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© Hitachi, Ltd. 2009. All rights reserved.Energy and Environmental Systems Laboratory

Hitachi, Ltd., Energy & Environmental Systems Laboratory

E-Journal of Advanced Maintenance (EJAM)

Hitachi Inspection Technologyfor Nuclear Power Plant

Masahiro Tooma 1

Yoshiaki Nagashima

Yutaka KometaniMasayoshi Sonobe

Masahiro KoikeKojiro Kodaira

Hitachi-GE nuclear energy, Ltd.


2

1 23

Contents

Underwater vehicleUnderwater vehicle4

Introduction (Overview)Introduction (Overview)

Phased array UT Phased array UT

Eddy current testing (ECT)Eddy current testing (ECT)

5 ConclusionConclusion

Japan Society of Maintenology EJAM Occasional Topics (OT) 8

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3

Piping CorrosionInspection

PipingInspection

Overview of Hitachi Inspection Technology for NPP

Turbine Inspection

Nuclear RadiationMonitoring

Eddy Current Testing (ECT)Ultrasonic Testing (UT)Underwater Vehicle (ROV)Guided Wave InspectionRadiation Monitoring

Core Internals, Bottom MountedInstruments (BMI)Inspection

Inspection/Monitoring Technology


4 Objectives of Bottom Head Inspection

CRDH: Control Rod Driving HousingICMH: Incore Monitoring Housing

Integrity Evaluation ofComponents at Bottom HeadIntegrity Evaluation ofComponents at Bottom Head

BWR Bottom Head Region

H9

H11

ICMH

CRDH

RPV

PlateShroudSupport

- Welded to the Reactor Pressure Vessel (RPV)

- Nickel Alloy (SCC)

Nondestructive Testing (NDT)Nondestructive Testing (NDT)

- Detection of StressCorrosion Crack (SCC)

- Length and DepthSizing Measurement

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1 2 3

Contents







6

Shroud

Shroud support

CRD stub

RPV

Expanding inspection area to BHDPurposePurpose

Conventional ECTConventional ECTSingle ECT sensor :High sensitivity for SCC,

but difficulty to apply tothe complicated area

�Rapid inspection: Multi coils�Complicated area inspection:

Flexible sensor�Noise reduction:

Phase mapping method

IdeaIdea

180mm Curveture

20mm

Purpose of flexible Multi ECT Inspection

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�Multi coil (51 coils: Length 60mmOptimization by the eddy current simulation.

Eddy current sensor

ImpedancePlane

Real-time C-scope

Strip Chart

ECT software display

Bend the probe

Radius of Curvature(20mm)

ECT detector

Flexible plate

Flexible Multi-coil ECT System


8

Result of IdentificationResult of Identification

180mm

60m

m

Min

Max

SCC SCC

Conventional: Signal Amplitude

Mockup Mockup

Visual Testing

PenetrantTesting

10mm

800mm

We have developed an automatic crack signal identification system.

SCC SCC

Developed: Identification by Phase Map

SCC Identification

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AccuracyAccuracy

0Actual length (mm)

EDM slit

SCCWeld crack

Accuracy < 3mm

60

60+3mm

-3mm

C scope

200

SUS Crack 20m

m40

40m

m

ECT Penetration testing

25m

m Cracklength

Mea

sure

d le

ngth

(mm

)

0

Out

put(

V)

-12dBVp-p

Estimated length of a crack

Position

Method of Crack Length SizingMethod of Crack Length Sizing

Curved Surface MockupCurved Surface Mockup

Crack length sizing method was authorized by JAPEIC.Crack length sizing method was authorized by JAPEIC.

JAPEIC: Japan Power Engineering and Inspection Corporation

Crack Length Sizing


10

6-axes robot arm

ECT scanner

Flexible sensor

Fig. C scope image obtained by robot ar

(a) Location image (b) C-scope image Fig. An example of ECT results

(a) Location image (b) C-scope image Fig. An example of ECT results

Access tools

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Contents







12

H9

Plate RPV

CladdingWeld

Thickness:150mm

RPV

Array Sensor

0

200

300

400

500

100

0 10 1 Amp.0

200

300

400

500

100150

Amp.

Aperture of SensorSmall Large

Sharp

Optimization by UT SimulationOptimization by UT Simulation

Dep

th (m

m)

Dep

th (m

m)

Array Sensor

Focal Beam

Y

Z

200x200mm

Y

Z

Array Sensors for OD Side of RPV

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Array Sensor

Control Unit Data Acquisition Unit

48Aperture

1-10MHz100 – 300 v

48 (Max. 144)Specification

Voltage

Elements

Frequency

Items

Electric Scanning of Ultrasonic Beam: Controlled by Phased Array System

Phased Array UT System (ES-3100: Hitachi Engineering & Service co,. Ltd.)

