No abstract

No abstract

No abstract

These days, world wide interest about global warming and environmental pollution and exhausting fossil fuel which have been main energy source in all around the world. So many country have tried to find out the solution by investing new & renewable and clean energy. Therefore LNG have been widely used as a substitution of fossil fuel and clean energy that emits less pollutant like SOx, NOx. Therefore LNG consumption has been quickly raised and LNG carriers have been getting larger for decades. In this study, high power fiber laser was used for welding of stainless steel for LNG carrier to increase its productivity. Used material was STS316L which has low carbon less than 0.03% and its thickness was 8 mm. We carried out bead, lap and butt welding by using the fiber laser which has maximum power up to 5kW. As a result, we could find out that lap and butt joint was possible at welding speed of 2.0m/min and 3.0m/min respectively.

With nuclear power plants worldwide approaching their design lifespans, plans for decommissioning nuclear power plants are increasing, and interest in decommissioning technology is growing. Laser cutting, which is suitable for high-speed cutting in underwater environments and is amenable to remote control and automation, has attracted considerable interest. In this study, the effects of laser cutting were analyzed with respect to relevant parameters to achieve high-quality underwater laser cutting for the decommissioning of nuclear power plants. The kerf width, drag line, and roughness of the specimens during the high-power laser cutting of 50 mm-thick stainless steel in an underwater environment were analyzed based on key parameters (focal position, laser power, and cutting speed) to determine the conditions for satisfactory cutting surface quality. The results indicated that underwater laser cutting with a speed of up to 130 mm/min was possible at a focal position of 30 mm and a laser power of 9 kW; however, the best-quality cutting surface was obtained at a cutting speed of 30 mm/min.