What is the concept of 60-year design life of nuclear power equipment?

A simple understanding of the design life of 60 years is that it can run safely and reliably within 60 years, mainly referring to equipment. In the design of nuclear power plants, large equipment, such as pressure vessels, need to be irradiated by strong radiation. Therefore, a sample box will be set in the irradiation area where the pressure of nuclear power plant is easy, and the same material as the pressure vessel will be stored in the sample box, and then the performance of the material will be analyzed regularly to ensure the reliability of the equipment.