Research On Anticoincidence Gas-sealed Proportional Counter

With the development of nuclear power,it is important to protect the environment,the health of the public and staff,and especially to prevent and reduce the harm of nuclear radiation to the workers.Radiation monitoring is a key prerequisite for protecting the healthy development of the nuclear industry.Therefore,the KRC system has been established in the nuclear facilities and each nuclear power plant.At the same time,surface contamination monitoring instruments are equipped in the control area to measure the level of radioactive contamination of the surface and the clothing of the personnel.However,in the actual working process,the surface contamination measurement is always carried out under the mixing field.In order to improve the accuracy of the measurement of?and?surface contamination,reduce the influence of natural background,electronic noise,?radiation on the measurement and the minimum detectable lower limit of the measuring equipment,this paper has carried out research on anticoincidence measurement technology and the realization of basic technology.Since the gas-flow proportional counter needs to be continuously supply the working gas when working,there must be a fixed gas supply station,which is easily interfered by the gas flow.Combined with the application and the continuity of research,this paper uses sealed gas detectors as research objects.Based on the investigation of sealed gas proportional counter and anticoincidence measurement technology at home and abroad,this paper introduces the design composition of anticoincidence gas detector in detail,and on this basis,the design of anticoincidence sealed gas detector is introduced.Through the design of the anticoincidence gas-flow proportional counter,the shape and structure of the anticoincidence detector and the material of the casing are determined.In the selection of the material and thickness of the detector measurement layer and the anticoincidence common cathode,the Monte Carlo method was used to simulate and calculate three metal materials.The results showed that5.2 mm aluminum plate was determined to be the best.The accuracy of the MCNP simulation results was verified by a series of experiments.In the selection of experimental conditions,a series of threshold selection experiments were carried out to determine a set of appropriate thresholds.Based on this,the performance of the detector was tested to verify the feasibility of the anticoincidence test system.Based on the design and experiment of the anticoincidence gas-flow proportional counter,the design of the upper and lower layers and the selection of the common cathode were adopted.The anticoincidence sealed gas proportional counter was designed,including the selection of sealant,the improvement of the sealing structure,the selection of fixing column and optimization of the production process.Through the performance test,it is verified that the anti- conformity closed proportional counter reduces the minimum detectable lower limit of the standard source ⁹⁰Sr-90Y by 77.78%,the minimum detectable lower limit of ²⁴¹Am is reduced by 51.85%,and the minimum detectable lower limit of ²³⁹Pu is reduced by 51.61%.The research results of this subject have laid a good foundation for the application of domestic sealed gas surface pollution monitoring equipment in nuclear power plants.