaluations performed at the direction of the Nuclear Regulatory Commission (NRC) continue to show that Diablo Canyon can safely withstand earthquakes, tsunamis and flooding that could potentially occur in the region."<ref>{{Cite web|url=https://www.pge.com/en_US/safety/how-the-system-works/diablo-canyon-power-plant/seismic-safety-at-diablo-canyon/seismic-safety-at-diablo-canyon.page|title=Seismic Safety at Diablo Canyon|website=www.pge.com}}</ref>

On July 15, 2011, PBS aired a 17-minute video documenting the controversy over the discovery of the Shoreline fault.<ref>{{Cite web|url=https://www.pbs.org/video/need-to-know-diablo-canyon/|title=Need To Know &#124; Diablo Canyon &#124; Season 1|via=www.pbs.org}}</ref> It details the differences of opinion between PG&E and a USGS geologist who disagrees with PG&E's assessment of the length of the Shoreline fault, and the potential for shaking should slippage occur at the Hosgri/Shoreline faults simultaneously.

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==Geological perspectives==

Three Pliocene-Miocene marine sedimentary units dominate the geology of Diablo Canyon: the Pismo Formation, the Monterey Formation, and the Obispo Formation. According to a Lawrence-Berkeley report entitled Geologic Investigation of a Potential Site for a Next-Generation Reactor Neutrino Oscillation Experiment – Diablo Canyon, San Luis Obispo County, CA

<ref name=onishietal>{{cite web|url=https://www.osti.gov/servlets/purl/836047|title=Geologic Investigation of a Potential Site for a Next-Generation Reactor Neutrino Oscillation Experiment -- Diablo Canyon, San Luis Obispo County, CA|date=2004|last1=Onishi|first1=Celia Tiemi|last2=Dobson|first2=Patrick|last3=Seiji|first3=Nakagawa|last4=Glaser|first4=Steven|last5=Galic|first5=Dom|publisher=US Department of Energy Office of Scientific and Technical Information|doi=10.2172/836047 |url-status=live|archive-date=2018-07-24|archive-url=https://web.archive.org/web/20180724152428/https://www.osti.gov/biblio/836047}}</ref> the area is tectonically active, located east of the active Hosgri Fault and in the southern limb

of the northwest trending Pismo Syncline."

The Obispo Formation is made up of marine and volcaniclastic sedimentary rocks.<ref name=onishietal/>

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===Shoreline Fault===

{{Main|Shoreline faultFault}}

The Shoreline Fault is a 25&nbsp;km long vertical [[strike-slip fault]],<ref name="sciencedaily.com"/> identified in 2008, which lies approximately three hundred meters from the [[Diablo Canyon Nuclear Power Plant]] in California. According to [[Pacific Gas & Electric]], the fault may produce quakes up to 6.5 magnitude. Mandated three-dimensional seismic studies have not been yet completed, and are not prerequisites for reissuance of the operating licenses for the two onsite units.<ref>{{cite news | title=In The World of Nuclear Power Crisis | url=http://www.mindfully.org/Nucs/TMI-LifeMay79.htm | work=Life Magazine | date=May 1979 | pages=23–30 | access-date=July 14, 2010 | archive-url=https://web.archive.org/web/20110512165416/http://www.mindfully.org/Nucs/TMI-LifeMay79.htm | archive-date=May 12, 2011 | url-status=dead }}</ref>

