Document: NRC Regulatory Guide
Document ID: 50995365-d97f-4101-970a-378af6b5374b
Document Type: regulatory_guide
Title: Qualification of Fiber-Optic Cables, Connections, and Optical Fiber Splices for Use in Safety Systems for Production and Utilization Facilities (Rev. 0)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2505/ML25052A253.pdf
Revision Date: 2025-08
Chapter: 
Section ID: RG-1.257
CFR Part: 
CFR Title: 

Content:
the Commission stated that RISC-3 SSCs continue to be required to be capable of performing their safety-related functions under applicable environmental conditions and effects and seismic conditions, albeit at a lower level of confidence compared to RISC-1 (safety-related, safety-significant) SSCs. RG 1.257, Rev. 0, Page 3 As specified by the Commission in the FR notice, a licensee implementing 10 CFR 50.69 must consider operating life (aging) and combinations of operating life parameters (synergistic effects) in the establishment of alternative treatments of RISC-3 electrical equipment. The Commission noted that this is particularly important if the equipment contains materials that are known to be susceptible to significant degradation due to thermal, radiation, and/or wear (cyclic) aging, including any known synergistic effects that could impair the equipment’s ability to meet its design-basis function. The Commission direction in the FR notice regarding the capability of RISC-3 SSCs to be able to perform their safety functions under applicable environmental and seismic conditions is clear for licensees who have received a license amendment to implement a 10 CFR 50.69 program. With respect to both RISC-3 and RISC-4 SSCs, the Commission decided to remove the RISC-3 and RISC-4 SSCs from detailed, specific requirements that provide a high level of assurance. However, the Commission stated in the FR notice that the functional requirements for these SSCs remain. o General Design Criterion (GDC) 4, “Environmental and Dynamic Effects Design Bases,” of Appendix A, “General Design Criteria for Nuclear Power Plants,” to 10 CFR Part 50, states in part that SSCs important to safety shall be designed to accommodate the effects of and to be compatible with the environmental conditions associated with normal operation, maintenance, testing, and postulated accidents, including loss-of-coolant accidents. o General requirements associated with equipment qualification