Document: NUREG-0800
Document ID: 33d57664-26a3-4d30-807d-2ce020de062a
Document Type: srp
Title: STATION BLACKOUT
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1007/ML100740424.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.4
CFR Part: 
CFR Title: 

Content:
REVIEW RESPONSIBILITIES Primary - Organization responsible for the electrical engineering review Secondary - None I. AREAS OF REVIEW The term Astation blackout@ (SBO) refers to the complete loss of alternating current (ac) electric power to the essential and nonessential switchgear buses in a nuclear power plant (NPP). An SBO; therefore, involves the loss of the offsite electric power system (referred to in industry standards and regulatory guides (RGs) as the Apreferred power system@) concurrent with a turbine trip and unavailability of the emergency ac (EAC) power system (typically emergency diesel generators (EDGs)). An SBO does not include the loss of available ac power to buses fed by station batteries through inverters or by alternate ac (AAC) sources specifically provided for SBO mitigation. Because many safety systems necessary for reactor core decay heat removal depend on ac power, an SBO could result in a severe core damage accident. The risk 8.4-2 Revision 1 - May 2010 of SBO involves the likelihood and duration of the loss of all ac power and the potential for severe core damage after a loss of all ac power. In 1980, the NRC designated SBO as an unresolved safety issue (USI A-44). The agency documented the findings of the technical studies completed for USI A-44 in NUREG-1032 (Ref. 30). In June 1988, the NRC resolved USI A-44 with the publication of a new rule under Title 10 of the Code of Federal Regulations (CFR), Section 50.63 (Ref. 2) (53 FR 23203) and an accompanying RG (RG 1.155 (Ref. 7)). Concurrently, the Nuclear Management and Resources Council (NUMARC) (now the Nuclear Energy Institute (NEI)) developed NUMARC-8700, Revision 0 (Ref. 38), which RG 1.155 endorses with certain exceptions. Table 1 of RG 1.155 provides a cross-reference to NUMARC- 8700, Revision 0, and it notes when the RG takes precedence. The information presented in the safety analysis report (SAR) should be sufficient to support the conclusion that the plant is capable of