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:
ambient temperature and seasonal physiological requirements of species; thus limiting conditions for operation may vary with season. The need for limiting conditions should be considered for all modes of plant operation, including startup, shutdown, and others. The bases for establishing limiting conditions for operation on thermal discharges should include infonma tion on the species to be protected, the criteria for protection from thermal stress, and the water quality parameters to be controlled. 2.1.1 Maximum AT Aacos the Condenser Limits on condenser AT should be provided when the temperature rise across the condenser can result in unacceptable environmental impact on entrained organisms. Maximum AT limits should include pro tection against unacceptable plankton and larval fish mortalities and gas bubble disease in fish. 2.1.2' Maximum Discharge Temperature The most effective method for controlling thermal stress to the aquatic environment is by controlling the maximum temperature of the plant effluent at the point of discharge to the receiving water. Limits on maximum temperature of the plant effluent at the point of discharge should be proviiled. 2.1.3 Maximum Btu/hr If applicable, or to comply with other regulatory restrictions, the thermal discharge may be limited to an allowable Btu/hr. 4.8-5 2.1.4 Rate of Change of Discharge Temperature For sites where thermal shock may result in un acceptable environmental impact, limits should be giFovided to control the rate of temperatire change (i.e., F/hr) of condenser and service water discharges and blowdown from closed cycle systems duiing normal operation. Limits should be provided for both power iuxcrease and power decrease. Generally, the limits should be defined as a function of.ambient receiving water temperature or seasonal temperature requirements of the species to be protected. 2.1.5 Heat Treatment of Circulating Water System Limits should be provided for the magnitude and duration of temperature increase