11.113. The Federal Water Pollution Control Act (FWPCA) Amend­ments of 1972 state that all sources of pollution, including condenser cool­ant water, “shall require application of the best available technology eco­nomically achievable.” In order to meet this objective the U. S. Environmental Protection Agency (EPA) has proposed regulations for several effluents from steam-electric plants. As far as condenser water is concerned, the EPA concluded that “the best available technology” would be the use of cooling towers or other recirculation systems, e. g., ponds or canals. In effect, the EPA regulations preclude the use of one-through cooling for power plants of more than 500 MW(el) capacity.

11.114. The FWPCA Amendments, however, provide for exemptions from the regulations in special cases. If state requirements can be satisfied, once-through cooling may be permitted when it can be shown that the ecological disturbance would be minimal. Exemptions might also be granted when sufficient land is not available for cooling towers or where salt drift or water vapor plumes from the towers (§11.119 et seq.) would be a serious problem. Nevertheless, it is probable that most future nuclear power plants will have to employ some form of closed-cycle cooling for the condenser water.

11.115. In addition to complying with EPA regulations, as authorized by the FWPCA Amendments, thermal discharges must meet the standards set by individual states in accordance with the Water Quality Act of 1965. These standards, which vary from one state to another and often within the same state, are determined by the aquatic life forms to be protected and the normal seasonal temperatures within a water body. As a general rule, the state specifies maximum temperature increases and maximum permissible temperatures. Some states also specify maximum rates of tem­perature change to minimize the danger of heat shock or cold shock.