Research On Methods Of Photon Dose Field Analysis Based On Ellipsoid Bounding-box

Nuclear power plants generate large amounts of radioactive material during normal operation or shutdown and overhaul,in which potential external gamma-ray radiation exposure can have a significant impact on the body of the nuclear operators.Therefore,how to quickly and accurately analyze the distribution of gamma-photon dose fields and how to accurately calculate the relevant dose values affecting the human body are of crucial importance for radiation protection analysis.In the traditional human dose analysis of radiation protection design process,the particle model is usually used combined with point kernel integration(PKI),the accuracy of this way can not meet the actual demand.So that the design process of engineering solutions needs to be improved in combination with different path directions and different task operations.In this paper,based on the theory of PKI,a dose estimation method based on bounding-box model has been proposed.This method is suitable for dose estimation of different paths,different operators and different source types in the radiation protection scheme of nuclear power plant.Among them,1)The Ellipsoid bounding-box model,which relates to the human dose calculation model of the human body,incorporates various organ or tissue parameters of the standard human body model of Chinese adults and takes into account factors such as different radiation sensitivity of different organs and tissues and based on the results given in the ICRP report dose formula has been improved;2)Taking into account various maintenance and repair operations of operators in actual project and analyzing the influence of radioactive sources on the human body under different irradiation directions,a dose calculation method based on theta weights and continuous radiation source geometric irradiance direction conditions has been proposed;3)According to the radiation protection plan,task stratification mode has been put forward combined with the actual project,combined with the above theoretical model and algorithm optimization.Based on the existing PKI program ARShield,the dose distribution calculation and evaluation program ARS hield-Dose has been completed.Finally,the test verification of the program ARShield-Dose program is divided into three aspects:basic function verification,accuracy verification and feasibility verification of application in project.Using different calculation examples to verify the validity and accuracy of the program.preliminary validation results show that the algorithm improvements in human dose assessment are correct,the program ARShield-Dose can deal with nuclear power plant radiation protection issues effectively and can also provide reference for the design process of project plan.