Hernández, Francisco A.

Leppänen, Jaakko

Lua, Yudong

Pereslavtsev, Pavel

Ye, Minyou

Zhou, Guangming

English

KITopen

Application of Serpent 2 code for shielding analyses of EU DEMO HCPB breeding blanket  Yudong Lua,b, Guangming Zhoub*, Francisco A. Hernándezb, Pavel Pereslavtsevb, Jaakko Leppänenc, Minyou Yea*  aUniversity of Science and Technology of China, Hefei 230026, China bKarlsruhe Institute of Technology, Eggenstein-Leopoldshafen 76344, Germany cVTT Technical Research Centre of Finland, Espoo FI-02150, Finland  *Corresponding authors: guangming.zhou@kit.edu; yemy@ustc.edu.cn  The Helium Cooled Pebble Bed (HCPB) breeding blanket is promising option for the EU DEMO driver blanket. This blanket should provide a reliable nuclear protection of the vacuum vessel from neutron and gamma irradiation. The search for the suitable shielding option is performed making use of the realistic geometry model being used for the particle transport simulations.  In this work, the Monte Carlo code Serpent 2 [1] is used to perform the 3D Monte Carlo particle transport making use of the suitable DEMO geometry representation. The plasma neutron source applied in the Serpent model is derived from a volume neutron source [2]. The results of calculations were compared with MCNP ones obtained to benchmark Serpent 2 performances in the shielding calculation of the fusion reactor. Different materials options and their geometry dimensions were analyzed to find the best solution for the HCPB shielding performance.  Additionally, a parametric investigation varying the radial thickness of the neutron multiplier by partial replacement with the different shielding materials has been performed. The results demonstrate promising performances of Serpent 2 for applications in the fusion related tasks. It has been proven that the shielding performance of HCPB blanket can be largely optimized with some shielding options, keeping tritium generation at a level acceptable for the DEMO design.  Keywords: Neutronics, Blanket, Monte Carlo, Serpent, Shielding optimization [1] Leppänen, J., et al. (2015) "The Serpent Monte Carlo code: Status, development and applications in 2013." Ann. Nucl. Energy, 82 (2015) 142-150. [2] Sirén, P. and Leppänen, J. (2016) "Expanding the use of Serpent 2 to Fusion Applications: Development of a Plasma Neutron Source." In proc. PHYSOR 2016, Sun Valley, ID, May 1-6, 2016. Topic Category  2. Blanket Technology Presentation Preference  Poster Presentation   

Benchmark of Serpent-2 with MCNP: application to EU fusion DEMO HCPB breeding blanket

