Fischer, Ulrich

Qiu, Yuefeng

Simakov, Stanislav

KITopen

KIT – The Research University in the Helmholtz AssociationInstitute for Neutron Physics and Reactor Technologywww.kit.eduApplication of an Advanced Variance Reduction Technique for Bulk Shield Calculations of the IFMIF-DONES facilityYuefeng Qiu, Stanislav Simakov, Ulrich FischerM&C 2017, Jeju, Korea, April 16-20, 20172 Dr. Yuefeng Qiu, Application of an Advanced Variance Reduction Technique for Bulk Shield Calculations of the IFMIF-DONES facilityOutlineIntroductionAssessment of ADVANTG for IFMIF-DONESImprovements: methods and codesSummary and outlook20.04.2017M&C 2017, Jeju, Korea, April 16-20, 20173 Dr. Yuefeng Qiu, Application of an Advanced Variance Reduction Technique for Bulk Shield Calculations of the IFMIF-DONES facilityIntroductionIFMIF-DONESIFMIF: the International Fusion Materials Irradiation FacilityDONES: DEMO Oriented Neutron Source (downgraded, early neutron source)Deuterium-Lithium neutron sourceDeuteron beam: 1 x 40 MeV, 125 mANeutron: up to 55 MeV, 1015 n/cm2/sMaterial irradiation: up to 20 dpa/fpy, 0.5 Liter high flux volume20.04.2017IFMIF-DONES buildingTest cell (TC)M&C 2017, Jeju, Korea, April 16-20, 20174 Dr. Yuefeng Qiu, Application of an Advanced Variance Reduction Technique for Bulk Shield Calculations of the IFMIF-DONES facilityIntroductionTest cell shieldingHeavy concrete up to 4 m in thicknessNeutron flux varies >1010 n/cm2/s Bulk shielding with penetrationsChallenging for both Monte Carlo (MC) and deterministic simulation method.20.04.2017Neutronics mode of Test cell Neutron flux (n/cm2/s)M&C 2017, Jeju, Korea, April 16-20, 20175IntroductionMonte Carlo (MC) methodCommon method for IFMIF-DONES shielding calculationMCNP code, e.g. MCNP5-1.6Variance reduction technique required for bulk shielding, e.g. superimposed weight-window (WW) meshADVANTGA tool for automatic generation of MCNP weight-window mesh for variance reduction. Version 3.0.3Is ADVANTG suitable for IFMIF-DONES ?MCNP source subroutine used instead of SDEF cardPenetration in the bulk shielding…Dr. Yuefeng Qiu, Application of an Advanced Variance Reduction Technique for Bulk Shield Calculations of the IFMIF-DONES facility20.04.2017M&C 2017, Jeju, Korea, April 16-20, 20176 Dr. Yuefeng Qiu, Application of an Advanced Variance Reduction Technique for Bulk Shield Calculations of the IFMIF-DONES facilityAssessment of ADVANTG for IFMIF-DONESMcDeLiciousA MCNP source subroutineSimulate the generation of source neutrons/photons from deuterium-lithium reactionsNormalized by deuteron: 1 d -> 1n, the source neutron weight varies as neutron yieldsWell validated against experiments, reference code for IFMIF-DONESIssueADVANTG code require a SDEF source in the MCNP input fileSolution Create a approximation 20.04.2017S. Simakov et al. S. Simakov et al. M&C 2017, Jeju, Korea, April 16-20, 20177 Dr. Yuefeng Qiu, Application of an Advanced Variance Reduction Technique for Bulk Shield Calculations of the IFMIF-DONES facilityAssessment of ADVANTG for IFMIF-DONESSDEF source Tally source neutron in a quasi-infinite slabNeutron spectrum, angular spectrum, neutron weightCreate a SDEF source in a box region. 