Nondestructive evaluation (NDE) is an important asset in the industrial world. In-service inspections (ISIs) by means of NDEs are widely applied in Nuclear Power Plants (NPPs). Implementing reliable and effective ISIs contributes to the safe operation of the NPP with satisfactory reliability and availability levels. In the 1980s, the nuclear sector and concerned organizations began to investigate the performance of the NDE inspection systems of the NPP critical components. In the early 2000s, a methodology to qualify NDE inspection systems was developed. The technological development that emerged in those years was incorporated into the inspection systems that began to be used in the NPPs with good results. Today, its capabilities have improved with the incorporation of digital advances and, especially with the advent of artificial intelligence (AI). This chapter describes the importance and characteristics of NDE inspection systems in NPPs. The methodology for qualification of NDE inspection systems in NPPs, and its importance to carry out reliable and efficient inspections, is explained. Critical component inspection systems incorporate a high number of functionalities and carry out inspections with great reliability. Two case studies of critical component inspections are also presented. The NDE 4.0 proposes digital connectivity and provides the new technologies described in the industry 4.0 approach. The NDE inspection systems in NPPs have a considerable level of digitization, thus, making progress toward universal data file, AI applications, the objective set by NDE 4.0 is feasible and represents an opportunity to improve the levels of quality, reliability, and efficiency.