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Environmental and Siting (Division 4): Regulatory Guides 4.21 - 4.30
This page lists the number, title, publication date, and revisions for each regulatory guide in Division 4, "Environmental and Siting," with references to draft guides and related documents (where applicable).
See also Draft Regulatory Guides for Public Comment.
See NRC Regulatory Guides for more general information.
Regulatory Guides are reviewed about every 10 years, although a guide may be reviewed more frequently if the staff believes an emerging issue affects the guide. The NRC began these reviews in 2010, and began posting the results of its reviews on this site in 2013. The review dates are hyperlinked to the review memorandum, which provide useful information about the status and any known issues with the associated regulatory guide.
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| Guide Number | Title | Revision Number | Issue Date | Additional Information |
|---|---|---|---|---|
| 4.21 | Minimization of Contamination and Radioactive Waste Generation: Life-Cycle Planning | 0 | 06/2008 | Periodic Review – June 2023 - Considerations Reviewed in 2013 – No issues identified |
| 4.22 | Decommissioning Planning During Operations | 0 | 12/2012 | Periodic Review - August 2024 - Considerations |
| 4.24 | Aquatic Environmental Studies for Nuclear Power Stations | 0 | 12/2016 | |
| 4.25 | Assessment of Abnormal Radionuclide Discharges in Ground Water to the Unrestricted Area at Nuclear Power Plant Sites | 0 | 03/2017 | |
| 4.26 | Volcanic Hazards Assessment for Proposed Nuclear Power Reactor Sites | 1 | 08/2023 | Rev 1 is an administrative change |
| 0 | 06/2021 | |||
| 4.27 | Use of Plant Parameter Envelope In Early Site Permit Applications for Nuclear Power Plants | 0 | 07/2023 | |
| 4.28 | Use of ARCON Methodology For Calculation Of Accident-Related Offsite Atmospheric Dispersion Factors | Cxl | re-assigned to Division 1 under RG 1.249 Revision 0 | |
| 4.29 | Graded Approach to Site Characterization | DG | 07/2026 | DG-4036 |
Page Last Reviewed/Updated Friday, July 24, 2026
Page Last Reviewed/Updated Friday, July 24, 2026