Automatic detection system and method for spherical fuel element fuel-free section

Abstract

The invention relates to the field of nondestructive testing, provides an automatic detection system and method for a spherical fuel element fuel-free section, and aims to solve the problem that spherical fuel element fuel-free sections in the prior art are insufficient in detection precision, detection speed, detection reliability. The automatic detection method comprise the following steps: the transmitted electron images of spherical fuel elements are acquired through an X-ray nondestructive detection real-time imaging technique, the distribution situation of more than ten thousand fuel particles with diameters of greater than 400 micrometers in fuel elements with diameters of greater than 600 millimeters can be acquired through processing the images, whether fuel particles exist in specific areas or not is examined, and finally qualified and unqualified spherical fuel elements are separated to finish the automatic detection process according to automatic detection results. According to the invention, the automatic detection system and the automatic detection method can realize the fast and automatic detection of the spherical fuel elements fuel-free section, meet the detection efficiency design objective of at least two fuel elements every minute, and reach the detection result that the omission ratio of the unqualified products is 0% in a series of verified experiments.

Description

technical field [0001] The invention relates to the field of non-destructive testing, in particular to an automatic testing system and method for a fuel-free region of a spherical fuel element. Background technique [0002] At present, the spherical fuel element used in my country's pebble bed high-temperature gas-cooled reactor has a diameter of 60 mm, and the structure is that spherical coated fuel particles (TRISO) are dispersed in a graphite matrix with a diameter of about 50 mm in the fuel area. The fuel-free area refers to the spherical shell area formed by shrinking 4-6mm inwardly from the outer surface of the fuel element along the radial direction. As a structural material for spherical fuel elements, matrix graphite enables thermohydraulic conditions for the coated fuel particles, including transfer of heat to the coolant helium. And as a moderator material, it has sufficient moderation ability for fast neutrons, and also has a certain ability to retain fission pr...

AI Technical Summary

Problems solved by technology

[0005] (1) The existing methods mostly use manual intervention detection methods. After working for a period of time, people will start to get tired, their attention will decrease, and their reactions will be slow, which will affect the accuracy of the detection results;

[0006] (2) The detection efficiency of the existing system is low and the detection period is long: since the transmission image cannot be displayed in full, it needs to be rotated in multiple directions to detect in all directions

Therefore, the detection time of each element ball is about 3 minutes, which cannot meet the requirement of on-line detection of at least 1000 elements per day on a large scale for fuel elements;

[0007] (3) The existing system images and data cannot be directly stored, and unqualified balls cannot retain valid evidence and cannot be traced;

[0008] (4) The shape and size of the marking line of the fuel-free area of ​​the spherical fuel element in the existing system is fixed and cannot be changed, but there is a deviation between the boundaries of the actual fuel-free area of ​​the fuel element, so the detection may miss unqualified products situation;

[0009] (5) The existing systems mostly use continuous and uninterrupted images, and the displayed images are captured by cameras, and the image resolution is not high, which restricts the improvement of detection accuracy

[0010] Based on the above reasons, the devices or methods for detecting the fuel-free region of spherical fuel elements in the prior art cannot meet the current needs in terms of detection accuracy, detection speed, and detection reliability.

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