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:
ndix D, Page D-2 The amount of dose contributed by each of these sources depends on the location of the equipment, the time-dependent and location-dependent distribution of the source, and the effects of shielding. D-2. Accident Radiation Dose D-2.1 Basic Assumptions Gamma and beta doses and dose rates should be determined for three types of radioactive source distributions: (1) activity suspended in the containment atmosphere, (2) activity plated out on containment surfaces, and (3) activity mixed in the containment sump water. A given piece of equipment may receive a dose contribution from any or all of these sources. The amount of dose contributed by each of these sources depends on the location of the equipment, the time-dependent and location-dependent distribution of the source, and the effects of shielding. For EQ components located outside the containment, additional radiation sources may include piping and components in systems that circulate containment sump water outside of containment. Activity deposited in ventilation and process filter media may be a source of post- accident dose. Shielded components need not be qualified to the beta radiation environment, provided that it can be demonstrated that the sensitive portions of the component or equipment are not exposed to significant beta radiation dose rates or that the effects of beta radiation, including heating and secondary radiation, have no deleterious effects on component performance. The integrated dose should be determined from estimated dose rates using appropriate integration factors determined for each of the major source terms (e.g., containment sump, containment atmosphere, emergency core cooling system, normal operation). The period of exposure should be consistent with the survivability period for the EQ equipment being evaluated. The survivability period is the maximum duration, post-accident, that the particular EQ component is expected to operate and perform its intended safety