VERA Industry Applications

Fausto Franceschini and Andrew GodfreyAdvanced Modeling Applications

CASL Industry Council MeetingCharleston, South Carolina

April 5, 2017

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The Rebirth of AMA• Focus Area brought back for FY17• Led and predominantly composed of experts from the

nuclear industry

• Purpose: A renewed and specific focus on the application of VERA to relevant industry problems

• Responsibilities:– Reactor Benchmarking– Challenge Problems– Test Stands– Industry Engagement– Feedback to developers

“AMA will work closely with the nuclear industry and provide compelling demonstrations of VERA capabilities and workflows.”

– Jess Gehin

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FY17 Staff

• 28 full and part-time engineers actively working with AMA

• 72% are current or former industry employees and experts

• 67% of national lab employees have some industry experience

Industry61%

National Labs25%

Universities3%

Independent Experts

11%

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FY17 Projects

• Two major projects with nearly 50/50 split– Reactor applications,

testing, and benchmarking

– Challenge problem related testing and applications (CRUD, PCI, RIA, etc.)

• Support for four different Test Stands

• User training and support functions

Reactor Applications

45%

Challenge Problems

41%

Test Stands7%

Training& Support

3%

Administration4%

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FY17 Power Plant Analyses• >50% of total budget

applied towards the analysis of current or future NPP

• Includes at least 14 different reactors

• Collaborating with at least 13 different organizations, including fuel vendors, owner/operators, and government agencies

Plant Units Type Fuel Purposes

Watts Bar 2 W 4-loop 17x17 V&V, CIPS

Sanmen 1 AP1000 17x17 V&V

Krško 1 W 2-loop 16x16 V&V

McGuire 2 W 4-loop 17x17 V&V

Catawba 2 W 4-loop 17x17 V&V, CIPS

Palo Verde 1 CE Sys 80 16x16 V&V, CIPS/CILC

Callaway 1 W 4-loop 17x17 CIPS

TMI 1 B&W 15x15 V&V,CIPS/CILC

Byron 1 W 4-loop 17x17 Test Stand,PCI

NuScale 1 SMR 17x17 Test Stand

Davis-Besse 1 B&W 15x15 Test Stand

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CASL Priority – Increasing Focus on Industry Applications• TVA - Simulation of Watts Bar Unit 1 (WBN1) Operation • TVA and Westinghouse – Simulation of Watts Bar Unit 2 (WBN2)

Startup• Duke Energy – CIPS Analysis of Catawba Unit 2• Arizona Public Services (APS) – CIPS Analysis of Palo Verde• Westinghouse – AP1000® Startup and First Cycle Simulations• Test Stands

AMA personnel is heavily engaged in these applications

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Watts Bar Unit 1 Analysis Update• VERA 3.6 used to model Cycles 1-14 • Overall good agreement with measurements

– RCCA bank worths (-0.7 ± 3.4%)– Isothermal temperature coefficients (-1.6 ± 0.7 pcm/F)– Critical boron concentrations (-16 ± 17 ppm)– In-core power distribution (1.7% radial, 3.3% total, 0.2% AO)

195 in-core flux maps

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0

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0 50 100 150 200 250 300 350 400 450 500

Criti

cal B

oron

Diff

eren

ce (p

pm)

Cycle Burnup (EFPD)

Cycle 1

Cycle 2

Cycle 3

Cycle 4

Cycle 5

Cycle 6

Cycle 8

Cycle 7

Cycle 9

Cycle 10

Cycle 11

Cycle 12

Cycle 13

Cycle 14

Trend

critical boron comparisonsBank Worth

960 processors~22 statepoints/cycle~21 hours per cycle20,600 core-hours

Spacer Grids

MixingGrids

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WBN1 Axial Offset Comparisons

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0 5 10 15 20

Axial

Offs

et D

iffer

ence

(C-M

,%)

Cycle Exposure (GWd/MTU)

Without MAMBAWith MAMBA

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Axial

Offs

et D

iffer

ence

(C-M

,%)

Cycle Exposure (GWd/MTU)

Without MAMBA HistoryWith MAMBA History

Cycle 7 Cycle 8

*Removed CRUD after outage

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Watts Bar 1 Cycle 7 - CIPS Calculations

Without MAMBA With MAMBA-1D

• MAMBA-1D not predictive but potential benefits are clear– ~50% improvement in power distribution comparisons– Cycle 7 flux map results are as good as non-CIPS cycles– Up to 40% improvement in 1st half of Cycle 8 as well

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0%

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5/23 6/6 6/20 7/4 7/18 8/1 8/15 8/29 9/12 9/26 10/10 10/24 11/7

