Yuanzineng kexue jishu (Dec 2022)
Research on Calibration Method of Relative Detection Efficiency for Large Number of 3He Detector
Abstract
In the development of some equipments or in the production environment of specific fissionable nuclear materials, neutron flux distribution measurements are required using a large number of neutron detectors to determine the production status. In this process, the relative efficiency of each neutron detector is particularly important. First of all, the 3He detector is chosen as the neutron detector to measure the high gamma dose and complex environment. In order to unify the measurement standard of this kind of production line and ensure the accuracy of the measurement of the target object, a set of calibration system for relative efficiency of batch 3He detectors was designed. By analyzing the design of the detector and combining the backend multichannel analyzer, the theoretical simulation and experimental verification of the calibration system of the detection efficiency of 3He detector were carried out. Firstly, the slowing down effect, shielding effect, external dose and detection efficiency of the device were simulated. The error sources of the calibration system were analyzed under the conditions that the slowing down ability and shielding effect of the device are good and the radiation dose level meets the radiation protection requirements. After measurement and analysis, the error sources of the calibration result of the system mainly include the statistical errors caused by background count, the uniformity of the device, the location distribution of the detector and the system error caused by the multichannel dead time. The counting rate of all detectors was measured based on the same neutron source, on the premise that the detectors have good performance and the above errors are eliminated. After selecting the standard detectors, the calibration coefficients of 292 3He detectors relative to the standard detectors were obtained, which provides an effective basis for the mass use, replacement and maintenance of 3He detectors in the production line. It also provides a technical basis for the practical development of post-treatment engineering.
