Kori Unit 1, pressurized water reactor, is the Korea’s first commercial nuclear power plant. It successfully generated electricity for a period of 30 years, commencing from April 19, 1978. Following its approval for continued operation in 2008, Kori Unit 1 continued to operate for an additional 9 years, resulting in a total operational period of 39 years. On June 18, 2017, Kori Unit 1 was permanently shut down. Since then, Korea is actively preparing for the decommissioning of nuclear power plant. During the decommissioning of a nuclear power plant, the heavy components such as reactor, steam generator, pressurizer, reactor coolant pump located in the containment building should be taken out of the containment building. To take out heavy components from the containment building, pipes connected to heavy component should be cut. There are numerous pipes connected to the heavy component, each with varying dimensions and material. Each pipe has a different level of contamination depending on its use. In this study, optimal cutting method of pipe connected to steam generator, one of the heavy components of nuclear power plant, is proposed during the decommissioning of Kori unit 1. In case of pipe connected to Kori unit 1 steam generator, material is stainless steel or carbon steel. These pipes have varying inner diameter, ranging from 0.6 cm to 74 cm, and thickness ranging from 0.15 cm to 7.1 cm. These pipes are classified as low and intermediate level waste (LILW) or very low level waste (VLLW). Because characteristics of pipes are different, each pipe optimal cutting methods are proposed differently considering material, dimension, contamination level, cutting cost, cutting time, and the management of secondary waste. As a result, the cutting method for pipe of reactor coolant system is selected to orbital cutting. The cutting method of main steam pipe and main feedwater pipe is selected to oxygen cutting. In case of other small pipes, cutting method is selected to circular saw.

In order to commercialize large diameter PP pipes, the cutting work was attempted with the cutting machine (∅18″and AL120 cutter, 2100 r.p.m) used for the conventional PE or PVC pipe(∅1200 mm, t 70), but the cutting work was failed because the material of “PP pipe” melted and sticked to the surface of the wheel-cutter. In order to find the optimal structure and number of blades for wheel-cutters, an experimental investigation the temperature measurement of specimen and wheel-cutter and the visualization of cutted specimen surface and chip shape were carried out during and after experiment. In addition, modelings for cutting and heat transfer mechanisms have been developed for theoretical analysis. The theoretical and experimental results were in good agreement. The results show that the appropriate structure and the rotational speed of wheel-cutter are W60 and 650 rpm for the large diameter PP pipe cutting machine.

This study is for a pipe cutting apparatus for use in a process of a pipe. The system refers to a novel structure comprised of a main bed, a feeder part and a cutter part. The feeder part is comprised of an AC servo motor unit, a feeding gear unit, a LM guide and a rail. The cutter part is comprised of a blade unit consisting of a blade for cutting, a AC servo motor to rotate the blade unit and a clamp unit to fix the pipe. This study proposes a mechanism of a product by designing the system and analyzes the cutting power. This study will be used as basic data for the design by analyzing the vibration and the structure