Document: NUREG-0800
Document ID: dd687b37-3f26-4512-91d8-633ddb655821
Document Type: srp
Title: DATA COMMUNICATION SYSTEMS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1602/ML16020A097.pdf
Revision Date: 2023-06
Chapter: 7
Section ID: 7.9
CFR Part: 
CFR Title: 

Content:
otection of Nuclear Power Plants,” for grounding and surge protection methods to provide lightning protection). Fiber optics typically offer resistance to such effects but have other attributes that prevent universal acceptability. For example, if the fiber-optic medium may be subject to radiation, fiber that does not become opaque or brittle under irradiation should be specified, or there should be a defined replacement schedule. NUREG/CR-6082, “Data Communications,” compares the qualities of optical and conductive media and provides guidance regarding environmental and performance criteria. • Diversity and Defense-in-depth (D3) analysis - If one or more DCSs are parts of systems (e.g., RTS, ESFAS, anticipated transient without scram [ATWS], diverse I&C) for which a D3 analysis is required, the analysis should be performed by the applicant, and the vulnerabilities to common-cause failure of all similar DCSs should be evaluated. Based on the credibility of postulated failures, potential consequences, availability of diverse preventive or mitigatory responses, and the NRC’s diversity requirements (see the Staff Requirements Memorandum (SRM) on SECY-93-087, “Policy, Technical, and Licensing Issues Pertaining to Evolutionary and Advanced Light-Water Reactor (ALWR) Designs”), the reviewer should determine that the design, including DCSs, has sufficient D3. See SRP BTP 7-19 for guidance on reviewing D3 analyses. • DCSs exposed to seismic hazard - The reviewer should determine whether the subject DCS equipment is located in seismic Category I structures. In certain designs, some connected data communication or multiplexer equipment may be located in non-seismic Category I structures. For these cases, the reviewer must ensure that simultaneous seismic destruction or perturbation of the exposed equipment does not simultaneously render redundant DCSs ineffective. For review of a DC application, the reviewer should follow the above procedures to verify that