Institute for Neutron Physics and Reactor Technology (INR)

1 Institute for Neutron Physics and Reactor Technology (INR)

1 20100511KIT ndash University of the State of Baden-Wuerttemberg andNational Research Center of the Helmholtz Association

Institute for Neutron Physics and Reactor Technology

wwwkitedu

New solutions for the OECD VVER-1000 LEU and MOX burnup computational benchmark

L Mercatali1 A Venturini2 VH Sanchez1

1KIT- Institute for Neutron Physics and Reactor TechnologyUniversity of Pisa (Italy)

AAA Workshop (GRS ndash December 01 2014)luigimercatalikitedu

Institute for Neutron Physics and Reactor Technology (INR)

2 L Mercatali ndash AAA Workshop 01122014 (GRS)

Outline

Introduction amp motivationThe ldquoOECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmarkrdquo

1 Modeling of the benchmark exercises2 Results

Monte Carlo amp deterministic static solutions Burn-up results

kinf

Nuclide concentrations Pin-by pin fission rates

Summary

Institute for Neutron Physics and Reactor Technology (INR)

3

Introduction amp motivation

L Mercatali ndash AAA Workshop 01122014 (GRS)

The loading of Mixed Uranium Plutonium OXide (MOX) and Low Enriched Uranium (LEU) fuels in commercial nuclear reactors requires well validated computational methods and codes capable to provide reliable predictions of the neutronicscharacteristics of such fuels in terms of reactivity conditions (kinf) nuclide inventory and pin power generation over the entire fuel cycle length

Within the framework of Joint United StatesRussian Fissile Materials Disposition Program an important task is to verify and validate neutronics codes for the use of MOX fuel in VVER-1000 reactors

In this work new solutions for the (UO2+Gd) and (UO2+PuO2+Gd) fuel assemblies proposed within the ldquoOECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmarkrdquo have been produced

The SCALE and SERPENT codes have been used with ENDFB-VII and JEFF31 nuclear data libraries (NDLs)

Institute for Neutron Physics and Reactor Technology (INR)

4

OECD VVER-1000 burnup computational benchmark ndashLEUMOX assemblies

The LEU assembly consists of low enriched fuel rods (37 wt ) and 12 rods poisoned with 40 wt of gadolinium (36 wt 235U)The MOX assembly contains fuel rods with three different plutonium loadings the central region with 42 wt of fissile plutonium (93 wt 239Pu) two outer rings a 30 wt and the outermost ring a 20 wt

LEU MOXL Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

5

OECD VVER-1000 benchmark ndash specifications

State Fuel temp K

Non-fuel tempK

135Xe149Sm Boron [ppm] Moderator density [gcm3]

S1 1027 575 Eq 600 07235S2 1027 575 00 600 07235S3 575 575 00 600 07235S4 575 575 00 00 07235S5 300 300 00 00 10033

Constant power density 108 MWm3

Requested responses kinf for state S1 at each burn-up step kinf for states S2-S5 at 0 20 40 MWdkgHM Pin-by-pin fission rate distribution Nuclide assembly average concentrations + nuclide average concentrations in cell 1

and cell 24 for 235U 236U 238U 239Pu 240Pu 241Pu 242Pu135Xe149Sm 155Gd and 157Gd

S1 - S2 Poisons (Xe + Sm) effectsS2 - S3 Doppler coefficientS3 - S4 Boron effectS4 - S5 Moderator temperature coefficient

Operational states

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

6

Modeling assumptions ndash SCALE 61

Transport solutions (SN6)Boundary condition whiteConvergence criterion (spatialeigenvalue) ε=1E-6Predictor-corrector algorithmsCross-section library ENDFB-VII0

LEU

MOX

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

7

LEU ndash sensitivity studies on burn-up steps

~100 pcm

~50 pcm

~10 pcm

Negligible effect of gadolinium mesh refinement (lt20 pcm)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

8

Modeling assumptions ndash SERPENT 21

Solution of Depletion Equations CRAMPredictor-corrector method (PC) vs Stochastic Implicit Euler (SIE)Pin-by-pin modelBoundary condition reflectiveGadolinium refinement10000 neutrons 4000 cycles 100 inactive cycles (Shannon enrtopy criterion)Tmp card (Doppler broadening) vs Temperature weighted compositions (~200 pcm)Cross-section library ENDFB-VII0 JEFF31 JEFF22

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

9

SERPENT and MCNP4B results for kinf at zero burnup with JEFF22 data

Monte Carlo solutions - kinf

Objective assess the validity of our model through comparison with the reference MCNP4B solutions

Overall good agreement Small deviations due to different data (ENDFBV) for 16O 152Gd natZr and 1H in the MCNP4B

results and different statistics

LEU SERPENT (S) MCNP4B (M) ∆k (M-S)105

S2 117987 plusmn 89E-05 11800 plusmn 6E-05 13S3 119365 plusmn 86E-05 11925 plusmn 6E-05 -115S4 125387 plusmn 85E-05 12531 plusmn 7E-05 -77S5 132394 plusmn 76E-05 13235 plusmn 6E-05 -44

MOX SERPENT (S) MCNP4B (M) ∆k (M-S)105

S2 119258 plusmn 86E-05 11922 plusmn 7E-05 -38S3 120919 plusmn 84E-05 12091 plusmn 6E-05 -9S4 124408 plusmn 85E-05 12430 plusmn 6E-05 -108S5 132487 plusmn 76E-05 13256 plusmn 7E-05 73

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

10 L Mercatali ndash AAA Workshop 01122014 (GRS)

Monte-carlo and deterministic solutions - kinf

LEUSERPENT (SJ)

[JEFF31]SERPENT (SE)[ENDFB-VII]

SCALE (SCE)[ENDFB-VII]

∆k(SE-SJ)105

∆k (SE-SCE)105

S2 117399 plusmn 89E-05 117587 plusmn 88E-05 117068 188 519S3 118787 plusmn 87E-05 118996 plusmn 86E-05 118557 209 439S4 124808 plusmn 85E-05 124993 plusmn 87E-05 124538 185 455S5 132088 plusmn 76E-05 132305 plusmn 77E-05 131770 217 535

MOXSERPENT (SJ)

[JEFF31]SERPENT (SE)[ENDFB-VII]

SCALE (SCE)[ENDFB-VII]

∆k(SE-SJ)105

∆k (SE-SCE)105

S2 119596 plusmn 85E-05 119762 plusmn 86E-05 119178 166 584S3 121259 plusmn 84E-05 121419 plusmn 84E-05 121005 160 414S4 124765 plusmn 84E-05 124923 plusmn 84E-05 124491 158 432S5 132908 plusmn 76E-05 133013 plusmn 76E-05 132652 105 361

Systematic under-prediction of JEFF31 with respect to JEFF22 (LEU)Systematic over-prediction of JEFF31 with respect to JEFF22 (MOX)ENDFB-VII-kinf larger with respect to JEFF31-kinf by ~100-200 pcmSCALE results are systematically higher than SERPENT ones due to the multi-group and spatial approximations

SERPENT and SCALE results for kinf at zero burnup with different NDLs

Institute for Neutron Physics and Reactor Technology (INR)

11 L Mercatali ndash AAA Workshop 01122014 (GRS)

Reactivity effects

Due to the harder neutron spectrum of the MOX assembly Xenon effect lower in MOX the difference becoming less important with the increasing of burnup Boron worth reduced in MOX Difference ~71 (BOC) - ~24 (EOC)

Doppler coefficient slightly more negative for the MOX at BOC and almost equals at EOCModerator temperature coefficient more negative in the case of MOX

Initial state Final stateBurnup

(MWdKgHM)LEU MOX

SERPENT SCALE Mean SERPENT SCALE Mean

S1 S20 -358 - -403 -263 - -333

20 -291 - -396 -244 - -34440 -237 - -329 -216 - -308

S2 S30 -141 -148 -136 -166 -183 -174

20 -148 - -152 -148 - -15540 -135 - -140 -133 - -140

S3 S40 -600 -598 -599 -350 -349 -346

20 -540 - -548 -376 - -38340 -481 - -491 -386 - -398

S4 S50 -728 -698 -690 -809 -816 -793

20 -687 - -672 -698 - -70340 -435 - -533 -549 - -541

LEU and MOX assemblies 100 x (kinit ndash kfin)

Institute for Neutron Physics and Reactor Technology (INR)

12 Institute for Neutron Physics and Reactor Technology (INR)

12 20100511

Burn-up calculations - kinfThe decrease of kinf is slower for MOXDifferent shapes of the burn-up swings due to different spectraSERPENT- kinf systematically higher than SCALE- kinf

The agreement in between SERPENTSCALE stands within plusmn039 (LEU) and plusmn033 (MOX)

E Bubelis amp M Schikorr ndash CDT technical meeting KIT internal

Institute for Neutron Physics and Reactor Technology (INR)

13

Burn-up calculations ndash assembly averaged nuclide concentrations (SERPENTBenchmark mean)

Excellent agreement for U Good agreement for Pu Slight discrepancies for

Sm-149 Gd-155 and Gd-157 in the MOX case

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

14

Burn-up calculations ndash Cell 1 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Excellentgood agreement for U and Pu isotopes Discrepancies for Sm-149 at high burn-up levels

Institute for Neutron Physics and Reactor Technology (INR)

15

Burn-up calculations ndash Cell 24 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Good agreement for U and Pu isotopes

Discrepancies for Xe-135 Sm-149 Gd-155 and Gd-157

Institute for Neutron Physics and Reactor Technology (INR)

16

Pin-by-pin fission rates

Good agreement SERPENTSCALE

Maximum deviationsLEU -42 (pin 35)MOX -16 (pin 63)

LEU Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 21 55 1

Max δ [] (SCALE-SERPENT) -078 214 322Average δ [] (SCALE-SERPENT) 025 069 145

MOX Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 10 4 46

Max δ [] (SCALE-SERPENT) -126 397 504Average δ [] (SCALE-SERPENT) 048 108 144

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

17 L Mercatali ndash AAA Workshop 01122014 (GRS)

Summary and conclusions

SERPENT and SCALE calculation schemes for VVER-1000 reactors have been tested on 2-D problems for fresh and depleted LEU and MOX fuel assemblies representative of the designs expected for the plutonium disposition mission

Small deviations have been generally observed between the SCALE and SERPENT computed kinf nuclide concentrations and pin-by-pin fission rates

Very good agreement is found between SERPENT solutions and the corresponding previous MCNP4B results making of this work also a new Monte Carlo reference solution for the OECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmark with modern NDLs

Institute for Neutron Physics and Reactor Technology (INR)

2 L Mercatali ndash AAA Workshop 01122014 (GRS)

Outline

Introduction amp motivationThe ldquoOECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmarkrdquo

1 Modeling of the benchmark exercises2 Results

Monte Carlo amp deterministic static solutions Burn-up results

kinf

Nuclide concentrations Pin-by pin fission rates

Summary

Institute for Neutron Physics and Reactor Technology (INR)

3

Introduction amp motivation

L Mercatali ndash AAA Workshop 01122014 (GRS)

The loading of Mixed Uranium Plutonium OXide (MOX) and Low Enriched Uranium (LEU) fuels in commercial nuclear reactors requires well validated computational methods and codes capable to provide reliable predictions of the neutronicscharacteristics of such fuels in terms of reactivity conditions (kinf) nuclide inventory and pin power generation over the entire fuel cycle length

