AP1000 FuelDesign CoreOperations RioJane 2010 24 Sumit Ray

7/29/2019 AP1000 FuelDesign CoreOperations RioJane 2010 24 Sumit Ray

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2010 Westinghouse Electric Company LLC. All Rights Reserved.Westinghouse Non-Proprietary Class 3

Introduction

AP1000 Reactor Design Achieves simplicity through the use of passive safety systems

Results in Significant Reduction in capital and O&M costs Large margins to safety limits while using proven technologies

Certified by the NRC

AP1000 Fuel design Adaptation of the 17X17 RFA design that has significant worldwide

operating experience Further enhancements to provide higher thermal and mechanical margins

AP1000 Core design & Operations 69 Control Rods provide high level of reactivity control

No requirement for Boron adjustment during load follow and power maneuvers Strategy Designated as Mechanical Shim (MSHIM)

AP1000 Core Monitoring BEACON TM used to provide core related technical specification monitoring

and operational support


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AP1000 Critical Fuel Parameters Selected to be

Within Experience Base

Design Parameter AP1000 TypicalXL Plant

W 3-Loop17X17

W 4-Loop17X17

Uprated

Units

Reactor Core Heat Output 3,400 3,800 2,900 3,850 MW

Number of fuel bundles 157 193 157 193

Active core height 4.267 4.267 3.658 3.658 m

Fuel latticeFuel rods per bundle

17x17XL264

17x17XL264

17x17264

17x17264

RCS System Pressure, nominal 15.5 15.5 15.5 15.5 MPa

Coolant Nominal Inlet TemperatureCore Outlet Temperature

279.4324.7

294.0332.2

289.4330.9

279.9321.0 C

Vessel minimum measure flow rateFlow/Assembly

19.030.121

25.430.132

17.890.114

24.140.125

M3/s

Minimum DNBR at nominal condition 2.74 2.47 2.21 2.35

CHF correlation WRB-2M WRB-1 WRB-2 WRB-2Nominal average heat flux 628.7 571.6 650.2 702.2 kW/M2

Nominal average linear power 18.77 17.06 18.67 20.18 kW/M

Peak linear power - normal operation 48.88 45.93 45.60 50.43 kW/M


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AP1000 Control and Shutdown Bank

Locations69 Total Control RodsM-

Bank

AO

S1S2

S3S4

AO-Bank

MBMC

M1MD

M2

MA

Shutdown-Bank

: 9

: 8: 8: 8: 8

: 4: 4

: 4: 4

: 8

: 4

(Black)

(Black)

(Gray)

(Black)

S4 MB S4

M2 S2 S2 M2

MC AO M1 AO MC

M2 S1 S3 S3 S1 M2

S4 AO MA MD MA AO S4

S2 S3 S1 S1 S3 S2

MB M1 MD AO MD M1 MB

S2 S3 S1 S1 S3 S2

S4

AO MA MD MA AO S4

M2 S1 S3 S3 S1 M2

MC AO M1 AO MC

M2 S2 S2 M2

S4 MB S4


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AP 1000 Reactivity Control System Description

Existing plants use the same control bank for both overall reactivity /temperature control and Axial Power Distribution control, along withchanges in RCS Boron concentration

Leads to high variation in local power distributions and propensityfor Xenon transients

AP1000 Uses two separate sets of Banks no changes in RCSBoron for load follow or power maneuvers

M banks for Reactivity/ Temperature control

AO banks for Axial Power Distribution Control

M banks include lower worth rods ( Gray rods)

Allow boron-adjustment free load-follow operation


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MSHIM Operation Provides Tighter Power DistributionControl

-25.0

-20.0

-15.0

-10.0

-5.0

0.0

5.0

10.0

0.0 10.0 20.0 30.0 40.0 50.0 60.0

AxialOffset(%)

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

0.0 10.0 20.0 30.0 40.0 50.0 60.0

Del-Xenon

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

0.0 10.0 2 0.0 30.0 40.0 50.0 60.0

FQ*

PREL

TrulyConstant AO

Control inMSHIM

Tight XenonControl with

MSHIM

Better FQ

Control withMSHIM

AP1000 First Cycle -- Daily Load Follow 100% to 50% Power

at Near MOL (Black Line = MSHIM, Red Line = CAOC)


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AP1000 Fuel Design & Operational Experience

AP1000 Fuel design Adaptation of the 17X17 Robust Fuel Assembly (RFA) design that has

significant worldwide operating experience Further enhancements to increase thermal and mechanical margins

Substantial field experience with this design In Operation since 1997

Over 12,700 assemblies (~3.3 million fuel rods) and 221 reloads haveoperated in 47 plants worldwide since 1997

Lead rod burnups close to regulatory limit of 62 GWD/MTU

Further enhancements to improve mechanical robustness and thermal margins Intermediate Flow Mixing Grids Enhanced RFA mid-grid design

