Why fatigue damage will stop the NRC from allowing Unit 2 to restart




FATIGUE DAMAGE TO SONGS STEAM GENERATORS

J. Hopenfeld 

Provided to the “DAB Safety Team” as additional explanation of the fatigue damage to SONGS steam generators which was discussed in a report by the author and was submitted to the California Public Utility Commission on March 29, 2013


Note: Links to these documents are listed below 
SCE/MHI made a mistake in their stress analysis, which directly impacts the safety of restarting Unit 2.  When the error is corrected, the result clearly shows that Unit 2 has already used up its allowed fatigue life and is not fit for service any longer.  This means that if Unit 2 is restarted at any power level an abrupt pressure change such as inadvertent closing or opening of a valve or a steam line break could lead to a sudden tube ruptures.   The ASME code and NRC regulations do not permit safety components to operate when their fatigue life has been exhausted.

The source of MHI’s error resulted from how they calculated the increase in the local stress at geometrical discontinuities  (notches), which are formed when two metal surfaces come in contact during vibration.  Since the worn surfaces of the tubes inside the steam generators cannot be seen, MHI made two key assumptions, which are inconsistent with the observation that both the tube and the supporting bar are worn into each other.  First, MHI assumed that the ASME endurance limit could be applied directly to the notched tube surfaces.  Since it is commonly known that surface roughness significantly reduces fatigue life and since the ASME data is for smooth polished surfaces, this assumption would underestimate the amount of fatigue damage.  Second, when using the Peterson chart, MHI assumed unrealistically large fillet radius and consequently derived a low concentration stress factor.  Large radii would decrease the local stress and cause the tube to fail at a higher stress thereby increasing its fatigue life.  Only by using these two, arbitrary non-conservative, assumptions was MHI able to conclude that Unit 2 did not suffer any fatigue damage.

As depicted in the MHI drawings the support bar and the tube form a sharp discontinuity at the contacting surface, therefore the appropriate geometry for calculating the stress concentration is an abrupt geometry change (very small radii), not a large radius shoulder fillet that was assumed by MHI.  When a correction is made to account for the sharp notch, the corrected stress indicates  (see Figure 1 below) that the tubes have used up their fatigue life during the first cycle of operation.  Structures with sharp notches can fail catastrophically when subjected to high cycle vibrations.  (MHI redacted their assumption so the exact value of the radius they used is unknown.)

 The loss of fatigue life is a major defect in the tube material; NRC regulations 10CFR50, Appendix B, Criterion 16 specify that for a licensee to maintain his operating license, such non-conformance must be promptly identified and corrected.   The licensee must assure that “corrective action (is) taken to preclude repetition.  NRC’s General Design Criteria 4 and 10CFR50 Appendix A also specify that steam generator tubes must be able to “ accommodate the effects of loss of coolant accidents “ The fact that the NRC has not already raised these issues in any of their  “Requests for Additional Information, RAIs” indicates that the NRC would be ignoring its own regulations if it allows SCE to restart Unit 2.

 In Summary: The SCE request for approval to operate Unit 2 at 70 % power for 150 days provided no explanation for the selection of this inspection interval.  The absence of such explanation and the absence of an indication of the actions that would follow demonstrate the unreliability of SCE entire assessment of restarting Unit 2.  Edison did not specify pass/fail criteria for the tubes during the outage inspection.  Given the fact that fatigue damage does not lend itself to detection, SCE request is unacceptable and should be rejected. 

  

Aging Nuke Plants On Fault Lines In Tsunami Hazard Zones = Fukushimas… Any Questions?
PLEASE Turn off a light for Fukushima USA / San Onofre

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San Onofre Unit 2 Retainer Bars Could Cause Massive ? Leakage


In an accident like a main steam line break at San Onofre, the badly designed retainers bars in Unit 2 could actually make things much worse by causing more damage to any of the 9,727 already fatigued tubes in each of its steam generators which could lead to additional leakage of highly radioactive reactor core coolant and/or cause a nuclear incident or worse a nuclear accident like Fukushima!


Radioactive Leaks and ruptures can happen without notice:



Allegation/Violations

The NRC has decided in AIT follow-up report dated 11/09/2012, “Item 3. “(Closed) Unresolved Item 05000362/2012007-03, ‘Evaluation of Retainer Bars Vibration during the Original Design of the Replacement Steam Generators” as a non-cited violation in accordance with Section 2.3.2 of the NRC’s Enforcement Policy.”  However, as shown below, SCE/MHI’s failure to verify the adequacy of the retainer bar design as required by SCE/MHI’s procedures have resulted in plugging of several hundred tubes in the brand new replacement generators. This has resulted in these violations:

1. Failure to meet NRC Chairman Standards on Nuclear Safety by SCE,
2. Failure to meet Senator Boxer’s Committee on Environment and Public Works
(EPW) Standards on Nuclear Safety by SCE,
3. Failure to enforce SCE Edison Contract Document instructions to MHI by SCE,
4. Failure to meet SONGS Technical Specifications by SCE,
5. Failure to meet general design criteria (GDC) in Appendix A, “General Design
Criteria for Nuclear Power Plants,” to 10 CFR Part 50, “Domestic
Licensing of Production and Utilization Facilities GDC 14, “Reactor
Coolant Pressure Boundary” by SCE/MHI,
6. Failure to demonstrate that Unit 2 retainer bars will maintain tube bundle
geometry at 70% power due to fluid elastic instability during a main line
steam break (MSLB) design basis event, and
7. SCE/MHI took shortcuts by avoiding the 10 CFR 50.90 License Amendment
Process under the false pretense of “like for a like” replacement steam
generator.  SCE added 377 more tubes, increased the average length of the
heated tubes and changed the thermal-hydraulic operation of the RSGs without

proper safety analysis and inadequate 10CFR 50.59 Evaluation.

This intentional action to produce more thermal megawatts out of the

RSGs compromised safety at SONGS Unit 2 due to the failure of 90

percent through wall thickness of a tube by the inadequate design of the

r

etainer bar.


Recommended Actions:

NRC San Onofre Special Panel is requested to resolve the above listed Allegations and/or Violations within 30 days of receipt of this email and prior to granting SCE’s permission to do any restart “testing” of Unit 2. Answer all allegations factually, don’t just void them.
 
See Full Document:
Media Alert: San Onofre Retainer Bar Problems

Aging Nuke Plants On Fault Lines In Tsunami Hazard Zones = Fukushimas… Any Questions?
PLEASE Turn off a light for Fukushima USA / San Onofre

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San Onofre Legacy (SOL Part 1, 2 and 3)

The DAB Safety Team released three Media Alerts today!


Together they describe (in technical detail) the current situation at San Onofre, along with what SCE, their experts and other public nuclear watchdogs are now saying about all the NRC RESTART QUESTIONS they have been told to answer:


snip:
The following paper shows that the entire NRC Regulatory Process is underfunded, broken and needs additional funding, oversight and extensive overhaul to ensure public safety.
snip:
The presentation by SCE, Mitsubishi and other experts to the NRC was very disappointing and disturbing to 8.4 million Southern Californians.  The presentation did not address U.S. Sen. Barbara Boxer and Congressman Edward J. Markey’s concerns expressed on February 6, 2013 in her letter to NRC Chairman McFarlane, “Southern California Edison was aware of problems with replacement steam generators at its San Onofre nuclear power plant but chose not to make fixes.
snip:
The structural integrity of SONGS degraded retainer bar system to withstand combined loads that result from postulated accident conditions events has not been demonstrated.
Aging Nuke Plants On Fault Lines In Tsunami Hazard Zones = Fukushimas… Any Questions?
PLEASE Turn off a light for Fukushima USA / San Onofre

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Unsafe NRC Computer Model Requires Investigation

Snip from:

Press Release 13-01-22 ATHOS Validity Questioned, Qualifying Investigation Required

The validity of the ATHOS T/H computer model for San Onofre Unit 2 at Main Steam Line Break  conditions requires that the NRC Office of Nuclear …

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Unsafe NRC Computer Model Requires Investigation

Snip from:

Press Release 13-01-22 ATHOS Validity Questioned, Qualifying Investigation Required

The validity of the ATHOS T/H computer model for San Onofre Unit 2 at Main Steam Line Break  conditions requires that the NRC Office of Nuclear …

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SCE Violated Federal Reg.’s And the Public Trust

Nuclear Experts Agree, San Onofre’s Replacement Steam Generators Are Unsafe

Summation: Based upon our ongoing review of evaluations, engineering analyses, inspections, technical and operational assessment reports prepared by the NRC’s Augment…

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SCE Violated Federal Reg.’s And the Public Trust

Nuclear Experts Agree, San Onofre’s Replacement Steam Generators Are Unsafe

Summation: Based upon our ongoing review of evaluations, engineering analyses, inspections, technical and operational assessment reports prepared by the NRC’s Augment…

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TEN Unresolved Items, Requires NRR Investigate The NRC

The Unsatisfactory Status Of The NRC Region IV Augmented Inspection Team
Report Which Contains TEN Unresolved
Items, Requires Additional NRR Investigation
And Resolution.

The DAB Safety Team has transmitted the following to
the Chair…

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TEN Unresolved Items, Requires NRR Investigate The NRC

The Unsatisfactory Status Of The NRC Region IV Augmented Inspection Team
Report Which Contains TEN Unresolved
Items, Requires Additional NRR Investigation
And Resolution.