Within the framework of Joint United StatesRussian Fissile Materials Disposition Program an important task is to verify and validate neutronics codes for the use of MOX fuel in VVER-1000 reactors

In this work new solutions for the (UO2+Gd) and (UO2+PuO2+Gd) fuel assemblies proposed within the ldquoOECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmarkrdquo have been produced

The SCALE and SERPENT codes have been used with ENDFB-VII and JEFF31 nuclear data libraries (NDLs)

Institute for Neutron Physics and Reactor Technology (INR)

4

OECD VVER-1000 burnup computational benchmark ndashLEUMOX assemblies

The LEU assembly consists of low enriched fuel rods (37 wt ) and 12 rods poisoned with 40 wt of gadolinium (36 wt 235U)The MOX assembly contains fuel rods with three different plutonium loadings the central region with 42 wt of fissile plutonium (93 wt 239Pu) two outer rings a 30 wt and the outermost ring a 20 wt

LEU MOXL Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

5

OECD VVER-1000 benchmark ndash specifications

State Fuel temp K

Non-fuel tempK

135Xe149Sm Boron [ppm] Moderator density [gcm3]

S1 1027 575 Eq 600 07235S2 1027 575 00 600 07235S3 575 575 00 600 07235S4 575 575 00 00 07235S5 300 300 00 00 10033

Constant power density 108 MWm3

Requested responses kinf for state S1 at each burn-up step kinf for states S2-S5 at 0 20 40 MWdkgHM Pin-by-pin fission rate distribution Nuclide assembly average concentrations + nuclide average concentrations in cell 1

and cell 24 for 235U 236U 238U 239Pu 240Pu 241Pu 242Pu135Xe149Sm 155Gd and 157Gd

S1 - S2 Poisons (Xe + Sm) effectsS2 - S3 Doppler coefficientS3 - S4 Boron effectS4 - S5 Moderator temperature coefficient

Operational states

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

6

Modeling assumptions ndash SCALE 61

Transport solutions (SN6)Boundary condition whiteConvergence criterion (spatialeigenvalue) ε=1E-6Predictor-corrector algorithmsCross-section library ENDFB-VII0

LEU

MOX

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

7

LEU ndash sensitivity studies on burn-up steps

~100 pcm

~50 pcm

~10 pcm

Negligible effect of gadolinium mesh refinement (lt20 pcm)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

8

Modeling assumptions ndash SERPENT 21

Solution of Depletion Equations CRAMPredictor-corrector method (PC) vs Stochastic Implicit Euler (SIE)Pin-by-pin modelBoundary condition reflectiveGadolinium refinement10000 neutrons 4000 cycles 100 inactive cycles (Shannon enrtopy criterion)Tmp card (Doppler broadening) vs Temperature weighted compositions (~200 pcm)Cross-section library ENDFB-VII0 JEFF31 JEFF22

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

9

SERPENT and MCNP4B results for kinf at zero burnup with JEFF22 data

Monte Carlo solutions - kinf

Objective assess the validity of our model through comparison with the reference MCNP4B solutions

Overall good agreement Small deviations due to different data (ENDFBV) for 16O 152Gd natZr and 1H in the MCNP4B

results and different statistics

LEU SERPENT (S) MCNP4B (M) ∆k (M-S)105

S2 117987 plusmn 89E-05 11800 plusmn 6E-05 13S3 119365 plusmn 86E-05 11925 plusmn 6E-05 -115S4 125387 plusmn 85E-05 12531 plusmn 7E-05 -77S5 132394 plusmn 76E-05 13235 plusmn 6E-05 -44

MOX SERPENT (S) MCNP4B (M) ∆k (M-S)105

S2 119258 plusmn 86E-05 11922 plusmn 7E-05 -38S3 120919 plusmn 84E-05 12091 plusmn 6E-05 -9S4 124408 plusmn 85E-05 12430 plusmn 6E-05 -108S5 132487 plusmn 76E-05 13256 plusmn 7E-05 73

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

10 L Mercatali ndash AAA Workshop 01122014 (GRS)

Monte-carlo and deterministic solutions - kinf

LEUSERPENT (SJ)

[JEFF31]SERPENT (SE)[ENDFB-VII]

SCALE (SCE)[ENDFB-VII]

∆k(SE-SJ)105

∆k (SE-SCE)105

S2 117399 plusmn 89E-05 117587 plusmn 88E-05 117068 188 519S3 118787 plusmn 87E-05 118996 plusmn 86E-05 118557 209 439S4 124808 plusmn 85E-05 124993 plusmn 87E-05 124538 185 455S5 132088 plusmn 76E-05 132305 plusmn 77E-05 131770 217 535

MOXSERPENT (SJ)

[JEFF31]SERPENT (SE)[ENDFB-VII]

SCALE (SCE)[ENDFB-VII]

∆k(SE-SJ)105

∆k (SE-SCE)105

S2 119596 plusmn 85E-05 119762 plusmn 86E-05 119178 166 584S3 121259 plusmn 84E-05 121419 plusmn 84E-05 121005 160 414S4 124765 plusmn 84E-05 124923 plusmn 84E-05 124491 158 432S5 132908 plusmn 76E-05 133013 plusmn 76E-05 132652 105 361

Systematic under-prediction of JEFF31 with respect to JEFF22 (LEU)Systematic over-prediction of JEFF31 with respect to JEFF22 (MOX)ENDFB-VII-kinf larger with respect to JEFF31-kinf by ~100-200 pcmSCALE results are systematically higher than SERPENT ones due to the multi-group and spatial approximations

SERPENT and SCALE results for kinf at zero burnup with different NDLs

Institute for Neutron Physics and Reactor Technology (INR)

11 L Mercatali ndash AAA Workshop 01122014 (GRS)

Reactivity effects

Due to the harder neutron spectrum of the MOX assembly Xenon effect lower in MOX the difference becoming less important with the increasing of burnup Boron worth reduced in MOX Difference ~71 (BOC) - ~24 (EOC)

Doppler coefficient slightly more negative for the MOX at BOC and almost equals at EOCModerator temperature coefficient more negative in the case of MOX

Initial state Final stateBurnup

(MWdKgHM)LEU MOX

SERPENT SCALE Mean SERPENT SCALE Mean

S1 S20 -358 - -403 -263 - -333

20 -291 - -396 -244 - -34440 -237 - -329 -216 - -308

S2 S30 -141 -148 -136 -166 -183 -174

20 -148 - -152 -148 - -15540 -135 - -140 -133 - -140

S3 S40 -600 -598 -599 -350 -349 -346

20 -540 - -548 -376 - -38340 -481 - -491 -386 - -398

S4 S50 -728 -698 -690 -809 -816 -793

20 -687 - -672 -698 - -70340 -435 - -533 -549 - -541

LEU and MOX assemblies 100 x (kinit ndash kfin)

Institute for Neutron Physics and Reactor Technology (INR)

12 Institute for Neutron Physics and Reactor Technology (INR)

12 20100511

Burn-up calculations - kinfThe decrease of kinf is slower for MOXDifferent shapes of the burn-up swings due to different spectraSERPENT- kinf systematically higher than SCALE- kinf

The agreement in between SERPENTSCALE stands within plusmn039 (LEU) and plusmn033 (MOX)

E Bubelis amp M Schikorr ndash CDT technical meeting KIT internal

Institute for Neutron Physics and Reactor Technology (INR)

13

Burn-up calculations ndash assembly averaged nuclide concentrations (SERPENTBenchmark mean)

Excellent agreement for U Good agreement for Pu Slight discrepancies for

Sm-149 Gd-155 and Gd-157 in the MOX case

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

14

Burn-up calculations ndash Cell 1 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Excellentgood agreement for U and Pu isotopes Discrepancies for Sm-149 at high burn-up levels

Institute for Neutron Physics and Reactor Technology (INR)

15

Burn-up calculations ndash Cell 24 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Good agreement for U and Pu isotopes

Discrepancies for Xe-135 Sm-149 Gd-155 and Gd-157

Institute for Neutron Physics and Reactor Technology (INR)

16

Pin-by-pin fission rates

Good agreement SERPENTSCALE

Maximum deviationsLEU -42 (pin 35)MOX -16 (pin 63)

LEU Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 21 55 1

Max δ [] (SCALE-SERPENT) -078 214 322Average δ [] (SCALE-SERPENT) 025 069 145

MOX Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 10 4 46

Max δ [] (SCALE-SERPENT) -126 397 504Average δ [] (SCALE-SERPENT) 048 108 144

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

17 L Mercatali ndash AAA Workshop 01122014 (GRS)

Summary and conclusions

SERPENT and SCALE calculation schemes for VVER-1000 reactors have been tested on 2-D problems for fresh and depleted LEU and MOX fuel assemblies representative of the designs expected for the plutonium disposition mission

Small deviations have been generally observed between the SCALE and SERPENT computed kinf nuclide concentrations and pin-by-pin fission rates

Very good agreement is found between SERPENT solutions and the corresponding previous MCNP4B results making of this work also a new Monte Carlo reference solution for the OECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmark with modern NDLs

Institute for Neutron Physics and Reactor Technology (INR)

3

Introduction amp motivation

L Mercatali ndash AAA Workshop 01122014 (GRS)

The loading of Mixed Uranium Plutonium OXide (MOX) and Low Enriched Uranium (LEU) fuels in commercial nuclear reactors requires well validated computational methods and codes capable to provide reliable predictions of the neutronicscharacteristics of such fuels in terms of reactivity conditions (kinf) nuclide inventory and pin power generation over the entire fuel cycle length

Within the framework of Joint United StatesRussian Fissile Materials Disposition Program an important task is to verify and validate neutronics codes for the use of MOX fuel in VVER-1000 reactors

In this work new solutions for the (UO2+Gd) and (UO2+PuO2+Gd) fuel assemblies proposed within the ldquoOECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmarkrdquo have been produced

The SCALE and SERPENT codes have been used with ENDFB-VII and JEFF31 nuclear data libraries (NDLs)

Institute for Neutron Physics and Reactor Technology (INR)

4

OECD VVER-1000 burnup computational benchmark ndashLEUMOX assemblies

The LEU assembly consists of low enriched fuel rods (37 wt ) and 12 rods poisoned with 40 wt of gadolinium (36 wt 235U)The MOX assembly contains fuel rods with three different plutonium loadings the central region with 42 wt of fissile plutonium (93 wt 239Pu) two outer rings a 30 wt and the outermost ring a 20 wt

LEU MOXL Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

5

OECD VVER-1000 benchmark ndash specifications

State Fuel temp K

Non-fuel tempK

135Xe149Sm Boron [ppm] Moderator density [gcm3]

S1 1027 575 Eq 600 07235S2 1027 575 00 600 07235S3 575 575 00 600 07235S4 575 575 00 00 07235S5 300 300 00 00 10033

Constant power density 108 MWm3

Requested responses kinf for state S1 at each burn-up step kinf for states S2-S5 at 0 20 40 MWdkgHM Pin-by-pin fission rate distribution Nuclide assembly average concentrations + nuclide average concentrations in cell 1

and cell 24 for 235U 236U 238U 239Pu 240Pu 241Pu 242Pu135Xe149Sm 155Gd and 157Gd

S1 - S2 Poisons (Xe + Sm) effectsS2 - S3 Doppler coefficientS3 - S4 Boron effectS4 - S5 Moderator temperature coefficient

Operational states

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

6

Modeling assumptions ndash SCALE 61

Transport solutions (SN6)Boundary condition whiteConvergence criterion (spatialeigenvalue) ε=1E-6Predictor-corrector algorithmsCross-section library ENDFB-VII0

