Mixed convection around calandria tubes in a ¼ scale CANDU-6 moderator circulation tank

Atkins, Michael D.; Rossouw, D.J.; Boer, Michael; Kim, T; Rhee, Bo Wook; Kim, H.T.

doi:10.1016/j.nucengdes.2017.03.010

Cited by 4 publications

(1 citation statement)

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“…또한, 레이저 펄스의 에너지 밀도 와 시편 가공 위치에 레이저 빔의 겹침 횟수를 가공 변 수로 두고 zircaloy-4의 표면 젖음성의 변화 양상을 확인하였다. 원자로의 주요 구조 재료인 zircaloy-4의 표면 젖음성은 반응로의 임계 열 유속(CHF; critical heat flux)과 밀접한 관계가 있음이 알려져 있으며, 열 교환 부에서 막비등 전환을 늦춰 원자로의 안정성을 확보하는 동시에 열 교환 효율을 높이기 위한 zircaloy-4의 CHF 향상 방안이 활발히 연구되고 있다 19) . Zircaloy-4 시편에 다양한 가공 조건의 레이저 표면 가공 공정 및 적절한 후가공을 20) 수행하여 가공 직후 부터 시간에 따른 시편의 표면 접촉각 변화를 추적하였 다.…”

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Study of the Change in Surface Wettability for Zircaloy-4 Utilizing Spatially Homogenized Nanosecond Laser Beam

Park¹,

Lee²,

Hwang³

et al. 2022

Journal of Welding and Joining

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This study introduces laser surface modification technology using a 532 nm Nd:YAG nanosecond laser. A laser beam homogenizer was used to spatially homogenize the laser beam into a square shape with an interference pattern of 30 μm. For laser surface modification processing, primary processing under 110 conditions was first performed, and then, 15 types of main processing conditions were determined based on the three-dimensional surface structure of laser surface modified zircaloy-4. Subsequently, the specimen was post-processed using three methods: left in the air (25 ℃), heated in the oven (200 ℃ for 2 h), and boiled in water (100 ℃ for 2 h). In the absence of post-processing or with heat post-processing, the laser surface modified zircaloy-4 showed super hydrophobicity with a contact angle of 150° or higher for specific laser surface processing parameters. Under specific laser surface processing conditions, the laser surface modified zircaloy-4 with boiling water post-processing exhibited properties close to super hydrophilic with a contact angle of less than 5°. It was confirmed that the surface wettability of zircaloy-4 can be controlled using a spatially shaped nanosecond laser beam.

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