Review of San Onofre Original Steam Generator Wear

Citizens Oversight (2015-02-26) Ray Lutz

This Page: https://copswiki.org/Common/M1553
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.

QUESTION

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

PROCEDURE

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

CHANGES TO THE PLANT, UPRATING AND T(COLD) REDUCTION

• ReductionOfTcold_ML022000203.pdf: Reduction of T(cold) (Feb 12, 1999)
  • T-Cold Reduction Comments regarding SG:
    

• 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):
  
• There were other changes requested concerning how the inspections would be performed in the tubesheet region (not uploaded yet)

INSPECTION REPORTS
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: http://www.copswiki.org/Common/M1553

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 raylutz@citizensoversight.org 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.

Sincerely,
Amy Anderson
EPRI Customer Assistance Center
askepri@epricom
800-313-3774

ESTIMATED OSG LIFE FROM SGRP PROCEEDING

• SCE-42_from_A05-02-026001.pdf: Exhibit SCE-42 from the RSGP proceeding in 2005 speculating on probability of reaching the plugging limit

TUBES PLUGGED SUMMARY BY YEAR

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

Notes:

• 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.

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• SONGS OSG dimensions:
  

• Tube Location Map:
  

• Overall dimensions in comparison with other steam generators:
  

• OSG components:
  

• OSG tubes at the top of the arc:
  

• RSG tube arch:
  

• Tube failures in RSG:
  

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