LEU

MOX

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

7

LEU ndash sensitivity studies on burn-up steps

~100 pcm

~50 pcm

~10 pcm

Negligible effect of gadolinium mesh refinement (lt20 pcm)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

8

Modeling assumptions ndash SERPENT 21

Solution of Depletion Equations CRAMPredictor-corrector method (PC) vs Stochastic Implicit Euler (SIE)Pin-by-pin modelBoundary condition reflectiveGadolinium refinement10000 neutrons 4000 cycles 100 inactive cycles (Shannon enrtopy criterion)Tmp card (Doppler broadening) vs Temperature weighted compositions (~200 pcm)Cross-section library ENDFB-VII0 JEFF31 JEFF22

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

9

SERPENT and MCNP4B results for kinf at zero burnup with JEFF22 data

Monte Carlo solutions - kinf

Objective assess the validity of our model through comparison with the reference MCNP4B solutions

Overall good agreement Small deviations due to different data (ENDFBV) for 16O 152Gd natZr and 1H in the MCNP4B

results and different statistics

LEU SERPENT (S) MCNP4B (M) ∆k (M-S)105

S2 117987 plusmn 89E-05 11800 plusmn 6E-05 13S3 119365 plusmn 86E-05 11925 plusmn 6E-05 -115S4 125387 plusmn 85E-05 12531 plusmn 7E-05 -77S5 132394 plusmn 76E-05 13235 plusmn 6E-05 -44

MOX SERPENT (S) MCNP4B (M) ∆k (M-S)105

S2 119258 plusmn 86E-05 11922 plusmn 7E-05 -38S3 120919 plusmn 84E-05 12091 plusmn 6E-05 -9S4 124408 plusmn 85E-05 12430 plusmn 6E-05 -108S5 132487 plusmn 76E-05 13256 plusmn 7E-05 73

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

10 L Mercatali ndash AAA Workshop 01122014 (GRS)

Monte-carlo and deterministic solutions - kinf

LEUSERPENT (SJ)

[JEFF31]SERPENT (SE)[ENDFB-VII]

SCALE (SCE)[ENDFB-VII]

∆k(SE-SJ)105

∆k (SE-SCE)105

S2 117399 plusmn 89E-05 117587 plusmn 88E-05 117068 188 519S3 118787 plusmn 87E-05 118996 plusmn 86E-05 118557 209 439S4 124808 plusmn 85E-05 124993 plusmn 87E-05 124538 185 455S5 132088 plusmn 76E-05 132305 plusmn 77E-05 131770 217 535

MOXSERPENT (SJ)

[JEFF31]SERPENT (SE)[ENDFB-VII]

SCALE (SCE)[ENDFB-VII]

∆k(SE-SJ)105

∆k (SE-SCE)105

S2 119596 plusmn 85E-05 119762 plusmn 86E-05 119178 166 584S3 121259 plusmn 84E-05 121419 plusmn 84E-05 121005 160 414S4 124765 plusmn 84E-05 124923 plusmn 84E-05 124491 158 432S5 132908 plusmn 76E-05 133013 plusmn 76E-05 132652 105 361

Systematic under-prediction of JEFF31 with respect to JEFF22 (LEU)Systematic over-prediction of JEFF31 with respect to JEFF22 (MOX)ENDFB-VII-kinf larger with respect to JEFF31-kinf by ~100-200 pcmSCALE results are systematically higher than SERPENT ones due to the multi-group and spatial approximations

SERPENT and SCALE results for kinf at zero burnup with different NDLs

Institute for Neutron Physics and Reactor Technology (INR)

11 L Mercatali ndash AAA Workshop 01122014 (GRS)

Reactivity effects

Due to the harder neutron spectrum of the MOX assembly Xenon effect lower in MOX the difference becoming less important with the increasing of burnup Boron worth reduced in MOX Difference ~71 (BOC) - ~24 (EOC)

Doppler coefficient slightly more negative for the MOX at BOC and almost equals at EOCModerator temperature coefficient more negative in the case of MOX

Initial state Final stateBurnup

(MWdKgHM)LEU MOX

SERPENT SCALE Mean SERPENT SCALE Mean

S1 S20 -358 - -403 -263 - -333

20 -291 - -396 -244 - -34440 -237 - -329 -216 - -308

S2 S30 -141 -148 -136 -166 -183 -174

20 -148 - -152 -148 - -15540 -135 - -140 -133 - -140

S3 S40 -600 -598 -599 -350 -349 -346

20 -540 - -548 -376 - -38340 -481 - -491 -386 - -398

S4 S50 -728 -698 -690 -809 -816 -793

20 -687 - -672 -698 - -70340 -435 - -533 -549 - -541

LEU and MOX assemblies 100 x (kinit ndash kfin)

Institute for Neutron Physics and Reactor Technology (INR)

12 Institute for Neutron Physics and Reactor Technology (INR)

12 20100511

Burn-up calculations - kinfThe decrease of kinf is slower for MOXDifferent shapes of the burn-up swings due to different spectraSERPENT- kinf systematically higher than SCALE- kinf

The agreement in between SERPENTSCALE stands within plusmn039 (LEU) and plusmn033 (MOX)

E Bubelis amp M Schikorr ndash CDT technical meeting KIT internal

Institute for Neutron Physics and Reactor Technology (INR)

13

Burn-up calculations ndash assembly averaged nuclide concentrations (SERPENTBenchmark mean)

Excellent agreement for U Good agreement for Pu Slight discrepancies for

Sm-149 Gd-155 and Gd-157 in the MOX case

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

14

Burn-up calculations ndash Cell 1 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Excellentgood agreement for U and Pu isotopes Discrepancies for Sm-149 at high burn-up levels

Institute for Neutron Physics and Reactor Technology (INR)

15

Burn-up calculations ndash Cell 24 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Good agreement for U and Pu isotopes

Discrepancies for Xe-135 Sm-149 Gd-155 and Gd-157

Institute for Neutron Physics and Reactor Technology (INR)

16

Pin-by-pin fission rates

Good agreement SERPENTSCALE

Maximum deviationsLEU -42 (pin 35)MOX -16 (pin 63)

LEU Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 21 55 1

Max δ [] (SCALE-SERPENT) -078 214 322Average δ [] (SCALE-SERPENT) 025 069 145

MOX Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 10 4 46

Max δ [] (SCALE-SERPENT) -126 397 504Average δ [] (SCALE-SERPENT) 048 108 144

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

17 L Mercatali ndash AAA Workshop 01122014 (GRS)

Summary and conclusions

SERPENT and SCALE calculation schemes for VVER-1000 reactors have been tested on 2-D problems for fresh and depleted LEU and MOX fuel assemblies representative of the designs expected for the plutonium disposition mission

Small deviations have been generally observed between the SCALE and SERPENT computed kinf nuclide concentrations and pin-by-pin fission rates

Very good agreement is found between SERPENT solutions and the corresponding previous MCNP4B results making of this work also a new Monte Carlo reference solution for the OECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmark with modern NDLs

Institute for Neutron Physics and Reactor Technology (INR)

4

OECD VVER-1000 burnup computational benchmark ndashLEUMOX assemblies

The LEU assembly consists of low enriched fuel rods (37 wt ) and 12 rods poisoned with 40 wt of gadolinium (36 wt 235U)The MOX assembly contains fuel rods with three different plutonium loadings the central region with 42 wt of fissile plutonium (93 wt 239Pu) two outer rings a 30 wt and the outermost ring a 20 wt

LEU MOXL Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

5

OECD VVER-1000 benchmark ndash specifications

State Fuel temp K

Non-fuel tempK

135Xe149Sm Boron [ppm] Moderator density [gcm3]

S1 1027 575 Eq 600 07235S2 1027 575 00 600 07235S3 575 575 00 600 07235S4 575 575 00 00 07235S5 300 300 00 00 10033

Constant power density 108 MWm3

Requested responses kinf for state S1 at each burn-up step kinf for states S2-S5 at 0 20 40 MWdkgHM Pin-by-pin fission rate distribution Nuclide assembly average concentrations + nuclide average concentrations in cell 1

and cell 24 for 235U 236U 238U 239Pu 240Pu 241Pu 242Pu135Xe149Sm 155Gd and 157Gd

S1 - S2 Poisons (Xe + Sm) effectsS2 - S3 Doppler coefficientS3 - S4 Boron effectS4 - S5 Moderator temperature coefficient

Operational states

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

6

Modeling assumptions ndash SCALE 61

Transport solutions (SN6)Boundary condition whiteConvergence criterion (spatialeigenvalue) ε=1E-6Predictor-corrector algorithmsCross-section library ENDFB-VII0

LEU

MOX

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

7

LEU ndash sensitivity studies on burn-up steps

~100 pcm

~50 pcm

~10 pcm

Negligible effect of gadolinium mesh refinement (lt20 pcm)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

8

Modeling assumptions ndash SERPENT 21

Solution of Depletion Equations CRAMPredictor-corrector method (PC) vs Stochastic Implicit Euler (SIE)Pin-by-pin modelBoundary condition reflectiveGadolinium refinement10000 neutrons 4000 cycles 100 inactive cycles (Shannon enrtopy criterion)Tmp card (Doppler broadening) vs Temperature weighted compositions (~200 pcm)Cross-section library ENDFB-VII0 JEFF31 JEFF22

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

9

SERPENT and MCNP4B results for kinf at zero burnup with JEFF22 data

Monte Carlo solutions - kinf

Objective assess the validity of our model through comparison with the reference MCNP4B solutions

Overall good agreement Small deviations due to different data (ENDFBV) for 16O 152Gd natZr and 1H in the MCNP4B

results and different statistics

LEU SERPENT (S) MCNP4B (M) ∆k (M-S)105

S2 117987 plusmn 89E-05 11800 plusmn 6E-05 13S3 119365 plusmn 86E-05 11925 plusmn 6E-05 -115S4 125387 plusmn 85E-05 12531 plusmn 7E-05 -77S5 132394 plusmn 76E-05 13235 plusmn 6E-05 -44

MOX SERPENT (S) MCNP4B (M) ∆k (M-S)105

S2 119258 plusmn 86E-05 11922 plusmn 7E-05 -38S3 120919 plusmn 84E-05 12091 plusmn 6E-05 -9S4 124408 plusmn 85E-05 12430 plusmn 6E-05 -108S5 132487 plusmn 76E-05 13256 plusmn 7E-05 73

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

10 L Mercatali ndash AAA Workshop 01122014 (GRS)

Monte-carlo and deterministic solutions - kinf

LEUSERPENT (SJ)

[JEFF31]SERPENT (SE)[ENDFB-VII]

SCALE (SCE)[ENDFB-VII]

∆k(SE-SJ)105

∆k (SE-SCE)105

S2 117399 plusmn 89E-05 117587 plusmn 88E-05 117068 188 519S3 118787 plusmn 87E-05 118996 plusmn 86E-05 118557 209 439S4 124808 plusmn 85E-05 124993 plusmn 87E-05 124538 185 455S5 132088 plusmn 76E-05 132305 plusmn 77E-05 131770 217 535

MOXSERPENT (SJ)

[JEFF31]SERPENT (SE)[ENDFB-VII]

SCALE (SCE)[ENDFB-VII]

