Study On Assessment And Optimization Methodology For Radiation Safety In Virtual Environment Of Nuclear Decommissioning

A production activity has a life cycle and nuclear facilities are no exception.Long-term running nuclear facilities will become a strong radiation source,every part of the facilities are contaminated by neutron activation and radionuclide pollution.Nuclear facilities decommissioning refers to shutting nuclear facilities down,removing contaminated equipment,decontamination and dismantling,to the level of unrestricted use or restricted use.In the preparation phase of nuclear facilities decommissioning,radiation and unradiation safety problems must be taken into account to optimize decommissioning engineering and ensure human health and environmental security.The nuclear facilities decommissioning simulation technology is a combination between theory and experimental research.It has been applied to scenario simulation,safety assessment and personnel training in nuclear facilities.It is an effective means to guarantee the scientific and reasonable implementation of decommissioning engineering,and to guide the subsequent decommissioning works.Under the background of nuclear facilities decommissioning,virtual simulation technology and theory are combined,radiation safety of nuclear decommissioning has been studied,such as ? radiation simulation in virtual environment of nuclear facilities,walking-path planning,and dose assessment for virtual human,safety training and the related issues.The research content is described as follows:(1)Radiation simulation method for nuclear facilities is studied,three-dimensional modeling software is used to build 3D model of nuclear facilities,and Unity is used as virtual simulation platform of nuclear facilities to simulate the virtual nuclear facilities scenario.The animation functions of virtual simulation are studied.point kernel method and virtual simulation technology are combined,the model with radiation information is built,3D model of nuclear facilities are converted into basic geometry,and radiation field is calculated by point kernel program.According to a little of collected dose information,the radiation field is constructed using neural network method.In order to deal with radiation information,radiation visualization method based on visualization technology is proposed,radiation field is overlayed onto nuclear facilities to solve the problem of real-time rendering.It provides users with intuitive and efficient graphical display of radiation field.(2)The walking-path optimization method is studied.The environment model of nuclear facilities is established based on grid to disperse the scene structure and the radiation field.Path optimization methods for 2D environment and complex environment are designed.For 2D environment,a path evaluation method based on grid and a minimum dose path searching method based on graph theory are designed.For complex environment,combinatorial optimization methods are used to get the optimal solution.Walking-path optimization simulation platform for radiation field is built using path optimization method and virtual simulation technology,helps user to design,evaluate,optimize and simulate the walking-path.(3)Dose assessment method for virtual human is studied: the virtual human model and skeletal animation is built using 3DsMax,a coarse-voxel-accuracy model is proposed.Based on the virtual human model and weight factors of tissues and organs,weights are designed for virtual human.Based on virtual engine,real-time dose monitoring for voxels and dose assessment method based virtual reality are designed.Dose visualization method for virtual human is designed based on virtual reality technology and visualization technology,for intuitively observing human exposure.Based on virtual reality,external radiation protection simulation platform is designed and developed.(4)Safety taining method for worker is studied: workers' unsafe behavior is analyzed,safety evaluation index system of worker behavior and fuzzy comprehensive evaluation model are established to evaluate safety of worker's behavior.A virtual training method based on safety evaluation method and virtual simulation is designed for quantifying evaluation factors to realize the safety assessment and provide guidance services for trainee.The related contents of nuclear facilities decommissioning simulation and safety assessment are studied in this paper.The research results can provide technical support for the development of nuclear facilities decommissioning simulation system.The simulation of working in nuclear facilities decommissioning can provide a safe,economic and effective platform for working scheme designing,training and radiation protection,has a certain application prospect.