Calibration method for detection efficiency of radioactivity iodine active carbon sampling filter box
A technology for detection efficiency and radioactive iodine, applied in the field of nuclear power plant gaseous effluent monitoring, can solve problems such as errors
Active Publication Date: 2017-10-27
CHINA INST FOR RADIATION PROTECTION +1
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One disadvantage of this method is that a large number of experiments need to be done in the early stage to obtain the fitting formula. Another disadvantage is that the measurement errors of these influencing parameters will not be transferred to the final measurement error. Neglected influence parameters, fitting formula method will bring immeasurable error
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[0022] The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.
[0023] Utilize the surface source detection efficiency measured by laboratory calibration to vary with the depth of the surface source in the sampling filter box and according to the experimentally measured detector full-energy peak counts when the sampling filter box is placed in the forward and reverse directions, the method designed in the present invention The exponential decline distribution parameter of iodine in the sampling filter box and the detection efficiency of the detector to iodine can be obtained simply and quickly, and the value of the method can be traced to the national measurement standard.
[0024] Step 1: Prepare a standard surface source certified by a first-level national metrology institution. This source is a multi-gamma nuclide mixed source and can cover the energy of 365keV gamma rays mainly emitted by I-131.
[0025] Step ...
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The invention discloses a calibration method for detection efficiency of a radioactivity iodine active carbon sampling filter box. The calibration method for detection efficiency of the radioactivity iodine active carbon sampling filter box comprises steps of using a standard plane source calibration detection device to detect various depths of a sampling filter box according to an adsorption rule of the iodine in the sampling filter box, and obtaining detection efficiency of a detector on iodine absorbed on the sampled filter box through measuring the sampling filter box by placing the sampling filter box forward and reversely for once. The calibration method for detection efficiency of the radioactivity iodine active carbon sampling filter box provides technology supports to accurately and reliably measuring a radioactivity iodine concentration in places, like a nuclear power station, which relates to gaseous state radioactivity iodine monitoring. The calibration method of the invention uses a changing curve which is measured by laboratory calibration and shows that the plane source detection efficiency changes along the depth of the plane source in the sampling filterbox and full-energy peak counting of the detection device which is detected when the filter box is respectively placed forward and reversely according to the experiment. The calibration method for detection efficiency of the radioactivity iodine active carbon sampling filter box is simple, can fast obtain an index progressive decrease distribution parameter of the iodine in the sampling filter box and detection efficiency of the detector on the iodine, and the calibration method can be traced back to a national metering standard.
Description
technical field [0001] The invention specifically relates to a detection efficiency calibration method of a traceable radioactive iodine activated carbon sampling filter box, and belongs to the technical field of nuclear power plant gaseous effluent monitoring. Background technique [0002] Radioactive iodine is produced during the daily operation of nuclear power plants. In order to protect the life and health rights of staff and the public, nuclear power plants must monitor the concentration of radioactive iodine activity in the gaseous effluent to ensure that it does not exceed the threshold specified by the national standard. The main forms of iodine in the gaseous effluent are gaseous element iodine and methyl iodide. Generally, activated carbon filter boxes impregnated with certain reagents are used to absorb and collect these iodine, and the activity is measured by NaI(Tl) detectors. The measured flow value can be used to calculate the activity concentration of radioa...
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IPC IPC(8): G01T7/00
CPCG01T7/005
Inventor 陈立唐智辉王勇韦应靖黄亚雯冯梅李强杨慧梅牛蒙青
Owner CHINA INST FOR RADIATION PROTECTION