Adding a Piece to the Seismic Puzzle

Clifford Munson
Sr. Technical Advisor for Nuclear Plant Siting
Office of New Reactors

One of the important lessons from 2011’s Fukushima Dai-ichi accident was the need for U.S. reactors to better understand their earthquake hazard. Reaching that understanding is a bit like assembling a jigsaw puzzle, and reactor owners in the central and eastern parts of the country are sending the NRC one of their pieces this month.

seismicThe graphic shows the three pieces of information U.S. reactor owners need in order to analyze their specific hazard:

• Where quakes are generated

• How the country’s overall geology transmits quake energy, and

• How an individual site’s geology can affect quake energy before it hits the reactor.

The first two pieces are taken care of. The NRC partnered with the Department of Energy and the Electric Power Research Institute to publish updated earthquake source information last year. We also recently approved the most recent model of quake energy transmission.

U.S. plants east of the Rocky Mountains have been enhancing their ability to describe their sites’ soil and rock properties, in some cases obtaining more information on what lies beneath the reactors. Sites made up primarily of hard rock (at left in the graphic) tend to amplify high-frequency quake energy, while sites with more of a soil-like makeup (at right) tend to amplify low-frequency energy.

Central and eastern U.S. reactor owners are starting the process of putting all three pieces together to update their site’s hazard. They’ll report the results to the NRC by March of next year. They’ve provided updates on their sites’ soil/rock makeup now so the NRC can examine the information and ensure it meets the basic standards needed for the overall hazard review. Plants west of the Rockies have a more complicated version of the puzzle to consider, so they’ll submit information to the NRC later.

Author: Moderator

Public Affairs Officer for the U.S. Nuclear Regulatory Commission

24 thoughts on “Adding a Piece to the Seismic Puzzle”

  1. To Anonymous
    A link, sure beats posting a bunch of blah blah, especially when it is not factual!

    Posting links to what the Former PM of Japan and/or the Former Chairman of the NRC are now saying are great ways to inject to this conversation!

  2. Learn about the studies done by award winning seismologist Jim Brune, who told us everything PG&E didn’t want us to know. En Echelon faults. Learn. stopthediablocanyonseismictesting on facebook

    Joey Racano, Director
    Ocean Outfall Group

  3. Anyone else notice that almost all of the anti-nuclear posters on this site post some sort of link to their own website in these replies? Fear sells, people.

  4. To: Clifford Munson
    What do you and the NRC have to say about what Robert J. Geller’s September 18, 2013 at 5:13 pm
    comment listed above?
    What does the Chairman of the NRC, a noted Geologist, have to say about the NRC siting methodology?

  5. Reply to Robert J. Geller September 18, 2013 at 5:13 pm
    Great comment ans I’d be interested in a short update on the two schools of thought you mentioned, especially the one that the NRC is not listening to…

  6. Great comment and thanks for the link to your paper, which I was glad to see included LUCK, which too often is left out of EQ analysis…

    I’d be very interested in your opinion of my comment just before yours which was written for the general public…:
    CaptD September 17, 2013 at 12:35 pm
    ===> Planning for the future by depending on the past does not guarantee nuclear safety!

  7. The Committee can do and/or say whatever they want but LUCK plays an important part of any earthquake defense as Robert J. Geller’s paper points out (see comment above).

    The NRC is now trying to somehow justify that the risk of another Fukushima nuclear accident happening is so small that it is “worth” taking the gamble, when in effect it is really a suckers bet when compared to using another form of energy which does not have any RISK of a nuclear accident…

    The NRC is protecting the nuclear industry while at the same time justifying its own usefulness, instead of protecting the USA from all future nuclear disasters caused by Nature…

  8. “Misrepresenting facts” in what way?

    You have a problem with probability being random?
    You don’t think the French Gov’t. did a good job with their investigation?

  9. As the only agency with regulatory discretion, the NRC should not allow any more plutonium production at least until such a time as its safe storage is solved.

    Joey Racano, Director
    Ocean Outfall Group .com

    On facebook: stop the diablo canyon seismic testing

  10. They are not doing it. The entire basis – MAAP and Relap – does not recognize the ignition and firestorm – the real process in the TMI-2, Chernobyl-4 reactors, Paks-2 fuel washing vessel, Fukushima Daiichi 1, 2 and 3 reactors – and misrepresent the rates of metal-coolant reaction.

    Therefore the required venting and cooling is for a false representation, not to prevent the real thing. See the Hydrogen re-combiners…

  11. In case you haven’t been following, the FLEX initiative and NRC orders require venting and cooling to prevent the metal-water reaction.

    If they are already doing it, how is it whitewashing?

  12. Random isn’t the right word. They happen in a more complex way than is prudent to have nuke plants on faults…

  13. This is a good question and the answer is that we don’t know yet. On a global level the “tapered Gutenberg-Richter” (G-R) distribution appears to be the best model of the frequency-magnitude relation. See a recent paper for example. As far as time-dependence, a Poisson model may be safest to use. There is unquestionably some time-dependence of probabilities, but absent an established model it may be dangerous to use more complex models of time-dependent probability variation.

    So this is a bit frustrating for everyone involved in this field. On the one hand, PSHA appears to work well, in the sense that if you turn the crank you get out definite numbers that seem to be authoritative, and give the customer what he/she wants to know to get on with the job. But, on the other hand, the hazard maps just don’t agree with the data The March 11, 2011 Tohoku earthquake (a magnitude-9 quake which occurred in a place where the national hazard map said only a magnitude-8 was expected, with a much lower hazard level than other regions of Japan that supposedly were at much greater risk) should have been a wake-up call not only for seismologists but for also for users of hazard maps, like the people reading this blog. But there seems to be a lot of cognitive dissonance here, as typified by the NRC post-Fukushima view that PSHA has solved the problem and that everything has been taken care of.

