Document: NRC Regulatory Guide
Document ID: eb3f5778-b26b-4ba0-9962-f7101bddfff7
Document Type: regulatory_guide
Title: (Rev. 3005)
Source: NRC Regulatory Guide Division 4
Source URL: https://www.nrc.gov/docs/ML0037/ML003739900.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-4.8
CFR Part: 
CFR Title: 

Content:
r 8 hours to verify compliance with technical specifications. The estimated accuracy of using the backup station temperatures and the correlation between backup and discharge-point temperature is 5 to 10%. Bases** The 90*F effluent temperature limit is established because most important species of this region cannot tolerate prolonged exposure to temperatures above 900 F. Based on a literature review and laboratory studies of important resident species, 90°F appears to be a maximum temperature that can be chronically tolerated. Discharge temperatures at the control structure are expected to approach 90PF for only a few weeks of the year. Mixing of the discharge and receiving water will limit temperatures which approach 90*F in the receiving water to' the immediate discharge area. Since the time duration and spatial extent of temperatures approaching 90OF are expected to be limited to short periods and to a relatively small area of the receiving water, changes detrimental to the aquatic ecosystem structure and function are not anticipated. The placement of the temperature monitoring instru ment at the control structure will give the tempcrature of the discharge water immediately before mixing with the receiving water. The placement of the temperature sensor at mid-depth in the discharge canal has been shown by temperature measurements at other depths in the canal to be representative of the discharge water entering the receiving stream. The transmission, com puter storage, and monitoring program is presently being used at other facilities in the applicant's system and has performed within the limits indicated in the above specification more than 98% of plant operating time. "*The bases should be supported by reference to appropriate published documents and data held by the licensee. 4.8-20 EXAMPLE 2 EXAMPLE OF AN ENVIRONMENTAL SURVEILLANCE PROGRAM ELEMENT* 3.12.a.(2) Impingement of Organisms * Objective The objective of the monitoring program is to determine the