demonstration of fatigue for lto borssele · pdf filetlaa 119 high cycle thermal fatigue amp...

DEMONSTRATION OF

FATIGUE FOR LTO

BORSSELE

RELATION TO IAEA IGALL

RELEVANT TLAAS AND AMPS

IAEA PLIM conference

Lyon, France

Frederic Blom, Marieke Hannink (NRG)

André de Jong (EPZ)

24 October 2017

2

IAEA, October 2017, EUDuc=N

CONTENTS

• Introduction

• IGALL TLAAs & AMP fatigue

• Borssele fatigue demonstration

• Scope

• Methodical review

• International developments

• Further assessment measures

• Load monitoring

• Fatigue management

• Conclusion

3


INTRODUCTION

• Long term operation of NPP Borssele, The Netherlands

40 years → 60 years

• Commercial operation since 1973

• LTO demonstration programme: demonstrate safe operation until

2034

4


INTRODUCTION

TULIP, LTO demonstration

• According to internationally accepted

IAEA standards (SR57 & IGALL SR82)

• Successful license renewal application

NPP Borssele

• Similar approach for NPPs in:

• Sweden

• Finland

• Argentina

• Generally applicable to other NPPs

5


• TLAA 101 Low cycle fatigue usage

• TLAA 106 Environmentally assisted fatigue

• TLAA 113 Thermal stratification

• TLAA 119 High cycle thermal fatigue

• AMP 101 Fatigue monitoring

• AMP 161 High cycle fatigue monitoring

(new from IGALL phase 3)

IGALL TLAAS AND AMPS

6


IGALL TLAAS AND AMPS

TLAA 113 Thermal stratification

TLAA 101 Low cycle fatigue usage

TLAA 106 Environmentally assisted fatigue

TLAA 119 High cycle thermal fatigue

AMP 101 Fatigue monitoring

AMP 161 High cycle fatigue monitoring

7


REVALIDATION OF TLAA

(i)

(ii)

(iii)

1980 1990 2000 2010 2020 20300

50

100

150

Year

Num

ber

of

cycl

es

Counted

Extrapolated

New CUF by more rigorous analysis

Partial usage factor recalculation (new CUF)

IGALL safety report:

i. Analysis remains valid for the intended period of LTO

ii. The analysis has been projected to the end of the intended period

of LTO

iii. The effects of ageing on the intended function(s) of the structure or

component will be adequately managed for the intended period of

LTO

8


AMP 101 FATIGUE MONITORING

1. Scope

2. Preventive actions to minimize and control ageing degradation

3. Detection of ageing effects

4. Monitoring and trending of ageing effects

5. Mitigating ageing effects

6. Acceptance criteria

7. Corrective actions

8. Operating experience feedback and feedback of research and

development results

9. Quality management

AMP 101 Fatigue Monitoring

9


SCOPE – BORSSELE NPP

Determination of TLAA fatigue scope1.

10


SCOPE

• Scope: components and locations for which fatigue assessments

are relevant

• Goal: determine a scope independent of existing analyses

available at EPZ

• Approach:

– International practice and guidelines

– Engineering judgment

4 steps:

1. Identify components

2. Identify component locations

3. Additional existing fatigue analyses locations

4. Comparison to scope of similar NPP

• Result: 50 locations in scope

11


METHODICAL REVIEW

11

Fatigue demonstration (LTO license) based on

conservatism in loads and number of loads

2.

12


METHODICAL REVIEW

Review of fatigue analyses for all component locations

• Approach

– Evaluation criteria (applied to fatigue analyses)

– Further assessed

� Projected number of cycles

� Calculation method

� Modifications of component

– Revalidate usage factor until 2034 if possible

• Environmental and high-cycle thermal fatigue considerations

• Concluding assessment per component location

(i) (ii)





13


METHODICAL REVIEW

Load cycles analysis

• Comparison of projected number of cycles until 2034 and number of cycles in analyses

• Aim: use conservatism in analyses for LTO

1980 1990 2000 2010 2020 20300

50

100

150

Year

Num

ber

of

cycl

es

Counted

Extrapolated

(i) (ii)

14


METHODICAL REVIEW

All fatigue analyses assessed

• If possible, cumulative usage factors (CUFs) revalidated until 2034

• Results

� 44 out of 50 component locations: CUF < 1 �

� Other component locations: further assessment measures

15

EdF, October 2016, EUDuc=N

INTERNATIONAL DEVELOPMENTS

High-cycle thermal fatigue

Environmental fatigue

3.

