Document: NUREG-0800
Document ID: 9cfc38bf-7808-446e-a43d-4ca9ff55df2a
Document Type: srp
Title: AC POWER SYSTEMS (ONSITE)
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1007/ML100740289.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.3.1
CFR Part: 
CFR Title: 

Content:
wed in detail in SRP Section 8.4. As documented in SECY 94-084, the electrical distribution system for evolutionary LWR design plants should include: 1) an alternate offsite power source available for non-safety-related loads, unless the design margins for loss of non-safety-related loads are no more severe than turbine-trip-only events in current plants, and 2) at least one offsite circuit to each redundant safety division supplied directly from offsite power sources, with no intervening non-safety-related buses. 8.3.1-19 Revision 4 - May 2010 For passive reactor design applications, such as the AP1000, the potential risk contribution of a SBO is minimized by not needing ac power sources for design-basis events. The safety-related passive systems in these plants do not need any ac power sources to perform safety-related functions. They are designed to automatically establish and maintain safe shutdown conditions after design-basis events for 72 hours, without operator action, following a loss of both onsite and offsite ac power sources. Consequently, a passive reactor design meets the requirements of 10 CFR 50.63 if it can establish and maintain safe shutdown conditions for the specified duration of the SBO event, without operator action, following a loss of both onsite and offsite ac power sources. Detailed reviews to verify the evolutionary and passive ALWR design applications satisfy the requirements of 10 CFR 50.63 are covered in SRP Section 8.4, "Station Blackout." Meeting the requirements of 10 CFR 50.63 provides assurance that the nuclear power plant will be able to withstand or cope with, and recover from, an SBO and will ensure that core cooling and appropriate containment integrity are maintained. 9. 10 CFR 50.65 (a)(4) requires that licensees assess and manage the increase in risk that may result from proposed maintenance activities before performing the maintenance activities. Grid stability and offsite power availability are examples of emergent