Document: NRC Regulatory Guide
Document ID: 46049842-54a7-40a0-a0cc-ab115059f05e
Document Type: regulatory_guide
Title: Ultimate Heat Sink for Nuclear Power Plants + HISTORY - HISTORY DG-1275 , Proposed Revision 3, published 09/2013 (Rev. 3)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1304/ML13043A624.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.27
CFR Part: 
CFR Title: 

Content:
rs in Light Water Reactor Power Plants” (Ref. 14), or an equivalent test method. d. Where a dam or other water-controlling structure is required to ensure that the UHS has sufficient water available for its safety function, the dam or other water-controlling structure and connecting piping systems should be included in the Structures Monitoring Program under the Maintenance Rule at 10 CFR 50.65. DG-1245, draft revision 2 of RG 1.127, “Inspection of Water-Control Structures Associated with Nuclear Power Plants” (Ref 15) provides more details on performance monitoring of water-controlling structures (the final version of this guidance will reference the final version of RG 1.127). 6. Water Chemistry and Microbiological Control a. The quality of the water used in cooling towers, spray ponds, and heat exchangers should be considered in the design and operation of the UHS because it can greatly affect the thermal performance of the UHS (see Generic Letter 89-13, “Service Water System Problems Affecting Safety-Related Equipment,” dated July 18, 1989 (Ref. 16), and IN 2007-28, “Potential Common Cause Vulnerabilities in Essential Service Water Systems Due to Inadequate Chemistry Controls,” dated September 19, 2007 (Ref. 17)). Chemicals or other preventive measures may be needed to treat microbiological growth, macrobiological growth, corrosion, suspended solids fouling and scaling in nuclear power plant water systems that are part of the UHS. However, licensees and applicants are cautioned that the use of specific chemicals may need to be approved by other Federal, State, and local environmental agencies. b. Redundant and infrequently used cooling loops should be flushed and flow tested periodically, as part of the In-service Test Program, at the maximum design flow to ensure that they are not fouled or clogged, and that they are capable of passing the design flow. DG-1275, Page 12 D. IMPLEMENTATION The purpose of this section is to provide information on how