Gamma radiation source item inversion method and system based on regularized least square method

Abstract

The invention discloses a gamma radiation source item inversion method and system based on a regularized least square method. The method comprises the following steps of S1, carrying out area divisionon a gamma radiation source item, wherein radioactivity in each source item division area is uniformly distributed in a space; S2, according to dose rate measurement data at multiple external measurement positions and uncertainty, and the dose rate contribution of the unit radioactivity of each source item division area to each measurement position, through an optimization problem, determining atarget function used for calculating a radioactivity value in each source item division area; and S3, calculating the target function and acquiring the radioactivity value in each source item divisionarea. By using the method and the system of the invention, based on a given source item division mode and a nuclide type, according to measured data and a dose rate contribution matrix, through a regularized least square principle, gamma radiation source item activity data which is relatively stable and matches with the accuracy of the measured data is inverted.

Description

technical field [0001] The invention relates to the technical field of characterization of radioactive source items during the overhaul and decommissioning of nuclear facilities, and in particular to a method and system for inversion of gamma radiation source items based on regularized least squares method. Background technique [0002] The characterization of radioactive source items runs through all stages of nuclear facility design, construction, operation, and decommissioning. In different stages, source item investigations have different objectives and roles. Among them, the monitoring of radiation source items in the operation stage is an important means to evaluate the operation status and pollution level of nuclear facilities, and also provides basic data for occupational exposure assessment, source item and dose control; at the same time, in the later stage of operation, carrying out targeted source item measurement is important. It provides an important basis for f...

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Problems solved by technology

[0004] Since the dose rate measurement results generally contain measurement uncertainty, the uncertainty is affected by factors such as the relative inherent error of the measurement equipment, direction response, energy response, on-site measurement conditions, and statistical fluctuations, and given the division of gamma radiation source items The normal matrix condition number of the dose rate response matrix of the system is relatively large, so the inversion of the gamma radiation source item directly based on the dose rate measurement results will produce overfitting phenomenon; If there is a large negative correlation, the solution will oscillate, and if the inversion algorithm is used improperly, negative values ​​will appear

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