Assessment and Management of Concrete Containment Buildings

Life time management of concrete structures in Finnish nuclear power plants

Jari PuttonenDepartment of Civil and Structural Engineering

Aalto Universityy

IAEA meeting 29.5-1.6.2012 1

Content

• Official requirements for Finnish NPPs

• Example of lifetime management in Loviisa NPP

• A computer tool for lifetime management of concrete structures in NPPs

• Concrete irradiation tests between 2012-2015 in a test reactor

(these slides are not included in pdf-file)

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Official requirements for life-time managementq g

• STUK (Radiation and Nuclear Safety Authority) has released a ( y y)new draft of the YVL- guide for the life-time management of nuclear power plants in 2011 (YVL A.8) (presently available

l i i i h)only in Finnish)

I h id h i b h h i l d di d– In the guide the aging covers both physical degrading and technological obsolescence aspects

– The licence holder has to identify the SSCs influencing on the nuclear y gsafety

– Aging mechanisms and their role for plant safety shall be defined for SSCsSSCs

– A special life time management program shall be developed for the SSCs of which aging may affect functionality of safety systems

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Some orders in the draft of YVL A.8

• Uncertainties of design assumptions should be covered by a conservative design. This requirement should be considered in defining eg. allowable level of deteriorationlevel of deterioration

• For a safety relevant SCC the minimum service life shall be defined

• During the commission reference levels shall be measured or defined for lifetime management of SCCs

• The condition monitoring program of the plant shall be extensive enough covering both deterioration and loading aspectscovering both deterioration and loading aspects

• The nature of maintenance should be proactive instead of corrective

• The authority (STUK) follows the implementation of the plant specific aging management program through the licence owner’s annual progress reports.

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Physical aging of concrete structures d ft f YVL A 8draft of YVL A.8

• Stress corrosion cracking • Prestressed tendons, anchor bolts,

• General corrosion and pitting

• Hydrogen embrittlement

• Prestressed tendons, anchor bolts, steel liner, carbon steel, ow alloy steel

• Anchor boltsHydrogen embrittlement

• Frost weathering • Outdoor structures in exposure class XF1-XF4

• Sea water tunnels pools• Salt weathering

• Ettringite damage

• Alkaline reaction

Sea water tunnels, pools

• Heat treatment of concrete

• Concrete with quartziferous aggregate

• Sulphate attack

• Lytic effect of soft water or

• Concrete in contact with sulphate soil

• Concrete surface inside NPP, sea • Lytic effect of soft water or

acid solutions (low pH)

• Biological organisms

water tunnels, foundations, pools

• Sea water tunnels, pools, p

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Physical aging of concrete structures d ft f YVL A 8draft of YVL A.8

• Thermal movements (forced • Structures not to be designed against forces d f tideformations)

• Carbonation

deformations

• Concrete in exposure classes XC1-XC4, reinforcement bars

• Chloride intrusion

• Stray current

• Concrete in exposure classes XS1-XS4 and XD1-XD4, reinforcement bars

• Structures where stray currents occur• Stray current

• Erosion

• High temperature

• Structures where stray currents occur

• Structures exposed to flowing water

• Damage caused by fire or high temperature

• Ionising radiation

• Relaxation

• Structures near a reactor pressure vessel, biological shield

• Prestressed tendonsRelaxation

• Creep

• Shrinkage

Prestressed tendons

• Concrete with high stress level or temperature

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Technological agingd ft YVL A 8draft YVL A.8

• National and international regulationsg– The SCCs of the plant do not fulfil new safety regulations

• Standards– The SCCs of the plant do not fulfil detailed technical requirements of

new standards

E i t t h l• Equipment technology– For systems, structures and components may be created new solution

that improve safetyp y

• Condition monitoring and maintenance– New technology may improve safety level

• Technical support or spare parts– Availability of services

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Containments of Finnish operating NPPsp g

LoviisaOlkiluoto

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Report: VTT-R-06470-09

Sea water systems of operating Finnish NPPsy p g

Report VTT-R-08960-11

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Loviisa ageing management, classification of SSCsg g g ,

• Assigned support person form Technical Support

Courtesy of Fortum Loviisa NPP

AAYB, YC, YD, YP,

Critical components and structures limiting plant life

• Components are divided into smaller elements• Power Division R&D programs

Full application of PLIM tools

XA, RLimited applicationof PLIM toolsBB

Esim.

Critical components, systems and structures(availability and economy) Esim.

AT, SA, SP, TJ, TH, TC, RL, VF ...