The DAB Safety Team has transmitted the following to
the Chair…

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NRC AIT Review Of San Onofre Requires An NRR Investigation

NRC AIT review of SCE 10CFR 50.59: The NRC AIT stated in its report, “Based on the updated final safety analysis report description of the original steam generators, the team determined that the steam generators major design changes were r…

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NRC AIT Review Of San Onofre Requires An NRR Investigation

NRC AIT review of SCE 10CFR 50.59: The NRC AIT stated in its report, “Based on the updated final safety analysis report description of the original steam generators, the team determined that the steam generators major design changes were r…

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Edison Pushes Restart, Despite UNSAFE Assessment

NRC No Restart at San Onofre

Steam
generator tubes and their support structures need to be extremely carefully
designed and manufactured within the allowed design tolerances.  These tubes preform a very important safety
function b…

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Edison Pushes Restart, Despite UNSAFE Assessment

NRC No Restart at San Onofre

Steam
generator tubes and their support structures need to be extremely carefully
designed and manufactured within the allowed design tolerances.  These tubes preform a very important safety
function b…

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San Onofre’s Unsafe Inspections Put SoCal At Risk

San Onofre Unit 2 Replacement Steam Generators Incomplete and Inadequate Tube Inspections

San Diego, CA (November 9, 2012) – The failure of eight Replacement Steam Generator (RSG) tubes (something which has never
happened before…

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San Onofre ALMOST Caused A Nuclear Disaster

PRESS RELEASE

DAB Safety Team   November 02, 2012

Media Contact: Don Leichtling
(619) 260-0160 or Ace Hoffman (760) 720-7261

FOR  IMMEDIATE  RELEASE 

Fluid Elastic Instability
(FEI) is a phenomenon that can…

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San Onofre ALMOST Caused A Nuclear Disaster

PRESS RELEASE

DAB Safety Team   November 02, 2012

Media Contact: Don Leichtling
(619) 260-0160 or Ace Hoffman (760) 720-7261

FOR  IMMEDIATE  RELEASE 

Fluid Elastic Instability
(FEI) is a phenomenon that can…

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10-18-12 SCE’s RSG Testing Update + New NRC Blog Topic

The NRC has just posted this new topic on their blog site:

In Response to Your Letters: Proposed Restart of SONGS Unit 2

by Allison Macfarlane

NRC Chairman

http://public-blog.nrc-gateway.gov/

You are encouraged to add you…

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CPUC – DRAFT ORDER INSTITUTING INVESTIGATION REGARDING SONGS UNITS 2 AND 3

The San Francisco-based California Public Utilities Commission on Tuesday published a draft investigation order regarding the idled San Onofre Nuclear Generating Station.

 It will take up the matter at a public meeting Oct. 25 in Irvine.&nb…

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FOE –> San Onofre – Feds Stonewall FOE’s Petition For Legal Hearing On Reactor Restart

Posted Oct. 16, 2012,           Salute to FOE!

WASHINGTON, D.C. —  The Nuclear Regulatory
Commission’s continued refusal to consider a legally binding hearing on the
future of the San Onofre nuclear plant h…

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Update 10-14-12, SCE’s Replacement Steam Generator $680 Million Debacle

The DAB
Safety Team’s – Update 10-14-12,  SCE’s Replacement
Steam Generator $680 Million Debacle

1.   If SCE’s and MHI’s Engineers had used all the following
guidelines, they would have p…

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SCE’s Restart PR Campaign Backfires in MV!

SCE’s RESTART PR campaign is now in full swing, please tell your friends to find out what SanO insiders are saying about all the technical issues AGAINST RESTARTING SanO, before they attend the NRC Dana Pt. meeting on 10-09-12.

The complet…

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California ISO prepares for another potential summer without San Onofre generation

News Release

News Release

For immediate release | September 13, 2012 Media Hotline ? 888.516.6397

For more information, contact:

Steven Greenlee | sgreenlee@caiso.com Stephanie McCorkle | smccorkle@caiso.com

California ISO prepares for another …

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The Number 1 US Nuclear Safety Concern ==> San Onofre’s Replacement Steam Generators

The DAB Safety Team is thankful to numerous
anonymous concerned SONGS Workers, who have provided factual information in the
interest of the Public Safety to us so that we could arrive at these “Reasonable
Conclusions?…

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San Onofre Nuke Questions That Need To Be Answered By The Nuclear Regulatory Commission (NRC) Prior To The Upcoming Oct. 9, 2012 Meeting

Here are some questions for the Public and MSM Reporters to ask the NRC prior to the Public Meeting scheduled about restarting San Onofre on Oct. 9, 2012:

Has the Mitsubishi Heavy Industry (MHI) Root Cause Evaluation been completed and a…

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