Underwater laser cutting of stainless steel up to 100 mm thick for dismantling application in nuclear power plants

•An underwater laser cutting study was performed for dismantling application in nuclear power plants.•Stainless steel specimens were cut up to 100 mm in thickness using a fiber laser with a power of 9 kW.•Excellent performance was obtained in terms of cutting speed and thickness even in an underwater environment.•The results obtained in this study are expected effectively used in actual nuclear power plant decommissioning sites.