Structure Dynamic Analysis For Wrapped Fuel Rod And Assembly In Lead-based Reactor

Lead(Pb)based reactor(lead bismuth(PbBi)eutectic(LBE)or Pb cooled reactor)is considered to be the most promising Generation Ⅳ nuclear energy system and is considered to be one of the most hopeful reactor(RX)choice for Accelerator driven sub critical System(ADS).Chinese Academy of Sciences(CAS),in 2011,initiated a project to design&develop an ADS for nuclear waste conversion.This system consists of spallation target,subcritical RX and a proton accelerator.Until 2030,CAS plan to construct a commercial prototype ADS system in three stages.China lead based reactor(CLEAR),proposed by the Institute of Nuclear Energy Safety Technology(INEST),CAS,was selected as the reference RX in the CAS ADS project.In the first stage,CLEAR-I of 10MWth coupled with proton accelerator(-250 MeV/～10 mA)will be designed and built.Earthquakes,as typical dynamic loading,can cause severe damage to the nuclear power plant(NPP)especially in the core region consisted of fuel assemblies(FA)containing fissile material should be particularly resistant.Seismic analysis(SA)in pool type Lead Cooled Fast RX(LFR)capacity is significant for advancement of Pb based RX technology because seismic qualification is a must for construction and operation of NPP.In this study,wire wrapped LFR fuel rods(FR)compared with that without wire wrapped(bare),has been established for different parameters,under different plant conditions,considering optimum fuel design.Most appropriate analysis options have been suggested for establishing contact between wire and cladding for wire wrapped design.A suitable contact analysis methodology has been selected and grid independence analysis proves accuracy of the results and confirms the selection of suitable procedure and validates the use of ANSYS Mechanical APDL for LFR FR analysis.And then,the structural dynamic characteristics of LFR fuel in LBE condition compared with that in a vacuum,has been studied using potential flow theory,considering added mass effect.Also,simple and accurate approach has been suggested for determination of LBE added mass effect and also verified with manually calculated added mass which further proves the practicality of potential flow theory for precise estimation of added mass effect.To verify structural integrity of cladding,stresses along cladding length were calculated during different transients(operational scenarios)and also calculated manually for static pressure.The manual calculations can be roughly compared with ANSYS results,which show a close agreement between these two.Followed by the structural integrity of FA and FA hexagonal prism shaped wrapper has been established for different parameters.Natural frequencies,mode shapes,stresses on FR cladding and wrapper of the FA and seismic aspect has been considered for comparison using ANSYS.Structural optimization technology of ANSYS finite element analysis(FEA)is now mature enough and can be applied for R&D of LFR fuel.Numerical optimization and the use of mathematical programming together with FEA techniques of ANSYS to solve the non linear contact analysis problem of the wire wrapped FR.Widely accepted FEM technology was used to solve the structural design problems of elastic,loosely supported FA at the lower core plate,under a combination of diverse loading conditions expected to be in the life of LFR.Numerical optimization technique provides to be time saving by selecting appropriate contact elements,a converged solution for optimum mesh size and suitable solution settings for accurate results with minimal processing time.The results provide detail insight for structural design of LFR FR considering different structural configuration,i.e.,bare and wire wrapped,in seismic loading.This not only provides a FEM procedure for LFR fuel with complex configuration but also guide the reference design of LFR FR.An approach for assessment of fast RX FR&FA performance has been drawn and calculated results are presented.The study is contributed to the validation of ANSYS APDL code for CLEAR-I to predict the regions of stress concentration on cladding and wrapper of the hexagonal FA to optimize the design of CLEAR-I FR and FA.