20.04.20175cmquasi-infinite slab SDEF sourceLithium targetNeutron spectrum Neutron angular distribution Neutron weight distributionM&C 2017, Jeju, Korea, April 16-20, 20178 Dr. Yuefeng Qiu, Application of an Advanced Variance Reduction Technique for Bulk Shield Calculations of the IFMIF-DONES facilityAssessment of ADVANTG for IFMIF-DONESNormal MCNP run (Case-Ref)MCNP5.1.6, FENDL3 release 4;Without WW, as reference108 neutron histories, mode nMesh tally covering the whole TCAdditional cell tally (T#), spectrum tallyADVANTG WW (Case-Adv)Mesh: 120 × 80 × 125 intervals in X, Y and Z direction, fine 10 × 3 × 2 cm, coarse 20 × 20 × 20 cm Library: 27n19gMethod: FW-CADIS, global weighting treatmentPn order: 5Source biasing turned off!20.04.2017T#1T#2T#3T#4Horizontal cut Test moduleTargetT#5T#6Vertical cut Spectra tally M&C 2017, Jeju, Korea, April 16-20, 20179 Dr. Yuefeng Qiu, Application of an Advanced Variance Reduction Technique for Bulk Shield Calculations of the IFMIF-DONES facilityAssessment of ADVANTG for IFMIF-DONESCase-RefOnly ~10% of cells has resultsStatistics < 0.15:  7% of cellsCase-AdvOnly finished 107 historiesGood statistics in beam up anddownstreamStatistics < 0.15: 13% of cellsVery slow!!20.04.2017Case-Ref 13999Case-Adv 54Computation speed (NPS/ CTM)Case-RefCase-Advfaction of cells with statistical error less than the given statistical errorM&C 2017, Jeju, Korea, April 16-20, 201710 Dr. Yuefeng Qiu, Application of an Advanced Variance Reduction Technique for Bulk Shield Calculations of the IFMIF-DONES facilityAssessment of ADVANTG for IFMIF-DONESSpectrumAgreed in high energy rangeVery large statistics error when E< 0.1 MeV Cell talliesAgreed very cell. 20.04.2017Neutron spectra and ratio Neutron flux of cell talliesTally positionsM&C 2017, Jeju, Korea, April 16-20, 201711 Dr. Yuefeng Qiu, Application of an Advanced Variance Reduction Technique for Bulk Shield Calculations of the IFMIF-DONES facilityImprovements: methods and codesIssue of computational speedWW lower-bounds does not consistent with the flux level through thebeam ductChange of flux: 10-2 to 10-3Change of WW:  more than 10-8Result in long-time simulation of over-splitting particles (long histories)20.04.2017WW lower-bounds of group 7 (~0.013 MeV)M&C 2017, Jeju, Korea, April 16-20, 201712 Dr. Yuefeng Qiu, Application of an Advanced Variance Reduction Technique for Bulk Shield Calculations of the IFMIF-DONES facilityImprovements: methods and codesA WW tuning programA Python script for reading, tuning, writing wwinp file Method-1Sweeping a block in X, Y, Z direction Method-2Sweeping a tunnel of rectangular or cylindrical shape in anydirectionLinear or exponential tuningMultiplying a factor to orignal value ( ௜ܹ) or to reference value ଴ܹߣ : factorߜ : relative distance20.04.2017Method-1Method-2Starting pointSweep (-X)Reference planeReference blockunit distancex௜ܹᇱ ൌ 	 ௜ܹߣߜ or ௜ܹᇱ ൌ 	 ௜ܹexpሺߣߜሻExponentialLinearM&C 2017, Jeju, Korea, April 16-20, 201713 Dr. Yuefeng Qiu, Application of an Advanced Variance Reduction Technique for Bulk Shield Calculations of the IFMIF-DONES facilityImprovements: methods and codesTuning of the ADVANTG WW  (Case-Tuned)Block-1 : Reduce the over-splitting in thebeam downstreamBlock-2: increase the WW arround thebeamductBeam duct: replace with the in-TC weight20.04.2017Block-1 Block-2 