CCImportant components,

Evaluation based on operating experience, engineering CC

Esim.BT, SR,, TQ, RM ,, RR, TY ...

p p ,systems and structures(availability and economy)

g gjudgement and applicable PLIM tools

Other components, systems and structures

Life management as part of routine maintenanceand operation

DDEsim. UK, UL , UU , VE ...

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Loviisa NPP's AM approach, classification of SSCsf

• Class A: Reactor pressure vessel, steam generator, pressurizer, main

Courtesy of Fortum Loviisa NPP

coolant pump, containment structures

• Class B: E.g. primary circuit, high and low pressure safety injectionClass B: E.g. primary circuit, high and low pressure safety injection systems, feed water system, condensers, turbine, generators, diesels, ice condenser system, ...

• Class C: E.g. nuclear intermediate cooling, sprinkler, drainage and vents, main steam line, main condensate, residual heat removal, circulating and service water systems ice condenser cooling systemcirculating and service water systems, ice condenser cooling system, ...

• Class D: E.g. condenser purification system, auxiliary boiler plant, drinking water supply seweragedrinking water supply, sewerage, ...

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Information flows of Loviisa AMCourtesy of Fortum Loviisa NPP

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System engineers write yearly system condition report which include:include:

1. Relevant ageing mechanisms

Courtesy of Fortum Loviisa NPP

Comments:2. Most significant ageing related

phenomena and actions taken during the previous fuel cycle

Comments:

• Co-operation of different organization has proven to be of paramount importance in efficient

3. Estimation of the current status of the their system

importance in efficient implementation of PLIM (AM)

Th i ti i hy

4. Action plan for the coming years

• The existing aging phenomena are known but it is a challenge to detect possible new degradation mechanisms early enough

5. Compliance verification

early enough.

• Documentation of operational loads,

Replacement/renewal projects

examinations and observations are of utmost importance in living PLIM (AM)

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Ageing management processin Loviisa NPPin Loviisa NPP Courtesy of Fortum Loviisa NPP

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R&D activities for life time management of concrete structures in NPP (SAFIR program)structures in NPP (SAFIR program)

Inspection of structuresInspection of structuresDatabase and service life management tool for concrete structures

DatabaseDatabase

Structures

Life cycle management toolLife cycle management tool

Timing of inspections

concrete structures

MR&R “Maintenance, Repair, Rehabilation”

Modules

MR&R Systems

Timing of MR&R actions

Project design

Repair, Rehabilation

Implementation of MR&R projectsImplementation of MR&R projects

Annual resources design

p p jp p j

[ Vesikari/ report VTT-R-08738-11]

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[ Vesikari/ report VTT R 08738 11]

Calculation process of the service life management tool[ Vesikari/ report VTT-R-08738-11][ / p ]

MR&R System St t d t b M d l d t bMR&R Systemdatabase• Protection systems• Repair systems• Rehabilitation systems

Structure database• Identification data• History data• References to moduledatabase.

Module database• Identification data• Material data• Inspection data• etc..

Data on the active module• Data check• Data check

Table of specified Design process goeson using the Table ofLC Analysis calculation table

• Condition analysis• Timing of actions• Cost analysis

E i t l i t l i

MR&R actions• Specification of action• Year of action• Quantification of actions• Costs of action

on using the Table of specified actions: Project design Annual resources

design• Environmental impact analysis • Environmental impacts of

action

g

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Display of the software[ k / ][ Vesikari/ report VTT-R-08738-11]

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Example of FTA for carbonation initiated corrosion of steel liner/[ Vesikari/ report VTT-R-08738-11]

C1 General conditions of corrosion ( i t ) i t

Corrosion is in it iated by carbonation

(moisture, oxygen) exist C2 CO2 is in the surrounding airC3 Errors in concreting allow carbonation up to the steel liner in 40 years

AND

C1Carbonation reaches steel

Fault Tree Analysis

carbonation up to the steel liner in 40 years.C4 Defective curing (plastic cracking etc.) allow carbonation up to the steel liner in 40 years

C1 liner

AN D

40 years.C5 Fires and other later effects allow carbonation up to the steel liner in 40 years.C6 Cracking caused by local tensile

C2

O R

Structu ral conditions for carbonation to reach steel l iner exist

C6 Cracking caused by local tensile stresses (eg. around penetrations)C7 Cracking caused by pressure and leaking tests

Quali ty o f concrete allows carbonation to steel l iner

Cracks to the dep th of s teel l iner ex is t

O RgC8 Cracking caused by forced deformations (e.g. sinking of foundations etc.)

O R

C3 C4 C5

OR

C6 C7 C8

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