Pre-submittal Meeting Westinghouse BWR ECCS Evaluation ...

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Pre-submittal MeetingWestinghouse BWR ECCS Evaluation Model:Supplement 5 – Application to the ABWR

John Blaisdell WestinghouseDave Shum WestinghouseScott Head STPNOC

Westinghouse Non-Proprietary Class 3

Westinghouse Electric CompanyP.O. Box 355

Pittsburgh, PA 15230-0355

©2009 Westinghouse Electric Company LLCAll Rights Reserved

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Agenda● Introduction● Attendees● Desired Outcomes● Overview of plan for ABWR fuel-related topicals● GOBLIN LOCA model for ABWR● Important features for ABWR LOCA transient● Benchmarking● Analysis and Results● Schedule

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Introduction● STP Team Attendees

– Scott Head STPNOC– Nirmal Jain Westinghouse– John Blaisdell Westinghouse– David Shum Westinghouse– Brad Maurer Westinghouse– Robert Quinn Westinghouse– Jeremy King Westinghouse– John Ghergurovich Westinghouse– Fumihiko Ishibashi TANE– Hirohide Oikawa Toshiba– Yoshihiro Kojima Toshiba

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Introduction● Desired Outcomes

– Provide an update to NRC on the plans for fuel related topical reports

– Provide NRC reviewers with an understanding of the scope content of the ABWR LOCA topical report

– Receive feedback from NRC

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Westinghouse BWR Code Overviewa,c

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LTR Schedulea,c

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ABWR LOCA Model LTR● Supplement to an approved GOBLIN LTR for BWR

– WCAP-17116-P– Westinghouse BWR ECCS Evaluation Model:

Supplement 5 – Application to the ABWR– Submittal date : September 2009

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ABWR LOCA Model for ABWR● Computer Codes

– Same as used for BWR applications– GOBLIN – system performance, hot assembly response

– Performs the analysis of the LOCA blowdown and reflood thermal hydraulic transient for the reactor, including interactions with various control and safety systems

– One dimensional, drift-flux, thermal equilibrium, point kinetics

– CHACHA – nodal heatup calculation– Performs detailed fuel rod mechanical and thermal response

analysis at a specified axial level within the hot assembly

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Flow of Information Between Codes

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Important Features of ABWR● 10 Reactor internal pumps (RIPs)

– On loss of offsite power, core flow decreases very rapidly

● Robust ECCS– 1 Reactor core isolation cooling (RCIC)

system (turbine driven) → FW piping– 2 High pressure core flooder (HPCF)

systems (motor driven) → upper plenum– 2 Low pressure flooder (LPFL) systems

(motor driven) → annulus– 1 LPFL system → FW piping– 8 Automatic depressurization system (ADS)

valves → suppression pool● Except for a small bottom drain line, all RPV

penetrations are above the top of active fuel– Two-phase mixture remains above the top of

active fuel throughout transients

Bottom of dryer

Top of separator

Bottom of separatorTop of shroud headdome

Top of fuel channel

Top of active fuel

Bottom of active fuelTop of core supportmounting flange

Top of pump deckTop of CRD housing

Steam line

Bottom of dryer skirt

Reactor internal pump

Steam dome

Core shroud

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Description of ABWR Evaluation Modela,c

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GOBLIN Nodalization Diagram (Typical)a,c

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Important Features of ABWR LOCA Transient

● As an example - HPCF line break– Break of HPCF line disables the affected HPCF

system and the single failure of the emergency diesel generator feeding the other HPCF system results in the following ECCS components:RCIC+ 2 LPFL + 8 ADS

– The break area of the HPCF line is limited by the sparger nozzles residing in the upper plenum of the reactor (0.099 ft2)

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ABWR HPCF Line Break Transient - PreliminaryShort Term Response

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

0 1 2 3 4 5 6 7 8 9 10

Time (s)

Nor

mal

ized

Par

amet

er (-

)

Pump Speed

Reactor Power

Dome Pressure

Long Term Response

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

0 100 200 300 400 500 600 700 800

Time (s)

Nor

mal

ized

Par

amet

er (-

)

Dome Pressure

System Mass

Core Flow

Hot Assembly Void - TAF

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ABWR HPCF Line Break Transient - PreliminaryBreak Flow and ECCS Flow

0

200

400

600

800

1000

1200

1400

0 100 200 300 400 500 600 700 800

Time (s)

Flow

Rat

e (lb

/s)

10

15

20

25

30

35

40

45

Wid

e R

ange

Wat

er L

evel

(ft)

Break Flow

ECCS Flow

Wide Range Level

LWL 2

LWL 1.5

LWL 1

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ABWR HPCF Line Break Transient (cont’d)

● Observations– Cladding temperature excursion is due to early dryout as

core flow decreases– Core remains covered by a two-phase mixture

throughout transient● Conclusions

– Pump modeling is important– Prediction of dryout is important– Hot assembly power can be set very conservatively– Peak cladding temperature is independent of ECCS

performance

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Important Features of ABWR LOCA Transient● Initial Conditions

a,c

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Pump Model Benchmarking● Pump model validation

