Document: NRC Regulatory Guide
Document ID: f457ed0f-1a93-47d5-a311-511c0346447e
Document Type: regulatory_guide
Title: Sizing of Large Lead-Acid Storage Batteries (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2311/ML23118A344.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.212
CFR Part: 
CFR Title: 

Content:
the guidance in the IEEE standard to determine the best battery for the application. To this end, IEEE Std. 485-2020 provides guidance on general considerations that should be included in defining the duty cycle; load classifications, including continuous, noncontinuous, and momentary loads; and the construction of a duty cycle diagram. In calculating the number of cells and minimum voltage section, IEEE Std. 485-2020 RG 1.212, Rev. 2, Page 5 cautions the user that the charging voltage needs to be recalculated and verified for adequacy if the numbers of cells are rounded off. It also discusses how to ensure all voltage drops are considered when calculating the allowable minimum voltage. IEEE Std. 485-2020 discusses defining loads and other considerations but notes that for sizing purposes the loads can be treated as constant power or constant current. The updated annexes A, B, C, D, E, F, G, and H are informative, and applicants and licensees should review them to assist with the battery design. IEEE Std. 485-2020, section 4.2.5, “Duty Cycle Diagram,” states that the total time span of the duty cycle is determined by the requirements of the installation. This duty cycle time depends on the type of production and utilization facility design and is typically discussed in a plant safety analysis report. This guidance does not apply to the emergency diesel generators (EDGs) or onsite emergency power source’s own battery if provided separately (which is exclusively sized based on the starting requirement of the EDG or onsite emergency power source, such as field flash). Consideration of International Standards The International Atomic Energy Agency (IAEA) works with member states and other partners to promote the safe, secure, and peaceful use of nuclear technologies. The IAEA develops safety requirements and safety guides for protecting people and the environment from harmful effects of ionizing radiation. This system of safety fundamentals, safety requirements,