IAEA CRP on Aging Management of Concrete Containment Buildings · PDF fileIAEA CRP on Aging...

IAEA CRP on Aging Management of

Concrete Containment Buildings

Dan J. Naus

First Consultancy on Assessment &

Management of Concrete Containment

Buildings and Other Structures

Vienna, Austria

29 May 2012

1

Olkiluoto NPP

In 1989 IAEA Initiated a Program to

Assist Member States in Understanding

and Managing Aging of NPP SSCs

“Safety Aspects of Nuclear Power Plant Ageing (IAEA-TECDOC-540),” January 1990

Increase awareness and understanding of aging and its relation to safety

Identify approach and actions needed to effectively manage NPP aging

“Methodology for Management of Ageing Of Nuclear Power Plant Components Important to Safety (IAEA Report 338),” 1992

Technical issues (e.g., safety impacts of aging, effectiveness of monitoring and mitigation techniques, and procedures to estimate future performance)

Methodologies for selection of key plant components important to safety and performing aging management studies

Representative components for pilot studies based on safety significance and aging susceptibility

Primary nozzle of reactor pressure vessel

Motor operated isolation valve

Concrete containment building

Instrumentation and control cables within containment building

2

Doel NPP

Pilot Studies Conducted on Management of

Aging of NPP Components

“Pilot Studies on Management of Ageing of Nuclear

Power Plant Components (IAEA-TECDOC-670),” October 1992

Phase I results provided for each of four components

Pilot study on concrete containment building

Design functions

Service conditions during normal/abnormal operating conditions

Potential degradation factors and aging mechanisms

Methods for mitigation of degradation

Phase II activities addressed aging of concrete containment buildings through a Co-ordinated Research Program

“Summary Results of the Survey on CCB Ageing (IAEA/NENS),” 1995

“Assessment and Management of Ageing of Major Nuclear Power Plant Components Important to Safety - Concrete Containment Buildings, (IAEA-TECDOC-1025),” June 1998

3

Thange NPP

Pilot Studies on Aging of NPP Components

Identified Several initial Objectives

Produce a summary of current

aging management practices and

experiences

Compile a state-of-the-art report

on repair techniques and materials

Develop crack mapping and

acceptance/repair guidelines

Develop a set of condition

indicators and associated

guidelines for monitoring aging

4

Worldwide Survey of Owners/Operators Conducted in

Support of CRP Objectives Provided Responses From

Over 150 Units in 15 Countries

Part 1: General Plant Information

Part 2: Inspection, Investigation, and Preventative Maintenance Programs

Part 3: Age-Related Degradation Experience

5

Concrete Containment Ageing Questionnaire

Part 1: General Plant Information

6


Part 1: General Plant Information (Cont.)

7


Part 2: Inspection, Investigation, and

Preventative Maintenance Programmes

8



Preventative Maintenance Programmes (Cont.)

9

Instrument No. Installed Frequency of Routine

Recording

Times Used in Repair

Investigation

Identify Formal

Procedures Used

Strain Gauges

Thermocouples

Stress Cell

Humidity Gauge

Length Change

Others

Instrumentation/Monitoring:

A.1 Concrete - Instrumentation

Please complete the following table by identifying the instrumentation installed and details of recording:

Is data logging computerized? No _______ Yes _______

Is data compared to original design specification? No _______ Yes _______

Are operating limits defined? No _______ Yes _______

If yes, please provide details.




10

Method

Frequency of

Routine

Inspection

Times Used in Repair

Investigation Procedure Used

Acceptance

Criteria

Pulse Velocity

Impact Hammer

Permeability

Leakage

Probe Penetration

Pullout

Others

Instrumentation/Monitoring (cont.):

A.1 Concrete - NDE/NDT




11

Other Techniques Frequency Times Used in Repair

Investigation

Formal Procedure

Used

Acceptance

Criteria

Frequency of core drills for routine inspection _______ years

Number of core drills as part of repair investigation _______

Are formal procedures used? No _______ Yes _______ (identify)

Is concrete core obtained used to obtain material properties? No _______ Yes _______

Which of the following properties obtained? (Record yes or no)

Strength _______ Modulus _______ Chemical _______ Porosity _______ Others _______

A.1 Concrete - Others:

Are any other procedures used aspart of the inspection/monitoring of concrete? No ____ Yes ____

If yes, please fill in the following table:


