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. 

  

The full DAB Safety Team's  Media Alert - 5 Parts:

https://docs.google.com/folder/d/0BweZ3c0aFXcFZGpvRlo4aXJCT2s/edit?pli=1&docId=15V8BD4YK0MjwUV6gPZt6ILS_lP7CpClzgnZentLfx8U

Which includes both Dr. Hopenfeld's CPUC documents as Parts 4 & 5:

Part 4 https://docs.google.com/folder/d/0BweZ3c0aFXcFZGpvRlo4aXJCT2s/edit?pli=1&docId=0BweZ3c0aFXcFMC1BNlpMeDQyM2M

Part 5 https://docs.google.com/folder/d/0BweZ3c0aFXcFZGpvRlo4aXJCT2s/edit?pli=1&docId=0BweZ3c0aFXcFX2gxRDFCRW9CVzg

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

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:

1. SONGS Unit 2 Fluid Elastic Instability, Thermal-Hydraulic Modeling, Enlightening Dr. Pettigrew, Concerned/Frustrated NRC Commissioners and Main Steam Break (28 Pages)

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.

2. SCE’s Dismal and Unconvincing Performance before NRC Commissioners (13 Pages)

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.

3. Unit 2 Retainer Bars Integrity Unproven and Unsafe During a MSLB  (12 Pages)

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.

NRC Reports Incomplete, Inconclusive, Inconsistent and Unacceptable

The REAL CAUSE of San Onofre's Unit 3 massively expensive failure...

It appears that a complacent SCE and the inexperienced Mitsubishi engineers did not perform proper academic research and industry comparisons about the potential adverse consequences of the reducing the pressures in the original steam generators. Lowering the pressures were the primary cause of shortening the life of the Original Generators due to increased tube wear and plugging caused by random vibrations and also caused the destruction of the new Unit 3 Replacement Steam Generators due to the same thing. 

In addition, Edison engineers prepared a defective NRC report and design specifications, which were not challenged by Mitsubishi, the manufacturer, and/or adequately reviewed by NRC Region IV. Mitsubishi then at the direction of SCE engineers made numerous untested and unanalyzed design changes to the steam generators under the pretense of “like for like”, exchange and even NRC Region IV Director Elmo Collins said, “The guts of the machinery look …. Different.”

So based on a review of the AIT Report and some of the World’s Experts, the three potential causes, which were significant contributors to the “fatigue damage” in San Onofre Unit 3 and the tube-to-tube wear resulting in the tube leak are as follows:

A. Insufficient internal supports and differences in manufacturing or fabrication of the tubes and other components between Units 2 & 3.

B. Due to modeling errors, the SONGS replacement generators were not designed with adequate thermal hydraulic margin to preclude the onset of fluid-elastic instability.

C. Differences between Unit 2 and Unit 3’s Operational Factors


CONCLUSIONS: Until the NRC can determine that San Onofre is 100% safe to operate at its approved rated power, granting any Unit 2 Restart testing is unacceptable, because if a nuclear accident occurred during testing who would be held liable, the Nuclear Utilities, the Insurance Carriers, the Federal Government, the State of California, the CPUC, the NRC Commissioners, NRC Region IV, EIX/SCE Shareholders & Employees or just the millions of affected southern Californians?  The DAB Safety Team believes that once the true amount of existing tube fatigue and all other associated damage is KNOWN, anything short of a total steam generator rebuild and/or replacement will be unacceptable prior to any restart being authorized by the NRC.

2013 is the year to Decommission San Onofre

For much more on this read:

Allegation – NRC AIT Report Incomplete, Inconclusive, Inconsistent and Unacceptable

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 Reactor Regulations complete a Qualifying Investigation to assure steam generator tube integrity before any restart decision is made.

PROBLEM STATEMENT: The computer thermal-hydraulic models cannot account for all the mechanical factors and extremely narrow tube-to-tube clearance differences, which would very likely contribute to catastrophic tube-to-tube wear (fluid elastic instability) in San Onofre Unit 2.  In light of the 8 tube failures of Unit 3 at Main Stream Line Break testing conditions, fluid elastic instability can cause cascading tube leakages/ruptures in Unit 2 even at 70% power due to Steam Generator pressure and temperature changes caused by, for example, a main steam line break, earthquake, loss of offsite power, stuck main steam safety valve and/or other operational transients.  The cascading tube failures would “pop like popcorn” (as described by nuclear expert Arnie Gundersen) and cause excessive offsite radiation exposures.  Operator Action as claimed by Edison to re-pressurize the steam generators is not feasible to stop a major nuclear accident in Unit 2 in the first 15 minutes of a Main Stream Line Break,  stuck open SG safety valve, earthquake, steam generator tube ruptures and other operational transients during the preposed 5-month trial TEST PERIOD.

