A method of measuring the coating thickness of coated fuel particles

Abstract

The invention provides a method for measuring the thickness of a coating layer of coated fuel particles. The method comprises the following steps: placing coated fuel particles in a sample-embedding die so that the coated fuel particles are closely arranged on the same sample plane, fixing the coated fuel particles in the sample-embedding die by using a curing agent to prepare a solid sample, grinding the solid sample, and enabling a grinding plane to be parallel to the sample plane until at least 80% of grinding surface of the coated fuel particles on the grinding plane observed under a microscope is tangent to the grinding surface of other coated fuel particles; polishing the ground solid sample so that the solid sample has no visible grinding crack on the grinding plane under the microscope, and the coating layers are clear in dividing line and free from height difference; acquiring an image of the solid sample on the grinding plane under the microscope; and then extracting the thickness of each coating layer from the image in combination of magnification times of the microscope. The method can be used for fast and accurately measuring the thickness of the coating layer of the coated fuel particles.

Description

technical field [0001] The invention relates to nuclear reactor engineering, in particular to a method for measuring the thickness of a coating layer covering fuel particles. Background technique [0002] Coated fuel particle (Coated fuel particle) is the basic unit of the fuel element of the high temperature gas-cooled reactor, which is composed of fuel core, loose pyrolytic carbon layer, inner dense pyrolytic carbon layer, silicon carbide layer and outer dense pyrolytic carbon layer . The loose pyrolytic carbon layer can store gaseous fission products, absorb the core swelling caused by radiation, buffer the stress caused by radiation and temperature changes, and prevent the damage of the fission recoil core to the dense pyrolytic carbon layer; the inner dense pyrolytic carbon layer prevents The hydrogen chloride produced during the deposition of the silicon carbide layer reacts with the uranium dioxide core to delay the corrosion of the silicon carbide layer by metal fis...

AI Technical Summary

Problems solved by technology

The thickness of the loose pyrolytic carbon layer and the inner dense pyrolytic carbon layer still needs to be measured by other methods, which leads to low efficiency in measuring the thickness of each layer of coated fuel particles in high-temperature gas-cooled reactors, which cannot meet the requirements of high-temperature gas-cooled reactor nuclear power plant demonstration Requirements for large-scale production of engineered fuel elements

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