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:
information unless the document requesting or requiring the collection displays a currently valid OMB control number. DG-1251, Page 5 B. DISCUSSION Reason for Revision RG 1.153, “Criteria for Safety Systems,” (Ref. 25) provides guidance on addressing the requirements of 10 CFR 50.55a(h) when implementing or modifying safety systems in nuclear power plants. This revision was issued to support the revision to 10 CFR 50.55a(h) that incorporates by reference IEEE Std 603-2018 in addition to IEEE Std 279-1968, IEEE Std 279-1971, and IEEE Std 603‑1991 including its correction sheet dated January 30, 1995, as discussed in Federal Register notice 64 FR 17944 (Ref. 26). Background IEEE Std 603-2018 provides criteria for functional and design requirements of power and I&C portions of safety systems in nuclear power plants. This revision provides guidance on criteria found in IEEE Std 603-2018. IEEE superseded IEEE Std 603-2009, “IEEE Standard Criteria for Safety Systems for Nuclear Power Generating Stations,” (Ref. 27) and its correction sheet “Errata to IEEE Standard Criteria for Safety Systems for Nuclear Power Generating Stations,” (Ref. 28) with IEEE Std 603-2018 and 10 CFR 50.55a(h) was revised to incorporate it by reference. Alternatives to IEEE Std 603-2018 Criteria The staff understands that applicants, particularly with new or advanced reactor designs (e.g., inherent reactor safety physics or multiple passive safety features), may be able to justify alternatives to certain criteria in IEEE Std 603-2018 to make its overall safety case. In these scenarios, the applicant may choose to apply 50.55a(z), “Alternatives to codes and standards requirements.” Addressing Common-Cause Failure The first sentence of Clause 5.16, “Common-cause failure,” of IEEE Std 603-2018 states, “The safety system design and development shall address common-cause failures (CCF) that create a potential to degrade or defeat the safety system function.” This statement is