National Environmental Policy Act, Joint Hearings Before ..., and the Committee on Interior Affairs, 92-2, March 1, 7, 8, 9, 1972

concentration decreased to an average (1969-1970) of 5.2 ppm in May, 1.0 ppm in July and 0.7 ppm in September (surface and 10-feet depth measurements were averaged). Concentrations equivalent to uplake and downlake areas were not reached until 4.8 miles downlake. The above study is comparable to the situation at this Station since a hypolimnetic withdrawal is planned. No discharge canal is present at Oconee, however, and the influence of the discharge configuration and the greater quantity of water available for dilution have not been assessed.

The minimal oxygen concentration that various fish species can tolerate may be affected by the temperature of the discharged condenser water. A temperature rise from 10° to 20°C (50° to 68°F) resulted in a decreased resistance to a lowering of oxygen concentration in perch, and in rainbow trout resistance to decreased oxygen was lowered when a temperature rise from 10°C to 16°C occurred. (33) However, avoidance of the discharge area by large fish during the time of low oxygen concentrati should occur long before the lethal oxygen concentration is reached. Less mobile eggs or fry may not be able to escape. In such an oxygendeficient environment, it can be expected that organisms with high oxygen requirements will be absent, either because of avoidance by mobile organisms or because of death of nonmobile organisms. The areas of oxygen-deficient water will probably be limited to the immediate vicinity of the discharge due to the rapid reoxygenation of surface waters.

d. Mechanical Impact

Mechanical damage to adult fish from the intake flow during normal operation of the Station will be minimal because of the low intake velocity of 0.4 foot per second (fps). The slow movement will allow most fish to move away from the retaining screens. The 3/8-inch openings in the fixed screens will exclude large fish, but some small ones will be drawn into the plant and through the condensers. A maximum velocity of 1.0 fps at the intake screens is projected for times of maximum drawdown, and it can be anticipated that fish could be pulled against the screens at this flow (35) The presence of trapping of threadfin shad, a warm-water species, in the intake canal during winter may present a problem. If the shad die in large numbers due to low temperatures in winter, which occurs many times at this latitude, clogging of the intake screens may occur, and frequent cleaning of the screens may be necessary.

rate.

Mechanical damage to aquatic organisms will probably occur also when the turbines at Keowee and Jocassee dams are running. The velocities at the turbine intakes will be approximately 22 and 16.5 fps respectively, and will in all probability entrain some organisms. The pumping of water into Jocassee reservoir from Lake Keowee can also be expected to cause some damage since the intake velocity during the pumped storage operation will be 14 fps. Although such mortality may be attributable directly to

the hydroelectric plants, studies should be made to insure that operation of the nuclear plant is not intensifying the mortality (e.g., herding of species by attraction to warm water or by movement away from areas of low dissolved oxygen).

The effluent discharge areas at both the nuclear plant and the hydroelectric plant are continually exposed to accelerated flow velocities, and a change in species diversity and abundance of benthic organisms in these localized areas may be attributable to scouring rather than temperature elevation. This will be especially true in the tailrace of Keowee Dam, where fluctuations in water level of 11 feet or more will be experienced at the onset of power generation (Section III.C.2).

e. Chemical Impact

Most of the consequences from release of chemicals (including radionuclides) will be manifested in the headwaters and main body of Hartwell Reservoir. A detailed evaluation of possible environmental effects of chemicals on aquatic biota in Hartwell is not possible at this time because detailed inventories or population studies of aquatic biota are not available.

Normal operation of power plant facilities requires the discharge of certain chemicals. The chemical wastes to be discharged from the. Station are listed in Table III-6.

The chlorine released from the sewage treatment system is immediately diluted to less than 0.00026 part per million (ppm) by the minimum 30 cubic feet per second flow in the tailrace of the Keowee Dam hydroelectric station. At a pH of 7.0, 0.08 ppm of residual chlorine killed half of a test

population of rainbow trout in 7 days. (36) Chlorinated sewage effluent

was

found to be toxic to minnows at concentrations of 0.04 to 0.05 ppm. population of rainbow trout could tolerate 0.23 ppm for only 96 hours, (38) and an avoidance response was demonstrated by rainbow trout to free chlorine levels of 0.001 ppm. (39) These concentrations are above those to be released at the Oconee Nuclear Station; consequently no effect from the Plant releases are expected.

