Document: NUREG-0800
Document ID: b6428ab0-2037-4bac-9b93-b46af9f2fdfb
Document Type: srp
Title: DATA COMMUNICATION SYSTEMS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0706/ML070650036.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.9
CFR Part: 
CFR Title: 

Content:
REVIEW RESPONSIBILITIES Primary - Organization responsible for the review of instrumentation and controls Secondary - None I. AREAS OF REVIEW The objectives of the review are to confirm that data communication systems (DCSs) (1) conform to applicable acceptance criteria and guidelines, (2) will perform the safety functions assigned to them, (3) will meet the reliability and availability goals assumed for the system, and (4) will tolerate the effects of random transmission failures. A particular concern is that the transmission of multiple signals over a single path may constitute a single point of failure that may have a larger impact on plant safety than would occur in previous analog systems. The scope and depth of the review and the acceptance criteria will vary according to the importance to safety of the system that the DCS is supporting. 1. This Standard Review Plan (SRP) section describes the review process and acceptance criteria for DCSs that are part of or support the systems described in SRP Sections 7.2 through 7.8 of the applicant’s safety analysis report (SAR). DCSs may include multiplexers and more general communication systems. The distinction between multiplexers and more general data communication systems is often blurred. For purposes of this SRP section, a multiplexer is defined as equipment that transmits, receives, or connects in turn several different signals over an electrical conductor or optical-fiber medium on a fixed schedule or rotation. Internal computer buses are specifically excluded from the definition of DCSs used in this SRP section. 7.9-2 Revision 5 - March 2007 Multiplexers may be analog or digital. More generally, a DCS transmits one or more signals on one or more electrical or optical media according to some analog or digital encoding. The schedule for transmission of the various signals may not be fixed, and particular signals or data may be transmitted at unpredictable intervals. Communications via media other than