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== Safety ==

According to USGS seismologist, [[Jeanne L. Hardebeck]], the Shoreline Fault has potential to trigger an earthquake of 6.4–6.8 magnitude,<ref>{{cite journal |last1=Hardebeck |first1=Jeanne L. |title=Geometry and earthquake potential of the shoreline fault, Central California |journal=Bulletin of the Seismological Society of America |volume=103 |issue=1 |date=2013 |pages=447–462 |doi=10.1785/0120120175 |bibcode=2013BuSSA.103..447H |url=https://pubs.er.usgs.gov/publication/70046870 |access-date=31 December 2018}}</ref> while the company asserts the facility is designed to withstand a 7.5 magnitude quake,<ref>{{cite web|url=http://www.santamariatimes.com/news/local/govt-and-politics/article_8c1f14cc-2c11-11df-b385-001cc4c03286.html|title=Supervisors request delay for Diablo relicensing|date=2010-03-10|publisher=Santa Maria Times|last=Charlton|first=April|access-date=2022-08-13}}</ref> and NRC's estimate of the risk each year of an earthquake intense enough to cause core damage to the reactor at Diablo Canyon was 1 in 23,810 according to an NRC study published in August 2010.<ref name="Dedman">{{cite news |first= Bill |last= Dedman | authorlink= Bill Dedman |title= What are the odds? US nuke plants ranked by quake risk |work= NBC News |date= March 17, 2011 |url= httphttps://www.nbcnews.com/id/42103936wbna42103936 |access-date= April 19, 2011 }}</ref><ref>{{Cite web |url=http://msnbcmedia.msn.com/i/msnbc/Sections/NEWS/quake%20nrc%20risk%20estimates.pdf |title=SAFETY/RISK ASSESSMENT RESULTS FOR GENERIC ISSUE 199, "IMPLICATIONS OF UPDATED PROBABILISTIC SEISMIC HAZARD ESTIMATES IN CENTRAL AND EASTERN UNITED STATES ON EXISTING PLANTS"|access-date=2011-06-23 |archive-date=2017-05-25 |archive-url=https://web.archive.org/web/20170525170632/http://msnbcmedia.msn.com/i/msnbc/Sections/NEWS/quake%20nrc%20risk%20estimates.pdf |url-status=dead }}</ref>

=== Preparedness ===

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The ongoing (as of 6/2011) seismic studies were recommended by the California Energy Commission and are approved and funded by the California Public Utilities Commission.<ref>{{cite web|url=https://www.waterboards.ca.gov/water_issues/programs/ocean/cwa316/powerplants/diablo_canyon/docs/rc_dc_ltr041011.pdf|title=PG&E Letter DCL-11-047date=April 10, 2011|publisher=Waterboards.ca.gov|url-status=live|archive-date=2013-06-13|archive-url=https://web.archive.org/web/20130613010044/https://www.waterboards.ca.gov/water_issues/programs/ocean/cwa316/powerplants/diablo_canyon/docs/rc_dc_ltr041011.pdf}}</ref>

On June 21, 2016, PG&E announced a Joint Proposal with labor and environmental organizations to increase investment in energy efficiency, renewables and storage, while phasing out nuclear power. Specifically, the operating licenses for Diablo Canyon Units 1 and 2 will not be renewed. These are set to expire on November 2, 2024 and August 26, 2025 respectively.<ref>{{Cite web|url=https://www.pge.com/en/about/newsroom/newsdetails/index.page?title=20160621_in_step_with_californias_evolving_energy_policy_pge_labor_and_environmental_groups_announce_proposal_to_increase_energy_efficiency_renewables_and_storage_while_phasing_out_nuclear_power_over_the_next_decade|title=In Step With California's Evolving Energy Policy, PG&E, Labor and Environmental Groups Announce Proposal to Increase Energy Efficiency, Renewables and Storage While Phasing Out Nuclear Power Over the Next Decade &#124; PG&E|website=www.pge.com|access-date=2016-06-22|archive-date=2019-09-03|archive-url=https://web.archive.org/web/20190903152925/https://www.pge.com/en/about/newsroom/newsdetails/index.page?title=20160621_in_step_with_californias_evolving_energy_policy_pge_labor_and_environmental_groups_announce_proposal_to_increase_energy_efficiency_renewables_and_storage_while_phasing_out_nuclear_power_over_the_next_decade|url-status=dead}}</ref>

== See also ==