Document: NRC Regulatory Guide
Document ID: e16da529-b6b4-4fdf-bc3f-7490180363f3
Document Type: regulatory_guide
Title: Environmental Qualification of Certain Electric Equipment Important to Safety for Nuclear Power Plants (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2018/ML20183A423.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.89
CFR Part: 
CFR Title: 

Content:
ed by the location of the equipment, the time-dependent and location-dependent distribution of the source, and the effects of shielding. DG-1361, Appendix D, Page D-4 Because of the large amount of EQ equipment and the complexity of system and component layout in plant buildings, it is generally not reasonable to model each EQ component. A reasonable approach is to determine the limiting dose rate from all sources in a particular plant area (e.g., cubicle, floor, building) to a real or hypothetical receptor and to base the integrated doses for all components in that area on this postulated dose rate. Individual detailed modeling of selected equipment may be performed. The integrated doses from components and piping in systems recirculating sump water should assume a source term based on the time-dependent containment sump source term described above. Similarly, the doses from components that contain air from the containment atmosphere should assume a source term based on the time-dependent containment atmosphere source term described above. Analyses of integrated doses caused by radiation from the buildup of activity on ventilation and process filter media (e.g., filters, charcoal beds, resin beds) in systems containing containment sump water or atmosphere or both should assume that the ventilation or process flow is at its nominal design value and that the filter media is 100-percent efficient for iodine and particulates. The duration of flow through the filter media should be consistent with the plant design and operating procedures. Radioactive decay in the filter media should be considered. Shielding by structures and components between the filter and the EQ equipment may be considered.