Document: NRC Regulatory Guide
Document ID: 0df18aa6-42a8-4990-aa7e-3df6d0907f3f
Document Type: regulatory_guide
Title: Criteria for Safety Systems (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2511/ML25114A021.pdf
Revision Date: 2025-11
Chapter: 
Section ID: RG-1.153
CFR Part: 
CFR Title: 

Content:
and the use of design techniques or mitigation measures other than diversity to address a potential CCF. If diversity is used as an approach, then independent and diverse means not susceptible to the same CCFs (e.g., a diverse and independent digital system, or a diverse and independent analog/hardware-based system) are acceptable for the system(s), that monitor and produce a diverse trip or actuation in the affected redundant portion of the digital safety systems if the common processing unit ceases operation or “locks-up.” 5. Table 1 below identifies relevant additional guidance applicable to certain clauses of IEEE Std 603-2018. (Note: The guidance described in this table is not exhaustive or comprehensive.) Table 1. IEEE Std 603-2018 Clauses - Relevant Additional Guidance Clause Relevant Additional Guidance 4.g – Includes electromagnetic interference as an additional environmental factor in the design basis RG 1.89, “Environmental Qualification of Certain Electric Equipment Important to Safety for Nuclear Power Plants” RG 1.180, “Guidelines for Evaluating Electromagnetic and Radio-Frequency Interference in Safety-Related Instrumentation and Control Systems” 5.1, “Single-failure criterion” RG 1.53, “Application of the Single-Failure Criterion to Safety Systems” 5.3, “Quality” RG 1.28, “Quality Assurance Program Criteria (Design and Construction)” 5.4, “Equipment qualification” RG 1.89, “Environmental Qualification of Certain Electric Equipment Important to Safety for Nuclear Power Plants” RG 1.209, “Guidelines for Environmental Qualification of Safety-Related Computer-Based Instrumentation and Control Systems in Nuclear Power Plants” 5.6, “Independence” RG 1.75, “Criteria for Independence of Electrical Safety Systems” RG 1.152, “Criteria for Programmable Digital Devices in Safety-Related Systems of Nuclear Power Plants” 5.6.3.2, “Equipment in proximity” RG 1.75, “Criteria for Independence of Electrical