neutronic analysis of th-233u self - a monte carlo reactor...

Neutronic analysis of Th-233U self

sustainable BWR fuel cycle with BGCore

and Serpent Codes

by

Y. Shaposhnik, E. Shwageraus

Department of Nuclear Engineering,

Ben-Gurion University of the Negev

2011 Serpent International Users Group Meeting - Helmholtz-Zentrum Dresden-Rossendorf (HZDR) September 15-16, 2011 2

Outline

Th-233U fuel cycle

BWR Seed-Blanket assembly

Computational tools BGCore system Serpent

Results: Code-to-Code comparison Nutronic parameters (kinf, FIR, nuclide densities)

Computational efficiency (CPU time, memory)

Summary and conclusions


Introduction to Th-233U fuel cycle

Self-sustainable fuel cycle:

ThO2-233UO2 Fuel with continuous recycling of 233U

Standard ABWR balance of plant

Heterogeneous reactor assembly structure

Modifications should not compromise reactor safety

Evaluated parameters:

K-inf vs. time

Fissile Inventory Ratio -

loading mass fissile Initial

at time mass Fissile tFIR


Th-233U methodology

0

1

2

3

4

1E-03 1E-02 1E-01 1E+00 1E+01 1E+02 1E+03 1E+04 1E+05 1E+06 1E+07

Energy, eV

Fis

sio

n n

eu

tro

ns y

ield

per a

bso

rp

tio

n

U-233

U-235

Pu-239

Core

Power

Void

Coefficient

Conversion

Ratio

Conversion Ratio

hard spectrum

Hard spectrum

Void Coefficient >0

Void Coefficient >0

heterogeneous geometry

Heterogeneous geometry

limits core power density

η-factor as a function neutron energy (JEFF-3.1)


Th-233U Seed-Blanket BWR assembly

BWR SB radial configuration

9x9 lattice

No water holes


Axial configuration

3 axial Seed zones (Th-233UO2)

4 axial Blanket zones (ThO2)

Dimensions derived from prior analyses

Bottom plenum - 40 cm

Blanket 1 - 40 cm

Blanket 2 - 30 cm

Seed 2 - 20 cm

Blanket 3 - 30 cm

Seed 3 - 30 cm

Blanket 4 - 50 cm

Top plenum - 40 cm

Seed 1 - 20 cm


Axial configuration

Variable seed enrichment to manage power peaking

18 burnable zones

Bottom plenum - 40 cm

Blanket 1 - 30 cm

Blanket 2 - 30 cm

Seed 2 - 20 cm

Blanket 3 - 30 cm

Seed 3 - 30 cm

Blanket 4 - 50 cm

Top plenum - 40 cm

Seed 1 - 20 cm

233UO2 Fraction Zone size Moderator density

[w/o] [cm] [

g/cc]

Top Plenum - 40 0.14421

Blanket 4-b 0 40 0.14421

Blanket 4-a 0 10 0.14457

Seed 3-d 14 10 0.15406

Seed 3-c 13 10 0.17560

Seed 3-b 12 5 0.19586

Seed 3-a 10 5 0.21274

Blanket 3 0 30 0.22372

Seed 2-d 14 5 0.23655

Seed 2-c 15 5 0.26300

Seed 2-b 14 5 0.29318

Seed 2-a 13 5 0.33603

Blanket 2 0 30 0.36729

Seed 1-d 13 5 0.40522

Seed 1-c 13 5 0.49771

Seed 1-b 10 5 0.63108

Seed 1-a 7 5 0.74098

Blanket 1-b 0 10 0.74564

Blanket 1-a 0 30 0.74573

Bottom Plenum - 40 0.74573

Type


Description of computational tools

BGCore

Neutron transport solution by MCNP

Multi-group cross sections for depletion (SARAF)

Thermo-hydraulic feedback (THERMO)

Serpent (ver. 1.1.14)

Unique features

delta-tracking method

uniform energy grid for cross section data

depletion using CRAM-method


Results: Nutronic parameters

Neutron multiplication factor - kinf

* PCC – Predictor Corrector algorithm in Serpent

0.990

0.995

1.000

1.005

1.010

1.015

1.020

1.025

1.030

1.035

1.040

1.045

1.050

1.055

1.060

0 500 1000 1500 2000 2500 3000 3500

Time [EFPD]

kin

f

kinf - Serpent with PCC

kinf- BGCore

kinf - Serpent no PCC

Δkinf=364 pcm Δkinf ~ 360 pcm



Fissile Inventory Ration - FIR

* PCC – Predictor Corrector isotope estimation in Serpent

0.975

0.980

0.985

0.990

0.995

1.000

1.005

1.010

0 500 1000 1500 2000 2500 3000 3500

Time [EFPD]

FIR

FIR - Serpent with PCC

FIR - BGCore

FIR - Serpent no PCC

ΔFIR ~ 0.4 %



Mass of 235U

Mass of 233Pa

Mass of 233U

Under investigation

235U

233U

233Pa

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0 500 1000 1500 2000 2500 3000 3500

