Document: NUREG-0800
Document ID: d52a97d0-a519-4817-9ad6-64d94c9518af
Document Type: srp
Title: DATA COMMUNICATION SYSTEMS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1515/ML15159B177.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.9
CFR Part: 
CFR Title: 

Content:
nnected, or if safety and nonsafety communications networks are not interconnected, the determination of communications independence is self-evident. If, however, there is such an interconnection, the determination of independence is significantly more complex and will take more effort and time. The review will need to ensure that the interconnection is such that each safety system will perform its safety function with no input or influence from the interconnected system, and that any failure of the interconnected system, failure of communications from that system or faulty data transmitted by that system will not prevent or influence that independent safety determination. The review should confirm that a physical, electrical, logical or software malfunction in one portion cannot adversely affect the safety functions of the connected system. 7.9-8 Draft Revision 6 - August 2015 • System testing and inoperable surveillance - See SRP Appendix 7.1-B, Subsections 4.9, 4.10, and 4.13 or SRP Appendix 7.1-C, Subsections 5.7, 6.5, and 5.8. Insofar as bypass or deliberate inoperability of a DCS may induce the same condition on the system of which it is a part, the review should confirm that the bypassed and inoperable indications for DCSs are consistent with those of the systems of which they are part. • Protocols - The actual protocol functions needed to perform the safety mission should be determined. Protocols proposed for use, whether standard or proprietary, should be analyzed for hazards and performance deficits posed by unneeded functionality and complication. Additional guidance on protocols may be found in NUREG/CR-6082. • Electromagnetic/radiofrequency interference (EMI/RFI) susceptibility - See SRP Appendix 7.1-B, Subsection 4.4, or SRP Appendix 7.1-C, Subsection 5.4. The review should confirm that data communication media do not present a fault propagation path for environmental effects, such as high-energy electrical faults or lightning, from one redundant