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Plant aging Steam Generator Corrosion

  1. Mar 24, 2010 #1

    I am told that steam generator is an area that is suseptible to aging effects and corrosion. I was wondering if anyone can elaborate on this a bit. Is it just due to the heat and humididty? I am studying BWRs and safety and maintanced aspects and I was thinking of focusing on this area of plant.

    Last edited: Mar 24, 2010
  2. jcsd
  3. Mar 25, 2010 #2
    No, the chemistry of the feedwater is critically important, as is the material of the SG tubes (e.g., Inconel 600 vs. 690). The fabrication method (how the tubes are held in the tubesheet) may also play a role (through the stress in the joint). Google 'stress corrosion cracking'. Look on the NRC site under 'Alloy 600'.

    This doesn't make sense: BWRs do not have steam generators.
  4. Mar 25, 2010 #3
    Thanks for the response. Sorry I misspoke the steam line. Forgot BWR make steam right in the vessel. Is it true that both require separation of water vs steam. Is that where the steam line comes in.

    Lastly why would a rupture in the steam line cause pressure in the reactor to decrease i would figure the opposite would occur.

    Anyway I am very new to this stuff so sorry if these questions seem obvious or whatever.

    I will look up stress corrosion though
    Last edited: Mar 25, 2010
  5. Mar 25, 2010 #4


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    Main Steam line break would cause loss of pressure because the system looses inventory.

    The primary cooling system is more or less closed (excluding make up and leakage).

    BWRs have steam separators and dryers that allow 'dry' steam (as dry at saturated conditions as possible without superheat) to pass to the high pressure turbine. The separators and dryers are stainless steel, which are subject to stress corrosion cracking.

    Corrosion is a function of material composition (chemistry), microstructure (which is affected by fabrication processes), and environment (time, temperature, stress and water chemistry, and radation to some extent). There are nickel-bearing materials (Inconels) in some BWR components.

    Stainless steels and Inconels are susceptible to Intergranular (IG) stress corrosion cracking (SCC), or Irradiation-Assisted (IA) SCC.
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