∆k(SE-SJ)105

∆k (SE-SCE)105

S2 119596 plusmn 85E-05 119762 plusmn 86E-05 119178 166 584S3 121259 plusmn 84E-05 121419 plusmn 84E-05 121005 160 414S4 124765 plusmn 84E-05 124923 plusmn 84E-05 124491 158 432S5 132908 plusmn 76E-05 133013 plusmn 76E-05 132652 105 361

Systematic under-prediction of JEFF31 with respect to JEFF22 (LEU)Systematic over-prediction of JEFF31 with respect to JEFF22 (MOX)ENDFB-VII-kinf larger with respect to JEFF31-kinf by ~100-200 pcmSCALE results are systematically higher than SERPENT ones due to the multi-group and spatial approximations

SERPENT and SCALE results for kinf at zero burnup with different NDLs

Institute for Neutron Physics and Reactor Technology (INR)

11 L Mercatali ndash AAA Workshop 01122014 (GRS)

Reactivity effects

Due to the harder neutron spectrum of the MOX assembly Xenon effect lower in MOX the difference becoming less important with the increasing of burnup Boron worth reduced in MOX Difference ~71 (BOC) - ~24 (EOC)

Doppler coefficient slightly more negative for the MOX at BOC and almost equals at EOCModerator temperature coefficient more negative in the case of MOX

Initial state Final stateBurnup

(MWdKgHM)LEU MOX

SERPENT SCALE Mean SERPENT SCALE Mean

S1 S20 -358 - -403 -263 - -333

20 -291 - -396 -244 - -34440 -237 - -329 -216 - -308

S2 S30 -141 -148 -136 -166 -183 -174

20 -148 - -152 -148 - -15540 -135 - -140 -133 - -140

S3 S40 -600 -598 -599 -350 -349 -346

20 -540 - -548 -376 - -38340 -481 - -491 -386 - -398

S4 S50 -728 -698 -690 -809 -816 -793

20 -687 - -672 -698 - -70340 -435 - -533 -549 - -541

LEU and MOX assemblies 100 x (kinit ndash kfin)

Institute for Neutron Physics and Reactor Technology (INR)

12 Institute for Neutron Physics and Reactor Technology (INR)

12 20100511

Burn-up calculations - kinfThe decrease of kinf is slower for MOXDifferent shapes of the burn-up swings due to different spectraSERPENT- kinf systematically higher than SCALE- kinf

The agreement in between SERPENTSCALE stands within plusmn039 (LEU) and plusmn033 (MOX)

E Bubelis amp M Schikorr ndash CDT technical meeting KIT internal

Institute for Neutron Physics and Reactor Technology (INR)

13

Burn-up calculations ndash assembly averaged nuclide concentrations (SERPENTBenchmark mean)

Excellent agreement for U Good agreement for Pu Slight discrepancies for

Sm-149 Gd-155 and Gd-157 in the MOX case

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

14

Burn-up calculations ndash Cell 1 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Excellentgood agreement for U and Pu isotopes Discrepancies for Sm-149 at high burn-up levels

Institute for Neutron Physics and Reactor Technology (INR)

15

Burn-up calculations ndash Cell 24 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Good agreement for U and Pu isotopes

Discrepancies for Xe-135 Sm-149 Gd-155 and Gd-157

Institute for Neutron Physics and Reactor Technology (INR)

16

Pin-by-pin fission rates

Good agreement SERPENTSCALE

Maximum deviationsLEU -42 (pin 35)MOX -16 (pin 63)

LEU Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 21 55 1

Max δ [] (SCALE-SERPENT) -078 214 322Average δ [] (SCALE-SERPENT) 025 069 145

MOX Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 10 4 46

Max δ [] (SCALE-SERPENT) -126 397 504Average δ [] (SCALE-SERPENT) 048 108 144

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

17 L Mercatali ndash AAA Workshop 01122014 (GRS)

Summary and conclusions

SERPENT and SCALE calculation schemes for VVER-1000 reactors have been tested on 2-D problems for fresh and depleted LEU and MOX fuel assemblies representative of the designs expected for the plutonium disposition mission

Small deviations have been generally observed between the SCALE and SERPENT computed kinf nuclide concentrations and pin-by-pin fission rates

Very good agreement is found between SERPENT solutions and the corresponding previous MCNP4B results making of this work also a new Monte Carlo reference solution for the OECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmark with modern NDLs

Institute for Neutron Physics and Reactor Technology (INR)

5

OECD VVER-1000 benchmark ndash specifications

State Fuel temp K

Non-fuel tempK

135Xe149Sm Boron [ppm] Moderator density [gcm3]

S1 1027 575 Eq 600 07235S2 1027 575 00 600 07235S3 575 575 00 600 07235S4 575 575 00 00 07235S5 300 300 00 00 10033

Constant power density 108 MWm3

Requested responses kinf for state S1 at each burn-up step kinf for states S2-S5 at 0 20 40 MWdkgHM Pin-by-pin fission rate distribution Nuclide assembly average concentrations + nuclide average concentrations in cell 1

and cell 24 for 235U 236U 238U 239Pu 240Pu 241Pu 242Pu135Xe149Sm 155Gd and 157Gd

S1 - S2 Poisons (Xe + Sm) effectsS2 - S3 Doppler coefficientS3 - S4 Boron effectS4 - S5 Moderator temperature coefficient

Operational states

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

6

Modeling assumptions ndash SCALE 61

Transport solutions (SN6)Boundary condition whiteConvergence criterion (spatialeigenvalue) ε=1E-6Predictor-corrector algorithmsCross-section library ENDFB-VII0

LEU

MOX

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

7

LEU ndash sensitivity studies on burn-up steps

~100 pcm

~50 pcm

~10 pcm

Negligible effect of gadolinium mesh refinement (lt20 pcm)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

8

Modeling assumptions ndash SERPENT 21

Solution of Depletion Equations CRAMPredictor-corrector method (PC) vs Stochastic Implicit Euler (SIE)Pin-by-pin modelBoundary condition reflectiveGadolinium refinement10000 neutrons 4000 cycles 100 inactive cycles (Shannon enrtopy criterion)Tmp card (Doppler broadening) vs Temperature weighted compositions (~200 pcm)Cross-section library ENDFB-VII0 JEFF31 JEFF22

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

9

SERPENT and MCNP4B results for kinf at zero burnup with JEFF22 data

Monte Carlo solutions - kinf

Objective assess the validity of our model through comparison with the reference MCNP4B solutions

Overall good agreement Small deviations due to different data (ENDFBV) for 16O 152Gd natZr and 1H in the MCNP4B

results and different statistics

LEU SERPENT (S) MCNP4B (M) ∆k (M-S)105

S2 117987 plusmn 89E-05 11800 plusmn 6E-05 13S3 119365 plusmn 86E-05 11925 plusmn 6E-05 -115S4 125387 plusmn 85E-05 12531 plusmn 7E-05 -77S5 132394 plusmn 76E-05 13235 plusmn 6E-05 -44

MOX SERPENT (S) MCNP4B (M) ∆k (M-S)105

S2 119258 plusmn 86E-05 11922 plusmn 7E-05 -38S3 120919 plusmn 84E-05 12091 plusmn 6E-05 -9S4 124408 plusmn 85E-05 12430 plusmn 6E-05 -108S5 132487 plusmn 76E-05 13256 plusmn 7E-05 73

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

10 L Mercatali ndash AAA Workshop 01122014 (GRS)

Monte-carlo and deterministic solutions - kinf

LEUSERPENT (SJ)

[JEFF31]SERPENT (SE)[ENDFB-VII]

SCALE (SCE)[ENDFB-VII]

∆k(SE-SJ)105

∆k (SE-SCE)105

S2 117399 plusmn 89E-05 117587 plusmn 88E-05 117068 188 519S3 118787 plusmn 87E-05 118996 plusmn 86E-05 118557 209 439S4 124808 plusmn 85E-05 124993 plusmn 87E-05 124538 185 455S5 132088 plusmn 76E-05 132305 plusmn 77E-05 131770 217 535

MOXSERPENT (SJ)

[JEFF31]SERPENT (SE)[ENDFB-VII]

SCALE (SCE)[ENDFB-VII]

∆k(SE-SJ)105

∆k (SE-SCE)105

S2 119596 plusmn 85E-05 119762 plusmn 86E-05 119178 166 584S3 121259 plusmn 84E-05 121419 plusmn 84E-05 121005 160 414S4 124765 plusmn 84E-05 124923 plusmn 84E-05 124491 158 432S5 132908 plusmn 76E-05 133013 plusmn 76E-05 132652 105 361

Systematic under-prediction of JEFF31 with respect to JEFF22 (LEU)Systematic over-prediction of JEFF31 with respect to JEFF22 (MOX)ENDFB-VII-kinf larger with respect to JEFF31-kinf by ~100-200 pcmSCALE results are systematically higher than SERPENT ones due to the multi-group and spatial approximations

SERPENT and SCALE results for kinf at zero burnup with different NDLs

Institute for Neutron Physics and Reactor Technology (INR)

11 L Mercatali ndash AAA Workshop 01122014 (GRS)

Reactivity effects

Due to the harder neutron spectrum of the MOX assembly Xenon effect lower in MOX the difference becoming less important with the increasing of burnup Boron worth reduced in MOX Difference ~71 (BOC) - ~24 (EOC)

Doppler coefficient slightly more negative for the MOX at BOC and almost equals at EOCModerator temperature coefficient more negative in the case of MOX

Initial state Final stateBurnup

(MWdKgHM)LEU MOX

SERPENT SCALE Mean SERPENT SCALE Mean

S1 S20 -358 - -403 -263 - -333

20 -291 - -396 -244 - -34440 -237 - -329 -216 - -308

S2 S30 -141 -148 -136 -166 -183 -174

20 -148 - -152 -148 - -15540 -135 - -140 -133 - -140

S3 S40 -600 -598 -599 -350 -349 -346

20 -540 - -548 -376 - -38340 -481 - -491 -386 - -398

S4 S50 -728 -698 -690 -809 -816 -793

20 -687 - -672 -698 - -70340 -435 - -533 -549 - -541

LEU and MOX assemblies 100 x (kinit ndash kfin)

Institute for Neutron Physics and Reactor Technology (INR)

12 Institute for Neutron Physics and Reactor Technology (INR)

12 20100511

Burn-up calculations - kinfThe decrease of kinf is slower for MOXDifferent shapes of the burn-up swings due to different spectraSERPENT- kinf systematically higher than SCALE- kinf

The agreement in between SERPENTSCALE stands within plusmn039 (LEU) and plusmn033 (MOX)

E Bubelis amp M Schikorr ndash CDT technical meeting KIT internal

Institute for Neutron Physics and Reactor Technology (INR)

13

Burn-up calculations ndash assembly averaged nuclide concentrations (SERPENTBenchmark mean)

Excellent agreement for U Good agreement for Pu Slight discrepancies for

Sm-149 Gd-155 and Gd-157 in the MOX case

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

14

Burn-up calculations ndash Cell 1 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Excellentgood agreement for U and Pu isotopes Discrepancies for Sm-149 at high burn-up levels

Institute for Neutron Physics and Reactor Technology (INR)

15

Burn-up calculations ndash Cell 24 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Good agreement for U and Pu isotopes

Discrepancies for Xe-135 Sm-149 Gd-155 and Gd-157

Institute for Neutron Physics and Reactor Technology (INR)

16

Pin-by-pin fission rates

Good agreement SERPENTSCALE

Maximum deviationsLEU -42 (pin 35)MOX -16 (pin 63)

