Document: NUREG-0800
Document ID: ac4cde5a-7464-48b8-9067-860c672cbb68
Document Type: srp
Title: STATION BLACKOUT
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0705/ML070550061.pdf
Revision Date: 2023-06
Chapter: 8
Section ID: 8.4
CFR Part: 
CFR Title: 

Content:
dc power needs for SBO may be estimated using the same methodology for which the plant is licensed; Institute for Electrical and Electronics Engineers (IEEE) Std 485 (Ref. 14) describes the generally accepted methodology. For passive plant designs (e.g., AP1000), where steady-state loads should operate for up to 72 hours under SBO conditions, the staff considers the steady-state loading condition to be the governing factor for determining the Class 1E battery size (Refs. 28 and 34). F. Since the capacity of battery storage varies with electrolyte temperature, calculations should assume the lowest temperature normally expected of the battery. G. The capability of all systems and components necessary to provide core cooling and decay heat removal following an SBO should be determined, including station battery capacity, condensate storage tank (CST) capacity, compressed air capacity, and instrumentation and control needs. The non-safety systems identified in Appendix A to RG 1.155 are acceptable to the NRC staff for responding to an SBO. 8.4-10 March 2007 H. The ability to maintain adequate reactor coolant system inventory to ensure that the core is cooled should be evaluated, taking into consideration shrinkage, leakage from pump seals, and inventory loss from letdown or other normally open lines dependent on ac power for isolation. I. The design adequacy and capability of equipment needed to cope with an SBO for the required duration and recovery period should be addressed and evaluated as appropriate for the associated environmental conditions. This should include consideration of the following: i. Potential failures of equipment necessary to cope with the SBO ii. Potential environmental effects on the operability and reliability of equipment necessary to cope with the SBO, including possible effects of fire protection systems iii. Potential effects of other hazards, such as weather, on SBO response equipment (e.g., auxiliary equipment to operate onsite buses or