A.1 Concrete - Cores




12

Techniques Used

for Anchorage

Element Inspection

Frequency

of Routine

Inspection

Times Used in

Repair

Investigation

Details of Procedures

or Methods Used

Acceptance Criteria/Details of

Procedures and Methods Used

Visual

Pullout

Others


A.2 Anchorage Elements

Techniques Used

for Reinforcing

Steel Inspection

Frequency

of Routine

Inspection

Times Used in

Repair

Investigation


or Methods Used



Visual

Half Cell

Cover Meter

Others

A.3 Reinforcing Steel




13


A.4 Prestressing Steel

Techniques Used

for Prestressing

Steel Inspection

Frequency of

Routine

Inspection

Times Used

in Repair

Investigation


or Methods Used



Liftoff Test

Load Cell

Visual

Mechanical

Property Tests on

Wires

Grease Chemistry

Others




14

Techniques Used for

Inspection

Frequency

of Routine

Inspection

Times Used

in Repair

Investigation


or Methods Used



Visual

Leak Test

Penetration Assemblies:

NDT

1. Ultrasonic

2. Local Leak Test

3. Others:

Seals:

NDT

1. Ultrasonic

2. Local Leak Test

3. Others:


A.5 Liner and Penetration Assemblies




15

Activity Frequency Location Details of

Methods Used

Applicable to Other

Plant Structures?

1. Protective Coating

2. Grouting Refurbishment

3. Sealant Removal or Replacement

4. Cathodic Protection

5. Others:

Preventative Maintenance

B. Preventative Maintenance Programmes



16



(cont.)

17



(cont.)

18



(cont.)

19



(cont.)

20



(cont.)

21

IAEA has Published Two Reports that Address

Assessment and Management of Aging of NPP

Containment Buildings

Containment descriptions and

design basis

Service conditions and aging

mechanisms

Inspection and assessment

methods

Operating experience

Aging management program

22

Survey Results and Knowledge of Practice in

CRP Member’s Countries Used to Prepare

Report on Aging Management

Introduction

Concrete Containment Buildings

Understanding Aging

Detecting Aging

Assessment and Repair of Aging Effects

Operating Experience

CCB Aging Management Program

Conclusions and Recommendations

Appendix I: Current Aging Management Practices and Operating Experience of Several Member States

Appendix II: Aging Experience of Non-Nuclear Concrete Structures

23

Point Lepreau NPP

Chapter One Provides General

Introductory Materials Related to

Ageing Management of CCBs

CCBs are designed to separate the reactor and other systems and equipment important to safety from outside environment

External and internal events considered

Although typically designed to a specified service life, economic pressures and decommissioning strategies mean that CCBs may have to perform safety functions for an extended period of time (100+ yrs)

Age-related degradation must be effectively controlled to assure adequate leak-tightness and structural integrity

Faulty design

Use of unsuitable or poor quality materials

Improper construction

Exposure to aggressive environments

Excessive structural loadings

Accident conditions

24

Angra 1/2 NPP

A Number of Existing NPP Programs, such as Periodic

Inspection and Testing, or Preventative and Corrective

Maintenance, Contribute to Aging Management of CCBs

Existing Programs should be Integrated and Modified

(As Appropriate) Within a Systematic AMP

25

Chapter Two Provides a General Description of

NPP CCBs that have been Developed to Address

Different Reactor Systems

Composed of several

constituents that, in concert,

perform multiple functions

Designed, constructed,

operated, and inspected in

accordance with national and

consensus codes and standards

Construction of PCC

26

Typical Design Parameters

for Selected PWR Plants

27

Type Material Ref. Plant Int. Diam

(m)

Free Vol.

(103 m3)

Des. P

(kPa)

Des. Leak Rate

(% Vol./day)

Large Dry RC Hemi. Dome Indian Pt. 3 41 74 324 0.1

Large Dry St. Cyl. Hemi Dome Davis Besse 40 81 276 0.5

Large Dry PC Shallow Dome Zion 43 81 324 0.1

Large Dry PC Hemi. Dome Trojan 38 57 414 0.2

Ice Condenser St. Cy. Hemi. Dome Sequoyah 32 -- 74 0.5

Subatmospheric RC Hemi. Dome Surry 38 51 414 0.1

Lg. Dry

Prestressed

Ice Condenser

Subatmospheric

Typical Design Parameters

for Selected BWR Plants

28

Drywell Wetwell

Type Material

Ref. Plant Des.