LEU Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 21 55 1

Max δ [] (SCALE-SERPENT) -078 214 322Average δ [] (SCALE-SERPENT) 025 069 145

MOX Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 10 4 46

Max δ [] (SCALE-SERPENT) -126 397 504Average δ [] (SCALE-SERPENT) 048 108 144

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

17 L Mercatali ndash AAA Workshop 01122014 (GRS)

Summary and conclusions

SERPENT and SCALE calculation schemes for VVER-1000 reactors have been tested on 2-D problems for fresh and depleted LEU and MOX fuel assemblies representative of the designs expected for the plutonium disposition mission

Small deviations have been generally observed between the SCALE and SERPENT computed kinf nuclide concentrations and pin-by-pin fission rates

Very good agreement is found between SERPENT solutions and the corresponding previous MCNP4B results making of this work also a new Monte Carlo reference solution for the OECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmark with modern NDLs

Institute for Neutron Physics and Reactor Technology (INR)

6

Modeling assumptions ndash SCALE 61

Transport solutions (SN6)Boundary condition whiteConvergence criterion (spatialeigenvalue) ε=1E-6Predictor-corrector algorithmsCross-section library ENDFB-VII0

LEU

MOX

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

7

LEU ndash sensitivity studies on burn-up steps

~100 pcm

~50 pcm

~10 pcm

Negligible effect of gadolinium mesh refinement (lt20 pcm)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

8

Modeling assumptions ndash SERPENT 21

Solution of Depletion Equations CRAMPredictor-corrector method (PC) vs Stochastic Implicit Euler (SIE)Pin-by-pin modelBoundary condition reflectiveGadolinium refinement10000 neutrons 4000 cycles 100 inactive cycles (Shannon enrtopy criterion)Tmp card (Doppler broadening) vs Temperature weighted compositions (~200 pcm)Cross-section library ENDFB-VII0 JEFF31 JEFF22

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

9

SERPENT and MCNP4B results for kinf at zero burnup with JEFF22 data

Monte Carlo solutions - kinf

Objective assess the validity of our model through comparison with the reference MCNP4B solutions

Overall good agreement Small deviations due to different data (ENDFBV) for 16O 152Gd natZr and 1H in the MCNP4B

results and different statistics

LEU SERPENT (S) MCNP4B (M) ∆k (M-S)105

S2 117987 plusmn 89E-05 11800 plusmn 6E-05 13S3 119365 plusmn 86E-05 11925 plusmn 6E-05 -115S4 125387 plusmn 85E-05 12531 plusmn 7E-05 -77S5 132394 plusmn 76E-05 13235 plusmn 6E-05 -44

MOX SERPENT (S) MCNP4B (M) ∆k (M-S)105

S2 119258 plusmn 86E-05 11922 plusmn 7E-05 -38S3 120919 plusmn 84E-05 12091 plusmn 6E-05 -9S4 124408 plusmn 85E-05 12430 plusmn 6E-05 -108S5 132487 plusmn 76E-05 13256 plusmn 7E-05 73

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

10 L Mercatali ndash AAA Workshop 01122014 (GRS)

Monte-carlo and deterministic solutions - kinf

LEUSERPENT (SJ)

[JEFF31]SERPENT (SE)[ENDFB-VII]

SCALE (SCE)[ENDFB-VII]

∆k(SE-SJ)105

∆k (SE-SCE)105

S2 117399 plusmn 89E-05 117587 plusmn 88E-05 117068 188 519S3 118787 plusmn 87E-05 118996 plusmn 86E-05 118557 209 439S4 124808 plusmn 85E-05 124993 plusmn 87E-05 124538 185 455S5 132088 plusmn 76E-05 132305 plusmn 77E-05 131770 217 535

MOXSERPENT (SJ)

[JEFF31]SERPENT (SE)[ENDFB-VII]

SCALE (SCE)[ENDFB-VII]

∆k(SE-SJ)105

∆k (SE-SCE)105

S2 119596 plusmn 85E-05 119762 plusmn 86E-05 119178 166 584S3 121259 plusmn 84E-05 121419 plusmn 84E-05 121005 160 414S4 124765 plusmn 84E-05 124923 plusmn 84E-05 124491 158 432S5 132908 plusmn 76E-05 133013 plusmn 76E-05 132652 105 361

Systematic under-prediction of JEFF31 with respect to JEFF22 (LEU)Systematic over-prediction of JEFF31 with respect to JEFF22 (MOX)ENDFB-VII-kinf larger with respect to JEFF31-kinf by ~100-200 pcmSCALE results are systematically higher than SERPENT ones due to the multi-group and spatial approximations

SERPENT and SCALE results for kinf at zero burnup with different NDLs

Institute for Neutron Physics and Reactor Technology (INR)

11 L Mercatali ndash AAA Workshop 01122014 (GRS)

Reactivity effects

Due to the harder neutron spectrum of the MOX assembly Xenon effect lower in MOX the difference becoming less important with the increasing of burnup Boron worth reduced in MOX Difference ~71 (BOC) - ~24 (EOC)

Doppler coefficient slightly more negative for the MOX at BOC and almost equals at EOCModerator temperature coefficient more negative in the case of MOX

Initial state Final stateBurnup

(MWdKgHM)LEU MOX

SERPENT SCALE Mean SERPENT SCALE Mean

S1 S20 -358 - -403 -263 - -333

20 -291 - -396 -244 - -34440 -237 - -329 -216 - -308

S2 S30 -141 -148 -136 -166 -183 -174

20 -148 - -152 -148 - -15540 -135 - -140 -133 - -140

S3 S40 -600 -598 -599 -350 -349 -346

20 -540 - -548 -376 - -38340 -481 - -491 -386 - -398

S4 S50 -728 -698 -690 -809 -816 -793

20 -687 - -672 -698 - -70340 -435 - -533 -549 - -541

LEU and MOX assemblies 100 x (kinit ndash kfin)

Institute for Neutron Physics and Reactor Technology (INR)

12 Institute for Neutron Physics and Reactor Technology (INR)

12 20100511

Burn-up calculations - kinfThe decrease of kinf is slower for MOXDifferent shapes of the burn-up swings due to different spectraSERPENT- kinf systematically higher than SCALE- kinf

The agreement in between SERPENTSCALE stands within plusmn039 (LEU) and plusmn033 (MOX)

E Bubelis amp M Schikorr ndash CDT technical meeting KIT internal

Institute for Neutron Physics and Reactor Technology (INR)

13

Burn-up calculations ndash assembly averaged nuclide concentrations (SERPENTBenchmark mean)

Excellent agreement for U Good agreement for Pu Slight discrepancies for

Sm-149 Gd-155 and Gd-157 in the MOX case

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

14

Burn-up calculations ndash Cell 1 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Excellentgood agreement for U and Pu isotopes Discrepancies for Sm-149 at high burn-up levels

Institute for Neutron Physics and Reactor Technology (INR)

15

Burn-up calculations ndash Cell 24 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Good agreement for U and Pu isotopes

Discrepancies for Xe-135 Sm-149 Gd-155 and Gd-157

Institute for Neutron Physics and Reactor Technology (INR)

16

Pin-by-pin fission rates

Good agreement SERPENTSCALE

Maximum deviationsLEU -42 (pin 35)MOX -16 (pin 63)

LEU Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 21 55 1

Max δ [] (SCALE-SERPENT) -078 214 322Average δ [] (SCALE-SERPENT) 025 069 145

MOX Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 10 4 46

Max δ [] (SCALE-SERPENT) -126 397 504Average δ [] (SCALE-SERPENT) 048 108 144

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

17 L Mercatali ndash AAA Workshop 01122014 (GRS)

Summary and conclusions

SERPENT and SCALE calculation schemes for VVER-1000 reactors have been tested on 2-D problems for fresh and depleted LEU and MOX fuel assemblies representative of the designs expected for the plutonium disposition mission

Small deviations have been generally observed between the SCALE and SERPENT computed kinf nuclide concentrations and pin-by-pin fission rates

Very good agreement is found between SERPENT solutions and the corresponding previous MCNP4B results making of this work also a new Monte Carlo reference solution for the OECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmark with modern NDLs

Institute for Neutron Physics and Reactor Technology (INR)

7

LEU ndash sensitivity studies on burn-up steps

~100 pcm

~50 pcm

~10 pcm

Negligible effect of gadolinium mesh refinement (lt20 pcm)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

8

Modeling assumptions ndash SERPENT 21

Solution of Depletion Equations CRAMPredictor-corrector method (PC) vs Stochastic Implicit Euler (SIE)Pin-by-pin modelBoundary condition reflectiveGadolinium refinement10000 neutrons 4000 cycles 100 inactive cycles (Shannon enrtopy criterion)Tmp card (Doppler broadening) vs Temperature weighted compositions (~200 pcm)Cross-section library ENDFB-VII0 JEFF31 JEFF22

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

9

SERPENT and MCNP4B results for kinf at zero burnup with JEFF22 data

Monte Carlo solutions - kinf

Objective assess the validity of our model through comparison with the reference MCNP4B solutions

Overall good agreement Small deviations due to different data (ENDFBV) for 16O 152Gd natZr and 1H in the MCNP4B

results and different statistics

LEU SERPENT (S) MCNP4B (M) ∆k (M-S)105

S2 117987 plusmn 89E-05 11800 plusmn 6E-05 13S3 119365 plusmn 86E-05 11925 plusmn 6E-05 -115S4 125387 plusmn 85E-05 12531 plusmn 7E-05 -77S5 132394 plusmn 76E-05 13235 plusmn 6E-05 -44

MOX SERPENT (S) MCNP4B (M) ∆k (M-S)105

S2 119258 plusmn 86E-05 11922 plusmn 7E-05 -38S3 120919 plusmn 84E-05 12091 plusmn 6E-05 -9S4 124408 plusmn 85E-05 12430 plusmn 6E-05 -108S5 132487 plusmn 76E-05 13256 plusmn 7E-05 73

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

10 L Mercatali ndash AAA Workshop 01122014 (GRS)

Monte-carlo and deterministic solutions - kinf

LEUSERPENT (SJ)

[JEFF31]SERPENT (SE)[ENDFB-VII]

SCALE (SCE)[ENDFB-VII]

∆k(SE-SJ)105

∆k (SE-SCE)105

S2 117399 plusmn 89E-05 117587 plusmn 88E-05 117068 188 519S3 118787 plusmn 87E-05 118996 plusmn 86E-05 118557 209 439S4 124808 plusmn 85E-05 124993 plusmn 87E-05 124538 185 455S5 132088 plusmn 76E-05 132305 plusmn 77E-05 131770 217 535

MOXSERPENT (SJ)

[JEFF31]SERPENT (SE)[ENDFB-VII]

SCALE (SCE)[ENDFB-VII]

∆k(SE-SJ)105

∆k (SE-SCE)105

S2 119596 plusmn 85E-05 119762 plusmn 86E-05 119178 166 584S3 121259 plusmn 84E-05 121419 plusmn 84E-05 121005 160 414S4 124765 plusmn 84E-05 124923 plusmn 84E-05 124491 158 432S5 132908 plusmn 76E-05 133013 plusmn 76E-05 132652 105 361

Systematic under-prediction of JEFF31 with respect to JEFF22 (LEU)Systematic over-prediction of JEFF31 with respect to JEFF22 (MOX)ENDFB-VII-kinf larger with respect to JEFF31-kinf by ~100-200 pcmSCALE results are systematically higher than SERPENT ones due to the multi-group and spatial approximations