Studies carried out by the Consolidated Edison Company of New York for its Indian Point Nuclear Station included tolerance lethal median tests on two fish species (white perch and striped bass) for chemicals to be discharged at Indian Point. (40) All maximum concentrations in water of the remaining

chemicals released at this Station are below the levels listed as toxic for the two Indian Point species at a 48-hour exposure. Similar tests need to be carried out for the prevalent fish species in the headwaters of Hartwell Reservoir in order to be exact, but in general the increases in normal river concentration due to this Station's discharge should not be significant in terms of lethality to present fish species.

The sources of radioactive material encountered in various plant components and systems and the Radwaste Systems provided to cope with the radioactivity are discussed in Section III. D. 2. of this Statement. Table III-4 presents identities and quantities of radioactive material anticipated to be released from the plant in liquid and gaseous effluents. The postulated release values are based upon experience with comparable operating reactors. Actual releases may differ somewhat from the postulated values owing to specific differences in plant equipment, operating experience, and mode of operation. The upper limits of release are established in the Commission's regulations 10 CFR Part 20 and in the Technical Specifications for the Oconee Nuclear Station. Operation of the Radwaste System must also comply with the provisions of 10 CFR Part 50, e.g., that the release of radioactive material and the exposure potential will be as low as practicable.

The liquid waste effluents will be mixed with the water flowing at an annual average rate of 1100 cubic feet per second (cfs) from the Keowee Reservoir through the tailrace of the hydroelectric station. The diluted effluent will flow from the tailrace to the Keowee river (1457 cfs) which, with other tributaries, will flow into the Hartwell Reservoir (4400 cfs). Two significant intakes for water supplies to population centers are located on the Keowee River (Clemson-Pendleton) and on the Hartwell Reservoir (Anderson).

The gaseous radwaste effluent is released from vents located about 200 feet above grade on the containment buildings. Dilution of the gaseous effluent will occur by diffusion and turbulent mixing as the plumes are carried by the winds. About 700,000 people are located within 50 miles of the Oconee Station. (See Table V-3.)

Estimates have been made of the exposure of persons to radiation from the Oconee Nuclear Station. The radiation dose estimates are based upon the postulated release of radioactive material, presented in Table III-4, the population distribution, the various dispersion modes applicable for the area, and the normal activities which determine the degree of intake or exposure by the individuals. (Specific data on meteorology, hydrology, and population distribution are presented in Sections III. C. 1, II. E. 2 and III. E. 3 of this Statement.) External exposure modes considered were the direct exposure from passing effluent clouds and from submersion in water (swimming). Internal exposure modes considered were those from ingesting food and water affected by the effluents and from breathing air containing effluents.

The results of the radiation dose estimates are presented in Table V-2 as annual averages to individuals at various locations. The cumulative population, cumulative population dose, and average dose from gaseous effluents (noble gases) for various radial distances from the Oconee Station are presented in Table V-3. The dose to the approximately 30,000 people who may get their drinking water from the Hartwell Reservoir is estimated to be 12 man-rem. Because very little commercial fishing is practiced from the Reservoir, the dose to the population by this pathway is estimated to be relatively small. For comparative purposes, the annual average radiation dose to individuals in the area from natural "background" sources is about 100 millirems and the annual dose to the same population who may get their drinking water from Hartwell Reservoir is about 3000 man-rem from natural sources.

The applicant began pre-operational environmental monitoring surveys in early 1969 to determine background levels of radioactivity in the area of the Oconee Station. Samples of water, air, rain, settled dust, silt, vegetation, algae and plankton, fish, milk, and animals have been analyzed. The analyses were for gross alpha and beta activities, gamma spectra, H-3, Sr-90, Cs-137 in milk, water, fish, and animals. The applicant proposed post-operational survey program is basically a continuation of the preoperational program and is presented in Table V-4.

The conclusion to be drawn from the above analysis is that the applicant has designed the radwaste system to assure releases of radioactive materials will be well below the limits of 10 CFR 20 and the radwaste equipment will be operated in a manner such that the releases to the environs will be as low as practicable in accord with 10 CFR Part 50. There will be no detectable adverse environmental effects associated with the release of relatively small quantities of radioactive materials from this plant.

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