Research On Safety Assessment Method And Its Applications For Fusion Reactors Based On PSA

Nuclear energy is an important part of the energy structure of human society.Compared with fission energy,fusion energy is cleaner,richer and more efficient in nuclear-fuel and less radioactive pollution of fusion products,so it is called the ultimate energy form of human society.Probabilistic Safety Assessment(PSA),which is adopted to evaluate the probabilistic safety of fission reactors,has been widely applied in fission nuclear power systems.Althrough the PSA application technology for fission reactors is mature,the applications for fusion reactors are still in the research stage.RAMI method,which was proposed by ITER organization,is used to evaluate the system reliability,availability and reduce the risk for fusion reactors.With the development of fusion reactors technology,it is very urgent and important to study the safety assessment method and its applications for fusion reactors based on PSA.The safety assessment method for fusion reactors based on PSA and RAMI,the items safety classification method for fusion reactors based on PSA,and the reliability allocation method for fusion reactors based on PSA and AHP are all grounded on the PSA model for fusion reactors.All the three methods are performed froom the perspective of probability,and they are internrelated and form a system engineering.The three aspects will be further studied in this contribution.PSA and RAMI methods are applied to evaluate the safety performance of the nuclear installations from the perspective of probability theory.By integrating PSA and RAMI methods,the safety assessment method for fusion reactors based on PSA and RAMI is studied.The safety assessment method for fusion reactors based on PSA and RAMI provides an integrated method for system reliability,availability and overall safety assessment,and also provides a technical way for system risk elimination and design optimization for fusion reactors.Reasonable items safety classification is greatly significant to the safety and economy for fusion reactors.The traditional items safety classification is conservative.From the perspective of probability,the calculated items importance information from the PSA for fusion reactors can be adopted to reclassify the items of fusion reactors.So combining PSA with traditional items safety classification is a new way to carry out the items safety classification for fusion reactor on the foundation of PSA method.The items safety classification method based on PSA provides a more thorough and in-depth method for items safety classification for fusion reactors.At present,the reliability index allocation is mainly applied to specific systems,which is lack of implementing the reliability index allocation in the design from the top to the specific components.In this study,the fusion reactor is divided into different levels by adopting Analytic Hierarchy Process(AHP).Through combining with the PSA model for fusion reactors,the reliability allocation method based on PSA and AHP is propoed.The reliability allocation method based on PSA and AHP provides a more systematic method for the reliability allocation for fusion reactors.The safety assessment method and its applications for fusion reactors based on PSA provide an integrated methodology for evaluating system reliability,availability,overall safety and eliminating risks of the fusion reactors,a more comprehensive and in-depth method for the items safety classification of the fusion reactors,and a more systematic method for the reliability index allocation of the fusion reactors,and the methodology of safety assessment,items safety classification and reliability index allocation for fusion reactors is improved and developed.