Temp

(˚C)

Free Vol.

(103 m3)

Des.

Temp

(˚C)

Free Vol.

(103 m3)

Des.

Pressure

(kPa)

Des. Leak Rate

(% Vol/day)

Pre MK Steel Sphere Big Rock Pt. 113 33 --- --- 186 0.5

MKI Steel Peach Bottom 138 5 138 4 386 0.5

MKII Rein. Concrete Limerick 138 7 138 4 386 0.5

MKIII Rein. Concrete Grand Gulf 166 8 85 36 103 0.35

BWR MKI BWR MKII BWR MKIII

Primary Regulations, Codes, and Standards

Identified Relative to Design, Construction, and

Inspection of Concrete Containment Buildings

29

Chapter Three Identifies Mechanisms that

can Affect the Long-Term Performance of CCBs

30

Degradation Factors that can Impact

Performance of CCB Construction Materials

were Summarized

31

Chapter Four Summarizes Methods Most

Commonly Used as Well as Those that Represent

Good Practice for Detection of Degradation

32

Detection and Evaluation of Impact of Relevant

Aging Mechanisms is the Key to an Effective

Aging Management Program

33

Direct and Indirect Methods are Utilized to

Assess Concrete Properties or Characteristics

34

Inspection Activities are Designed to Detect and

Characterize Degradation Before Fitness-for-

Service is Compromised

Aggressive Ions (P)

Coating Bond Performance (P)

Broken Wires (T)

Coating Thickness (P)

Weld Cracks (L)

Coating Distress (P)

Elongation (T)

Free Water Quantity (P)

Leakage (L)

pH Value (P)

Prestressing Force Loss (T)

Reinforcement Corrosion (R)

Structural Degradation (L, T)

Surface Cracks (L, P)

Ultimate Strength (T)

Wall Thickness (L)

Yield Strength (T)

Coa

tin

g M

easu

rem

ent

Cro

ss-C

ut

Tes

t

Fou

r-E

lect

rod

e M

eth

od

Gre

ase

Tes

ts

Ha

lf-C

ell

Po

ten

tial

Lif

t-O

ff T

est

Liq

uid

Pen

etra

nt

Loca

l L

eak

Tes

t

Ma

gn

etic

Pa

rtic

le T

est

Rate

of

Co

rro

sio

n P

rob

es

Ten

do

n M

ech

an

ica

l T

ests

Ult

raso

nic

Tes

ts

Vis

ua

l In

spec

tio

n

Evaluation Method

Property or Characteristic*

X

X

X

X

X

X

X

X

X

X

X

X X

X

XX

X

X

X

X

X

X

X

X

X

X

X

*L = liner, P = protective media, R = mild steel reinforcement, and T = tendon.

35

Instrumentation is Aimed at Providing Verification of Design

Assumptions, Monitoring Short-Term Performance, and/or

Monitoring Long-Term Performance

Vibrating-Wire Strain Gages

Thermocouples

Pendulums

Extensometers

Load Cells

Humidity Gages

Precise Level Surveying

36

Examples of

Concrete Embedded Sensors

Chapter Five Addresses Condition Assessment

and Remediation of Aging Effects

Reinforced concrete structures almost from time of construction can start to deteriorate in one form or another due to exposure to the environment

Condition assessment programs monitor progress of deterioration and provide input to develop and implement remedial actions

No active intervention

More frequent inspections

Carry out repairs to maintain or restore

Demolish and rebuild

Repair can restore a structure to its former condition and (hopefully) a lower deterioration rate and repair frequency