Core

Pow

er L

evel

(%)

Date

Watts Bar Unit 2 Startup History

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-3 -4 -5 -7 -7-10 -13

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Boro

n Co

ncen

tratio

n Di

ffere

nce (

ppm

)

-7 ± 3.3 ppm

Watts Bar Unit 2 Startup ResultsOriginal

VERA DifferenceVERA 3.6Difference

ShiftDifference

Initial Critical Boron Concentration (ppmB) -17 -2 -1

Isothermal Temperature Coefficient (pcm/ºF) -0.8 -0.8 --

Critical Boron Differences after each shutdown

Control Bank Worth

0.5% 0.4%

2.6%

-0.6%

3.0%

0.7% 0.7%

-1.1%

0.7%

-10%

-8%

-6%

-4%

-2%

0%

2%

4%

6%

8%

10%

D C B A SD SC SB SA Total

Ban

k W

orth

Diff

eren

ce (%

)

RCCA Bank

MPACT

Shift0.7 ± 1.4 %

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WBN2 Critical Boron Differences• Initial results exhibited large axial power oscillations at times• Fuel temperatures were artificial increased to dampen the

oscillations• Resulting boron differences are too negative

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0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Solu

ble

Bor

on C

once

ntra

tion

Diff

eren

ce (p

pmB

)

Core Power (%)

VERA - Measured-37 ± 11.1 ppmB

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WBN2 In-Core Power Distributions

• Vanadium detector modeled and response calculated by MPACT

• Response integrated onto five level axial mesh and compared to measured distributions

• Both response distributions and relative wire currents compared

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WBN2 In-Core Power Distributions:Detector Response Comparison

• Map 12 Segments:– Radial RMS = 1.9%– Total RMS = 3.2%– Axial RMS = 1.5%

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• Map 12 Currents:– All Wires = 0.5 ± 2.2%– Long Wires = 0.3 ± 2.1%

WBN2 In-Core Power Distributions:Detector Current Comparison

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WBN2 In-Core Power Distributions

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1%

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1 2 3 4 5 6 7 8 9 10 11 12

RM

S D

iffer

ence

(%)

Case Number

RadialAxialTotal

• Comparisons improved as power and burnup increased

• Results dependent of fuel temperature set used and transient Xe-135 condition

• Most recent results comparable to WBN1

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1%

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RM

S E

rror

(%)

Case Number

All

Long

Comparison of Vanadium Wire Relative Currents

Detector segment distribution differences

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WBN2 VERA vs. Online Monitor

VERAAll Wire Currents = 0.7 ± 2.4%Long Wire Currents = 0.3 ± 2.3%

Online Core MonitorAll Wire Currents = -0.1 ± 3.4%Long Wire Currents = 0.4 ± 3.1%

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WBN2 VERA vs. Online Monitor

Online

• In the most recent maps, VERA is demonstrating less variance from wire to wire consistently for each length of wire

• Result is about 1% better agreement in radial and total power distributions compared to online core monitoring software

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WBN2 VERA 3.6 PerformanceTotal Number of Jobs 35Total Number of Statepoints 4,130Total Number of MPACT/CTF Iterations 16,605Average Iterations per Statepoint 4.0Total Wall Time 13.5 daysTotal Number of Core-Hours 892,837 core-hoursAverage Wall Time per Statepoint 4.7 minsTypical number of cores utilized 2,784

62%

25%

13%MPACT

CTF

ORIGEN

Xenon-135 distribution for 28% power flux map

Runtime Fractions for each component during startup

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CIPS Analysis of Catawba Unit 2• Collaboration with Duke Energy investigating

application of VERA to Catawba Unit 2, Cycle 22 (current cycle)

• Industry CIPS Risk Analysis Follows EPRI Guidelines – Does not directly assess impact of CIPS on key parameters – AO, SDM, etc.

• CASL simulation first of a kind direct analysis of CIPS axial offset for three core designs –Explicitly including the feedback of of boron on power distribution and calculating A/O

• Shows more aggressive core designs may be acceptable

• Additional validation of VERA showing good comparison to measurement data (cycles 19-21)

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CE System-80 Support• Evaluation and Testing of VERA for

CE System-80 Design (end of March)– Implemented large guide tubes and control rods

in MPACT and CTF– Added erbium cross sections and depletion

chains– Tested 2- and 4-finger control rods in lattice– Calculated fuel temperatures for larger fuel rods– Depleted example cores with representative fuel

• Will be working with Arizona Power (APS) to model Palo Verde plants the second half of the year– Including early cycles CIPS

Increasing Validation Base

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AP1000® Startup and First Cycle Simulations