16



HIGH CYCLE THERMAL FATIGUE

Turbulent mixing

International cracking events are listed

and influence on NPP Borssele

components judged

Based on available information, none of

the events of reported incidents are

applicable to NPP Borssele

Thermal stratification

Thermal cycling


17


ENVIRONMENTAL FATIGUE

Approach

• Initial usage factor

KTA or ASME guideline of existing analysis

• Environmental fatigue screening

Awareness thresholds KTA 3201.2 (2011)� CUF > 0.2 Austenitic steels

� CUF > 0.4 Ferritic steels


18


FURTHER ASSESSMENT MEASURES

Further assessment measures

Revalidation, including environmental fatigue

4.

19


FURTHER ASSESSMENT MEASURES

• New fatigue analyses including environmental fatigue

• Detailed assessment using state-of-the-art techniques/methods

� Finite element models generated in ANSYS

� Fatigue loading determined using FAMOS

� Assessment performed according to original code

� Different fatigue assessment methods (consistent with KTA and ASME)

• Result: CUF < 1 for pressure boundary of all locations

(iii)

20


LOAD MONITORING

Implementation of fatigue monitoring (FAMOS)5.

21


LOAD MONITORING

• FAMOS installed in April 2010

• Temperature measurements to register thermal transients

• 25 measurement sections

� Stratification 7 thermocouples

� Other locations 2 thermocouples

TLAA 113 Thermal stratification

22


LOAD MONITORING

FAMOS

Measurement system

23


LOAD MONITORING

Application

• Basis for new load catalogue and load specifications

� Fatigue basis

� 5 cycles necessary for statistical representation

• Optimize operation if required

• Fatigue management (entire period of LTO)

� Register thermal transients

� Yearly summary of fatigue statusAMP 101 Fatigue Monitoring

24


FATIGUE MANAGEMENT

Fatigue management up to 60 years

Using up-to-date models, load catalogue and

fatigue monitoring (FAMOS)

6.

25


FATIGUE MANAGEMENT

Basis for fatigue demonstration

� Scope

� Load catalog

� Load specifications

� Fatigue analyses

Fatigue management (entire period of LTO)

� Yearly summary of fatigue status (based on occurred transients and FAMOS)

� Integrated approach that couples

load monitoring, transient counting and fatigue assessment

26


AMP 101 Fatigue monitoring


TLAA 106 Environmental fatigue

TLAA 113 Stratification

TLAA 119 high cycle fatigue

1-scope

2-preventive actions

3-detection of ageing

4-monitoring & trending

5-mitigation

6-acceptance criteria

7-corrective actions

8-operating experience9-quality management


27


28


CONCLUSION

• Methodology for revalidation of fatigue TLAAs for LTO

• In line with international standards and guidelines

• Sound basis for prevention of crack initiation by fatigue

• Method is in-line with current IGALL TLAAs and AMPs

• LTO demonstration project including fatigue demonstration led to

successful license revision of NPP Borssele for LTO

29


Thank you for your attention Merci pour votre attention

Kiitokset mielenkiinnostanneHvala za vašo pozornost

谢谢大家的关注。Köszönöm a figyelmet

Tack för er uppmärksamhetGracias por su atención

Vielen Dank für Ihre Aufmerksamkeit

Frederic Blom

[email protected]

30


RESERVE SLIDES

• TLAA 101 Low cycle fatigue

• Description of i,ii and iii as in the IGALL TLAA

• AMP 101 Fatigue Monitoring

• Description of the 9 attributes as in the IGALL AMP

(these can give more information about the relation of Borssele fatigue

revalidation and fatigue management and IGALL TLAAs and AMPs)

31


TLAA 101 LOW CYCLE FATIGUE

Acceptance by (i):

In this case, the number of cycles for each transient is determined for the long-term operating period based on:

a) A baseline cycle count for the transient that is determined from a review of the operating experience for the plant.

b) A projection of the expected number of cycles from the end of the baseline cycle count to the end of the long-term operating period.

c) The sum of these two counts provides the projected cycle count for the long-term operating period for the transient.

