Document: NRC Regulatory Guide
Document ID: 05969442-49ea-4f4a-a9e2-de3a14628b5e
Document Type: regulatory_guide
Title: Minimization of Contamination and Radioactive Waste Generation:  Life-Cycle Planning - HISTORY 07/2013 – Periodic Review of Revision 0 – No issues identified
Source: NRC Regulatory Guide Division 4
Source URL: https://www.nrc.gov/docs/ML0805/ML080500187.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-4.21
CFR Part: 
CFR Title: 

Content:
ntial environmental contaminating events, and (3) assess the effect of construction on the hydrogeological characteristics of the site. The conceptual site model should address both the horizontal and vertical variability of the onsite hydrogeology and the potential effect of the layout of structures, foundations, footings, and backfills. A plan for implementing and updating the conceptual site model should comprise one component of the proposed facility operating procedures. Specifically, following facility construction, any impacts of site construction activities on final site hydrogeological characteristics should be identified. If there are significant changes at the site during the operating life of the facility, the conceptual site model should be reevaluated and adjusted, and appropriate adjustments/changes should be made to the onsite and offsite monitoring program. Appendix A to RG 4.21, Page A-4 b. As a general design consideration, any SSCs containing radioactive material should have at least two impermeable boundaries to the environment with the capability for periodic testing and inspection. If the design cannot incorporate such features, the applicant should propose specific environmental monitoring (e.g., sampling of ground water in close proximity to potential sources) to periodically verify the integrity of the system. c. Tanks, sumps, and ponds containing radioactive materials should have at least two impermeable boundaries to the environment, with an integrated leak detection system capability that triggers an alarm at an operator station. Tank catch basins should be of solid construction, sealed, and leakproof, and they should have a capacity sufficiently larger than the maximum tank volume to accommodate the contents of the tank, including the contents of related piping, and in the event of a system failure. d. Exterior tanks should be located on or above bermed concrete pads. The berms should have a capacity sufficiently larger than the maximum