Benchmark of Serpent-2 with MCNP: application to EU fusion DEMO HCPB breeding blanketYudong Lua,b, Guangming Zhoub*, Francisco A. Hernándezb, Pavel Pereslavtsevb, Jaakko Leppänenc, Minyou Yea*aSchool of Physical Sciences, University of Science and Technology of China, Hefei 230026, ChinabKarlsruhe Institute of Technology, Eggenstein-Leopoldshafen 76344, GermanycVTT Technical Research Centre of Finland, Espoo FI-02150, Finland*E-mail:  guangming.zhou@kit.edu (G. Zhou) and yemy@ustc.edu.cn (M. Y. Ye)ABSTRACT：Magnetic confinement fusion reactors such as the European fusion demonstration reactor (EU DEMO) have a very complex geometry, which makes the modelling of the nuclear analyses rather tedious and time consuming. The Monte Carlo neutron transport code Serpent-2 developed by VTT in Finland, is able to directly import CAD geometry, then is considered an attractive alternative to the Monte Carlo N-Particle Transport code (MCNP) for its application in fusion reactors. A comparison activity is carried out to benchmark the Serpent-2 with MCNP calculations. Serpent-2: Volume checker routine, sample 1010 points,statistical errors< 0.13% MCNP: Track length estimate with a spherical source ,sample 1010 points, statistical errors< 0.02% Results: Within 1.1σ of the combined error with a relativedifference of less than 0.05%. Lost: Particle loss in MCNP and Serpent-2 did not appear-----no undefined regions or overlaps.Volume CalculationEU-DEMO 2017 Model  FW: 67.7% Eurofer and 32.3% Helium BZ: 12.8% Eurofer, 10.3% mixture ofLi4SiO4 plus 37 mol.% of Li2TiO3,40.8% Be12Ti and 36.1% Helium BSS: 100% EuroferEU-DEMO 2017 Serpent-2 model horizontal cuts in OB sideThe modeling process consists of thefollowing five steps: Step 1: Simplify and decomposethe reference CAD model and convertit to a CSG model for MCNP usingMcCad; Step 2: Manually fill the backsupport structure into the blanket; Step 3: Check and fix geometricerrors in the model. Step 4: Translate the MCNPgeometry model to the Serpent-2 inputfile format by utilizing the csg2csgtool. Step 5: Set model symmetry, sourceemissivity, boundary conditions, etc.MCNP: 40*40 discrete volumesource, Gaussian distribution of14.1MeV.Serpent-2: 40*40 source cells, 14energy bins.Neutron SourceNormalized sources densities distribution10-710-610-510-410-310-210-1100101102108109101010111012101310141015MCNP fluxSerpent fluxNeutron Flux (n/cm2/s)Energy (Mev)10-710-610-510-410-310-210-1100101102-0.15-0.10-0.050.000.050.100.15 Statistical error (1 sigma) Relative differenceRelative differenceEnergy (MeV)10-310-210-110010110210810910101011101210131014 MCNP flux Serpent fluxPhoton Flux (n/cm2/s)Energy (Mev)10-210-1100101102-0.15-0.10-0.050.000.050.100.15 Statistical error (1 sigma) Relative differenceRelative differenceEnergy (MeV)Neutron flux are within 2σ of the combined error in all energy bins, most of which are within 1σ with a relative difference of below 1%.Photon flux are within 5σ of the combined error in all energy bins, most of which are within 2σ with a relative difference of below 3%.Neutron and Photon Energy Spectrumblk1blk2blk3blk4blk5blk6blk7blk8blk9blk10blk11blk12blk13blk14blk15blk16blk17blk18_midblk19_midblk20_midblk21_midblk22_midblk23_midblk24_midblk25_midblk26_midblk27_midblk28_midblk29_midblk30_midblk31_midblk32_midblk33_midblk34_midblk35_midblk36_midblk37_midblk18_leftblk19_leftblk20_leftblk21_leftblk22_leftblk23_leftblk24_leftblk25_leftblk26_leftblk27_leftblk28_leftblk29_leftblk30_leftblk31_leftblk32_leftblk33_leftblk34_leftblk35_leftblk36_leftblk37_left-0.02-0.010.000.01NeutronRelative differenceBlanket breeding zone Differenceblk1blk2blk3blk4blk5blk6blk7blk8blk9blk10blk11blk12blk13blk14blk15blk16blk17blk18_midblk19_midblk20_midblk21_midblk22_midblk23_midblk24_midblk25_midblk26_midblk27_midblk28_midblk29_midblk30_midblk31_midblk32_midblk33_midblk34_midblk35_midblk36_midblk37_midblk18_leftblk19_leftblk20_leftblk21_leftblk22_leftblk23_leftblk24_leftblk25_leftblk26_leftblk27_leftblk28_leftblk29_leftblk30_leftblk31_leftblk32_leftblk33_leftblk34_leftblk35_leftblk36_leftblk37_left-0.02-0.010.000.010.02Relative differenceBlanket breeding zone DifferencePhotonNeutron and Photon Heating in Breeder Zone Neutron heating:Relative Difference < 1.5% Photon heating:Relative Difference < 1.6%Compared with MCNP, theneutron heating of BZ inSerpent-2 are noted to be0.38% lower, while thephoton heating are 0.44%higher.Nevertheless, the agreementof the two codes is wellNuclear Energy Generation of Various Componentsblk-1blk-2blk-3blk-4blk-5blk-6blk-7blk-8blk-9blk-10blk-11blk-12blk-13blk-14blk-15blk-16blk-17blk-18blk-19blk-20blk-21blk-22blk-23blk-24blk-25blk-26blk-27blk-28blk-29blk-30blk-31blk-32blk-33blk-34blk-35blk-36blk-370.020.040.060.080.100.12TBRBlanket module Serpent MCNPblk-1blk-2blk-3blk-4blk-5blk-6blk-7blk-8blk-9blk-10blk-11blk-12blk-13blk-14blk-15blk-16blk-17blk-18blk-19blk-20blk-21blk-22blk-23blk-24blk-25blk-26blk-27blk-28blk-29blk-30blk-31blk-32blk-33blk-34blk-35blk-36blk-37-0.8%-0.6%-0.4%-0.2%0.0%0.2%0.4%0.6%Relative differenceBlanket module  Difference Relative Difference in each blanket: < 0.6% Relative Difference in each nuclide: 6Li: -0.18%   7Li: -0.037%   9Be: negligible TBR totel: Serpent: 1.1718;    MCNP: 1.1738 ;     Relative Difference: -0.18%Tritium Breeding RatioNuclear Heating Loading on ANSYSSerpent-2 mesh detector resultswere post-processed by Excelcontaining X, Y, Z coordinates andthe corresponding power density.SummaryNeutron and photon flux spectra, neutron heating and photon heating in the breeder zone, nuclear energy generation in blanket, divertor, vacuum vessel and magnet system, tritium breeding ratio werecompared, and most results are within 3σ of the combined error with a relative difference of below 1%. Since the variance reduction was not used successfully, magnet system is statistically poor.Besides, nuclear heat was loaded on ANSYS as heat generation by simple post-processing. Notable, the relative errors of Serpent-2 are generally two to five times higher than MCNP for the samemodel in the simulation. Overall, the Serpent-2 shows excellent agreement against MCNP.Component Volume (cm3) DifferenceSerpent-2 MCNPBlanket 1.4814E+09 1.4819E+09 -0.033%Dirvertor 1.5125E+08 1.5123E+08 0.016%VV 2.3871E+09 2.3879E+09 -0.031%TF 1.3261E+09 1.3255E+09 0.048%CS 1.0623E+09 1.0625E+09 -0.019%PF 1.7264E+08 1.7272E+08 -0.044%Component Neutron Energy generation (MW) Photon Energy generation (MW)serpent mcnp difference serpent mcnp differenceBlanket 1206.1 1209.2 -0.26% 695.6 694.5 0.15%Divertor 29.42 29.31 0.38% 139.18 139.61 -0.31%VV 3.07 3.08 -0.31% 46.57 46.72 -0.31%Magnet system 6.46E-03 6.36E-03 1.65% 1.04E-01 9.93E-02 4.40%中国科学技术大学核科学技术学院School of Physical Science University of Science and Technology of China （USTC）This work has been funded by the National Key Research, Development Program of China (Grant No.: 2017YFE0301501 and No.: 2017YFE0301305) and China Scholarship Council (No.: 201806340163)Karlsruhe Institute of Technology (KIT)Institute of Neutron Physics and Reactor Technology (INR)

https://publikationen.bibliothek.kit.edu/1000092122/24131182

Benchmark of Serpent-2 with MCNP: application to EU fusion DEMO HCPB breeding blanket

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