Document: NUREG-0800
Document ID: d9e9d0a9-6390-4154-94dc-7d5e6d8145cd
Document Type: srp
Title: A-C POWER SYSTEMS (ONSITE)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052350489.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.3.1
CFR Part: 
CFR Title: 

Content:
safety buses. As an outcome of reviewing the parallel operation of the offsite and I onsite power systems, the use of the standby power supply diesel- generator sets to supply power to the electrical system during peak load demand periods was found by the staff to be unacceptable. The basis for this conclusion is that the required frequent intercon- nections of the -offsite and standby power supplies do not minimize the probability of their coincident loss (General Design Crite- rion 17) nor can the design be made immune to common failure modes (Section 5.2.1(5) of IEEE Std 308). Further details amplifying the basis for this conclusion are included in Branch Technical Position ICSB 8 (PSB) which sets forth the basis for prohibiting the use of diesel-generator sets for purposes other than emergency standby power supplies. 4. Standby Power Supplies In ensuring that the requirements of General Design Criterion 17 and IEEE Std 308 have been met with regard to the standby power supply diesel-generator sets having sufficient capacity and capability to supply the required distribution system loads, the design bases, design criteria, analyses, description, and implementation as depicted on electrical drawings and functional P&IDs, the diesel- generator sets are reviewed to verify that the bases for their selection satisfy the positions of Reyulatory Guide 1.9. Specifi- cally, the reviewer first becomes familiar with the purpose and operation of each safety system, including system component arrangement as depicted on functional P&MDs, expected system performance as established in the accident analyses, modes.of system operation and their interactions during normal and accident conditions, and interactions between systems. Following this, it is verified that the tabulation of all safety-related loads to be connected to each diesel generator is consistent with the informa- tion establishing the safety-related systems and loads and their required redundancy. The