Document: NUREG-0800
Document ID: f90f6920-8ff7-4a39-b6a6-85bf7887d69f
Document Type: srp
Title: CONTAINMENT HEAT REMOVAL SYSTEMS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0523/ML052340671.pdf
Revision Date: 2023-06
Chapter: 6
Section ID: 6.2.2
CFR Part: 
CFR Title: 

Content:
ressure and sump water temperature transients have been conservatively used in the NPSH calculations. The CSB reviews information provided by the applicant to identify and justify the conservatisms in the analysis of the containment atmosphere pressure and sump water temperature transients. The CSB also reviews the conservatisms used in determining the water level in the containment and the friction losses in the recirculation system piping. The CSB compares the NPSH requirements for the containment heat removal system pumps to the minimum calculated NPSH available to the pumps to assure that a positive margin is maintained. The CSB also reviews the preoperational test programs, and periodic inservice inspection and test programs, to verify that adequate NPSH is available to the pumps and the continuing operability of the pumps during the lifetime of the plant. If in the judgment of the CSB, the NPSH analyses were not done in a sufficiently conservative manner, confirmatory analyses are performed using the CONTEMPT-LT computer code. The CSB also reviews the evaluation of the volume of the containment covered by the sprays and the extent of overlapping of the sprays with respect to heat removal capabilities. A judgment will be made regarding the acceptability of the spray coverage and extent of overlapping; the volume of the containment covered by the sprays should be maximized and the extent of overlapping kept to a minimum. Elevation and plan drawings of the containment showing the spray patterns are used to determine coverage and overlapping. In general, the design requirements for the spray systems with respect to spray drop size spectrum and mean drop size, spray drop residence time in the containment atmosphere, containment coverage by the sprays, and extent of overlapping of the sprays are more stringent when the acceptability of the system is being considered from an iodine removal capability standpoint rather than from a heat removal capability standpoint.