INVESTIGATION REQUEST: The DAB Safety Team seeks to assist the NRR by requesting a Qualifying Investigation, as noted above and by providing additional information, as noted below.

For much more read  DAB Safety Team Documents     “Media Alert 13-01-22 Faulty Modeling And Unreasonable Operator Actions Make San Onofre Restart Unsafe”, “Emergency Preparedness at San Onofre”, “Managing Control Room Safety” and Press Release: “TEST: Viability of Operator Actions to Prevent Offsite Radiation Releases 

=====

Some useful nuclear phrases:

Normal operational conditions

Normal operational conditions mean that the nuclear power plant is operated according to the Technical Specifications and operational procedures. These also include tests, plant start-up and shutdown, maintenance and refueling.

Anticipated operational transient

An anticipated operational transient means a deviation from normal operational conditions, which is milder than an accident and which can be expected to occur once or several times over a period of a hundred operating years.

 Unanticipated operational transient

An unanticipated operational transient means a deviation from normal operational conditions, which is not proceduralized and Plant Operator does not recognize that condition.   A good example are the so called SONGS Unit 3 false alarm from loose parts vibration monitoring system for which there is no explanation from SCE, NRC or Westinghouse.  Another example would be a leakage from a pump pumping radioactive fluid without any area radiation monitors to warn the operators of the leakage.

=====

Accident

An accident means such a deviation from normal operational conditions as is not an anticipated operational transient. There are two classes of accident: postulated accidents and severe accidents. Based on the initiating event, postulated accidents are further divided into two sub-classes whose acceptance criteria are described in Guide YVL 6.2.

Postulated accident

A postulated accident means such a nuclear power plant safety system design-basis event as the nuclear power plant is required to withstand without any serious damage to the fuel and without discharges of radioactive substances so large that, in the plant’s vicinity, extensive measures should be taken to limit the radiation exposure of the population.

Severe accident

OMG................. Talk about SanO Nuclear Denial* “severe accident” is not even listed in the 130 page NRC Collection of Abbreviations, but if you do a computer search for it on the NRC website you find this:

Severe accident

A type of accident that may challenge safety systems at a level much higher than expected.

* http://is.gd/XPjMd0
The illogical belief that Nature cannot destroy any land based nuclear reactor, any place anytime

NRC Violating Presidential Directive and the Public Trust

SCE’s PR Machine Is Capable Of Overcoming ALL Hurdles,

Except Good Science And Safety

Albert Einstein also described INSANITY as

Doing the same thing over and over again and expecting different results. 

The DAB Safety Team has challenged previously in their published DAB Safety Team Documents, that Southern California Edison’s controversial plan to restart San Onofre Unit 2 as a “Bogus and dangerous SCE experiment.”  

According to SONGS Anonymous Insiders, SCE’s Engineers were under the false impression that Unit 3 Anti-vibration Structure was built better than Unit 2.  Therefore, SCE Engineers were operating Unit 3 at lower steam pressures than Unit 2 in a test mode to generate more thermal megawatts and thereby generate more electricity.

 To add to Arnie Gundersen’s and John Large’s Technical Affidavits, DAB Safety Team’s investigation reveals that in the process of this “money-hungry experiment”, lower steam pressures in combination with other unapproved and unanalyzed design changes destroyed Unit 3 due to Fluid Elasticity Instability (FEI). SCE and NRC AIT Team both blamed Unit 3 FEI on botched up MHI Computer Modeling and insufficient tube-to-AVB gaps. AREVA, Westinghouse, John Large and the DAB Safety Team findings dispute these statements. The NRC Augmented Inspection Team and the NRR Panel have swept the DAB Safety Team Findings consistently under the rug, in what must be now labeled as a Gov’t cover-up!

