Simulation Study On A Minitype Reference Radiation With Monte Carlo Method And Its Application

The 137 Cs minitype reference radiation(MRR)device in this paper is a mobile calibration device used for gamma ray instrumentation calibration. Limited of the experimental conditions, the current research work is only part of the experiment study, not be comprehensive and depth. In addition, to carry out the design and manufacture mobile calibration device, radiation protection of MRR is needed.Base on the experimental device, to build the physical mode. By analysis the gamma-ray characteristic component in MRR field, a feasibility study was carried out. Using the Monte Carlo simulation code MCNP to simulate the metrological characteristics of MRR. This paper clarified the metrological and scattered radiation characteristics of MRR, by analyzing the scattering spectrum, to get the influence of probe size to MRR scattering component and the position of scattering feature point. The results show that lead shielding walls and gamma dose rate meter probe(105mm) cause the dose rate increased 7% and 15.4% in the test point. The relatively optimal measurement characteristic point in the MRR, which the scattering of shielding box and gamma probe is distinctive, is using for indicating the physical information of instrument probe. The simulation work has been confirmed by experimental result.The MRR is used for the ray radiation dose measurement instrumentation's calibration or scale, which should meet the shielding the technical requirements. The result shows the shielding design method by MCNP simulation can exhaustive reflect various surfaces' dose distribution characteristics of MRR device. The shielding solution which used the MCNP simulation can achieve the shielding design of MRR device, also significantly optimize the shielding structure. The MCNP optimize method compare with the traditional design method, reducing the weight of the MRR shield up to 44%. This work can develop the mobile gamma-ray dose meter calibration device and gamma-ray measurement technology in the actual work.Currently, the MRR device has been formed, which based on the paper work. The model involves eleven types of instrument, the device prediction model achieves the uncertainty less than 5%. To provide a feasible and practical method for radiation protection instrumentation‘s calibration or scale.