Document: NRC Regulatory Guide
Document ID: e7cef6d0-2869-4d77-9a08-126120ae6043
Document Type: regulatory_guide
Title: Fuel Oil Systems for Emergency Power Supplies + HISTORY – HISTORY 06/2012 – DG-1282 , Proposed Revision 2 Prior to the issuance of DG-1282, RG 1.137 was entitled "Fuel –Oil Systems for Standby Diesel Generators (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1210/ML121090447.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.137
CFR Part: 
CFR Title: 

Content:
running time, as disaster conditions can temporarily prevent access to the plant site for replenishment of fuel oil supplies. 5. Section 5.4, “Calculation of Usable Fuel Oil Storage Requirements,” provides two methods for calculation of the required capacity for fuel oil storage. The first calculation method is based on providing onsite storage for 7 days of continuous operation at the rated diesel generator capacity and requires an explicit allowance for fuel consumption during periodic testing. Appendix B of ANSI/ANS-59.51-1997, “Alternate Calculation of Usable Fuel Oil Storage Capacity,” although not a required appendix, provides the second method for calculation of fuel oil storage capacity requirements that bases the capacity on operation of the diesel generator or generators at the minimum required capacity, including the capacity to power the safety-related systems and components, for the plant condition that is most limiting for the calculation of such capacity. In view of the varying plant conditions that may prevail during emergency situations and flexibility afforded to plant operators to manually add loads, the staff does not consider the time and load dependent method as acceptable for meeting the intent of onsite fuel oil storage requirements. The calculation for supply tank capacity should include the following considerations: 5.1. Provide for a 7-day usable volume in the fuel oil supply tank and should not assume any contribution from any other fuel oil system components, including the day or integral tanks, piping, valves, transfer pumps, strainers, and filters. 5.2. Account for the unusable volume of the fuel supply tank. This unusable volume is the volume below the elevation at which air in the tank can enter the suction piping or at which vortex effect could impact system performance. The location of this suction connection should be at an elevation that prevents influx of particulates that could plug filters and strainers and should also