Results show good agreement with in-house predictions for global parameters

Startup Soluble Boron and ITC are almost identical to nodal methods predictions. Good agreement in critical boron letdown

AP1000 Advanced First Core

VERA Simulations performed on WEC Computers

MA MB

MC

MD

M1

M2

AO

S1

S2

S3

S4

-15%

-10%

-5%

0%

5%

10%

15%

SHIFT MPACT Nodal Diffusion

Good agreement in Control Rod Worth Prediction

• Obtain high-fidelity results to support startup of AP1000 plants in China– Supports in-house prediction. Reduce risk for large mispredictions– Identify areas for improvement– Expand VERA validation as AP1000 startups– Support VERA development enabling modeling of advanced PWRs

* Per statepoint

3D Core Cores # Core hr* Wall Time hr*

Falcon 896 682 0.8Binford (WEC) 392 722 1.8

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AP1000 MSHIM PCI Assessment• VERA MPACT/BISON used to evaluate local stresses during MSHIM operation• Purpose is to assess the relative capability of MPACT and BISON to identify peak

local stress conditions that could challenge PCI margins• Quarter core BISON rodwise analyses completed for AP1000 Cycle 1

Initial MPACT depletion for Cycle 1 incorporated MSHIM bank swap into depletion steps• 1/3 of rods failed to converge in BISON (in black)

MPACT Cycle 1 depletion repeated with explicit MSHIM bank swap steps • All rods converge successfully in BISON

Maximum fuel centerline temperatures at 100 EFPD• Expected Benefits

– Better understanding of local power changes near rod tips during rodded maneuvers– Better understanding of the impact of variations in AP1000 MSHIM control strategy on

local cladding stresses and PCI risk.

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• Seabrook Cycle 1 at BOL, D bank fully inserted, all others out.• Central CR ejected in 0.1 seconds• MPACT with internal TH (preliminary assessment)

Assessing VERA RIA Capability

• 61 state points for a 0.3 s transient• ~12 hrs on 816 on cores on INL’s falcon

• For a better assessment, AP1000 rod ejection will be modeled• Results will be compared to ANCK/VIPRE to gain a better understanding of

VERA capabilities and performance

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Benchmarking of VERA Neutronics Toolset• Assessed agreement of MPACT vs. CE Monte Carlo (Shift and Serpent) using AP1000 (challenging) lattice models• Very good reactivity agreement for MPACT vs. Serpent (+/- 100 pcm) and remarkable power distribution agreement• Exceptional agreement for Shift and Serpent, strengthening confidence in both as benchmark references tools

MPACT ShiftEigenvalue Differences Eigenvalue Differences

Pin Power Differences Pin Power Differences

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Extended VERA Reflector Capabilities• Pin-wise radial reflector modeling of structural

components (barrel, pads, vessel, etc.) has been added to MPACT.

• Allows for improved accuracy along core periphery.• New default is a truncated model that does not

increase the problem size, but captures reflector effect.

• Will allow for future estimates of vessel fluence and/or ex-core detection.

• Implemented in AMA plants modeling

2D slice of AP1000 with shroud and full reflector

Pin power differences (BOC)

Impact of Extended Reflector Capability on Several Models (Old vs. New)

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Status of Test Stands – Moving Forward with External Test Stands

• Three test stands have been completed: WEC: VERA-CS core simulator – 2015 EPRI: BISON fuel performance code for PCI application – 2015 TVA: Hydra-TH CFD for lower plenum anomaly – 2016

− AREVA: Modeling core follow and CRUD formation completing validation using Davis Besse Cycle 15 plant data and fuel examinations

− University of Illinois/Exelon: Evaluating fuel duty under load follow conditions as relates to PCI in cooperation with Exelon for Byron NPPs

− Westinghouse – Accident Tolerant Fuels (joint with NEAMS) analysis for Westinghouse SiC and U3Si2 concepts

− NuScale – Analysis of CRUD in SMRs under natural circulation and investigation on integral reactor crud sources

− US NRC – In planning – application of CASL tools to Accident Tolerant Fuels

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• VERA being applied with increasing confidence to a variety of fuel and reactor types, current and advanced

• Valuable support to reactor startup (WBN2, AP1000)• Strengthened confidence and validation basis• Advanced benchmarking

• Advanced applications to key industry Challenge Problems • CIPS and CILC Analysis – already showing potential improvements• RIA, PCI, DNB – testing capabilities

• Increasing success with industry engagement and test stands• Providing key feedback to the developers

• Capabilities• Usability

• Laying the foundations to expand industry use of VERA

Conclusions

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