United States Nuclear Regulatory Commission - Protecting People and the Environment

Key Issues

Digital instrumentation and controls (I&C) raise issues that were not relevant to analog systems. Examples of such issues include the following.

A common-cause failure attributable to software errors was not possible with analog systems. This potential weakness may require a consideration of diversity and defense in depth in the application of digital I&C systems.

Digital system network architectures also raise issues such as interchannel communication, communication between nonsafety and safety systems, and cyber security that must be reviewed closely to ensure that public safety is preserved.

Highly integrated control room designs with safety and nonsafety displays and controls will be the norm for new reactor designs.Quality assurance during all phases of software development, control, and validation and verification is critical to minimize the possibility of common-cause failures.

Qualification and dedication of commercial off-the-shelf equipment in safety-related applications are other important aspects of the implementation of digital I&C systems.

Key issues include those discussed in this section.

Page Last Reviewed/Updated Thursday, December 31, 2015