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Question About AP1000's PCCS

  1. Jun 11, 2010 #1
    Hello, my mother recently sent me a very mediocre article showing concerns regarding the Westinghouse AP1000 PWR with PCCS. The thrust of the concern seemed to be the possibility that the steel shielding could corrode, or be otherwise compromised by an earthquake, leading to a radioactive release a la the chimney effect. I am not a nuclear engineer, but it didn't seem likely to me, given the proposed construction. I did say that I would ask some people who are nuclear engineers, and I would guess there are a few here. To me, the massive reduction in moving parts, and the explosive locks seem to be enhancing safety. I assume this reactor can be SCRAMed like any other as well. Am I missing something, or is this the usual anti-nuclear hysteria?
  2. jcsd
  3. Jun 11, 2010 #2


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    Explosive locks?

    Reactors are designed to scram at level below a design basis earthquake.

    Reactors are enclosed in a containment of reinforced concrete, which has a steel liner. The objective in passive cooling is to have a reservoir of cooling water that does not have to be forced by pumps.

    I believe that article's premise is faulty.
  4. Jun 12, 2010 #3
    Excellent, that is what I was hoping to hear. Thanks very much.

    I've been informed that I am twice the fool; not explosive locks, but explosive and DC operated valves:
    . I believe the concern is that there is a space between the steel and concrete structures, and that the convection cooling at the top of the stack could draw radioactive contaminants through a space between the concrete and the steel. To me, it still sounds extremely safe, and the valves are just another means to scram with redundancy.

    I just asked for a link to the article, and here it is (a blog, not an article it turns out). There is talk of a lack of backup containment, but I've never heard of a reactor with so much steel shielding, and what is the concrete if not "backup"?


    I'll be blunt: I think this is nonsense, but I want to be able to say I asked the questions asked of me. Thanks again Atronuc, I don't think any of this changes your conclusion.
    Last edited: Jun 12, 2010
  5. Jun 12, 2010 #4


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    I'm curious about the article, particularly the basis for any claims as to what might occur and what might be the consequences thereof.

    It's not like we site plants without consideration as to the geologic/seismic history. In fact, site characterization includes a detailed assessment regarding the geology and seismic history, including the presence of faults and other features. The plants containment and mechanical systems are designed according to accelerations that are expected to occur, and for some systems or components, much higher - like 4 g or 6 g.

    Thanks for posting the link.

    It will take time to work through Gunderson's report, but from a cursory glance there's some apples-oranges associations.
    Last edited: Jun 12, 2010
  6. Jun 12, 2010 #5
    Thanks Atronuc, you're a scholar and a gentleman. :) I look forward to your conclusions, but as you say, how would a huge earthquake be different for this than a LWR, or even a Gen IV reactor? If it cracks that much steel and concrete, I think a little radioactive steam is the least concern for that region. Anyway, take your time, and thanks for giving this a read.
  7. Jun 18, 2010 #6
    I'm reminded of a little extract from some classic literature:

  8. Jun 18, 2010 #7
    That is one of my favorite books of all time, along with Joyce's Ulysses. Neal Stephenson is god. :)

    Your point is well taken too, thanks!
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