Research On Monte Carlo Coupled Burnup Calculation Method Based On Model Conversion Technology

Nuclear power takes an important role in energy system all over the world.However,with the rise of development of nuclear energy,one of the biggest challenges facing the nuclear industry is how to dispose the nuclear waste in nuclear plants safely and efficiently.According to the actual situation,all the countries around the world put forward the strategy of fuel cycle that is suitable for their own development.The partitioning and transmutation(P&T)fuel cycle is an optimized fuel cycle mode to minimize nuclear waste and to achieve safe and efficient disposal.One of the goals of the advanced nuclear energy system is how to achieve the closure of the fuel cycle.During the past decades,Accelerator Driven System(ADS)has been consider as one of the most likely device for industrialized transmutation of HLW in the future.ADS is an advanced nuclear system with high inherent safety feature,which can transmute the nuclear waste including MA and long-lived fission products(LLFPs)into short-lived fission products.In this thesis,a model conversion technology based Monte Carlo coupled burnup calculation method has been proposed for studying the neutronic features of ADS,which consists two modules namely CAD-PSFO(FreeCAD based parsing script for FLUKA and OpenMC)and OMCB(OpenMC based Burnup code).In the first modeling block,basic geometry and boolean logic classes have been established with a mapping relationship to FLUKA and OpenMC codes,and ray-casting technology based iteration method has been proposed to solve the problem of higher-order surfaces in complex geometries.For the second burnup module,transmutation trajectory analysis(TTA)method and Bateman equations have been employed in coupling with OpenMC code for ADS facilities.In order to make the depletion calculation process more effective and accurate,three kinds of iterations and one terminate criteria have been proposed for searching the depletion chains.Moreover,a scan mode method based high order differential expression has been proposed to remove the infinite terms in Bateman equations.Furthermore,a concept of sub-step predictor calculation has been introduced by combining both linear and quadratic interpolation methods,which makes cross section time-dependent in each depletion step.Numerical tests demonstrate that the model conversion technology based burnup calculation method has a good performance in solving ADS modeling process and burnup calculations.Finally,the proposed method has been used in the design of the lead-bismuth cooled ADS,in which a gravity-driven dense granular flow spallation target has been designed to substitute the traditional solid or liquid heavy metal spallation target.In the simulation process,sensitive parameters of the spallation target have been investigated.Moreover,an optimized design of sub-critical reactor has been proposed with three zone loading pattern as a consequence of eliminating the power peak factor,which thermal power is 10 MW with the operation cycle 600 EFPD.The simulation of neutronic parameters present good performance,which will provide important reference value to the engineering design of ADS.