Key Elements of Long -term Operation of WWER -440/213 ... · Key Elements of Long -term Operation of WWER -440/213 Units at Paks NPP ... order to amend them to meet the ASME BPVC

Key Elements of LongKey Elements of Long--term Operation of term Operation of WWERWWER--440/213 Units at Paks NPP440/213 Units at Paks NPP

RATKAI Sandor, PAKS NPPDr. KATONA Tamas, PAKS NPPTelephone: +36-75-508576, +36-75-508558, fax: +36-75-507036E-mail address: [email protected], [email protected]

15-18 October Shanghai, China

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Europe is „nuclear”HUNGARY 4

HungaryHungary

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Paks town and the site

Where is PaksWhere is Paks??

Area: 93 000 square kilometers Population: 10 million inhabitants

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4 x WWER440/ V-213type Units Designed lifetime is 30 yearsCapacity: 4 x 500 MW after power up-rate License valid until 2012 -201738% of domestic production

Plant viewPlant view

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– Safety– Competitiveness

• Power up-rate• License Renewal for

additional 20 years (operating lifetime limited to design lifetime 30 years)

– Acceptance

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Elements of the strategy Safely operate as long as reasonable

0,00E+001,00E-042,00E-043,00E-044,00E-045,00E-046,00E-047,00E-04

1995 1997 1999 2000 2002 2003 2004Co

re da

mage

prob

abilit

y Shut downFull power

Safety is the paramount

Change of CDP as a result of the safety enhancement measures

LTO strategy of Paks NPP

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Gov. Decree

No. 108/1997

ActNo.

CXVI/1996about

Nuclear Energy

NuclearSafety

Regulation1 2 3 4 5 6

Safety Guidelines

Local Regulations

Otherregulations

The four-leg model of the LTO

Features of the Nuclear Regulation forLong Term Operation

1.1.Ageing

Management

2.2.Maintenance

Rule

3.3.Equipment

Qualification

4.4.DBR

LTOLTO 10CFR5410CFR50.65

Adaptation of USA practice

in LR

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New licenseUnit 1

Application for licence renewal*

Submittal of the Program of LTO*

Feasibility studies;

Preparation of the project

2005. 2006. 2007. 2008. 2009. 2010. 2011. 2012. 2013. Preliminary

environmentalimpact study**

Environmental impact study**

Public hearing * Act on nuclear energy 1996. CXVI. ** Act on environmental protection 1995. LIII.

2nd PSR2nd PSR

Time schedule for LRTime schedule for LR

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• Assessment of the safety of the plant (based on the first Periodic Safety Review)

• Assessment of the technical condition of the plant and the plant existing practice for ensuring the required plant status (maintenance, ISI)

• Evaluation of the measures (safety upgrade, replacements, reconstructions) needed for longer-term operation

• Business evaluation: costs, prices, profit

• Other conditions (regulation, acceptance)

• Plant safety level satisfactory • Plant technical condition is good due to good plant practice

• No safety or technical limitations which could not be overcome

• Longer term operation is reasonable from business point of view

• A 20 years extension of operational life-time seems to be optimal and it is feasible via licence renewal

• Longer-term operation is supported by the public

8 Scope of the study:checking the preconditions Conclusions

Feasibility StudyFeasibility Study

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Environmental Licensing

Implementation of the technical tasks (AM,MR, EQ,DBR)

LTO Programme Development and

submittal

Authority review of

LTO Program

Implementation of the LTO Program -

Demonstration of commitment

Implementation of the LTO Program -

Demonstration of commitment

2008. 2011. 2012.2000.

Authority approval

NEW LICENSE

Unit 12009.1 2

LR Application

Operation according to NEW Licence

Implementation of LTO Program and Regulatory conditions

Ageing Management Review, review, validation and

reconstitution of TLAAs

2 step nuclear licensing

Licensing processLicensing process

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Feasibility Study Verification of

Preconditions for LTO/LR

Scoping and Screening Identification of TLAAs

Ageing Management Review

Re-validation, reconstitution of TLAAs

Documentation

Regulatory Review/Approval

Implementation of LTO Commitments and Regulatory requests/conditions

Prior

to

LTO

Proces

s As

sessm

ent

of SC

s&TL

AAs

Regu

latory

Re

view,

Ap

prova

l

Environmental Impact Study

Environmental licensing of extended operation

Licence Renewal Process and Licence Renewal Process and Preparation of LPreparation of LTOTO

Source: IAEA Safety Reports Series

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Documentation



Prior

to

LTO

Proces

s As

sessm

ent

of SC

s&TL

AAs

Regu

latory

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view,

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prova

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Scoping anScoping andd ScreeningScreening


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Scoping & ScreeningScoping & Screening & Commodities& Commodities1. Separately managed components:

• Reactor pressure vessel• Reactor cover• Reactor inner components • Pressurizer• Steam generator• Main circulation pump• Main gate valve• Primary piping

2. Commodity groups (mechanical components):

Screening: Long lived, passive~ 160,000 items

Scoping: Safety Class 1- 3+~ 250,000 items

Safety classSafety Class 1Safety Class 2Safety Class 3

Non safety class 4 which may inhibit safety

functions

Component typeHousing of valvesHousing of pumps

PipingVessels

Heat exchangersTanks

MediumBorated water

Dematerialized waterRiver water

Steam, gas-steam mixtureOil,Etc..