SERPENT and SCALE results for kinf at zero burnup with different NDLs

Institute for Neutron Physics and Reactor Technology (INR)

11 L Mercatali ndash AAA Workshop 01122014 (GRS)

Reactivity effects

Due to the harder neutron spectrum of the MOX assembly Xenon effect lower in MOX the difference becoming less important with the increasing of burnup Boron worth reduced in MOX Difference ~71 (BOC) - ~24 (EOC)

Doppler coefficient slightly more negative for the MOX at BOC and almost equals at EOCModerator temperature coefficient more negative in the case of MOX

Initial state Final stateBurnup

(MWdKgHM)LEU MOX

SERPENT SCALE Mean SERPENT SCALE Mean

S1 S20 -358 - -403 -263 - -333

20 -291 - -396 -244 - -34440 -237 - -329 -216 - -308

S2 S30 -141 -148 -136 -166 -183 -174

20 -148 - -152 -148 - -15540 -135 - -140 -133 - -140

S3 S40 -600 -598 -599 -350 -349 -346

20 -540 - -548 -376 - -38340 -481 - -491 -386 - -398

S4 S50 -728 -698 -690 -809 -816 -793

20 -687 - -672 -698 - -70340 -435 - -533 -549 - -541

LEU and MOX assemblies 100 x (kinit ndash kfin)

Institute for Neutron Physics and Reactor Technology (INR)

12 Institute for Neutron Physics and Reactor Technology (INR)

12 20100511

Burn-up calculations - kinfThe decrease of kinf is slower for MOXDifferent shapes of the burn-up swings due to different spectraSERPENT- kinf systematically higher than SCALE- kinf

The agreement in between SERPENTSCALE stands within plusmn039 (LEU) and plusmn033 (MOX)

E Bubelis amp M Schikorr ndash CDT technical meeting KIT internal

Institute for Neutron Physics and Reactor Technology (INR)

13

Burn-up calculations ndash assembly averaged nuclide concentrations (SERPENTBenchmark mean)

Excellent agreement for U Good agreement for Pu Slight discrepancies for

Sm-149 Gd-155 and Gd-157 in the MOX case

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

14

Burn-up calculations ndash Cell 1 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Excellentgood agreement for U and Pu isotopes Discrepancies for Sm-149 at high burn-up levels

Institute for Neutron Physics and Reactor Technology (INR)

15

Burn-up calculations ndash Cell 24 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Good agreement for U and Pu isotopes

Discrepancies for Xe-135 Sm-149 Gd-155 and Gd-157

Institute for Neutron Physics and Reactor Technology (INR)

16

Pin-by-pin fission rates

Good agreement SERPENTSCALE

Maximum deviationsLEU -42 (pin 35)MOX -16 (pin 63)

LEU Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 21 55 1

Max δ [] (SCALE-SERPENT) -078 214 322Average δ [] (SCALE-SERPENT) 025 069 145

MOX Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 10 4 46

Max δ [] (SCALE-SERPENT) -126 397 504Average δ [] (SCALE-SERPENT) 048 108 144

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

17 L Mercatali ndash AAA Workshop 01122014 (GRS)

Summary and conclusions

SERPENT and SCALE calculation schemes for VVER-1000 reactors have been tested on 2-D problems for fresh and depleted LEU and MOX fuel assemblies representative of the designs expected for the plutonium disposition mission

Small deviations have been generally observed between the SCALE and SERPENT computed kinf nuclide concentrations and pin-by-pin fission rates

Very good agreement is found between SERPENT solutions and the corresponding previous MCNP4B results making of this work also a new Monte Carlo reference solution for the OECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmark with modern NDLs

Institute for Neutron Physics and Reactor Technology (INR)

8

Modeling assumptions ndash SERPENT 21

Solution of Depletion Equations CRAMPredictor-corrector method (PC) vs Stochastic Implicit Euler (SIE)Pin-by-pin modelBoundary condition reflectiveGadolinium refinement10000 neutrons 4000 cycles 100 inactive cycles (Shannon enrtopy criterion)Tmp card (Doppler broadening) vs Temperature weighted compositions (~200 pcm)Cross-section library ENDFB-VII0 JEFF31 JEFF22

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

9

SERPENT and MCNP4B results for kinf at zero burnup with JEFF22 data

Monte Carlo solutions - kinf

Objective assess the validity of our model through comparison with the reference MCNP4B solutions

Overall good agreement Small deviations due to different data (ENDFBV) for 16O 152Gd natZr and 1H in the MCNP4B

results and different statistics

LEU SERPENT (S) MCNP4B (M) ∆k (M-S)105

S2 117987 plusmn 89E-05 11800 plusmn 6E-05 13S3 119365 plusmn 86E-05 11925 plusmn 6E-05 -115S4 125387 plusmn 85E-05 12531 plusmn 7E-05 -77S5 132394 plusmn 76E-05 13235 plusmn 6E-05 -44

MOX SERPENT (S) MCNP4B (M) ∆k (M-S)105

S2 119258 plusmn 86E-05 11922 plusmn 7E-05 -38S3 120919 plusmn 84E-05 12091 plusmn 6E-05 -9S4 124408 plusmn 85E-05 12430 plusmn 6E-05 -108S5 132487 plusmn 76E-05 13256 plusmn 7E-05 73

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

10 L Mercatali ndash AAA Workshop 01122014 (GRS)

Monte-carlo and deterministic solutions - kinf

LEUSERPENT (SJ)

[JEFF31]SERPENT (SE)[ENDFB-VII]

SCALE (SCE)[ENDFB-VII]

∆k(SE-SJ)105

∆k (SE-SCE)105

S2 117399 plusmn 89E-05 117587 plusmn 88E-05 117068 188 519S3 118787 plusmn 87E-05 118996 plusmn 86E-05 118557 209 439S4 124808 plusmn 85E-05 124993 plusmn 87E-05 124538 185 455S5 132088 plusmn 76E-05 132305 plusmn 77E-05 131770 217 535

MOXSERPENT (SJ)

[JEFF31]SERPENT (SE)[ENDFB-VII]

SCALE (SCE)[ENDFB-VII]

∆k(SE-SJ)105

∆k (SE-SCE)105

S2 119596 plusmn 85E-05 119762 plusmn 86E-05 119178 166 584S3 121259 plusmn 84E-05 121419 plusmn 84E-05 121005 160 414S4 124765 plusmn 84E-05 124923 plusmn 84E-05 124491 158 432S5 132908 plusmn 76E-05 133013 plusmn 76E-05 132652 105 361

Systematic under-prediction of JEFF31 with respect to JEFF22 (LEU)Systematic over-prediction of JEFF31 with respect to JEFF22 (MOX)ENDFB-VII-kinf larger with respect to JEFF31-kinf by ~100-200 pcmSCALE results are systematically higher than SERPENT ones due to the multi-group and spatial approximations

SERPENT and SCALE results for kinf at zero burnup with different NDLs

Institute for Neutron Physics and Reactor Technology (INR)

11 L Mercatali ndash AAA Workshop 01122014 (GRS)

Reactivity effects

Due to the harder neutron spectrum of the MOX assembly Xenon effect lower in MOX the difference becoming less important with the increasing of burnup Boron worth reduced in MOX Difference ~71 (BOC) - ~24 (EOC)

Doppler coefficient slightly more negative for the MOX at BOC and almost equals at EOCModerator temperature coefficient more negative in the case of MOX

Initial state Final stateBurnup

(MWdKgHM)LEU MOX

SERPENT SCALE Mean SERPENT SCALE Mean

S1 S20 -358 - -403 -263 - -333

20 -291 - -396 -244 - -34440 -237 - -329 -216 - -308

S2 S30 -141 -148 -136 -166 -183 -174

20 -148 - -152 -148 - -15540 -135 - -140 -133 - -140

S3 S40 -600 -598 -599 -350 -349 -346

20 -540 - -548 -376 - -38340 -481 - -491 -386 - -398

S4 S50 -728 -698 -690 -809 -816 -793

20 -687 - -672 -698 - -70340 -435 - -533 -549 - -541

LEU and MOX assemblies 100 x (kinit ndash kfin)

Institute for Neutron Physics and Reactor Technology (INR)

12 Institute for Neutron Physics and Reactor Technology (INR)

12 20100511

Burn-up calculations - kinfThe decrease of kinf is slower for MOXDifferent shapes of the burn-up swings due to different spectraSERPENT- kinf systematically higher than SCALE- kinf

The agreement in between SERPENTSCALE stands within plusmn039 (LEU) and plusmn033 (MOX)

E Bubelis amp M Schikorr ndash CDT technical meeting KIT internal

Institute for Neutron Physics and Reactor Technology (INR)

13

Burn-up calculations ndash assembly averaged nuclide concentrations (SERPENTBenchmark mean)

Excellent agreement for U Good agreement for Pu Slight discrepancies for

Sm-149 Gd-155 and Gd-157 in the MOX case

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

14

Burn-up calculations ndash Cell 1 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Excellentgood agreement for U and Pu isotopes Discrepancies for Sm-149 at high burn-up levels

Institute for Neutron Physics and Reactor Technology (INR)

15

Burn-up calculations ndash Cell 24 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Good agreement for U and Pu isotopes

Discrepancies for Xe-135 Sm-149 Gd-155 and Gd-157

Institute for Neutron Physics and Reactor Technology (INR)

16

Pin-by-pin fission rates

Good agreement SERPENTSCALE

Maximum deviationsLEU -42 (pin 35)MOX -16 (pin 63)

LEU Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 21 55 1

Max δ [] (SCALE-SERPENT) -078 214 322Average δ [] (SCALE-SERPENT) 025 069 145

MOX Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 10 4 46

Max δ [] (SCALE-SERPENT) -126 397 504Average δ [] (SCALE-SERPENT) 048 108 144

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

17 L Mercatali ndash AAA Workshop 01122014 (GRS)

Summary and conclusions

SERPENT and SCALE calculation schemes for VVER-1000 reactors have been tested on 2-D problems for fresh and depleted LEU and MOX fuel assemblies representative of the designs expected for the plutonium disposition mission

Small deviations have been generally observed between the SCALE and SERPENT computed kinf nuclide concentrations and pin-by-pin fission rates

Very good agreement is found between SERPENT solutions and the corresponding previous MCNP4B results making of this work also a new Monte Carlo reference solution for the OECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmark with modern NDLs

Institute for Neutron Physics and Reactor Technology (INR)

9

SERPENT and MCNP4B results for kinf at zero burnup with JEFF22 data

Monte Carlo solutions - kinf

Objective assess the validity of our model through comparison with the reference MCNP4B solutions

Overall good agreement Small deviations due to different data (ENDFBV) for 16O 152Gd natZr and 1H in the MCNP4B

results and different statistics

LEU SERPENT (S) MCNP4B (M) ∆k (M-S)105

S2 117987 plusmn 89E-05 11800 plusmn 6E-05 13S3 119365 plusmn 86E-05 11925 plusmn 6E-05 -115S4 125387 plusmn 85E-05 12531 plusmn 7E-05 -77S5 132394 plusmn 76E-05 13235 plusmn 6E-05 -44

MOX SERPENT (S) MCNP4B (M) ∆k (M-S)105

S2 119258 plusmn 86E-05 11922 plusmn 7E-05 -38S3 120919 plusmn 84E-05 12091 plusmn 6E-05 -9S4 124408 plusmn 85E-05 12430 plusmn 6E-05 -108S5 132487 plusmn 76E-05 13256 plusmn 7E-05 73