The NRC keeps issuing both controversial and conflicting press statements that a decision to allow the restart of Unit 2 could come as early as March 2013.  According to SONGS anonymous insiders, Edison officials have announced in internal SONGS Staff Meetings that a restart decision is imminent in March despite the huge public outcry about safety problems by SCE.  Press reports as of January 14, 2013 state, “Small steps are being taken to prepare for possibly restarting the troubled San Onofre nuclear power plant, even as its future remains clouded with uncertainty, officials said Monday. Nuclear Regulatory Commission senior inspector Greg Warnick said Monday that the agency is beginning to prepare a detailed plan of what would need to be done to bring the plant safely back to service.” (SOURCE: CBS Los Angeles, Associated Press)

NRC’s enforcement history, drama and pre-rehearsed tough questions, press reports, casual relationship and/or protection of SCE officials and utility biased public meetings are just old and cheap regulatory tricks that are now being used to protect the NRC’s own public image and to fool the public into believing that the NRC is really concerned about public safety regarding SCE’s Restart Plan.  The Justice Department & NRR Officials need to set up a legal/technical taskforce to publically question Edison’s design and MHI Engineer’s listed below under oath regarding their:

1. Understanding of their legal obligations under the 10 CFR 50.59 Process,
2. Understanding of problems with the original steam generators,
3. Critical questioning and professional/investigative skills,
4. Efforts made in industry and academic benchmarking to identify and resolve problems with the original steam generators
5. What part did they play in the preparation of design specifications, fabrication, computer modeling, mock-up testing, anti-vibration bar structure, and research required to prevent the adverse effects of fluid elasticity and flow-induced random vibrations in these unique San Onofre Combustion Engineering replacement generators.

Any NRC decision to grant a restart of Unit 2 without a formal 50.90 licensing review along with public participation will be seen as an invitation to risk a Fukushima-type disaster happening in Southern California. 

Read More:  Allegation - NRC Violating President’s Directive And the Public Trust is posted on the web at this link: DAB Safety Team Documents.

Copyright January 17, 2013 by The DAB Safety Team. All rights reserved. This material may not be published, broadcast or redistributed without crediting the DAB Safety Team. The contents cannot be altered without the Written Permission of the DAB Safety Team Leader and/or the DAB Safety Team’s Attorney

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 Augmented Inspection Team, MHI, SCE, Westinghouse, AREVA, Professor Daniel Hirsch, industry experts and knowledgeable whistle blowers, along with the recent affidavits prepared by Arnie Gundersen and John Large, we reaffirm the following statements which have been previously substantiated in numerous DAB Safety Team Documents:

1. The DAB Safety Team has been saying for months for a long time that SCE and MHI Engineers did a very poor job in their review of Academic Research Papers and Industry Comparisons about how to prevent the adverse effects of fluid elastic instability in the design of San Onofre's replacement steam generators because the original Combustion Engineering designed steam generators did not experience the adverse effects of fluid elastic instability. Nuclear Expert, John Large statesA, “I have little confidence in the outcome of AREVA’s projection of the time period through which the U2 nuclear plant could be reliably expected to operate without incurring a tube failure or running at a greater risk of a tube failure occurring. ... In my opinion, simply sweeping the fluid elastic instability issue under the carpet on the basis ... it will not reoccur at 70% power is not only disingenuous but foolhardy.” TheNRC chairman has publicly stated, “SCE is responsible for the work of its vendor and its contractor.” DAB Safety Team alleges that SCE actions are in violation of the Federal Regulations, its CPUC Charter, the NRC Chairman Standards and even its own advertised charter of “Overriding Obligations to Shareholders and Public Safety.”


2. Accidents involving steam generator depressurization (main steam line break), station blackout and other anticipated transient events causing steam generators over-pressurization can occur at any time over the full range of normal operating conditions up to Reactor Thermal Power (3438 MWs). Therefore BY DESIGN, these replacement steam generators are NOT capable of protecting their already worn and cracked tubes from radioactive leakages and/or ruptures caused by the above.

3. In Unit 2, these already fatigued, cracked, and heavily degraded tubes can snap, leak and/or rupture at the tube sheet, tube support plate or the unsupported anti-vibration bars mid and free spans during these postulated adverse accident conditions. John Large statesA, “For the MSLB event very high, two-phase fluid cross-flow velocities would be expected to instantaneously develop in the U-bend region, triggering vigorous FEI that could, particularly if the AVB restraints are ineffective, promote violent tube to tube clashing and the potential for a multiple tube failure event.”

