This paper provides an overview of the existing and new cybersecurity standards for I&C and Electrical Systems in nuclear power plants around the world. The IEC 62645 is a standard by the International Electrotechnical Commission (IEC) focused on the issue of requirements for computer security programs and system development processes to prevent and/or minimize the impact of cyberattacks against digital instrumentation and control (I&C) systems. The IEC 62859 is a standard, officially issued at the end of 2016, which coordinates the safety and cybersecurity requirements.