37

A Remedial Measures Program Includes

Diagnosis, Prognosis, Scheduling, Method

Selection, Preparation, and Application

38

Repair of Corrosion-Damaged Concrete Involves

Halting One of the Three Process Necessary for

Corrosion Occurrence: Anodic, Cathodic, and

Electrolytic

39

Although Overall Performance of Concrete

Containment Buildings has been Good,

Degradation Requiring Repair has Occurred

40

Chapter Six Provides a Summary of Operating

Experience Related to CCB Degradation,

Inspection, and Repair Actions

Information on Several Member States

Aging Management Practices was also Assembled

41

Responses Representing Over 150 Nuclear

Power Units were Received From

Owners/Operators in 15 Countries

42

Res

po

nd

ing

Co

un

try

Un

it T

yp

e

Plant Design Dates Ranged from pre-1965 to

1985 and In-Service Dates from 1964 to 1994

43

Most Frequently Reported Manifestation of

Concrete Degradation was Cracking

Freeze/thaw

Elevated temperature

Thermal gradient

Sulfate attack

Seawater exposure

Chemical attack

Leaching

Abrasion

Impact

Shrinkage

Sealant failure

Creep

Leakage test

Irradiation

Chloride penetration

Carbonation

Alkali/aggregate reaction

Fatigue/vibration

Stray electrical currents

Construction defects

Design defects

Other

Subtotal of events

Cra

ckin

g

Sca

lin

g

Del

amin

atio

n

Sta

inin

g

Spal

lin

g

Eff

lore

scen

ce

Pop

ou

t

Du

stin

g

Vo

ids/

ho

ney

com

b

Incr

ease

d p

erm

eabil

ity

Oth

er

Sub

tota

l o

f ev

ents

Manifestation and Numberof Incidences Reported

Degradation FactorReported

10

7

12

--

6

--

--

--

--

54

1

10

7

--

--

--

--

10

--

23

1

4

145

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

2

--

2

1

--

1

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

3

2

--

7

--

--

--

--

--

4

--

--

--

--

--

--

--

--

--

--

--

--

1

--

--

--

5

--

--

--

--

--

--

--

--

--

--

--

--

3

--

--

--

--

--

--

10

--

2

15

2

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

9

--

--

11

--

--

--

--

--

4

--

--

--

--

--

--

--

--

--

--

--

--

--

--

1

--

5

--

--

--

--

--

--

11

--

--

--

1

--

--

--

--

--

--

--

--

--

--

--

12

7

--

2

--

--

--

--

--

--

2

--

--

--

--

2

--

--

--

--

7

2

2

24

--

--

--

--

--

--

3

--

--

--

--

--

--

--

--

1

--

--

--

--

7

3

14

--

--

--

--

--

--

--

--

--

--

--

--

--

--

1

--

--

--

--

2

1

4

20

7

15

--

6

8

14

--

--

56

2

10

10

--

3

1

--

10

1

54

16

11

244

44

Cracks Resulted from a Number of Causes and

Appeared in Several Locations

45

Age at Which Cracks were First Reported could

not be Determined and about Forty-Five Percent of

Incidences Reported Required No Action

46

The Most Frequently Reported Manifestation of

Metallic Material Degradation was Corrosion

Freeze/thaw

Elevated temperature

Sulfate attack

Seawater exposure

Chemical attack

Shrinkage

Sealant failure

Creep

Leakage test

Irradiation

Chloride penetration

Carbonation

Fatigue/vibration

Stray electrical currents

Construction defects

Design defects

Other

Subtotal of events

Rei

nfo

rcin

g s

teel

corr

osi

on

Pre

stre

ssin

g t

end

on c

orr

osi

on

Co

nta

inm

ent

pen

etra

tio

n

Pre

stre

ss l

oss

Su

bto

tal

of

even

ts

Manifestation and Numberof Incidences Reported

Degradation FactorReported

--

--

--

--

--

--

--

--

--

--

4

--

--

--

6

--

2

12

--

--

--

2

--

--

--

--

--

--

--

2

--

--

--

1

--

5

--

4

--

--

--

--

2

--

--

--

--

--

--

--

-

1

--

7

--

--

--

--

--

--

--

--

--

--

--

--

--

--

--

2

--

2

--

4

--

2

--

--

2

--

--

--

4

2

--

--

6

4

2

26

47

Most Commonly Used Methods of Inspection

were Prescribed by Codes and Regulations

Visual Inspection

Instruments

NDE/NDT

Coring

Pullout Tests

Half-Cell Potential

Cover Meter

Lift-Off Tests

Load Cell

Mechanical Tests

Grease Inspection

Leakage-Rate Test

Other Tests

Percentage of Unitswith this Element, %

Concrete Anchorage Reinforcing Prestressing Liner/ E lements Steel Steel Penetrations

