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Defect detection in the graphite components and carbon bricks in high temperature gas-cooled reactors using helical CT |
| LIU Renjie, SUN Yuewen, LIU Ximing, MIAO Jichen, ZHOU Liye, CONG Peng |
| Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China |
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Abstract The graphite components and carbon bricks are essential materials for the core and reflector of the high temperature gas-cooled reactor (HTGR). However, production and transport create defects. Defective graphite components or carbon bricks can lead to serious safety hazards in the HTGR. The current defect detection methods are mainly based on visual inspections, which cannot detect internal defects. This paper describes a method to detect defects inside the graphite components and carbon bricks using helical CT. Numerical simulations of large carbon bricks were used to study the influence of pitch, rotational speed and reconstruction algorithm on the quality of the reconstructed images. The results show that the pitch greatly influences the reconstructed image quality with 0.8 as the optimal pitch for the best image quality. The rotational speed has less influence on the image quality. The CGLS reconstruction algorithm with the optimal parameters can detect holes as small as 2 mm and cracks as small as 1 mm. These results are important when designing defect detection systems for graphite components and carbon bricks.
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| Keywords
nuclear graphite components and carbon brick
high temperature gas-cooled reactor (HTGR)
defect detecting
helical CT
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Issue Date: 16 April 2021
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2021,
Vol. 61