Beam ductMethod Method-1 Method-1 Method-2Tuning Exponential Exponential ExponentialMultiply OriginalvalueOriginalvalueReferencevalueFactor 6.9 11.5 -6.9 Effect at the last cell103 ↑ 105 ↑ 10-3↓BeforetuningAftertuningM&C 2017, Jeju, Korea, April 16-20, 201714 Dr. Yuefeng Qiu, Application of an Advanced Variance Reduction Technique for Bulk Shield Calculations of the IFMIF-DONES facilityImprovements: methods and codesCase-RefOnly ~10% of cells has resultsStatistics < 0.15:  7% of cellsCase-Adv1.4 time fast than Case-RefLong-histories problem imtigatedStatistics < 0.15: 15% of cells20.04.2017Case-Ref 13999Case-Tuned 19663Computation speed (NPS/ CTM)Case-RefCase-TunedM&C 2017, Jeju, Korea, April 16-20, 201715 Dr. Yuefeng Qiu, Application of an Advanced Variance Reduction Technique for Bulk Shield Calculations of the IFMIF-DONES facilityImprovements: methods and codesSpectrumAgreed in high energy rangeStill large statistics error when E< 0.1 MeV Due to the response-weighted optionCell talliesAgreed very cell. 20.04.2017M&C 2017, Jeju, Korea, April 16-20, 201716 Dr. Yuefeng Qiu, Application of an Advanced Variance Reduction Technique for Bulk Shield Calculations of the IFMIF-DONES facilityImprovements: methods and codesMcDeLicious with constant weight (Case-ConstW)Choosing a ߱଴ weight larger than the maximum weightUsing the Russian roulette techniqueNeutron kill: ߱ ൏ 	ߦ߱଴, resamplingNeutron survived: new weight of ߱଴Results renormalized by ௞ܰ௜௟௟: mount of neutrons killed௡ܰ௣௦: total particle histories.20.04.2017ߟ ൌ 1 െேೖ೔೗೗ேೖ೔೗೗ାே೙೛ೞ.  M&C 2017, Jeju, Korea, April 16-20, 201717 Dr. Yuefeng Qiu, Application of an Advanced Variance Reduction Technique for Bulk Shield Calculations of the IFMIF-DONES facilityImprovements: methods and codesCase-RefOnly ~10% of cells has resultsStatistics < 0.15:  7% of cellsCase-Adv1.4 speed upLong-histories problem imtigatedStatistics < 0.15: 15% of cells20.04.2017Case-tuned 19663Case-ConstW 14176Computation speed (NPS/ CTM)Case-TunedCase-ConstWM&C 2017, Jeju, Korea, April 16-20, 201718 Dr. Yuefeng Qiu, Application of an Advanced Variance Reduction Technique for Bulk Shield Calculations of the IFMIF-DONES facilityImprovements: methods and codesSpectrumAgreed in high energy rangeStill large statistics error when E< 0.1 MeV Due to the response-weighted optionCell talliesAgreed very cell. 20.04.2017M&C 2017, Jeju, Korea, April 16-20, 201719 Dr. Yuefeng Qiu, Application of an Advanced Variance Reduction Technique for Bulk Shield Calculations of the IFMIF-DONES facilitySummary and outlookThe effect of using an ADVANTG generated WW mesh for the DONES has been assessed.The long histories problem has been mitigated by tuning the WW mesh using a python script. The MCNP run with the tuned ADVANTG WW mesh has 2 times more mesh tallies cells with statistical error < 15%, the computational speed is 1.4 times faster compared to normal MCNP run. 20.04.2017

Application of an advanced variance reduction technique for bulk shield calculations of the IFMIF-DONES facility

https://publikationen.bibliothek.kit.edu/1000070472/4193011

Application of an advanced variance reduction technique for bulk shield calculations of the IFMIF-DONES facility

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