If the projected number of cycles for each transient in the TLAA is less than or equal to the number of cycles used in the original analysis, then the original analysis is still valid and acceptable for the long-term operating period according to (i).

1980 1990 2000 2010 2020 20300

50

100

150

Year

Num

ber

of

cycl

es

Counted

Extrapolated

(i)

32



Acceptance by (ii):

As with case (i), the projected number of cycles for the long-term operating period is determined for each transient in the TLAA. However, for (ii) the projected number of cycles for one or more of the transients in the TLAA is greater than the number of cycles used in the original CUF analysis. For this case the projected CUF value for the long-term operating period is evaluated using a number of cycles for each transient in the CUF analysis that is equal to or greater than the projected number of cycles for each transient. If the resultant CUF value meets the regulatory limit or criterion, then the TLAA is acceptable for the long-term operating period according to (ii).

1980 1990 2000 2010 2020 20300

50

100

150

Year

Num

ber

of

cycle

s

Counted

Extrapolated

Partial usage factor recalculation (new CUF)

(ii)

33



Acceptance by (iii):

In this case AMP101 “Low-Cycle Fatigue Ageing Management Programme“ is used to manage the CUF value by counting transient occurrences, periodically updating the CUF value, and ensuring that corrective actions are taken prior to the CUF value exceeding the regulatory limit or criterion. AMP101 provides for corrective actions, including repair or replacement of components, design modifications, revision of operating procedures, and more rigorous analysis to demonstrate that the design code limit will not be exceeded during the long-term operating period.

New CUF by more rigorous analysis

(iii)

34



1. Scope of the ageing management programme based on

understanding ageing:

The scope includes those components subject to the occurrence of fluid conditions having the potential for inducing cyclic thermal stresses.

Monitoring (part from AMP 101, under scope):data collection (temperature, pressure, flow rate, etc), at selected locations, to characterize actual operational transients in severity and number of occurrences

to ensure that the total number of transient occurrences is less than the design number,to ensure that the actual transient loads are bounded by those for the licensing basis transients;

35



2. Preventive actions to minimize and control ageing degradation:

The programme prevents the current fatigue analyses from becoming invalid by assuring that the fatigue usage factor resulting from actual operational transients does not exceed the design limit, including anticipated and new unanticipated transients, and environmental effects where applicable.

3. Detection of ageing effects:

Fatigue monitoring is a preventive programme and does not directly detect ageing effects.

4. Monitoring and trending of ageing effects:

Projections of future transient occurrences, in combination with action limits on CUF values, can provide assurance that corrective actions will be made prior to the CUF exceeding the design limit.

36



5. Mitigating ageing effects:

Fatigue monitoring is a preventive ageing management programme, and no specific mitigating actions are provided. In some cases, mitigation of fatigue can occur through improved operational procedures or equipment replacement to reduce transient occurrences or severity, for example mitigation of thermal shock in steam generator feeding through replacement of feed-water valves by better controlled ones.

6. Acceptance criteria:

The acceptance criterion is maintaining the fatigue cumulative usage factor below the design limit through the current operating period as well as extended operation periods, with consideration, where applicable, of the reactor coolant environmental fatigue effects mentioned in the programme description and scope of program.

37



7. Corrective actions:

The programme provides for corrective actions to prevent the usage factor from exceeding the design code limit during the current license and extended operation periods. Acceptable corrective actions may include repair or replacement of components, design modifications, revision of operating procedures, and more rigorous analysis to demonstrate that the design code limit will not be exceeded during the current license and extended operation periods.

38



8. Operating experience feedback and feedback of research and development results:The programme reviews industry experience relevant to fatigue. Applicable operating experience relevant to low cycle fatigue is to be considered in selecting transients and locations for monitoring.Research and development (..) help operators of nuclear power plants to:• identify transients and component locations to be included in the programme; • establish assessment methods and acceptance criteria;• select monitoring approaches, sensor types, mounting devices, data acquisition systems, and computer codes for data analysis.

9. Quality management:Administrative controls, quality assurance procedures, review and approval processes, are implemented in accordance with the different national regulatory requirements

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