Addition of bottom plenum to improve Rod Internal Pressure margins Westinghouse Integral Nozzle (WIN)

Ability to use either discrete or a variety of Integral Burnable Absorber

Designs


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AP1000 Fuel Assembly Design Features

AP1000

Skeleton structure Enhanced dimensional stability ZIRLO tubing Thick thimble tubes Tube-in-tube dashpot design

Anti-bowing design prevents IRI

Westinghouse Integral Nozzle (WIN) One piece casting

4 Intermediate Flow Mixing (IFM) Grids Heat transfer enhancement Structural capability/stability Enhanced outer strap

ZIRLO Tubing

Stand-off Piece/Bottom Plenum

Protective Grid (P-Grid)

With Standard End-Plug

Top Mounted Core

Instrumentation

Inconel Top Grid

Enriched Axial Blanket

RFA Mid-Grid Enhanced strengthEnhanced fretting margin ZIRLO

Enriched ZrB2 Integral

Burnable Absorber

Oxide Coated Cladding

Low Profile Debris Filter

Bottom Nozzle (LP DFBN)

Inconel Bottom Grid


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Fuel

Design &

Management

Fuel

Manufacturing

Reactor Design &

Operations

AP1000 Fuel Reliability Program Zero from the Start

Address plant design issues during

design finalization that can adversely

impact fuel performance

Implement design features and

manufacturing processes to

maximize margins to failure

Specify bounds of reactor operation

and monitor using BEACON

software

Specify and implement a robust PIE

program to obtain early feedback onfuel performance

BEACON is a tr ademark of Westinghouse Elec tric Company LLC in the United States and

may be regis tered in other countries throughout the world. All rights res erved. Unauthorized

use is s trictly prohibited


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Specific INPO 2010 Focus Areas

INPO 2010 requires specific attention to the following areas PWR Grid-to-rod fretting

Crud induced corrosion

PCI induced failures

Debris related failures

Manufacturing related failures

Specific focus also on Post Irradiation Exams (PIE) on healthy fuel forearly identification of potential issues

AP1000

Significant Attention Paid to of All of the AboveIssues During theAP1000Fuel Design

Finalization Process


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Reactor Design Key Aspects Designed to Improve

Fuel Reliability

Core Shroud Design

All welded design that does not require baffle bolts for assembly

Removes potential for baffle jetting failures

Addition of inlet Flow skirt

Provides significantly better inlet flow distribution and minimizes the

potential for inlet flow distribution anomalies

Orientation of Gray banks

Optimized to minimize power peaking


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Highlights of Steps Taken to Address

Specific Failure Mechanisms

PWR Grid-to-rod fretting

Grid to rod-contact areas significantly increased for additional margin

Extensive testing to ensure excellent performance

Crud induced corrosion Thermal parameters selected to ensure boiling duties are within

experience base

Zinc injection will be implemented during hot functional testing

PCI induced failures MSHIM designed to provide extremely tight power distribution control

Axial Offset and Xenon distributions can be controlled to an extremely narrow band

Low worth gray rods have little impact on axial or radial power distribution relativeto black rods

Peaking factors & local power changes remain low even during power maneuvers


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Highlights of Steps Taken to Address

Specific Failure Mechanisms

Debris related failures Aggressive debris prevention and system cleanup being implemented

during plant construction through procedural requirements

Full complement of Westinghouse fuel debris features Debris Filter Bottom Nozzle, Protective Grid and Oxide Coating

Manufacturing related failures 100% eddy current testing to pick up cladding flaws or surface defects

Tighter pellet chip acceptance criteria to maximize margins to PCIfailures

Incorporation of an automated system for pellet diameter inspection

Pellet Drying prior to rod loading to minimize the probability of primaryhydride failures

Specific focus also on Post Irradiation Exams (PIE) on healthy fuel

for early identification of potential issues


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AP1000 Power Distribution Monitoring

System Description

Uses the Westinghouse BEACONTM system Utilized in over sixty reactors over the world

BEACONTM signals generated by seven section fixed incore detectorsutilizing long life Vanadium emitters

Detailed power distribution input used to continuously update and

deplete a 3D Core Neutronics model BEACONTM allows

Online Core Thermal margin Monitoring ( DNBR and Linear HeatRate)

Core Reactivity and Shutdown margin monitoring

Input to Control Room alarms Excore detector calibration

General core diagnostic and predictive simulation capability

C CC


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Summary

AP1000 Fuel Design and Core Operations utilizes proven technologies while

enhancing thermal and operational margins

Operational & safety margins within current W experience base

MSHIM Operational strategy allows load follow & power changes without

Boron concentration changes

provides significantly enhanced power distribution control

The AP1000 fuel reliability program aims for Zero from the Start

Use of the BEACONTM system allows for improved operational as well as safety

margins

Documents

AP1000 FuelDesign CoreOperations RioJane 2010 24 Sumit Ray