Percentage of Units Utilizing, %

84

52

28

<1

--

--

--

--

--

--

--

--

5

99

73

--

--

--

1

--

--

--

--

--

--

--

5

65

26

--

--

--

--

6

3

--

--

--

--

--

--

99

26

--

--

--

--

--

--

18

45

16

16

--

3

65

53/--

--/--

--/10

--/--

--/--

--/--

--/--

--/--

--/--

--/--

--/--

53/30

--/8

68/100

InspectionTechnique

48

Visual Inspections of Concrete Structures were

Often Supplemented by Crack Mapping

Concrete visual inspection/crack mapping frequency

Summarized by percentage of units/owners responding

Crack mapping information summarized by

percentage of units/owners responding

49

Owners Supplementing Regulatory

Requirements Generally Used Longer

Inspection Intervals

Thermocouple

Strain Gauge

Stress Cell

Humidity Gauge

Invar Wire

Other

Percentage ofUnits Utilizing,

%

Percentage ofOwners Utilizing,

% Range Median

52

46

5

3

12

42

Number Used

20

17

10

5

5

10

27

103

8

1

4

--

8 to 1335

18 to 240

4 to 80

1 to 2

4

--

InstrumentationType

Leakage Rate

Impact Hammer

Pulse Velocity

Permeability

Others

Percentage ofUnits Utilizing,

%

Percentage ofOwners Utilizing,

%

26

17

17

5

5

24

7

10

5

12

Test Type

50

Chapter Seven Provides a Framework for an

Aging Management Program for CCBs

Objective is to Ensure Timely Detection and Mitigation of

Any Degradation that could Impact Safety Functions

51

Understanding Relevant Aging Mechanisms and

Their Potential Impact is the Key to an Effective,

Optimized AMP

Baseline, Construction and Commissioning, Operational History,

and Inspection and Surveillance Data, as well as Generic issues, Provide Data

52

Indicators of AMP Effectiveness Identified in

”Implementation and Review of NPP Ageing

Management Programme”

53

Details of the Containment’s Design/Construction and

Operational History are Required for Effective

Comparison or Correlation with External Experience

54

An Inspection/Monitoring Program must be

Defined as well as Criteria Against which Results

are to be Judged

To be Effective, an AMP should be Periodically Reviewed

and Updated to Reflect Plant Experience

55

Operate Plant Within Limits to Minimize Age-

Related Degradation, and, in Particular, Error-

Induced Degradation

It is Prudent to attempt to Control and Monitor the

Operating Environment of Inaccessible Parts of the CCB

Where Detection and Repair would be Difficult and Costly

56

Results help Provide Basis for Decisions

Regarding Type and Timing of Maintenance

Actions to Correct Detected Aging

57

Examples Illustrating Use of Performance Trending

as Part of an AMP and Use of Maintenance to

Reestablish Acceptable Performance

Example of how performance trending

can be used as part of

an aging management program

Example of how maintenance can be

used to reestablish acceptable

performance of a reactor building

58

Measu

red

Perf

orm

an

ce P

ara

mete

r

Re

ac

tor

Bu

ild

ing

Le

ak

ag

e R

ate

(% v

ol/

da

y a

t 1

24

kP

a)

Pa

inti

ng

Pro

gra

m (

% C

oa

ted

)

Maintenance and Remedial Work are Implemented

in Response to an Identified Defect

59

Chapter Eight Provides a Summary of CRP

Conclusions and Recommendations

Based on Input of Operators, Experience of CRP Participants,

and Information in Working Material Document

60

Coordinated Research Program on Concrete

Containment Buildings Derived Several

Conclusions

Performance of RC structures has been good, majority of identified defects initiated during construction and were repaired at that time

Techniques for detecting effects of concrete aging provide vital input for evaluating the structural condition of CCBs

Condition assessment methods for RC structures are well established and generally start with visual examination of the structure’s exposed surfaces

Concrete maintenance and repair techniques are well established and effective when properly selected and applied

Many utilities worldwide have responded to potential for CCB age-related degradation and implemented AMPs

Most effective AMPs had clearly defined and documented activities aimed at understanding, effectively monitoring, and mitigating aging

A framework for aging management of CCBs, consistent with existing IAEA guidelines, has been defined based on international experience and best practice

61

Confrentes NPP

Coordinated Research Program on

Concrete Containment Buildings Made Several

Recommendations

Utilities and Plant Owners that Do Not have an

AMP for CCBs should Build on Existing Aging

Management Activities to Develop a Systematic

AMP Based on Key Features of Understanding

Aging, Information Management, and Condition

Assessment

Information Exchange Initiated at the International

Level (IAEA, CSNI) should be Combined and

Expanded so that Individual Plant AMPs can be

Enhanced through a Wider Experience Database

Results Developed Under this CRP should be

Extended to Address Other Safety-Related

Concrete Structures

62

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