Transactions of the Korean Society of Pressure Vessels and Piping (한국압력기기공학회 논문집)

Korean Society of Pressure Vessels and Piping (한국압력기기공학회)
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A Study on the Surface Roughness Behavior of Reactor Vessel Stud Holes in APR1400 Nuclear Power Plants

APR1400 원자로 용기 스터드 홀의 표면거칠기 거동에 관한 연구

  • Received : 2019.04.30
  • Accepted : 2019.06.18
  • Published : 2019.06.30
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Abstract

The APR1400 reactor may be operated for a long time under high temperature and pressure conditions, causing damage to the stud holes and causing stud bolts and holes to stick. The present practice is to manually remove the anti-sticking agent and foreign matter remaining in the APR1400 reactor stud hole and to visually check the surface condition of the thread to check the damage status of the threads. In the case of the APR1400 reactor stud holes, manually cleaning the threads increases the risk of radiation exposure and operator's fatigue. To avoid this, the autonomous mobile robot is used to automatically clean the reactor stud holes. The purpose of this study is to optimize the cleaning performance of the mobile robot by looking at the behavior of the surface roughness of the stud surface cleaned by the brush attached to the mobile robot due to changes in brush material, thickness of wire, and rotation speed. A microscopic approach to the surface roughness of the flank is needed to investigate the effects of the newly proposed brush of the autonomous mobile robot on the thread holes. According to this experiment, it is reasonable to use STS brush rather than Carbon one. Optimal operating conditions are derived and the safety of APR1400 reactor stud holes maintenance can be improved.

Keywords

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Fig. 1 APR1400 reactor stud hole

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Fig. 2 Stud repair damaged

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Fig. 3 Reactor stud hole work procedure

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Fig. 4 Overview of system

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Fig. 5 Sequence of gripping

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Fig. 6 Brush module

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Fig. 7 Cleaning zone

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Fig. 8 Brushing stud hole

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Fig. 9 GUI Environment

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Fig. 10 Arithmetic mean roughness

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Fig. 11 Ten point average roughness

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Fig. 12 VX-X200

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Fig. 13 Sample & installation point

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Fig. 14 Thickness of wire

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Fig. 15 Measurement point

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Fig. 16 Measurement data

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Fig. 17 Ra of carbon on thickness

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Fig. 18 Rz of Carbon on thickness

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Fig. 19 Ra of STS on thickness

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Fig. 20 Rz of STS on thickness

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Fig. 21 Ra of Carbon on different velocity

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Fig. 22 Rz of carbon on different velocity

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Fig. 23 Ra of STS on different velocity

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Fig. 24 Rz of STS on different velocity

Table 1 Specifications of laser microscope

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Table 2 Measurement data of Carbon Ra

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Table 3 Measurement data of Carbon Rz

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Table 4 Measurement data of STS Ra

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Table 5 Measurement data of STS Rz

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Table 6 Measurement data of Carbon Ra

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Table 7 Measurement data of Carbon Rz

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Table 8 Measurement data of STS Ra

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Table 9 Measurement data of stainless steel Rz

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