For application in nuclear decommissioning, underwater laser cutting studies were conducted on thick stainless-steel plates for various cutting directions using a 6 kW fiber laser. For cutting along the horizontal direction with horizontal laser irradiation, the maximum cutting speed was 110 mm∙min−1 for a 48 mm thick stainless-steel plate. For cutting along the vertical direction with horizontal laser irradiation, a maximum speed of 120 mm∙min−1 was obtained for the same thickness, which confirmed that the cutting performance was similar but slightly better. Moreover, when cutting with vertically downward laser irradiation, the maximum cutting speed was 120 mm∙min−1 for a plate of the same thickness. Thus, the cutting performance for vertical irradiation was nearly identical to that for horizontal irradiation. In conclusion, it was possible to cut thick stainless-steel plates regardless of the laser irradiation and cutting directions, although the assist gas rose up due to buoyancy. These observations are expected to benefit laser cutting procedures during the actual dismantling of nuclear facilities.

1. Introduction
2. Experimental Setup and Procedure
3. Experimental Results
    3.1 Cutting With Horizontal Laser Irradiation
    3.2 Cutting With Vertically Downward LaserIrradiation
4. Conclusions
REFERENCES

• Jae Sung Shin(Korea Atomic Energy Research Institute) Corresponding Author
• Seong Y. Oh(Korea Atomic Energy Research Institute)
• Seung-Kyu Park(Korea Atomic Energy Research Institute)
• Taek-Soo Kim(Korea Atomic Energy Research Institute)
• Hyunmin Park(Korea Atomic Energy Research Institute)
• Jonghwan Lee(Korea Atomic Energy Research Institute)