– The coolant conservation and the pump angular momentum equations are coupled in GOBLIN through the pump homologous curves

a,c

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Pump Model Benchmarking● ABWR Modeling

– Use homologous curves for ABWR internal pumps

– Biased inputs to predict pump

coastdown time constant design specification

– Pump efficiency– Pump / motor inertia

a,c

a,c

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Pump Model Benchmarking● Olkiluoto 1 Pump Trip

– OL1 is an internal recirculation pump reactor operated by TVO in Finland

– GOBLIN was used to predict a pump trip test that was performed during startup

– Calculated core flow compares well with measured flow

● Conclusion– GOBLIN can be used to

conservatively model pump coastdown for LOCA applications

0

1000

2000

3000

4000

5000

6000

7000

0 1 2 3 4 5 6 7 8

Time (s)

Cor

e Fl

ow R

ate

(kg/

s)

GOBLINTVO1 Data

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Boiling Transition Benchmarking

● The onset of boiling transition is calculated using a boiling length CPR correlation that was developed for the fuel being analyzed (e.g., SVEA-96 Optima2)

● The CPR correlation was developed from steady-state dryout test data collected from the FRIGG loop in Västerås Sweden.

● GOBLIN was used to predict transient dryout experiments performed in the FRIGG loop

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Boiling Transition Benchmarkinga,c

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Boiling Transition Benchmarkinga,c

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Boiling Transition Benchmarking● FRIGG tests benchmarked

● Results– All flow ramp tests predicted conservatively– Most power ramp tests predicted

conservatively– Note that typical ABWR LOCA

indicates power decreasing● Conclusion

– GOBLIN predicts dryout conservatively for LOCA transients

a,c

a,c

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Analysis and Results

● Break Spectrum / Single Failure Study

– Case resulting in highest PCT will be evaluated in CHACHA to show compliance with 10CFR50.46 criteria.

– Case resulting in minimum inventory evaluated to demonstrate no core uncovery.

a,c

a,c

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LPFL break + fail 1 EDG8111RHR (LPFL) injection line break

Fail 1 EDG8211Main steam line break (outside containment)

8

8

88

88

ADS

Fail 1 EDG211Drain line break

Fail 1 EDG211RHR shutdown suction line break

RCIC side break + fail 1 EDGLPFL side break, fail 1 EDG

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11

01

Feedwater line break

RCIC (turbine) break + fail 1 EDG

210Main steam line break(inside containment)

HPCF break + fail 1 EDG201HPCF line break

RemarksLPFLHPCFRCICBreak Location

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Large and Small Breaks●HPCF line break (Small Break)

– Break area: 92 cm2 (0.099 ft2)– Limited by area of sparger nozzles

– Available ECCS: RCIC + 2 LPFL + 8 ADS● FW line break (Large Break)

– Break area: 838.9 cm2 (0.903 ft2)– Limited by area of sparger nozzles

– Available ECCS: 1 HPCF + 2 LPFL + 8 ADS

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Comparison of FWLB and HPCF - Preliminary

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0 50 100 150 200 250 300 350 400 450 500

Time (s)

Syst

em M

ass

(Mlb

)

hpcf

fwlb

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0 50 100 150 200 250 300 350 400 450 500

Time (s)Vo

id F

ract

ion

(TA

F)

hpcf

fwlb

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Comparison of FWLB and HPCF - Preliminary

400

500

600

700

800

900

1000

1100

1200

1300

1400

0 100 200 300 400 500

Time (s)

Peak

Cla

d Te

mp

(F)

hpcf

fwlb

400

500

600

700

800

900

1000

1100

1200

1300

1400

0 5 10 15 20

Time (s)

Peak

Cla

d Te

mp

(F)

hpcf

fwlb

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Spectrum Study Results - Preliminary

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.0 0.2 0.4 0.6 0.8 1.0 1.2

Break Area (ft2)

Min

imum

Sys

tem

Mas

s (M

lb)

fwlb hpcf mslb

800

900

1000

1100

1200

1300

1400

0.0 0.2 0.4 0.6 0.8 1.0 1.2

Break Area (ft2)

PCT

(F)

fwlb hpcf mslb

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Results Summary●Observations

– PCT occurs before actuation of ECCS

– Hot assembly is cooled by a two-phase mixture throughout transient

– PCT is not a strong function of break size– Minimum inventory decreases with increasing

break size

a,c

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Technical Contents of Topical Report●Overview of ABWR LOCA Methodology

– Differences between BWRs and ABWRs– Description of ABWR ECCS– Description of ABWR model nodalization– Break spectrum results

●Qualification of ABWR Evaluation Model– Pump coastdown prediction– Prediction of boiling transition

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Conclusions● Major differences between BWRs and ABWRs

– Internal recirculation pumps coastdown much faster than external recirculation pumps– Early boiling transition

– All ABWR breaks are above top of active fuel– No core uncovery predicted for ABWR

● Topical report provides justification for the extension of the approved Westinghouse BWR LOCA methodology to the ABWR design

● Topical report to be submittal by September 30 as planned

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