Sectorial Scanning- Range: +/- 60 deg.- Pitch: 0.5 deg- 2MHz Longitudinal Wave

Array Sensor

Equipment (2): Phased Array System


14

ISI GuideRail

Scanner

Scanner

ISI GuideRail

RPV RPV

Array Sensor

Array Sensor

H9 Shroud SupportH9 Shroud Support H11 Shroud SupportH11 Shroud SupportSupport

Plate

Array Sensor: Scanned on the OD Surface of RPVby Automated Scanner mounted on the Guide Rail

Equipment (1): Automated Scanners

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Close upClose upTip of Notch

Weld

Array Sensor

Horizontal Notch

UltrasonicBeam

Cladding

Depth

Signal of Tip(Tip Echo)

100 300 500

100

50

0

Propagation Length (mm)

Bottom Surface

Am

plitu

de

Horizontal NotchHorizontal Notch

RPV

SN Ratio of Tip Echo:More than 6dB

Results: H9(1) Horizontal Notch


16

Sizing accuracy for horizontal and vertical notches is Sizing accuracy for horizontal and vertical notches is less than 3mm (< ASME Code 0.125 inch)less than 3mm (< ASME Code 0.125 inch)

0

10

20

30

40

50

60

0 10 20 30 40 50 60Actual Depth (mm)

Horizontal NotchVertical Notch

SD: 2.6mmError Av. : -1.2mmRMS Error: 2.7mm

SD: 2.6mmError Av. : -1.2mmRMS Error: 2.7mm

SD: Standard DeviationRMS: Root Mean Square

Mea

sure

d D

epth

(mm

)

Results of Depth Sizing (Notches)

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Outputs

Electrical Volumetric Scans(Faster than 2D)

Fast InspectionsPoint-Focused Beam

High Resolution

Electrical Planar Scans

(Faster than 1D)Focused Beam

Unable to Scan Electrically

Light and Inexpensive

Features

PhasedArray

Methods

SingleElementMethod

3D3D Focus-UT

2DConventional

1DConventional

Ultrasonic Scanning Methods

3D Image

2D ImageLinearArray Probe

Monolithic Probe

Waveform (1D)

Features of 3D Phased Array UT Features of 3D Phased Array UT

Matrix Array Probe

VolumetricScan

PlanarScan

One Direction

Point-Focus

Focus


18

Fast data acquisitions by 256 simultaneously active elementsFast data acquisitions by 256 simultaneously active elements

Pulser / Receiver

Matrix Array Probe(256 elements: 16×16)Matrix Array Probe

(256 elements: 16×16)

511mm 400mm

480m

m

Data Acquisitions for 3D ScansData Acquisitions for 3D Scans

3D Scanning

Transmit or receiveultrasoundsby 256 elements simultaneously

Photo of 3D Focus-UT

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19 Applications / FBHs in Metal Test Piece

With CAD of Test Piece

100 mm

20

RotationalSectorialScan

FBH

φ1mm FBH

φ2mm FBH

ScanningRegion

3D Image of FBH3D Image of FBHMatrix Array256 elementsLongitudinal 2MHz

Metal Test PieceMetal Test Piece10

0 m

m50

mm

FBH: Flat Bottom Hole

FBH Echoesφ1mm

FBH Echoesφ2mm

Bottom Echo

• Scanned results can be evaluated at one time in a 3D view. • Scanned results can be evaluated at one time in a 3D view. • Echoes can be easily related to the reflection sources

with the help of CAD data.• Echoes can be easily related to the reflection sources

with the help of CAD data.


20

EDM Slit: depth of 3.2mm

Rotational SectorialScan

Bolt

Applications / Bolt InspectionsApplications / Bolt Inspections

Bolts (φ24)Bolts (φ24) 3D Image of Thread and Slit 3D Image of Thread and Slit

• Bolt inspections can be performed without any mechanical motions.

• Bolt inspections can be performed without any mechanical motions.

Matrix Array256 elementsLongitudinal2MHz

One of the Sectors(Conventional Image)

Thread Echo

Slit Echo

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Contents







22 ROVs Lineup

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CABLE Bottom head ROV

Dep

th o

f the

wat

er a

bout

30m

CameraUnit

Thruster

ThrusterThruster

352m

m

120mm250mm

Movement image

(10/17)

CRD housing

(1) Detail of the C-type ROV

SizeW120mm H352mm L250mmFunction The thrusters in back are for cruising forward and backwardThe camera pans 360 degrees and tilt 90 degreesRadiation ToleranceDepth of the water about 30m

360

90

C-type ROV


24 Inspection ROV : Specifications

165mm

60mm

Pitch control mechanism

Specifications

CCD Camera (Wide view)

High brightness LED

CameraSystem

Driving thrustercircling screw

Pitch control mechanism

Actuators

60 165mm

Underwater weight 0g(Weight in air 450g)

Housing

Main Specifications

Driving thruster

CCD Camera High brightness LED

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forward

right

upward

Up and down thruster

The examples of motion

Horizontal thruster

right

circling

forward

up down

Generate any motion by allocating thrust force to five thruster

The vector control using multiple thruster


26

Water flow

Hovering controlExperimental setup Experimental result

The hovering area: about 0.04m

-0.10

-0.05

0

0.05

0.10

0 10 20 30 40Time [s]

Distance of the initial position [m

]

Control on Control off

Moving by water flow

ObjectMoving by

disturbance

0.2m/s (right)0.1m/s (right)0.2m/s (backward)0.1m/s (backward)

The experimental result of the hovering control

ROV Object

Appearance of the experiment

Water flow

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27 Conclusion

To carry out efficient inspection for core internal, shroud support and bottom mounted instrument of reactor pressure vessel, we have developed

the flexible multi-coil ECT system for novel identification and length sizing of surface breaking crack,the phased array UT system for depth sizing

of sub-surface breaking crack in thick-wall structure, the remotely operated vehicles with these

sensors.

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