4. It is ABSOLUTELY CLEAR, that San Onofre Unit 2 replacement steam generators will likely experience single to multiple tube-to-tube failures (e.g., San Onofre Unit 3, Mihama Unit 2, North Anna, Indian Point 2 and Craus, France, etc.) during these postulated adverse licensed conditions at any power level up to 100% Power (Licensed Reactor Thermal Power of 3438 MWTs).


5. The proposed Defense-in-Depth instrumentation, along with unreliable and unproven operator actions to detect multiple tube leaks/ruptures and/or to re-pressurize the steam generators during these postulated adverse licensed conditions as claimed by Edison are not practical to stop a major nuclear accident from progressing and causing a Unit 2 meltdown.

6. There are conflicting, contradicting, ambiguous and confusing findings between the experts in the Unit 2 Operational Assessments: Such conflicting disagreements over the cause of Tube To Tube Wear reflects poorly on the depth of understanding of this crucially important FEI issue by SCE, each of these SCE consultants and the designer/manufacturer of the Replacement steam generators. The DAB Safety Team’s findings contradict the SCE and all the three NEI qualified, “US Nuclear Plant Designers” findings about Unit 2 FEI (See, Overview – Consequences of a Main Steam Line Break).

7. The DAB Safety Team Comments about SCE 10 CFR 50.59 Safety Evaluation for RSGs: The Big Number 1 Attachment Notes shows the comparison between San Onofre and Palo Verde's Replacement Steam Generator design parameters. Palo Verde has the largest CE RSGs in the world (~ 800 Tons each) and SONGS Replacement Steam Generators are the second largest CE Replacement Steam Generators in the world (~ 620 Tons each). John Large statesA, “In my opinion, the changes, tests and experiments (CTE) inherent in the SCE proposal to restart Unit 2: (a) involve a significant increase in the probability or consequences of an accident previously evaluated; (b) create the possibility of a new or different kind of accident previously evaluated; and (c) involve a significant reduction in a margin of safety. Arnie Gundersen statesB, “It is my professional opinion that Edison should have applied for the 50.59 process so that the FSAR license amendment evaluation and public hearings would have occurred six years ago, prior to creating an accident scenario and facing losses that by the end of this process will easily total more than $1 Billion.” Therefore, the DAB Safety Team concludes that SCE claims as stated are not factual. SCE did not meet the 10CFR50, Appendix B, Quality assurance Standards and has violated the NRC 10 CFR 50.90 Regulations.

8. The Public expects that the Offices of Nuclear Reactor Regulation (NRR) comply with President Barack Obama, Senator Barbara Boxer and NRC Chairman’s Open Government Initiative. Under no circumstances should the NRR permit SCE to restart unit 2 without replacing the defective replacement steam generators, a full NRC 50.90 Licensing Amendment and transparent trial-like public hearings.
A http://libcloud.s3.amazonaws.com/93/80/a/2680/R3218-Large-AF2-redacted_proprietary.pdf
B http://libcloud.s3.amazonaws.com/93/b5/f/2677/2013_1_11_FOE_Gundersen_Affidavit_reEdisonSanOnofreRSG.pdf

Full Media Alert 13-01-15 Allegation - SCE Violated Federal Reg's And The Public Trust is posted on the web at this link: DAB SafetyTeam Documents.

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The DAB Safety Team: Don, Ace and a BATTERY of safety-conscious San Onofre insiders plus industry experts from around the world who wish to remain anonymous. These volunteers assist the DAB Safety Team by sharing knowledge, opinions and insight but are not responsible for the contents of the DAB Safety Team's reports. We continue to work together as a Safety Team to prepare additional: DAB Safety Team Documents, which explain in detail why a SONGS restart is unsafe at any power level without a Full/Thorough/Transparent NRC 50.90 License Amendment and Evidentiary Public Hearings. For more information from The DAB Safety Team, please visit the link above.

Our Mission: To prevent a Trillion Dollar Eco-Disaster like Fukushima, from happening in the USA.

Copyright January 14, 2013 by The DAB Safety Team. All rights reserved. This material may not be published, broadcast or redistributed without crediting the DAB Safety Team. The contents cannot be altered without the Written Permission of the DAB Safety Team Leader and/or the DAB Safety Team’s Attorney