Document: NUREG-0800
Document ID: 88ed0d92-9d6e-40b1-b060-6d7334f66eb8
Document Type: srp
Title: Revision 3 - March 2007
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0707/ML070710478.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8
CFR Part: 
CFR Title: 

Content:
ly initiate the disconnection of offsite power sources whenever the voltage setpoint and time delay limits (cited in item 1.b.2 above) have been exceeded. v. Capability for test and calibration during power operation should be provided. vi. Annunciation must be provided in the control room for any bypasses incorporated in the design. d. The technical specifications should include limiting conditions for operations, surveillance requirements, trip setpoints, and maximum and minimum allowable values for the first level of undervoltage protection (LOOP) relays and the second-level (degraded voltage) protection sensors and associated time delay devices. 2. The Class 1E bus load shedding scheme should automatically prevent shedding during sequencing of the emergency loads to the bus. The load shedding feature should, however, be reinstated upon completion of the load sequencing action. The technical specifications must include a test requirement to demonstrate the operability of the automatic load shedding features at least once every refueling outage/cycle. An adequate basis must be provided if the load shedding feature is retained during the above load sequencing of the emergency loads to the bus. 3. The voltage levels at the safety-related buses should be optimized for the maximum and minimum load conditions that are expected throughout the anticipated range of voltage variations of the offsite power sources by appropriate adjustment of the voltage tap settings of the intervening transformers. The tap settings selected should be based on an analysis of the voltage at the terminals of the Class 1E loads. The analyses performed to determine minimum operating voltages should typically consider maximum unit steady-state and transient loads for events, such as a unit trip, loss-of-coolant accident, startup or shutdown, with the offsite power supply (grid) at minimum anticipated voltage and only the offsite source being considered available. Maximum voltages should be