Application Of SuperMC For Neutronics Analysis:PWR,GCFR,and Fusion Reactor

The surge in nuclear energy development is based on the world's energy demand,and the consideration to the choice of primary energy resources'availability,sustainability,safety,and its process impact on the environment and economics.Nuclear energy is advantaged by its high energy density and relatively benign impact on the environment.The current nuclear energy development is tilting from the existing PWRs to more efficient high safety advanced reactors(i.e.,GEN-?,accelerator-driven sub-critical reactors,fusion reactors,etc.).In addition to improved safety,advanced reactor engineering is forecasted to make optimum use of uranium resources(60%-70%)and re-use existing spent fuels to ensure a reduction of nuclear waste and increased economic competitiveness.Neutronics simulation plays a critical role in the development and safety analysis of nuclear systems.It provides fair leverage for complex physics and prohibitively high experimental cost.The computing environment allows for systems design and optimization.In this work,different reactor models(MNSR,VENUS-3-PWR,PROTEUS reactor-GCFR,and ITER-fusion reactor)have been simulated using SuperMC Multi-functional Calculation Program for Nuclear Design and Safety Evaluation(SuperMC).The SuperMC is developed by the INEST-FDS Team.The aim is to validate and optimize a new ITER bio-shield plug shielding design and demonstrate the application of SuperMC for advanced neutronics analysis(i.e.,for the assessment of nuclear data via benchmark calculations).Utilizing the interactive based CAD/image modeling platform of SuperMC,a detailed 3-D MNSR reactor and VENUS-3 reactor neutronics models were accurately constructed.Several reactor parameters were calculated for MNSR:core criticality and excess reactivity;control rods worth and reactor shutdown margin;fission power density and fuel pin power;thermal neutron characterization,etc.Each of these results compared to the MNSR Ghana Research Reactor-1 safety analysis report(SAR),and consistency was achieved in all cases.The validation of VENUS-3 experiments includes predicting structure damage due to neutron radiation via the calculation of reaction rate for 115In(n,n'),58Ni(n,p)and 27Al(n,?),the determination of iron atom displacement rate(dpa)in reactor pressure vessel locations.The results were within the required accuracy of 5%-15%.The range of the results adequately meets the criterion consistent with the U.S Nuclear Regulatory Guide(Guide 1.190)on reactor dosimetry calculations.The preliminary calculations,therefore,advance the correctness of the SuperMC calculation and modeling processes.A comprehensive neutronics analysis for the GCFR PROTEUS reactor's shielding integral benchmark experiments was conducted using SuperMC.A detailed assessment of fast neutron spectrum and fast neutron-material interactions have been accomplished:It was discovered that higher energy neutron(and deep into test shield)spectra were systematically underestimated.The discrepancies are attributed to inaccurate data for inelastic scattering cross section;identified through performance evaluation of different data sets(ENDF/B?.1,ENDF/B?.0,JEFF 3.2,and FENDL 3.1).The calculated core parameters(238U and 239Pu fission reaction rate)show an average deviation of less than 3%(which indicated the correctness of the modeling and calculation process).The calculated threshold reactions;103Rh(n,n')103mRh,115In(n,n')115mIn,and 32S(n,p)32P,were achieved within 10%-15%.The corresponding distribution of fast neutron spectrum in iron test shields(steel-37 and steel-18/8)showed consistent distribution pattern with the experiments'.The work identifies FENDL 3.1 56Fe data as most suitable for fast neutron interaction calculation,however,a more improved data set are required to make an accurate prediction at higher neutron energies.The analysis has provided an in-depth understanding of fast neutron-material interactions(56Fe),and demonstrated the need to fine-tune the inelastic scattering cross section for 56Fe to suit experiments.The work has cataloged a systematic neutronics approach for large complicated structures(ITER)shielding design and calculation.The development process includes reprocessing of a new CMM/CAD for ITER bio-shied plug(TCP and IVVS)to its corresponding neutronics model for inclusion in the tokamak complex model.The new TCP and IVVS bio-shield plugs were validated for their shielding performance against plasma neutron.The results showed total neutron flux of 1.71 × 106 n/cm2/s and 2.86×105 n/cm2/s respectively,against a requirement of 6.0×104 n/cm2/s.While the spatial neutron distributions in port cells showed significant shielding improvement compared to the former(original)design of IVVS and TCP bio-shield plug,it still required additional shielding improvement to meet the validation requirement.This work has proposed optimum shielding design and calculation based on iterative process,taking into consideration the individual radiation contributions from shielding materials,structure gap,dog-legs,etc.The iterative procedure can optimize a shielding scheme which can reduce the total neutron flux from 1.71×106 n/cm2/s to 8.8×104 n/cm2/sand from 2.86×105 n/cm2/s to 6.4×104 n/cm2/s respectively for IVVS and the TCP bio-shield plugs.This work has developed a consistent approach for obtaining a high fidelity whole neutronics core model for reactor analysis:It has itemized systematic calculation strategy for achieving improved reactor shielding design(i.e.,the case of ITER bio-shield plugs)and calculation.It has developed a calculation protocol for reactor pressure vessel dpa assessment consistent with standards of nuclear regulations.The work comprehensively demonstrates the efficient and diverse modeling process options in SuperMC and its accurate calculation process.There results therein,therefore,support the comprehensive application of SuperMC for general and advanced neutronics.