| Personal dosimeter is not only a basic instrument for radiation measurement,but also a necessary means to monitor and ensure radiation protection safety and public health,which has the characteristics of wide application range,short verification period and high verification demand.In order to ensure the accuracy and reliability of measured value,it has to rely on the standard reference radiation(SRR)for regular verification or calibration.However,constrained by the IEC 60846 and ISO 4037 series of standards,SRR is large in size and cannot be moved.As a result,the regular fixed-point inspection of the personal dosimeter is time-consuming and laborious,affecting the inspection efficiency,and even unable to guarantee the inspection rate.This is contrary to the original intention of timely,effective and reliable verification.In view of this,it is imperative to achieve the miniaturization and implementation of personal dosimeter verification devices.This thesis relies on the National Natural Science Foundation of China Youth Fund Project(project number: 11805111)and bases on the research work of China Academy of Engineering Physics(CAEP)in the minitype reference radiation(MRR)research work,aiming at the needs of on-site calibration of personal dosimeters,and has carried out in-depth MRR research.The research of gamma reference radiation starting from Monte Carlo(MCNP)simulation and experimental verification,conducted simulation research and experimental verification on the influence of the internal scattering components of the MRR device and the influence of parameter changes,verified the feasibility of calibrating personal dosimeters based on MRR,and completed the first experimental research on the application of MRR device to personal dosimeter calibration..By theoretical analysis and MCNP simulation methods,this thesis summarizes the qualitative and quantitative analysis of the scattering influence of MRR device parameter.Through analysis,the main factors that affect the value of the inspection points in the MRR are obtained.Sum up,when the reference thickness of the carrier is 15 mm,the impact on the dose rate value at the inspection point is up to 3.13%;The size of personal dosimeters can affect up to 2.91% within the scope of the standard requirements,and the range of change can reach 4.45%;The impact of quantitative changes can reach 1.78%,and the range of changes can reach 3.51%.Combined with the analysis of the characteristics of the scattering gamma energy spectrum,the influence of the parameters of the MRR device cannot be ignored.This thesis relies on the MRR device and the simulation results to carry out the feasibility study experiment of MRR for personal dosimeter calibration.The experiment verified the spatial distribution of dose rate value the range and uniformity of the internal rays at the inspection point of the MRR device.MRR device has realized a total of 6 range spans of 0.1μGy/h-10 mGy/h,verified the range and uniformity of the internal radiation of MRR,and provided data support for the verification work.The experiment realized the range transfer during the calibration of personal dosimeters based on the standard instrument transfer method,and obtained the optimal selection of the parameters of the MRR device by simulation and experimental verification.When the thickness of the fixture is 5mm,the corresponding scattering influence is 0.34%.The results of the personal dosimeters quantity experiment and calibration experiment show that the MRR device can realize the measurement of the dose rate true value at the test of point in the radiation field,and the error is within the standard allowable range.The experimental results show that the MRR device can meet the verification needs of different types,different quantities,and different ranges of personal dosimeters,which provides a practical design plan for the in-situ and performed calibration of personal dosimeters,and promotes the research and development of MRR for personal dosimeter calibration technology. |
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