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

10 L Mercatali ndash AAA Workshop 01122014 (GRS)

Monte-carlo and deterministic solutions - kinf

LEUSERPENT (SJ)

[JEFF31]SERPENT (SE)[ENDFB-VII]

SCALE (SCE)[ENDFB-VII]

∆k(SE-SJ)105

∆k (SE-SCE)105

S2 117399 plusmn 89E-05 117587 plusmn 88E-05 117068 188 519S3 118787 plusmn 87E-05 118996 plusmn 86E-05 118557 209 439S4 124808 plusmn 85E-05 124993 plusmn 87E-05 124538 185 455S5 132088 plusmn 76E-05 132305 plusmn 77E-05 131770 217 535

MOXSERPENT (SJ)

[JEFF31]SERPENT (SE)[ENDFB-VII]

SCALE (SCE)[ENDFB-VII]

∆k(SE-SJ)105

∆k (SE-SCE)105

S2 119596 plusmn 85E-05 119762 plusmn 86E-05 119178 166 584S3 121259 plusmn 84E-05 121419 plusmn 84E-05 121005 160 414S4 124765 plusmn 84E-05 124923 plusmn 84E-05 124491 158 432S5 132908 plusmn 76E-05 133013 plusmn 76E-05 132652 105 361

Systematic under-prediction of JEFF31 with respect to JEFF22 (LEU)Systematic over-prediction of JEFF31 with respect to JEFF22 (MOX)ENDFB-VII-kinf larger with respect to JEFF31-kinf by ~100-200 pcmSCALE results are systematically higher than SERPENT ones due to the multi-group and spatial approximations

SERPENT and SCALE results for kinf at zero burnup with different NDLs

Institute for Neutron Physics and Reactor Technology (INR)

11 L Mercatali ndash AAA Workshop 01122014 (GRS)

Reactivity effects

Due to the harder neutron spectrum of the MOX assembly Xenon effect lower in MOX the difference becoming less important with the increasing of burnup Boron worth reduced in MOX Difference ~71 (BOC) - ~24 (EOC)

Doppler coefficient slightly more negative for the MOX at BOC and almost equals at EOCModerator temperature coefficient more negative in the case of MOX

Initial state Final stateBurnup

(MWdKgHM)LEU MOX

SERPENT SCALE Mean SERPENT SCALE Mean

S1 S20 -358 - -403 -263 - -333

20 -291 - -396 -244 - -34440 -237 - -329 -216 - -308

S2 S30 -141 -148 -136 -166 -183 -174

20 -148 - -152 -148 - -15540 -135 - -140 -133 - -140

S3 S40 -600 -598 -599 -350 -349 -346

20 -540 - -548 -376 - -38340 -481 - -491 -386 - -398

S4 S50 -728 -698 -690 -809 -816 -793

20 -687 - -672 -698 - -70340 -435 - -533 -549 - -541

LEU and MOX assemblies 100 x (kinit ndash kfin)

Institute for Neutron Physics and Reactor Technology (INR)

12 Institute for Neutron Physics and Reactor Technology (INR)

12 20100511

Burn-up calculations - kinfThe decrease of kinf is slower for MOXDifferent shapes of the burn-up swings due to different spectraSERPENT- kinf systematically higher than SCALE- kinf

The agreement in between SERPENTSCALE stands within plusmn039 (LEU) and plusmn033 (MOX)

E Bubelis amp M Schikorr ndash CDT technical meeting KIT internal

Institute for Neutron Physics and Reactor Technology (INR)

13

Burn-up calculations ndash assembly averaged nuclide concentrations (SERPENTBenchmark mean)

Excellent agreement for U Good agreement for Pu Slight discrepancies for

Sm-149 Gd-155 and Gd-157 in the MOX case

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

14

Burn-up calculations ndash Cell 1 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Excellentgood agreement for U and Pu isotopes Discrepancies for Sm-149 at high burn-up levels

Institute for Neutron Physics and Reactor Technology (INR)

15

Burn-up calculations ndash Cell 24 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Good agreement for U and Pu isotopes

Discrepancies for Xe-135 Sm-149 Gd-155 and Gd-157

Institute for Neutron Physics and Reactor Technology (INR)

16

Pin-by-pin fission rates

Good agreement SERPENTSCALE

Maximum deviationsLEU -42 (pin 35)MOX -16 (pin 63)

LEU Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 21 55 1

Max δ [] (SCALE-SERPENT) -078 214 322Average δ [] (SCALE-SERPENT) 025 069 145

MOX Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 10 4 46

Max δ [] (SCALE-SERPENT) -126 397 504Average δ [] (SCALE-SERPENT) 048 108 144

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

17 L Mercatali ndash AAA Workshop 01122014 (GRS)

Summary and conclusions

SERPENT and SCALE calculation schemes for VVER-1000 reactors have been tested on 2-D problems for fresh and depleted LEU and MOX fuel assemblies representative of the designs expected for the plutonium disposition mission

Small deviations have been generally observed between the SCALE and SERPENT computed kinf nuclide concentrations and pin-by-pin fission rates

Very good agreement is found between SERPENT solutions and the corresponding previous MCNP4B results making of this work also a new Monte Carlo reference solution for the OECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmark with modern NDLs

Institute for Neutron Physics and Reactor Technology (INR)

10 L Mercatali ndash AAA Workshop 01122014 (GRS)

Monte-carlo and deterministic solutions - kinf

LEUSERPENT (SJ)

[JEFF31]SERPENT (SE)[ENDFB-VII]

SCALE (SCE)[ENDFB-VII]

∆k(SE-SJ)105

∆k (SE-SCE)105

S2 117399 plusmn 89E-05 117587 plusmn 88E-05 117068 188 519S3 118787 plusmn 87E-05 118996 plusmn 86E-05 118557 209 439S4 124808 plusmn 85E-05 124993 plusmn 87E-05 124538 185 455S5 132088 plusmn 76E-05 132305 plusmn 77E-05 131770 217 535

MOXSERPENT (SJ)

[JEFF31]SERPENT (SE)[ENDFB-VII]

SCALE (SCE)[ENDFB-VII]

∆k(SE-SJ)105

∆k (SE-SCE)105

S2 119596 plusmn 85E-05 119762 plusmn 86E-05 119178 166 584S3 121259 plusmn 84E-05 121419 plusmn 84E-05 121005 160 414S4 124765 plusmn 84E-05 124923 plusmn 84E-05 124491 158 432S5 132908 plusmn 76E-05 133013 plusmn 76E-05 132652 105 361

Systematic under-prediction of JEFF31 with respect to JEFF22 (LEU)Systematic over-prediction of JEFF31 with respect to JEFF22 (MOX)ENDFB-VII-kinf larger with respect to JEFF31-kinf by ~100-200 pcmSCALE results are systematically higher than SERPENT ones due to the multi-group and spatial approximations

SERPENT and SCALE results for kinf at zero burnup with different NDLs

Institute for Neutron Physics and Reactor Technology (INR)

11 L Mercatali ndash AAA Workshop 01122014 (GRS)

Reactivity effects

Due to the harder neutron spectrum of the MOX assembly Xenon effect lower in MOX the difference becoming less important with the increasing of burnup Boron worth reduced in MOX Difference ~71 (BOC) - ~24 (EOC)

Doppler coefficient slightly more negative for the MOX at BOC and almost equals at EOCModerator temperature coefficient more negative in the case of MOX

Initial state Final stateBurnup

(MWdKgHM)LEU MOX

SERPENT SCALE Mean SERPENT SCALE Mean

S1 S20 -358 - -403 -263 - -333

20 -291 - -396 -244 - -34440 -237 - -329 -216 - -308

S2 S30 -141 -148 -136 -166 -183 -174

20 -148 - -152 -148 - -15540 -135 - -140 -133 - -140

S3 S40 -600 -598 -599 -350 -349 -346

20 -540 - -548 -376 - -38340 -481 - -491 -386 - -398

S4 S50 -728 -698 -690 -809 -816 -793

20 -687 - -672 -698 - -70340 -435 - -533 -549 - -541

LEU and MOX assemblies 100 x (kinit ndash kfin)

Institute for Neutron Physics and Reactor Technology (INR)

12 Institute for Neutron Physics and Reactor Technology (INR)

12 20100511

Burn-up calculations - kinfThe decrease of kinf is slower for MOXDifferent shapes of the burn-up swings due to different spectraSERPENT- kinf systematically higher than SCALE- kinf

The agreement in between SERPENTSCALE stands within plusmn039 (LEU) and plusmn033 (MOX)

E Bubelis amp M Schikorr ndash CDT technical meeting KIT internal

Institute for Neutron Physics and Reactor Technology (INR)

13

Burn-up calculations ndash assembly averaged nuclide concentrations (SERPENTBenchmark mean)

Excellent agreement for U Good agreement for Pu Slight discrepancies for

Sm-149 Gd-155 and Gd-157 in the MOX case

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

14

Burn-up calculations ndash Cell 1 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Excellentgood agreement for U and Pu isotopes Discrepancies for Sm-149 at high burn-up levels

Institute for Neutron Physics and Reactor Technology (INR)

15

Burn-up calculations ndash Cell 24 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Good agreement for U and Pu isotopes

Discrepancies for Xe-135 Sm-149 Gd-155 and Gd-157

Institute for Neutron Physics and Reactor Technology (INR)

16

Pin-by-pin fission rates

Good agreement SERPENTSCALE

Maximum deviationsLEU -42 (pin 35)MOX -16 (pin 63)

LEU Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 21 55 1

Max δ [] (SCALE-SERPENT) -078 214 322Average δ [] (SCALE-SERPENT) 025 069 145

MOX Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 10 4 46

Max δ [] (SCALE-SERPENT) -126 397 504Average δ [] (SCALE-SERPENT) 048 108 144

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

17 L Mercatali ndash AAA Workshop 01122014 (GRS)

Summary and conclusions

SERPENT and SCALE calculation schemes for VVER-1000 reactors have been tested on 2-D problems for fresh and depleted LEU and MOX fuel assemblies representative of the designs expected for the plutonium disposition mission

Small deviations have been generally observed between the SCALE and SERPENT computed kinf nuclide concentrations and pin-by-pin fission rates

Very good agreement is found between SERPENT solutions and the corresponding previous MCNP4B results making of this work also a new Monte Carlo reference solution for the OECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmark with modern NDLs

Institute for Neutron Physics and Reactor Technology (INR)

11 L Mercatali ndash AAA Workshop 01122014 (GRS)

Reactivity effects

Due to the harder neutron spectrum of the MOX assembly Xenon effect lower in MOX the difference becoming less important with the increasing of burnup Boron worth reduced in MOX Difference ~71 (BOC) - ~24 (EOC)

Doppler coefficient slightly more negative for the MOX at BOC and almost equals at EOCModerator temperature coefficient more negative in the case of MOX

Initial state Final stateBurnup

(MWdKgHM)LEU MOX

SERPENT SCALE Mean SERPENT SCALE Mean

S1 S20 -358 - -403 -263 - -333

20 -291 - -396 -244 - -34440 -237 - -329 -216 - -308

S2 S30 -141 -148 -136 -166 -183 -174

20 -148 - -152 -148 - -15540 -135 - -140 -133 - -140

S3 S40 -600 -598 -599 -350 -349 -346

20 -540 - -548 -376 - -38340 -481 - -491 -386 - -398

S4 S50 -728 -698 -690 -809 -816 -793

20 -687 - -672 -698 - -70340 -435 - -533 -549 - -541

LEU and MOX assemblies 100 x (kinit ndash kfin)

