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Review of San Onofre Original Steam Generator Wear

Citizens Oversight (2015-02-26) Ray Lutz

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More Info: Coalition To Decommission San Onofre, Shutdown Diablo, Shut San Onofre

Southern California Edison was the licensee and primary operator of the San Onofre nuclear plant.
  1. On Feb 12, 1999, SCE obtained NRC approval to reduce T(cold)
  2. On April 3, 2001, SCE obtained NRC approval for core 'uprating'

  • In both of the applications, SCE explained at some length how these changes could put additional stress on the original steam generators (OSGs). But they said they would monitor the situation carefully.
  • SCE claimed in their 2005 application to replace the OSGs that they were going to reach their safe plugging limit prior to their expected life.
  • They replaced the OSGs and the replacement steam generators failed very quickly, with Unit 3 experiencing an emergency shutdown and leak in only 11 months.

  • Did the changes to uprate the core and reduce T(cold) result in premature plugging of tubes in the OSGs?


Citizens Oversight obtained many of the OSG inspection reports. Unfortunately, as of the date of this writing (2015-02-26) only reports back to 2000 were available on line at the NRC, with the exception of one (combination) report from the 1986 timeframe. To complete this investigation, we will need all the reports. They are probably available only in hardcopy form from the NRC. We have not pursued getting these yet.

From these reports we will extract the number of tubes plugged to get an idea of the rate of deterioration of the OSGs. Did the change of T(cold) and the uprate of the core accelerate the wear?

The documents


  • CoreThermalUprating_ML010950020.pdf: Core Thermal Uprating (April 3, 2001)
  • Excerpt of comments on SG tubes due to uprate (See document for full description as it goes on for several pages):
    Power Uprate Comments on SG Tubes.JPG
  • There were other changes requested concerning how the inspections would be performed in the tubesheet region (not uploaded yet)

Listed here are all the In-Service Inspection (ISI) reports on the NRC website for the SONGS OSGs.
  • 1987-02-20-U2U3-ML13304A328.pdf: Combined report from 1987 for Unit 2 and 3 (Cycle 01?)
  • 1987-04-27-Unit2-ML13303B837.pdf: 1987-04-27-Unit2-ML13303B837.pdf (Cycle 01?)
  • U2C02 In-Service Inspection Report - (N/A from NRC Website)
  • U3C02 In-Service Inspection Report - (N/A from NRC Website)
  • U2C03 In-Service Inspection Report - (N/A from NRC Website)
  • U3C03 In-Service Inspection Report - (N/A from NRC Website)
  • U2C04 In-Service Inspection Report - (N/A from NRC Website)
  • U3C04 In-Service Inspection Report - (N/A from NRC Website)
  • U2C05 In-Service Inspection Report - (N/A from NRC Website)
  • U3C05 In-Service Inspection Report - (N/A from NRC Website)
  • U2C06 In-Service Inspection Report - (N/A from NRC Website)
  • U3C06 In-Service Inspection Report - (N/A from NRC Website)
  • U2C07 In-Service Inspection Report - (N/A from NRC Website)
  • U3C07 In-Service Inspection Report - (N/A from NRC Website)
  • U2C08 In-Service Inspection Report - (N/A from NRC Website)
  • U3C08 In-Service Inspection Report - (N/A from NRC Website)
  • U2C09 In-Service Inspection Report - (N/A from NRC Website)
  • U3C09 In-Service Inspection Report - (N/A from NRC Website)
  • U2C10 In-Service Inspection Report - (N/A from NRC Website)
  • 2000-03-30-U3C10-ML003703380.pdf: 2000-03-30-U3C10-ML003703380.pdf
    • This report contains extensive theoretical discussion on models of the rate of wear.
  • 2000-11-13-U2C11-ML003769006.pdf: 2000-11-13-U2C11-ML003769006.pdf
  • 2001-01-26-U3C11-ML010300267.pdf: 2001-01-26-U3C11-ML010300267.pdf (9 months)
  • 2002-06-14-U2C12-ML021690382.pdf: 2002-06-14-U2C12-ML021690382.pdf (18 months)
  • 2003-02-07-U3C12-ML030420183.pdf: 2003-02-07-U3C12-ML030420183.pdf (12 months)
  • 2004-03-17-U2C13-ML040850599.pdf: 2004-03-17-U2C13-ML040850599.pdf (21 months)
  • 2004-10-25-U3C13-ML043020275.pdf: 2004-10-25-U3C13-ML043020275.pdf (20 months)
  • 2006-02-07-U2C14-ML060400103.pdf: 2006-02-07-U2C14-ML060400103.pdf (23 months)
  • 2007-05-25-U3C14-ML071520093.pdf: 2007-05-25-U3C14-ML071520093.pdf (19 months)
  • 2008-06-19-U2C15-ML081780098.pdf: 2008-06-19-U2C15-ML081780098.pdf (28 months)
  • 2009-04-24-U3C15-ML091210114.pdf: 2009-04-24-U3C15-ML091210114.pdf (23 months)