MaterialStainless steel

Cast stainless steelCarbon steel

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Displaying the final scopeDisplaying the final scope

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Documentation



Prior

to

LTO

Proces

s As

sessm

ent

of SC

s&TL

AAs

Regu

latory

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view,

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prova

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Ageing Management ReviewAgeing Management Review


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Goal:• To demonstrate that the effects of ageing will be managed adequately during

the extended operational lifetime, therefore the intended functions assured;• The Ageing Management programs are able to discover the unexpected

failures in time;

Review attributes: NUREG-1801 (GALL report) & IAEA DG 382

1. Scope of the program2. Preventive actions3. Parameters monitored or inspected4. Detection of ageing effects5. Monitoring and trending6. Acceptance criteria 7. Corrective actions8. Confirmation process9. Administrative controls10. Operating experience

Review of the Ageing Management Review of the Ageing Management programsprograms

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Mechanical components:• Reviewed items: ~ 30,000 234 commodities• The currently applied AM practice basically comply with the Hungarian

AM&LR guidelines, but some modifications are needed. Thesemodifications were identified.

• New AM program development is underway, using the findings of the reviews.

Building structures and supports or housing of I&C:• Reviewed buildings: 31 25 commodities• New AM programs were developed.

Cables:• Review items: ~ 130,000 46 commodities• Currently, the „good industrial practice” is used. • New AM programs will be developed.

Results of the Ageing Management ReviewResults of the Ageing Management Review

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Documentation



Prior

to

LTO

Proces

s As

sessm

ent

of SC

s&TL

AAs

Regu

latory

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view,

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prova

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Identification & Reconstitution of TLAAsIdentification & Reconstitution of TLAAs


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Identification of usual TLAAsIdentification of usual TLAAs

1. Embrittlement of Reactor Pressure Vessel • PTS • derivation of p-T curves

2. Fatigue calculations / + check of the design /• load catalog• strength & fatigue calculations

3. Analyses of the currently known indications (crack growth calculations)

4. Extension of Environmental Qualifications (I&C)5. Fatigue of cranes6. MC pump flywheel fatigue

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Identification of Identification of PaksPaks specific specific TLAAsTLAAs

1. TLAAs coming from the FSAR• High cycle fatigue (vibrations of RPV internals or SG

tubes)• Changing in material properties (embrittlement)

2. Review of operational limits• Heat up & cool down temperature velocity• Temperature differences during transients

3. Reconstitution of missing design information• Stress calculations of civil structures

4. Paks specific issues coming from the feasibility study• Building settlement analyses (Unit 4)

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20 The required PTS analysis shall be completely deterministic. (Scope of PTS analysis covers transients with 10-5/year frequency). It includes the well-known tasks:

• Selection of thermo-hydraulic transients;• Performance of thermo-hydraulic transient analyses;• Performance of reactor-physical calculations to determine the 3D neutron

flux distribution in the RPV wall;• Evaluation of results of reactor dosimetry;• Evaluation of ageing of RPV materials;• Calculation of temperature, deformation, stress field and fracture

mechanics; • Evaluation of integrity criteria;

Analysis has been performed in two phases. In the first phase a simplified and conservative calculation method is used for largenumber of scenarios in order to screen out the most demanding cases which require more sophisticated and less conservative analysis.

PTS analysesPTS analyses

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• ASME Boiler & Pressure Vessel Code, Section III (edition 2001) had been selected for the reconstitution of TLAAs and associated strength verification.

• Use of ASME code is a generic decision of the PaksNPP. Currently the ISI programs are under review in order to amend them to meet the ASME BPVC Section XI requirements.

i. Methodology should be in compliance with Hungarian Nuclear Safety Regulations. Several guidelines exist with methodological information.

ii. Methodology should be widely acceptable.

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StreStressss & Fatigue calculations& Fatigue calculations

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22 • Selection of material properties• Dimensions and tolerances• Consideration of Aging Effect on the Wall Thickness• Load Catalogue• Use of other standards• Specific Aspects of Fatigue Analysis

–Fatigue Curves–Specification of Fatigue Strength Reduction Factor–Application of ASME XI Appendix L in Case CUF>1

• Specific Aspects of Brittle Fracture Analysis• Thermal Stratification Analysis• Analysis of RPV

ProblemProblemss requiring some considerationsrequiring some considerations

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In cases of non-compliances, one of the following measures can be implemented:– Performing additional analyses (eliminating initial

conservatism with more refined methods);– Performing re-qualification test with improved

methodologies– Augmentation of AMP– Replacing or upgrading the component (reconstruction

program)– Changing the operational conditions– Improving ISI programs

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Cases of TLAA nonCases of TLAA non--compliancescompliances

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Documentation



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LTO

Proces

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sessm

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of SC

s&TL

AAs

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Program for LTOProgram for LTO


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Program for LTOProgram for LTO

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• Ageing management• EQ• Maintenance (and other plant programmes)• Monitoring of effectiveness of the maintenance, performance monitoring of active systems and components• Replacements/reconstructions (obsolescence)• Human resources and knowledge management for LTO

LTO Programme +– Improvement of

organisation– Optimisation in terms

of time and money– Improvement of the

competitiveness

26 LTO Programme PLiM

LTO program and PLiMLTO program and PLiM

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• A comprehensive system has been developed for the justification of safety of long-term operation at Paks NPP.

• This system includes the review of ageing management programmes and revalidation of TLAAs as well as the specific aspects of justification of safety of LTO at Paks NPP, i.e. the reconstitution of majority of TLAAs, review and update of design calculation of structures and components, necessity of the development of new AMPs.

• State of the art methodologies have been established for the solution of engineering problems related the tasks. Works for the justification of safety of long-term operation are going on.

• On the basis of our present knowledge and preliminary results, the safe long-term operation and license renewal of Paks NPP seems to be feasible and the issues already identified are manageable.

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ConclusionConclusion

Thanks for your Thanks for your attention!attention!

Documents

Key Elements of Long -term Operation of WWER -440/213 ... · Key Elements of Long -term Operation of WWER -440/213 Units at Paks NPP ... order to amend them to meet the ASME BPVC