Institute for Neutron Physics and Reactor Technology (INR)

12 Institute for Neutron Physics and Reactor Technology (INR)

12 20100511

Burn-up calculations - kinfThe decrease of kinf is slower for MOXDifferent shapes of the burn-up swings due to different spectraSERPENT- kinf systematically higher than SCALE- kinf

The agreement in between SERPENTSCALE stands within plusmn039 (LEU) and plusmn033 (MOX)

E Bubelis amp M Schikorr ndash CDT technical meeting KIT internal

Institute for Neutron Physics and Reactor Technology (INR)

13

Burn-up calculations ndash assembly averaged nuclide concentrations (SERPENTBenchmark mean)

Excellent agreement for U Good agreement for Pu Slight discrepancies for

Sm-149 Gd-155 and Gd-157 in the MOX case

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

14

Burn-up calculations ndash Cell 1 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Excellentgood agreement for U and Pu isotopes Discrepancies for Sm-149 at high burn-up levels

Institute for Neutron Physics and Reactor Technology (INR)

15

Burn-up calculations ndash Cell 24 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Good agreement for U and Pu isotopes

Discrepancies for Xe-135 Sm-149 Gd-155 and Gd-157

Institute for Neutron Physics and Reactor Technology (INR)

16

Pin-by-pin fission rates

Good agreement SERPENTSCALE

Maximum deviationsLEU -42 (pin 35)MOX -16 (pin 63)

LEU Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 21 55 1

Max δ [] (SCALE-SERPENT) -078 214 322Average δ [] (SCALE-SERPENT) 025 069 145

MOX Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 10 4 46

Max δ [] (SCALE-SERPENT) -126 397 504Average δ [] (SCALE-SERPENT) 048 108 144

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

17 L Mercatali ndash AAA Workshop 01122014 (GRS)

Summary and conclusions

SERPENT and SCALE calculation schemes for VVER-1000 reactors have been tested on 2-D problems for fresh and depleted LEU and MOX fuel assemblies representative of the designs expected for the plutonium disposition mission

Small deviations have been generally observed between the SCALE and SERPENT computed kinf nuclide concentrations and pin-by-pin fission rates

Very good agreement is found between SERPENT solutions and the corresponding previous MCNP4B results making of this work also a new Monte Carlo reference solution for the OECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmark with modern NDLs

Institute for Neutron Physics and Reactor Technology (INR)

12 Institute for Neutron Physics and Reactor Technology (INR)

12 20100511

Burn-up calculations - kinfThe decrease of kinf is slower for MOXDifferent shapes of the burn-up swings due to different spectraSERPENT- kinf systematically higher than SCALE- kinf

The agreement in between SERPENTSCALE stands within plusmn039 (LEU) and plusmn033 (MOX)

E Bubelis amp M Schikorr ndash CDT technical meeting KIT internal

Institute for Neutron Physics and Reactor Technology (INR)

13

Burn-up calculations ndash assembly averaged nuclide concentrations (SERPENTBenchmark mean)

Excellent agreement for U Good agreement for Pu Slight discrepancies for

Sm-149 Gd-155 and Gd-157 in the MOX case

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

14

Burn-up calculations ndash Cell 1 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Excellentgood agreement for U and Pu isotopes Discrepancies for Sm-149 at high burn-up levels

Institute for Neutron Physics and Reactor Technology (INR)

15

Burn-up calculations ndash Cell 24 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Good agreement for U and Pu isotopes

Discrepancies for Xe-135 Sm-149 Gd-155 and Gd-157

Institute for Neutron Physics and Reactor Technology (INR)

16

Pin-by-pin fission rates

Good agreement SERPENTSCALE

Maximum deviationsLEU -42 (pin 35)MOX -16 (pin 63)

LEU Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 21 55 1

Max δ [] (SCALE-SERPENT) -078 214 322Average δ [] (SCALE-SERPENT) 025 069 145

MOX Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 10 4 46

Max δ [] (SCALE-SERPENT) -126 397 504Average δ [] (SCALE-SERPENT) 048 108 144

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

17 L Mercatali ndash AAA Workshop 01122014 (GRS)

Summary and conclusions

SERPENT and SCALE calculation schemes for VVER-1000 reactors have been tested on 2-D problems for fresh and depleted LEU and MOX fuel assemblies representative of the designs expected for the plutonium disposition mission

Small deviations have been generally observed between the SCALE and SERPENT computed kinf nuclide concentrations and pin-by-pin fission rates

Very good agreement is found between SERPENT solutions and the corresponding previous MCNP4B results making of this work also a new Monte Carlo reference solution for the OECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmark with modern NDLs

Institute for Neutron Physics and Reactor Technology (INR)

13

Burn-up calculations ndash assembly averaged nuclide concentrations (SERPENTBenchmark mean)

Excellent agreement for U Good agreement for Pu Slight discrepancies for

Sm-149 Gd-155 and Gd-157 in the MOX case

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

14

Burn-up calculations ndash Cell 1 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Excellentgood agreement for U and Pu isotopes Discrepancies for Sm-149 at high burn-up levels

Institute for Neutron Physics and Reactor Technology (INR)

15

Burn-up calculations ndash Cell 24 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Good agreement for U and Pu isotopes

Discrepancies for Xe-135 Sm-149 Gd-155 and Gd-157

Institute for Neutron Physics and Reactor Technology (INR)

16

Pin-by-pin fission rates

Good agreement SERPENTSCALE

Maximum deviationsLEU -42 (pin 35)MOX -16 (pin 63)

LEU Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 21 55 1

Max δ [] (SCALE-SERPENT) -078 214 322Average δ [] (SCALE-SERPENT) 025 069 145

MOX Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 10 4 46

Max δ [] (SCALE-SERPENT) -126 397 504Average δ [] (SCALE-SERPENT) 048 108 144

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

17 L Mercatali ndash AAA Workshop 01122014 (GRS)

Summary and conclusions

SERPENT and SCALE calculation schemes for VVER-1000 reactors have been tested on 2-D problems for fresh and depleted LEU and MOX fuel assemblies representative of the designs expected for the plutonium disposition mission

Small deviations have been generally observed between the SCALE and SERPENT computed kinf nuclide concentrations and pin-by-pin fission rates

Very good agreement is found between SERPENT solutions and the corresponding previous MCNP4B results making of this work also a new Monte Carlo reference solution for the OECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmark with modern NDLs

Institute for Neutron Physics and Reactor Technology (INR)

14

Burn-up calculations ndash Cell 1 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Excellentgood agreement for U and Pu isotopes Discrepancies for Sm-149 at high burn-up levels

Institute for Neutron Physics and Reactor Technology (INR)

15

Burn-up calculations ndash Cell 24 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Good agreement for U and Pu isotopes

Discrepancies for Xe-135 Sm-149 Gd-155 and Gd-157

Institute for Neutron Physics and Reactor Technology (INR)

16

Pin-by-pin fission rates

Good agreement SERPENTSCALE

Maximum deviationsLEU -42 (pin 35)MOX -16 (pin 63)

LEU Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 21 55 1

Max δ [] (SCALE-SERPENT) -078 214 322Average δ [] (SCALE-SERPENT) 025 069 145

MOX Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 10 4 46

Max δ [] (SCALE-SERPENT) -126 397 504Average δ [] (SCALE-SERPENT) 048 108 144

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

17 L Mercatali ndash AAA Workshop 01122014 (GRS)

Summary and conclusions

SERPENT and SCALE calculation schemes for VVER-1000 reactors have been tested on 2-D problems for fresh and depleted LEU and MOX fuel assemblies representative of the designs expected for the plutonium disposition mission

Small deviations have been generally observed between the SCALE and SERPENT computed kinf nuclide concentrations and pin-by-pin fission rates

Very good agreement is found between SERPENT solutions and the corresponding previous MCNP4B results making of this work also a new Monte Carlo reference solution for the OECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmark with modern NDLs

Institute for Neutron Physics and Reactor Technology (INR)

15

Burn-up calculations ndash Cell 24 nuclide concentrations (SERPENTSCALEBenchmark mean)

L Mercatali ndash AAA Workshop 01122014 (GRS)

Good agreement for U and Pu isotopes

Discrepancies for Xe-135 Sm-149 Gd-155 and Gd-157

Institute for Neutron Physics and Reactor Technology (INR)

16

Pin-by-pin fission rates

Good agreement SERPENTSCALE

Maximum deviationsLEU -42 (pin 35)MOX -16 (pin 63)

LEU Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 21 55 1

Max δ [] (SCALE-SERPENT) -078 214 322Average δ [] (SCALE-SERPENT) 025 069 145

MOX Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 10 4 46

Max δ [] (SCALE-SERPENT) -126 397 504Average δ [] (SCALE-SERPENT) 048 108 144

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

17 L Mercatali ndash AAA Workshop 01122014 (GRS)

Summary and conclusions

SERPENT and SCALE calculation schemes for VVER-1000 reactors have been tested on 2-D problems for fresh and depleted LEU and MOX fuel assemblies representative of the designs expected for the plutonium disposition mission

Small deviations have been generally observed between the SCALE and SERPENT computed kinf nuclide concentrations and pin-by-pin fission rates

Very good agreement is found between SERPENT solutions and the corresponding previous MCNP4B results making of this work also a new Monte Carlo reference solution for the OECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmark with modern NDLs

Institute for Neutron Physics and Reactor Technology (INR)

16

Pin-by-pin fission rates

Good agreement SERPENTSCALE

Maximum deviationsLEU -42 (pin 35)MOX -16 (pin 63)

LEU Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 21 55 1

Max δ [] (SCALE-SERPENT) -078 214 322Average δ [] (SCALE-SERPENT) 025 069 145

MOX Assembly 0 MWdkgHM 20 MWdkgHM 40 MWdkgHMPin number 10 4 46

Max δ [] (SCALE-SERPENT) -126 397 504Average δ [] (SCALE-SERPENT) 048 108 144

L Mercatali ndash AAA Workshop 01122014 (GRS)

Institute for Neutron Physics and Reactor Technology (INR)

17 L Mercatali ndash AAA Workshop 01122014 (GRS)

Summary and conclusions

SERPENT and SCALE calculation schemes for VVER-1000 reactors have been tested on 2-D problems for fresh and depleted LEU and MOX fuel assemblies representative of the designs expected for the plutonium disposition mission

Small deviations have been generally observed between the SCALE and SERPENT computed kinf nuclide concentrations and pin-by-pin fission rates

Very good agreement is found between SERPENT solutions and the corresponding previous MCNP4B results making of this work also a new Monte Carlo reference solution for the OECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmark with modern NDLs

Institute for Neutron Physics and Reactor Technology (INR)

17 L Mercatali ndash AAA Workshop 01122014 (GRS)

Summary and conclusions

SERPENT and SCALE calculation schemes for VVER-1000 reactors have been tested on 2-D problems for fresh and depleted LEU and MOX fuel assemblies representative of the designs expected for the plutonium disposition mission

Small deviations have been generally observed between the SCALE and SERPENT computed kinf nuclide concentrations and pin-by-pin fission rates

Very good agreement is found between SERPENT solutions and the corresponding previous MCNP4B results making of this work also a new Monte Carlo reference solution for the OECD VVER-1000 LEU and MOX Assemblies BurnupComputational Benchmark with modern NDLs