[en] Stress corrosion cracking(SCC) of stainless steel in pressurized water reactor (PWR) serves as a critical issue in nuclear power plants. Stainless steel exhibits an excellent hightemperature strength, ductility, toughness and corrosion resistance, and has been applied not only in nuclear power plants but also in various heavy industries. However, stress corrosion cracks in stainless steel result in aggravated microstructure, physical and mechanical properties, which critically affect the operation of nuclear power plants. To overcome this problem, several studies on stress corrosion cracking of stainless steel components have been carried out, however, the range of environmental conditions that lead to vulnerable stress corrosion cracking remains yet to be defined. In this study, slow strain rate tests(SSRT) were conducted to produce stress corrosion cracking in 316L stainless steel specimen, with adjusted dissolved oxygen and chlorine concentrations. Since dissolved molecules and ions inside the aqueous solution such as dissolved oxygen and chlorine ions are expected to penetrate the grain boundary, we aim to check whether intergranular stress corrosion cracking (IGSCC) occurs in the specimen under the environment (360°C, 20 MPa, and LiOH (2 ppm) + H₃BO₃ (1200 ppm)) similar to the primary coolants employed in nuclear power plants. To determine the effect of dissolved oxygen and chlorine on the nature of stress corrosion cracking, the experiments were conducted under three distinct environments: air (25°C), primary coolant environment, and primary coolant environment with dissolved oxygen (5 ppm) and chlorine (4 ppm). The stress-strain curve shows that the yield strength, tensile strength, and elongation rate of 316L stainless steel are reduced depending on the environment, leading to the deteriorated mechanical properties. Factors such as temperature, pressure, lithium, boron, and other solutes in the solution affect the microstructure of the material, thus increasing the occurrence rate and sensitivity of stress corrosion cracking. In particular, the mechanical properties of stainless steel 316L greatly deteriorated due to stress corrosion cracking under 5 ppm of dissolved oxygen, 4 ppm of chlorine ions, and 2×10^-7/s strain rate. Observing the cross section of the fractured tensile specimen under scanning electron microscopes (SEM) reveal that the reduction in cross sectional area of the stress-corrosion cracked specimen is the lowest under dissolved oxygen and chlorine (9.7%). Under ambient air and primary environment, further reduction in area has been observed due to necking during ductile fracture. Experiments with dissolved oxygen and chlorine show that cracks form due to stress corrosion cracking. SEM analyses also reveal widely distributed oxides on the surface. Cracks occur on the fracture surface of the specimen along the grain boundary and confirms that IGSCC occurred