The other reports have been requested from the NRC, submitted on 2015-02-26:
We are doing a research project regarding the rate of deterioration of the Original Steam Generators (OSGs) at the San Onofre Nuclear Generating Station (SONGS) units 2 and 3. The information I need is in the "In Service Inspection" (ISI) reports. I have found some reports for the 1987 time frame on ADAMS and then from 2000 on, cycle 10 to cycle 15. But prior to that time, nothing is in ADAMS. Plus, I do not know how to do a search for those documents so I can give you the exact accessor number.

The documents I have accessed that are relevant are on this web page:

For example, these two documents are from 1987. However, they do not provide the same level of detail as subsequent reports

  • 1987-02-20-U2U3 -- ML 13304 A 328.pdf: Combined report from 1987 for Unit 2 and 3 (Cycle 01?)
  • 1987-04-27-Unit2 -- ML 13303 B 837.pdf (Cycle 01?)

The first one in ADAMS after that is this one for Unit 3 Cycle 10 (U 3 C 10)
  • 2000-03-30-U3C10 -- ML003703380.pdf

If all the cycles are available for both units, I am looking for probably 17 additional ISI reports. U 2 C 2, U 3 C 2, U 2 C 4, U 3 C 4 ... U 2 C 10 (But I am not sure if the 1987 reports are for Cycle 1). Can you give me an idea of whether this is easily available and what the cost would be? I am in San Diego so a trip to the reading room would be quite expensive... (plus I'm not looking forward to your weather this time of year!!) Should I submit a FOIA request or ??

CONTACT INFO: Ray Lutz Citizens Oversight 619-820-5321 Your help is very much appreciated!

A similar email was sent to EPRI, and this response was received:
Dear Ray,

Thank you for contacting the EPRI Customer Assistance Center. Unfortunately, we do not have the information you are looking for. Your Utility Commission may have other resources to assist you.

Amy Anderson
EPRI Customer Assistance Center


SG C10 C10 C11 C12 C12 C13   C14 C14 C15 C15
  1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
U2-088     724 773 773 939 939 1257 1257 1390 1390
U2-089     765 817 817 960 960 1126 1126 1251 1251
U3-088   529 586 586 658 704 704 704 733 733 753
U3-089   481 522 522 589 651 651 651 662 662 678

  • Although we have reports from 1987, they do not report total tubes already plugged.
  • When OSGs were first installed, there was substantial tube damage to the central area of tubes near the central support.
  • Numbers above are repeated from prior years if no Refueling Outage (RFO) occurred in that year to provide continuous line in chart.


  • SONGS OSG dimensions:
    CE Model 3410 TubeSupportDwg.jpg

  • Tube Location Map:

  • Overall dimensions in comparison with other steam generators:
    Examples of steam generators made by Mitsubishi to be sold outside of Japan.jpg

  • OSG components:

  • OSG tubes at the top of the arc:

  • RSG tube arch:
    steam generator tubes  t700.jpg

  • Tube failures in RSG:
    SONGS RSG wear.jpg


Media Form edit

Title Review of San Onofre Original Steam Generator Wear
Publisher Citizens Oversight
Author Ray Lutz
Pub Date 2015-02-26
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Note Decisions by Southern California Edison to 'uprate' the core and decrease T(cold) may have shortened OSG life.
Keywords Coalition To Decommission San Onofre, Shutdown Diablo, Shut San Onofre
Media Type Article, Dataset
Media Group News, Research
Curator Rating Plain
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Topic attachments
I Attachment Action Size Date Who Comment
1987-02-20-U2U3-ML13304A328.pdfpdf 1987-02-20-U2U3-ML13304A328.pdf manage 428 K 2015-02-27 - 00:49 Raymond Lutz Combined report from 1987 for Unit 2 and 3
1987-04-27-Unit2-ML13303B837.pdfpdf 1987-04-27-Unit2-ML13303B837.pdf manage 266 K 2015-02-27 - 00:51 Raymond Lutz  
2000-03-30-U3C10-ML003703380.pdfpdf 2000-03-30-U3C10-ML003703380.pdf manage 2 MB 2015-02-27 - 00:52 Raymond Lutz  
2000-11-13-U2C11-ML003769006.pdfpdf 2000-11-13-U2C11-ML003769006.pdf manage 3 MB 2015-02-27 - 00:53 Raymond Lutz  
2001-01-26-U3C11-ML010300267.pdfpdf 2001-01-26-U3C11-ML010300267.pdf manage 3 MB 2015-02-27 - 00:55 Raymond Lutz  
2002-06-14-U2C12-ML021690382.pdfpdf 2002-06-14-U2C12-ML021690382.pdf manage 2 MB 2015-02-27 - 00:55 Raymond Lutz  
2003-02-07-U3C12-ML030420183.pdfpdf 2003-02-07-U3C12-ML030420183.pdf manage 7 MB 2015-02-27 - 00:58 Raymond Lutz  
2004-03-17-U2C13-ML040850599.pdfpdf 2004-03-17-U2C13-ML040850599.pdf manage 4 MB 2015-02-27 - 01:00 Raymond Lutz  
2004-10-25-U3C13-ML043020275.pdfpdf 2004-10-25-U3C13-ML043020275.pdf manage 3 MB 2015-02-27 - 01:01 Raymond Lutz  
2006-02-07-U2C14-ML060400103.pdfpdf 2006-02-07-U2C14-ML060400103.pdf manage 3 MB 2015-02-27 - 01:07 Raymond Lutz  
2007-05-25-U3C14-ML071520093.pdfpdf 2007-05-25-U3C14-ML071520093.pdf manage 3 MB 2015-02-27 - 01:08 Raymond Lutz  
2008-06-19-U2C15-ML081780098.pdfpdf 2008-06-19-U2C15-ML081780098.pdf manage 2 MB 2015-02-27 - 01:27 Raymond Lutz  
2009-04-24-U3C15-ML091210114.pdfpdf 2009-04-24-U3C15-ML091210114.pdf manage 3 MB 2015-02-27 - 01:36 Raymond Lutz  
CE_Model_3410_TubeSupportDwg.jpgjpg CE_Model_3410_TubeSupportDwg.jpg manage 37 K 2015-02-27 - 04:53 Raymond Lutz SONGS OSG dimensions
Chart-C10-15.jpgjpg Chart-C10-15.jpg manage 33 K 2015-02-27 - 02:29 Raymond Lutz  
CombustionEngineeringTubeSheetMap.jpgjpg CombustionEngineeringTubeSheetMap.jpg manage 143 K 2015-02-27 - 04:53 Raymond Lutz Tube Location Map
CoreThermalUprating_ML010950020.pdfpdf CoreThermalUprating_ML010950020.pdf manage 4 MB 2015-02-27 - 00:46 Raymond Lutz  
Examples_of_steam_generators_made_by_Mitsubishi_to_be_sold_outside_of_Japan.jpgjpg Examples_of_steam_generators_made_by_Mitsubishi_to_be_sold_outside_of_Japan.jpg manage 88 K 2015-02-27 - 04:54 Raymond Lutz Overall dimensions in comparison with other steam generators
Power_Uprate_Comments_on_SG_Tubes.JPGJPG Power_Uprate_Comments_on_SG_Tubes.JPG manage 73 K 2015-12-01 - 21:51 Raymond Lutz Excerpt of comments on SG tubes due to uprate
ReductionOfTcold_ML022000203.pdfpdf ReductionOfTcold_ML022000203.pdf manage 898 K 2015-02-27 - 00:47 Raymond Lutz  
SCE-42_from_A05-02-026001.pdfpdf SCE-42_from_A05-02-026001.pdf manage 407 K 2015-02-27 - 00:48 Raymond Lutz Exhibit SCE-42 from the RSGP proceeding in 2005 speculating on probability of reaching the plugging limit
SONGS-OSG.jpgjpg SONGS-OSG.jpg manage 75 K 2015-02-27 - 04:55 Raymond Lutz OSG components
SONGS_RSG_wear.jpgjpg SONGS_RSG_wear.jpg manage 96 K 2015-02-27 - 04:58 Raymond Lutz Tube failures in RSG
San-Onofre-SG2.pngpng San-Onofre-SG2.png manage 451 K 2015-02-27 - 04:57 Raymond Lutz OSG tubes at the top of the arc
T-Cold-Reduction-Comments-On-SG.JPGJPG T-Cold-Reduction-Comments-On-SG.JPG manage 68 K 2015-12-01 - 21:41 Raymond Lutz T-Cold Reduction Comments regarding SG
steam_generator_tubes__t700.jpgjpg steam_generator_tubes__t700.jpg manage 37 K 2015-02-27 - 04:58 Raymond Lutz RSG tube arch
Topic revision: r5 - 2015-12-18, RaymondLutz
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