Time [EFPD]

Mass o

f 2

35U

[kg

]

U235-Serpent with PCC

U235-BGCore

U235-Serpent no PCC

6.05

6.10

6.15

6.20

6.25

6.30

6.35

6.40

6.45

0 500 1000 1500 2000 2500 3000 3500

Time [EFPD]

Mass o

f 2

33U

[kg

]

U233-Serpent with PCC

U233-BGCore

U233-Serpent no PCC

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0 500 1000 1500 2000 2500 3000 3500

Time [EFPD]

Mass o

f 2

33P

a [

kg

]

Pa233-Serpent with PCC

Pa233-BGCore

Pa233-Serpent no PCC


Remarks on computational efficiency

Total Execution time

Machine Configuration

SUN Intel(R) Xeon X2270

16 CPU’s 2933 MHz

24 GB RAM memory

Speed-Up

factor

3CPU - Serpent no PCC

Exe. Time [min]

3CPU - Serpent with PCC

Exe. Time [min]

1.59 1113.92 1771.19

Speed-Up

factor


Exe. Time [min]

3CPU - BGCore no PCC

Exe. Time [min]

5.77 1113.92 6431.80

Speed-Up

factor


Exe. Time [min]

16CPU - BGCore no PCC

Exe. Time [min]

2.25 1113.92 2508.60

* PCC – Predictor Corrector algorithm in Serpent


Memory Limitation

Machine Configuring

SUN AMD Opteron 2218

4 CPU’s 2613 MHz

32 GB RAM memory

Machine Configuration

SUN Intel(R) Xeon X2270

16 CPU’s 2933 MHz

24 GB RAM memory

Serpent Execution with 4 CPU

Memory Swapped

Start Serpent Start Serpent


CPU time

Depletion + Transport Execution time

0

20

40

60

80

100

120

140

0 500 1000 1500 2000 2500 3000 3500

Time [EFPD]

Dep

leti

on

+N

eu

tro

nic

Execu

tio

n t

ime [

min

]

Exe.time - BGCore 3 CPU


Exe.time - Serpent 3 CPU With PCC

Exe.time - Serpent 3 CPU No PCC


CPU time

Total Execution time

Machine Configuring

SUN AMD Opteron 2218

4 CPU’s 2613 MHz

32 GB RAM memory

Speed-Up

factor

1CPU - Serpent

Exe. Time [min]

1CPU - BGCore

Exe. Time [min]

7.59 3812.40 28940.30

Speed-Up

factor

1CPU - Serpent

Exe. Time [min]

4CPU - Serpent

Exe. Time [min]

3.76 3812.40 1013.93


Summary and Conclusions

Good agreement in neutronic parameters between Serpent and BGcore Up to 360 pcm in multiplication factor (at EOL)

Up to 0.4% in Fissile Inventory Ratio (at EOL)

Minor discrepancy in 233U concentration (under investigation)

Calculation performance Serpent is ~ 7 faster than BGCore

1CPU – 7.6

3CPU – 5.8

Memory allocation restricts Serpent performance

Bottleneck - Initial data preparation

At least 1 additional CPU is lost


Thank you


Statistical Accuracy - k-eigenvalue

100,000 - Source neutrons

50 - Inactive cycles

100 - Active cycles

1.0 - Initial guess for k-eigenvalue

set pop 100000 100 50 1.0 - Serpent

kcode 100000 1.0 50 150 - MCNP

0.60

0.65

0.70

0.75

0.80

0.85

0.90

0.95

1.00

1.05

1.10

0 50 100 150 200 250 300 350 400 450 500 550

Cycle

kin

f

0.88

0.89

0.9

0.91

0.92

0.93

0.94

0.95

0.96

0.97

0.98

0.99

Sh

an

no

n E

ntr

op

y

k

Shannon


Problem definition

Data libraries

Operational

parameters

Materials

Geometry

MCNP

3D core neutronics

SARAF

Fuel depletion

(composition)

THERMO

Temp. distribution

Output

Keff, Fuel Composition

Spent Fuel Emissions

Power Distribution

Moderator/Coolant, Fuel

and cladding Temperatures.

Initial TH conditions

BGCore system Serpent

Problem definition

Data libraries

Operational

parameters

Materials

Geometry

PSG

3D core neutronics

BURNUP

Fuel depletion

(composition)

Output

Keff, Fuel Composition

Power Distribution


0

1000

2000

3000

4000

5000

6000

7000

0 500 1000 1500 2000 2500 3000 3500

Time [EFPD]

To

tal Execu

tio

n t

ime [

min

]

Exe.time - Serpent 3CPU

Exe.time - BGCore 3CPU

Exe.time - Serpent No PCC 3CPU


neutronic analysis of th-233u self - a monte carlo reactor...

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