CO2 laser beam cutting with long-focused optics system

In cutting the decommissioned nuclear facility, it is required to ensure the safety for dismantling workers, to control the amount of wastes generated by cutting, to reduce the costs, etc. Recently, the laser power has increased remarkably and its application tests are carried out at various fields. In this work, cutting tests were carried out with the CO2 laser having a long-focused optics system of the meter scale. Then, in the optics system of 5 m focal length, it is possible to cut the steel plates of 30 and 40 mm thickness with the laser power of 20 and 40 kW respectively and 42 mm out diameter steel pipe of 5 mm thickness with that of 20 kW without using assistant gas. This cutting process can be developed such a new dismantling method that may dismantle crowded overhead pipes without a scaffolding, so it is expected to ensure the safety for dismantling workers, to decrease the amount of total radiation exposure and to reduce the costs. (author)