United States Nuclear Regulatory Commission - Protecting People and the Environment
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Digital Instrumentation and Control

The Instrumentation and Controls (I&C) systems of a nuclear power plant (NPP) function as the "nervous system" of the plant. They provide operators with critical safety information on plant operation, allow operators to control various plant safety systems during routine operations, and automatically protect the reactor core during potential accident events. These systems may employ digital technologies.

Digital technologies can be used to combine safety functions together for improved control and increased operational efficiency. Digital systems can also improve the self-diagnostics of automatic plant protection systems. Finally, the increased use of digital technology is expected to improve safety. These benefits have been demonstrated in domestic and foreign nuclear facilities, as well as other non-nuclear process industries (e.g. petrochemical). New reactor designs have highly integrated digital systems, and the existing fleet of operating reactors are implementing digital upgrades to address obsolescence issues with analog equipment.

The NRC applies the same regulatory requirements to analog and digital systems, although the applicable guidance may be considerably different due to technical considerations. The regulatory focus for digital systems is tailored to the unique nature of the digital technologies and uses proposed by licensees and applicants. For example, implementation of digital equipment into the operating fleet results in new equipment employing software and new I&C design configurations. Through licensing activities and inspection oversight, the NRC verifies that licensees employ robust digital designs commensurate with risk significance, and that licensees use high-quality software development practices. Part of the NRC regulatory focus includes the prevention and mitigation of inadvertent digital failures and maintaining an appropriate level of diversity and defense-in-depth within the plant.

In summary, the NRC is committed to the expanded safe use of digital technologies in nuclear power plants and strives to maintain reasonable assurance of safety that is commensurate with risk significance. See the following links for more information on the NRC's digital I&C regulatory program and continuing efforts to modernize the regulatory infrastructure.

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Page Last Reviewed/Updated Thursday, May 23, 2019