    Tthere seems to be a great demand for products that produce PSHA-type answers. Some research is being undertaken now (by the UCLA group, for example) on trying to get PSHA-type modeling done without using the characteristic earthquake model. But if it is appropriate to use the tapered G-R distribution on a regional basis (and this has not yet been established) the answers will vary enormously depending on the value of the “corner magnitude” which is selected.

    So, I suppose the bottom line is that nuclear engineers have to be aware that the PSHA models they are using appear to be giving answers that don’t agree with the data, so they’re probably not reliable, but that research has not come up with a consensus on what to replace them with. The nuclear community should also be aware that there is an ongoing debate in the seismological community, but that so far the nuclear community has only been listening to one side in this debate. So the nuclear community has to take responsibility for seismic and tsunami risk assessment issues rather than just taking whatever the usual group of consultants may tell them as established truth. Not what the nuclear community wants to hear, I suppose, but that’s the way it is.

  14. You say that the assumption of characteristic seismic events occurring periodically is incorrect. This seems fairly intuitive.

    If this is incorrect, then what is the correct assumption? That they occur at random?

  15. Another whitewashing effort from the NRC.
    The issue is the ignition and firestorm of the cladding, reducing the steam and generating metal oxide and Hydrogen. The earthquake is just one of the possible causes of this key process in a severe accident.
    Yes, there is a possibility to avoid such events, the severe destruction of reactor cores, if we prevent the ignition of cladding-coolant interaction. Yes, we can keep cold the cladding, if we vent the steam and relieve the pressure in the reactor and provide sufficient staged by the different pressure levels passive coolant reserves.
    Why are there such whitewashing efforts instead in the NRC?

  16. The people of the United States and elsewhere have already done your work for you. And we have found that the dangers posed by the use of nuclear energy far outweigh any benefits. The waste lasts so long that something is bound to happen no matter what we do, or how we plan or prepare. 200 thousand years is a long time and you won’t be around to see your waste safely through the bottleneck. Earth movement is a danger as well, but your seismic tests can actually cause Earth movement, so your disease is terrible but your cure is fatal! No nukes is no fukushima. No nukes is no Chernobyl. No nukes is good news. Goodbye nukes. hello sunshine.

    On Facebook: stop the diablo canyon seismic testing

    Joey Racano, Director
    Ocean Outfall Group .com

  17. Sorry, but Dr. Munson appears not to have been following recent research in seismology. Let me bring you up to date. The research in the pdf file he cites is based on a probabilistic model that makes particular assumptions about how earthquakes occur. Essentially the assumption being used is that “characteristic earthquakes” (the hypothetical “maximum earthquake” in each region) recur more or less periodically. That assumption unfortunately has failed to survive statistical testing. For example, see our paper which explains this (Y.Y. Kagan, D.D..Jackson, R.J. Geller: Seismological Research Letters, 2012):

    Then please take a look at the our paper that I cited in my earlier post, which shows that in fact the hazard maps simply aren’t working:

    Finally, you can take a look at a criticism of our paper on the problems of current hazard maps by one of the leading hazard map makers and our reply to his criticism, published in Tectonophysics in 2013: Essentially the hazard mapper says that lots of guys have all agreed on a consensus, so how can they possibly be wrong. To which we reply, because physics works by objective testing, not consensus, and your models don’t agree with the data, so they’re wrong.

    It would be desirable for the people in the nuclear industry to keep up on current research in seismology, and to realize that to date you’ve apparently only been listening to one group of people who are wedded to a particular model, one that alas fails to agree with the data. There should be a better and more inclusive dialog from now on.

  18. The NRC is aware how important it is to clearly identify and incorporate uncertainty into seismic hazard evaluations. We use a detailed and comprehensive approach for modeling seismic hazards that seeks to include all technically defensible interpretations into the final hazard estimates. This “Senior Seismic Hazard Analysis Committee” approach is described in detail in NUREG 2117, online at .

    Clifford Munson

  19. ===> Planning for the future by depending on the past does not guarantee nuclear safety!

    FACT: A once in a hundred year or even a thousand year event is just as likely to happen tomorrow as many years in the future; then what?

    This is where the NRC and the nuclear Industry fails the public trust because they live in Nuclear Denial* because they believe nothing BAD will happen to any Nuclear Power Plants (NPP’s) because nothing BAD has happened before…

    The USA cannot afford a Trillion Dollar Eco-Disaster like Fukushima.

    French Nuclear Disaster Scenario Was So Bad The Government Kept It Secret… via @bi_contributors


    Catastrophic nuclear accidents, like Chernobyl in 1986 or Fukushima No. 1 in 2011, are, we’re incessantly told, very rare, and their probability of occurring infinitesimal.

    But when they do occur, they get costly. So costly that the French government, when it came up with cost estimates for an accident in France, kept them secret.

    But now the report was leaked to the French magazine, Le Journal de Dimanche. Turns out, the upper end of the cost spectrum of an accident at the nuclear power plant at Dampierre, in the Department of Loiret in north-central France, amounted to over three times the country’s GDP.


    The illogical belief that Nature cannot destroy any land based nuclear reactor, any place anytime 24/7/365!

  20. Unfortunately the situation may be somewhat more complicated than is suggested by this post. The problem is that the methods being used to make the seismic hazard maps have not been validated, and in many recent cases cases damaging earthquakes have occurred in areas specified by the hazard maps as being at relatively low risk. Please see our recent the paper in Tectonophysics (by S. Stein, R.J. Geller, and M. Liu, 2012) for more details.

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